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34th International Workshop on Vertex Detectors
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Europe/Zurich
Stoos Lodge, Stoos, Swtizerland
Anna Macchiolo
(University of Zurich (CH)),
Lea Michaela Caminada
(Paul Scherrer Institute (CH)),
Florencia Canelli
(University of Zurich (CH)),
Ben Kilminster
(University of Zurich (CH)),
Stefanos Leontsinis
(University of Zurich (CH)),
Malte Backhaus
(ETH Zurich (CH)),
Rainer Wallny
(ETH Zurich (CH))
Description
The 34th International Workshop on Vertex Detectors is organised by the UZH, PSI, ETH in Stoos, Switzerland.
The annual series of the International Workshop on Vertex Detectors (VERTEX) is an international forum with the aim of reviewing the recent, the ongoing, and the future activities on silicon based vertex detectors, covering a wide range of topics: existing and future detectors, new detector developments, radiation hardness, simulation, tracking and alignment performance, electronics, triggering, applications to medical and other fields.
The Workshop will start on Monday at 12 am and will finish on Friday at 14 pm.
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Registration
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IntroductionConvener: Giacomo Sguazzoni (INFN (IT))
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Future directions of particle physics at acceleratorsSpeaker: Michele Selvaggi (CERN)
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Status Report of the DRD3 Collaboration on Solid-State Detector Technologies
The DRD3 Collaboration is the CERN-hosted framework that coordinates the worldwide R&D effort on semiconductor detectors for future HEP experiments. DRD3 pursues the strategic developments outlined in the ECFA Detector R&D Roadmap. This contribution will report on the latest activities within the collaboration's four strategic research lines: monolithic sensors, hybrid sensors, extreme radiation tolerance (covering both radiation-induced damage and wide-bandgap semiconductors), and integration and interconnection technologies. In addition, recent progress in the transversal research areas underpinning these strategic lines — simulation and characterization — will be presented. A separate mention will be given on the status of the collaboration's outreach and training activities.
Speaker: Prof. Ivan Vila Alvarez (Instituto de Física de Cantabria (CSIC-UC)) -
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Vertex reconstruction at the LHC experiments and new developments
The identification of primary collision vertices and secondary decay vertices are important parts of event reconstruction for LHC experiments.
Challenges and solutions are evolving with increasing pile-up and data volumes.
The talk will review the latest developments at CMS, ATLAS and LHCb.
New possibilities are opened by the addition of precision timing.Speaker: Wolfram Erdmann (Paul Scherrer Institute (CH))
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15:15
Coffee break
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Operational experience on current detectorsConvener: Giacomo Sguazzoni (INFN (IT))
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Lessons learned from the CMS Pixel and Strip Detector operation in Phase-1
The CMS Silicon Pixel and Strip detectors have been central to charged-particle tracking since the beginning of LHC operations in Run 1, and, in their Phase-1 configuration, throughout Run 2 and Run 3 under progressively more demanding conditions of luminosity, pileup, and radiation. This talk presents a comprehensive overview of the operational experience accumulated throughout Phase-1, highlighting key lessons learned from more than a decade of detector operation and the collection of several hundred inverse femtobarns of data. We review the evolution of detector performance as a function of increasing integrated luminosity, with particular emphasis on the cumulative effects of radiation damage on silicon sensors and front-end electronics. While the pixel detector was replaced in 2017, both pixel and strip systems have operated over extended periods in an environment of sustained high radiation, making the CMS tracker one of the most extensively irradiated silicon detector systems ever deployed. Strategies developed to mitigate performance degradation—including advanced calibration workflows, alignment procedures, and continuous data-quality monitoring—have enabled the tracker to maintain excellent tracking and vertexing performance throughout its lifetime. Operational challenges such as detector aging, cooling and power stability, and maintenance interventions are discussed, together with the solutions implemented to ensure reliable data-taking up to the end of operations. With the end of Run 3 marking the completion of LHC-era operations for the current CMS tracker, and the transition to Long Shutdown 3 (LS3), these results provide a unique and comprehensive view of silicon detector performance over its full lifetime. This guides the design and operation of future tracking systems for the HL-LHC.
Speaker: Davide Zuolo (University of Colorado - Boulder (US)) -
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Lessons learned from the ATLAS Pixel, SCT and TRT Detectors operation in Phase-1
After more than 15 years of operation, the ATLAS Inner Detector (ID) will take its final data this June before being replaced with a new all-silicon detector (ITk) during LHC Long Shutdown 3. The ID, consisting of a Pixel detector, a strip detector (SCT), and a straw tube detector (TRT), successfully collected data during LHC runs 1-3, under conditions that exceeded the original specifications by a large factor. Over the years, the ID faced a number of technical and operational challenges, particularly in terms of radiation damage, occupancy, and trigger rate. This talk will describe the main issues encountered and the solutions that were found to ensure highest data quality and smooth operation throughout the lifetime of the detector. The lessons learned from the ATLAS Inner Detector can provide valuable guidance for the design and operation of future experiments.
Speaker: Martin Kocian (SLAC National Accelerator Laboratory (US)) -
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Operation and performance of the ALICE Inner Tracking System
The ALICE Inner Tracking System (ITS) is responsible for vertex reconstruction and charged particle tracking in the vicinity of the interaction point. The current ITS2 was installed during the LHC Long Shutdown 2 (2018-2022) and is completely based on the Monolithic Active Pixel silicon Sensor (MAPS). It has an active surface of 10 m2 with nearly 12.5 billion pixels, thus representing the largest application of MAPS. The ITS2 is composed of seven concentric layers equipped with the ALPIDE chip, a sensor implemented in a 180 nm CMOS technology, designed specifically for the ALICE ITS2.
ITS2 has an enhanced tracking performance in terms of impact-parameter resolution and efficiency at low transverse momentum during Pb-Pb collisions at interaction rates of up to 50 kHz. This is achieved through its increased granularity (pixel pitch of 27×29 μm2), low material budget of 0.36% X0 per layer for the three innermost layers, and the placement of the first layer at a radial distance of 23 mm from the interaction point.
This contribution will give an overview of ITS2 operational experience during LHC Run 3 (2022-2026), with a particular focus on detector calibration and tracking performance, including operational insights as beam background effects, investigations on data reconstruction for readout frames of variable timing/length and exploratory studies on energy-loss measurements, from which the development of future detectors as ITS3 and ALICE 3 will profit.
Speaker: Anna Villani (Universita e INFN Trieste (IT)) -
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Operation and Radiation Damage of the LHCb Upgrade I VELO
The LHCb (Large Hadron Collider Beauty) detector is a machine dedicated to precision measurements of heavy flavour physics, CP (Charge Parity) violation, exotic spectroscopy, and rare decays. The VELO (VErtex LOcator) was completely redesigned for operation in the increased luminosity and radiation targets in Runs III and IV at the LHC - with an expected fluence of up to $8\times 10^{15}$ MeV neq/cm$^2$ by the end of Run IV. The original strip detector was replaced with a new 55 µm pitch pixel detector, with a hybrid-pixel design using a 130 nm CMOS process. The Upgrade I VELO was installed and commissioned in 2022, and has since received a fluence dose of $O(10^{15})$ MeV neq/cm$^2$ in its most inner regions; recording 5 times more integrated luminosity than in Run I and II. This contribution will present new results on the operational characteristics of the Upgrade I VELO after 3 years of operation, with a focus on demonstrating performance through hit efficiency, impact parameter resolution and detector occupancy. Alongside this, novel techniques for characterising radiation damage with the digital readout will be presented showcasing through life performance of the detector. These novel results will support detector development as we reach the next radiation and luminosity frontiers in high energy physics.
Speaker: David Vico Benet (University of Oxford (GB))
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5
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Reception at Fronalpstock
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Operational experience on current detectorsConvener: Rainer Wallny (ETH Zurich (CH))
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Operational experience and performance of the Belle II Vertex Detector after the first long shutdown
The Belle II vertex detector consists of an inner two-layer pixel detector (PXD2) and an outer four-layer double-sided silicon-strip detector (SVD).
In 2024 the Belle II experiment resumed data taking after its Long Shutdown 1, which was required to install PXD2 and upgrade components of the SuperKEKB accelerator. We describe the challenges of this upgrade and report on the operational experience during the subsequent data taking. With new data, the SVD confirmed high hit efficiency, large signal-to-noise and good cluster-position resolution. Operation of PXD2 has been limited because it had to be turned off as a precautionary measure for much of the data taking. Once the stability of the SuperKEKB beams improve the PXD will resume operation. Details of the performance of SVD and PXD2 will be shown. In addition, for the SVD, we present studies that show a moderate radiation-induced increase in sensor current and strip noise. However, such damage will not degrade the performance during the lifespan of the detector.Speaker: Kookhyun Kang (Kyungpook National University) -
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Status of the LHCb Upstream Tracker
The Upstream Tracker (UT) is a silicon strip detector of the LHCb experiment and a key component of the upgraded LHCb tracking system. Located upstream of the dipole magnet, the UT provides precise position measurements that improve track reconstruction efficiency, momentum determination, and enable the reconstruction of downstream tracks originating from long-lived particles.
Following its installation and commissioning for LHC Run 3, the detector has been operating successfully under the significantly increased luminosity conditions of the upgraded experiment. This contribution presents an overview of the commissioning activities, detector calibration procedures, and operational experience accumulated during Run 3. The performance of the detector is discussed in terms of data quality and operational reliability.
The excellent performance of the Upstream Tracker has contributed significantly to the LHCb physics program during Run 3. Lessons learned from detector operation and maintenance will be presented, together with perspectives for Upgrade II phase for LHCb, in particular the proposed Upstream Pixel Tracker.
Speaker: Basem Khanji (Syracuse University (US))
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Detectors in design and constructionConvener: Rainer Wallny (ETH Zurich (CH))
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Design and construction of the CMS Inner Tracker for the Phase-2 Upgrade
The CMS Inner Tracker (IT) is a central element of the Phase-2 upgrade, designed to sustain and extend tracking performance in the extreme conditions of the High-Luminosity LHC. It will replace the current pixel detector with a new system featuring increased granularity, enhanced radiation tolerance, and extended geometrical coverage, ensuring excellent vertexing and impact parameter resolution at unprecedented particle densities. This talk presents the design and construction of the Inner Tracker, focusing on advances in pixel sensor technology, front-end electronics, and low-mass mechanical structures. The detector is optimized to cope with the high radiation levels and occupancies expected at the HL-LHC, while maintaining precise spatial resolution and fast readout capabilities. We discuss the large-scale production of pixel modules, including assembly procedures, quality assurance protocols, and results from extensive laboratory measurements and beam tests. Integration aspects such as powering, cooling, and services routing are addressed, together with the challenges of assembling and validating complex detector substructures within tight mechanical and thermal constraints. As the experiment transitions through Long Shutdown 3 (LS3), the Inner Tracker construction is entering its final phase. The readiness of detector components and integration efforts will be reviewed, outlining the path toward installation and commissioning for HL-LHC operations.
Speaker: Giacomo Sguazzoni (INFN (IT)) -
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Design and construction of the ATLAS ITk Pixel Detector
Starting this year, the Large Hadron Collider will undergo a high-luminosity upgrade. For the ATLAS detector, the instantaneous luminosity is expected to reach unprecedented values, resulting in up to 200 proton-proton interactions in a typical bunch crossing. To cope with the resulting increase in occupancy, bandwidth and radiation damage, the current Inner Detector will be replaced by an all-silicon Inner Tracker (ITk). The innermost part of the ITk will consist of a pixel detector, with an active area of about 13 m^2. To deal with the changing requirements in terms of radiation hardness, power dissipation and production yield, several silicon sensor technologies will be employed in the five barrel and endcap layers. As a timeline, it is facing the production of components: sensor, building modules, mechanical structures and services. The pixel modules assembled with RD53 readout chips have been built to evaluate their production rate. Irradiation campaigns were done to evaluate their thermal and electrical performance before and after irradiation. A new serial powering scheme will be employed for the first time in the ITk pixel detector, helping to reduce the material budget of the detector as well as power dissipation. This contribution presents design and construction of the ITk-pixel project, updates on the status by focusing on the lessons learned and the biggest challenges towards production, and summarises the latest results on closest-to-real demonstrators built using module, electric and cooling services prototypes.
Speaker: Denise Muller (Universitaet Siegen (DE))
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10:20
Coffee break
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Detectors in design and constructionConvener: Stefanos Leontsinis (University of Zurich (CH))
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Construction of the ATLAS ITk strip detector for the HL-LHC era
The current inner detector of the ATLAS experiment was designed to operate under the conditions of the Large Hadron Collider (LHC). In the forthcoming High-Luminosity LHC (HL-LHC) era, particle densities and radiation levels will increase by approximately an order of magnitude. The instantaneous luminosity is expected to reach unprecedented levels of $7 \times 10^{34}\,\mathrm{cm^{-2}\,s^{-1}}$, resulting in up to 200 proton-proton interactions per bunch crossing. These conditions impose stringent requirements on the tracking detector upgrade. The new system must provide faster readout and significantly higher granularity, while maintaining robust performance in a harsh radiation environment. At the same time, increased power delivery to the front-end electronics is required, without introducing excess material that would degrade tracking performance. To meet these challenges, the ATLAS experiment will replace its current inner detector with an all-silicon Inner Tracker (ITk) of extended coverage. The ITk comprises multiple layers of silicon sensors: pixel detectors in the innermost region, surrounded by a large-area strip detector. The ITk strip detector consists of four layers in the central tracker region (barrel) and six disks in each endcap region, covering a pseudorapidity range of $|\eta| < 2.7$. Silicon sensors, front-end ASICs, and power distribution are integrated into silicon strip modules mounted on lightweight support structures (staves and petals), which also provide common electrical, optical, and cooling services. The 256-channel ABCStar ASIC performs front-end readout of silicon strip signals. The scale of this upgrade is substantial, requiring the assembly of approximately 11,000 silicon strip modules in the barrel and 7,000 modules in the endcap regions. An overview of the ITk strip detector and its underlying technologies is provided. Current production status, performance results, and integration plans are presented, together with challenges encountered during pre-production and early production and their successful resolution, paving the way for large-scale international production.
Speaker: Botho Paschen (Lawrence Berkeley National Lab. (US)) -
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Design and construction of the CMS Outer Tracker for the Phase-2 Upgrade
The CMS Outer Tracker (OT) extends precision tracking to large radii while introducing novel capabilities for real-time data reduction at the hardware trigger level, a key requirement for operation at the High-Luminosity LHC. Designed to operate in an environment of extreme occupancies and radiation, the OT combines radiation-hard silicon strip and macro-pixel sensors with innovative module concepts, enabling on-detector transverse momentum discrimination. This talk describes the design and construction of the Outer Tracker, with emphasis on the development of pT-modules, front-end electronics, and high-speed readout architectures. The mechanical design, based on lightweight and thermally efficient support structures, ensures detector stability and precise alignment over large volumes while minimizing material budget. We present the status of module production and large-scale assembly, including quality control strategies and results from system-level tests and integration campaigns. Particular attention is given to the challenges associated with mass production, logistics, and the integration of detector elements into complex substructures. As CMS progresses through Long Shutdown 3 (LS3), the Outer Tracker construction and integration activities are advancing toward completion. The detector readiness and expected performance, including its impact on tracking and trigger capabilities, are discussed in the context of the demanding HL-LHC operating conditions.
Speaker: Suman Chatterjee (Deutsches Elektronen-Synchrotron (DE)) -
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Upgrade of the Belle II vertex detector with depleted monolithic CMOS active pixel sensors
The Belle II experiment currently records data at the SuperKEKB $e^+e^-$ collider, which holds the world luminosity record of $5.2\times10^{34}$ $\textrm{cm}^{-2}$ $\textrm{s}^{-1}$ and plans to push up to $6\times10^{35}$ $\textrm{cm}^{-2}$ $\textrm{s}^{-1}$, after an upgrade of its interaction region. To cope with the increased backgrounds, a new fully pixelated vertex detector (VTX) is under design. Spanning from 14 mm to 140 mm from the interaction point, its 5 layers will be instrumented with the same DMAPS, OBELIX, recently submitted for fabrication. The OBELIX sensor is designed in the Tower 180 nm technology, inheriting the pixel matrix from the TJ-Monopix2 sensor, whose characterization has focused on its performance after irradiation with integrated fluences up to the expected $5\times10^{14}$ $1$ $\textrm{MeV}$ $\textrm{n}_\textrm{eq}$ $\textrm{cm}^{-2}$. The new sensor features a 33 µm pitch with a 7-bit Time-Over-Threshold digitization. The new read-out architecture has been designed to support triggered operation and additional features needed for improving time-stamping and contributing to Belle II track triggering. The specifications require the detector to sustain a maximum average hit rate of $120$ $\textrm{MHz}$ $\textrm{cm}^{-2}$, while keeping an overall material budget lower than 3% X0. To meet this target, a light mechanical structure has been pursued, with two different approaches. The ladders of the 2 innermost layers are cut out directly from the processed wafers and connected with a post-process redistributed metal layer. Passive cooling using a thin layer of high-conductance material (TPG) beneath the sensors and connected to actively cooled blocks has been chosen. The post-irradiation performance of TPG was recently validated. The 3 outermost layers, instead, are composed of staggered ladders, realized with a light carbon fibre structure supporting a liquid-cooled plate in contact with the sensors connected to a flex printed cable. This contribution will review the status of the development of the sensor and the detection modules.
Speaker: Guglielmo Francesco Benfratello (Istituto Nazionale di Fisica Nucleare) -
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ITS3, a truly cylindrical MAPS tracker for the ALICE Experiment
During LHC Long Shutdown 3, the ALICE Experiment will replace its innermost tracking layers with a novel, truly cylindrical pixel tracker (ITS3). The detector will consist of three layers of low power ($40\, \mathrm{mW/cm}^2$) Monolithic Active Pixel Sensors (MAPS) thinned to the point of flexibility ($50\,\mathrm{\mu m}$). By bending these sensors into half-cylinders around the beam pipe, the design gains inherent mechanical stability; this enables the use of air cooling and a minimal mechanical support structure of carbon foam, reducing the material budget to an unprecedented value of approximately $0.09\%\,\mathrm{X_0}$ per layer.
To achieve this, stitched, wafer-scale sensors for each half-layer were developed. The sensors feature between 30 and 50 million pixels ($20.8\,\times\,22.8\,\mathrm{\mu m^2}$), a length of 26.6 cm and a width of up to 9.8 cm, covering 180 degrees of the azimuth and the full longitudinal extent of the tracking layers. The final prototype sensor, MOSAIX, features 12 "repeated sensor units" interconnecting common power and data transmission lines by stitching on silicon, which in traditional detector designs are added externally, again reducing material budget.
Initial tests of the MOSAIX Engineering Run 2 (ER2), conducted both at the wafer level and on bonded chips, show very promising results regarding both the yield of the stitched sensors and their core functionality. A comprehensive testing program is currently underway to verify the full chip functionality and characterise its efficiency, spatial resolution, and radiation hardness. Concurrently, the mechanical integration procedures are being qualified using full-scale engineering models with bent silicon. This presentation provides an overview of the ITS3 project, details the MOSAIX architecture, and reports on the latest performance results and integration progress.
Speaker: Markus Keil (CERN)
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12:10
Lunch
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Detectors in design and constructionConvener: Koji Nakamura (KEK High Energy Accelerator Research Organization (JP))
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The LHCb Mighty Tracker Upgrade for the HL-LHC Era
The LHCb experiment is a forward spectrometer dedicated to precision measurements of heavy-flavour hadron decays, enabling sensitive probes of physics beyond the Standard Model through studies of CP violation, rare decays, and searches for new weakly coupled particles. In the High-Luminosity LHC era, the experiment aims to collect an integrated luminosity of approximately 300 fb$^{-1}$ at instantaneous luminosities $1.5 \times 10^{34} cm^{-2} s^{-1}$, imposing stringent requirements on detector performance, radiation tolerance, and data throughput.
To address these challenges, the LHCb tracking system will be replaced during Long Shutdown 4 (2034-35) as part of Upgrade II by the Mighty Tracker. This hybrid system combines an upgraded Scintillating Fibre (SciFi) tracker in the outer regions with a high-granularity silicon pixel detector, the Mighty Pixel, in the innermost acceptance. The upgraded SciFi detector employs microlens-enhanced silicon photomultipliers together with cryogenic liquid-nitrogen cooling to improve light collection efficiency and mitigate radiation-induced noise. Mighty Pixel is based on High-Voltage Monolithic Active Pixel Sensor technology implemented in commercial CMOS processes, delivering excellent spatial and timing resolution ($< 3 ns$) in the harsh HL-LHC environment while enabling robust tracking and pile-up mitigation. A key challenge is the integration of pixel detector modules into serial power chains on ultra-light support structures, requiring careful optimisation of mechanical integration, powering, cooling, and grounding.
This contribution presents the design and ongoing R&D activities of the Mighty Tracker detector systems towards the Technical Design Report, highlighting the technological developments required for efficient operation in the HL-LHC environment.
Speaker: Atanu Modak (Science and Technology Facilities Council STFC (GB)) -
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MAPS-based Upstream Pixel Tracker for LHCb upgrade II
The LHCb Upstream Tracker (UT), a silicon micro-strip detector introduced during Upgrade I and operational since Run 3 of the Large Hadron ollider, is a key component for track reconstruction and ghost track suppression.
Looking ahead, LHCb Upgrade II is scheduled for the LHC Long Shutdown 4, with the goal of fully exploiting both the flavour physics programme and the heavy-ion physics potential, including central heavy-ion collisions, at the High-Luminosity LHC. The substantially increased luminosity
will result in significantly higher occupancies, pile-up, and radiation levels, exceeding the capabilities of the current UT.
To address these challenges, a new Upstream Pixel Tracker (UP) based on Monolithic Active Pixel Sensors (MAPS) is under development. The detector is required to operate at maximum hit rates up to 80 MHz/cm², withstand radiation levels up to 3×1015 neq cm−2 and about 190 MRad total
ionizing dose, and deliver high in-time efficiency (>99% within 25 ns).
This talk will present the MAPS-based UP concept and the latest developments of the detector, together with key results from performance studies, including tracking performance. It will also discuss ongoing work on module and stave optimisation, prototyping, and future developments toward the Technical Design Report.Speaker: Carolina Arata (Université Paris-Saclay (FR)) -
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Sensor and Module Development and Construction of the CBM Micro Vertex Detector
The Micro Vertex Detector (MVD) is the first downstream detector of the fixed-target CBM experiment at the future Facility for Antiproton and Ion Research (FAIR). It extends the high-precision tracking towards low momenta in direct proximity of the target with the first station being placed 8cm downstream the interaction point. The four planar stations operate in the target vacuum and are equipped with $\sim$300 MIMOSIS CMOS Monolithic Active Pixel Sensors (MAPS) which have been developed in a joint R&D effort by IPHC Strasbourg, Goethe University Frankfurt and GSI Darmstadt. MIMOSIS is produced in the TJ-180nm process and features a $1024\times504$ pixel matrix with a global shutter ($5\mu$s frame time). A large variety of different designs have been tested, e.g. standard and modified pixel variants, two epitaxial options (25/50$\mu$m), and AC and DC-coupled front-ends. The performance has been validated both for radiation tolerance (5Mrad and 1$\times$10$^{14}n_{\text{eq}}$/cm$^2$), and for its full-system compatibility (e.g. realistic powering and data transport). Its free-streaming DAQ compatibility has been validated in the mCBM@SIS-18 test setup with a first system-level prototype (mMVD).
In the MVD, the sensors will be wire-bonded to thin flex cables and glued onto Thermal Pyrolytic Graphite (TPG; 380$\mu$m) carriers, which provide stiff, low-$X_0$ support with a high in-plane thermal conduction ($\sim$1500 W/m.K) in the acceptance. Actively cooled heat sinks outside the acceptance extract the heat. Sensors are integrated double-sided, achieving a 100% fill factor.
With the final MIMOSIS expected end of 2026 and module pre-production ongoing with prototype sensors, we are preparing the full-system integration. In this contribution, we present the detector concept, results from the prototype MIMOSIS sensors and its integration into the Micro Vertex Detector. A focal point will be the challenges associated with the stringent material budget constraints (0.3-0.5%$X_0$) and vacuum operation as we progress toward CBM commissioning end of 2028.
Speaker: Franz Matejcek (Goethe-Universität Frankfurt, Institut für Kernphysik) -
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Developments towards the ALICE 3 Inner Tracker
ALICE 3 is pursued as the next-generation heavy-ion detector for LHC Run 5. Its design is driven by the need to achieve unprecedented vertexing performance, tracking over a wide range of transverse momenta combined with good particle identification over an extended pseudorapidity range. In order to achieve a pointing resolution better than 10 µm for transverse momenta of 200 MeV/c, three layers of monolithic pixel sensors with a position resolution of 2.5 µm and a material budget of 0.1% of a radiation length per layer will be installed in a secondary vacuum within the beam pipe. The proximity to the interaction point poses an important challenge in terms of particle hit rate and in turn bandwidth and radiation load. The vertex detector will be surrounded by tracking layers and disks. Particular effort has to be made to achieve spatial and temporal resolution, without exceeding a material budget of ~1% of a radiation length per layer throughout the detector acceptance to achieve the required momentum resolution.
This presentation discusses the design considerations for the Inner Tracker, reviews the performance studies and presents the R&D activities towards the ALICE 3 Inner Tracker.Speaker: Andrea Sofia Triolo (CERN) -
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Development of the MAPS-based inner tracker for the Super Tau-Charm Facility
The proposed Super Tau-Charm Facility (STCF) is a next generation high-luminosity $e^+e^-$ collider with a designed peak luminosity exceeding $0.5\times{10}^{35}cm^{-2}s^{-1}$. Its inner tracker is required to operate under high-rate and high-background conditions while maintaining an ultra-low material budget. MAPS is considered a promising technology for the STCF inner tracker (ITKM), which is designed with four layers of staves targeting a material budget of about 0.3% $X_0$ per layer. To meet the specific requirements of the STCF, a series of monolithic sensors, CharTPix, is being developed to simultaneously achieve low power consumption (~$50 mW/cm^2$), ~20 ns time resolution, energy deposition measurement capability, and good spatial resolution. The concept and specifications of the STCF ITKM, together with its recent R&D progress, are presented, with a focus on the design and characterization of the CharTPix prototypes.
Speaker: Ruiyang Zhang (USTC)
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17
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15:10
Coffee break
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Detectors in design and constructionConvener: Danek Kotlinski (Paul Scherrer Institute (CH))
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Mu3e Pixel Tracker: Construction & Performance Studies
Mu3e is an experiment currently under construction at PSI, designed to search for the charged lepton flavour violating decay µ⁺ → e⁺e⁻e⁺. It will make use of the πE5 intense DC surface muon beam of 10⁸ µ⁺/s to reach a sensitivity of 2 × 10⁻¹⁵. The nature of this decay imposes strict requirements on the detector system, especially concerning design compactness, material budget, efficiency and time resolution. This can be achieved only by implementing depleted Monolithic Active Pixel Sensors (dMAPS) in the Pixel Tracker, ultra-thin Aluminum-Kapton HDIs for the services and mechanical support, and several other technical features. A first version of the Vertex detector, the two innermost layers of the tracking system, has been produced and operated in 2025 at πE5 experimental conditions and with the design DAQ system. This campaign successfully validated many key features and proved the integration of the Pixel Tracker with the high-intensity muon beamline under a 1 T magnetic field. These results represent a major milestone towards readiness for Phase I measurements. This contribution will cover the experimental design, the sensor qualification and the first results from the recent commissioning run campaign at PSI, along with the perspectives for the next data taking campaigns.
Speaker: Luigi Vigani (Heidelberg University (DE)) -
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The NA62 Gigatracker and 4D track reconstruction
The GigaTracKer is a hybrid silicon pixel detector of the fixed-target experiment NA62 at the CERN SPS that aims to precisely measure the branching ratio of the very rare $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ decay. The detector was designed to provide measurements of the momentum, direction, and time of beam particles arriving at a rate of 750 MHz. The tracking system consists of four stations installed in vacuum ($\sim10^{-6}$ mbar), $60.8 \times 27\ \text{mm}^2$ each, with a total material budget of less than 2$\%$ X$_0$. Each station is cooled with a microchannel cooling plate used for the first time in a high-energy physics experiment. The beam particles are tracked in four dimensions using time-stamping pixels ($300\times300\ \mu \text{m}^{2}$) with a single-hit time resolution of 115 ps. This performance must be maintained despite the beam irradiation that amounts to $4.5 \times 10^{14}$ 1 MeV neutron equivalent yearly fluence (integrated over a data taking period of 200 days). The detector has been fully operational since 2016. We describe the GigaTracKer design, performance, and developed 4D track reconstruction algorithms.
Speaker: Alina Kleimenova (EPFL - Ecole Polytechnique Federale Lausanne (CH)) -
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The ATAR, a dense and compact vertex detector for the PIONEER experiment
PIONEER is an approved experiment at the Paul-Scherrer-Institute (PSI) that aims to measure the charged-pion branching ratio to electrons vs. muons with an accuracy of $0.01\,\%$. This is an order of magnitude improvement in precision compared to its predecessors and approaches the accuracy of the theoretical calculation. The key elements of PIONEER are a high resolution calorimeter built concentrically around the high granularity active target (ATAR).
The ATAR is composed of a stack of 48 low gain avalanche strip detectors (LGADs) to stop the beam pions and provide detailed information of the event topology. This will include precise timing (in the order of $200\,$ps), spatial information (to an accuracy of about $60\,\mu$m) and pulse height information with a high dynamic range to separate pion stops from muons and MIPs. In order not to affect the energy measurement of the positrons, the readout electronics is placed outside the acceptance angle of the calorimeter. It is composed of a fast amplifier and a fast sampling chip digitizing the LGAD signal for real time analysis.
The paper describes the PIONEER-experiment with focus on the ATAR and its readout. The status of the development and this year’s activities will be reported.
Speaker: Tilman Rohe (Paul Scherrer Institute (CH)) -
25
Precision Timing with the CMS MIP Timing Detector for High-Luminosity LHC
To cope with the challenging environment of the High-Luminosity Large Hadron Collider (HL-LHC), the CMS Experiment is being upgraded to include the new MIP Timing Detector (MTD). The MTD is designed to mitigate pileup effects by providing time measurements of charged particles with a resolution better than 50 ps. The barrel section of the MTD, the Barrel Timing Layer (BTL), covering a pseudorapidity region of η < 1.5, consists of approximately 166,000 scintillating LYSO:Ce crystals coupled to silicon photomultipliers (SiPMs) and readout with a custom TOFHIR ASIC. The Endcap Timing Layer (ETL), covering the pseudorapidity region 1.6 < η < 3, will utilize low-gain avalanche diodes (LGADs), a novel silicon-based technology, read out by a custom-designed ASIC called ETROC. This presentation will provide an overview of the MTD design, focusing on module and sensor performance, and will present the overall project status and recent achievements.
Speaker: Irene Dutta (Fermi National Accelerator Lab. (US)) -
26
Design and Construction of the ATLAS High-Granularity Timing Detector
The HGTD is a novel detector introduced by ATLAS to augment the new all-silicon Inner Tracker (ITk) in the pseudorapidity range from 2.4 to 4.0, adding the capability to measure charged-particle trajectories in time as well as space. Two double-sided layers of silicon sensors will provide precision timing information for charged particles with a resolution as good as 30 ps per track to help assign each particle to the correct vertex, recovering the ATLAS reconstruction performance at HL-LHC, enhancing the experiment’s pile-up rejection and providing bunch-by-bunch luminosity measurements. Readout cells have a size of 1.3mm x 1.3 mm, leading to a highly granular detector with ~3.7 million channels. Low-Gain Avalanche Detectors (LGAD) technology has been chosen as it provides enough gain to reach the large signal over noise ratio needed. The requirements and overall specifications of the HGTD will be presented as well as the technical design and the project status. The R&D efforts on the detector components and construction, supported by laboratory and test beam results, will also be presented.
Speaker: Annika Stein (Johannes Gutenberg Universitaet Mainz (DE))
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22
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Poster session
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27
Integration of the LIGHT01 ASIC with Ti-LGADs: a pixel detector demonstrator for precision timing
LIGHT01 is a prototype pixel readout ASIC developed in 28 nm CMOS to investigate precision timing with highly segmented LGAD-based sensors for future 4D tracking detectors. This work presents the integration of the LIGHT01 chip with trench-isolated LGADs (Ti-LGADs), forming the first LIGHT01 detector demonstrator, and discusses the main challenges encountered during assembly and early characterization.
The demonstrator combines the 8 × 8 LIGHT01 pixel matrix with small-pitch Ti-LGAD sensors, aiming to preserve the timing performance of LGAD technology while addressing the constraints of fine segmentation, sensor-to-ASIC coupling, and scalable hybrid integration. Particular attention is given to bump-bonding requirements, parasitic input capacitance, channel uniformity, threshold tuning, noise behavior, and the operation of a fast front-end coupled to per-pixel timing circuitry.
First laboratory measurements confirm the functionality of the readout chain and provide an initial assessment of the hybrid system response using electrical calibration. These results represent an important step toward validating LIGHT01 as a detector demonstrator and preparing future beam-test campaigns, where timing performance, time-walk correction, and spatially resolved response of TI-LGAD pixels will be studied in detail.
Speaker: Abderrahmane Ghimouz (Paul Scherrer Institute (CH)) -
28
DAQTRS: A Modular ATX-Based Data Acquisition and Control Platform for Experimental Systems
DAQTRS is a flexible and scalable data acquisition and control platform designed to streamline the development of detector readout and instrumentation systems. It integrates hardware, software, middleware and firmware into a unified framework that minimizes development effort while ensuring robustness and reliability. The system is built around the Enclustra system-on-module ecosystem and follows the ATX computer specification, enabling modularity and ease of integration. It supports multiple PCI Express slots for custom expansion cards, allowing seamless interfacing with a wide range of detectors and control systems. Standard communication interfaces, including Gigabit Ethernet, SFP+, UART, JTAG, and beam interfaces, are provided to support diverse experimental requirements. DAQTRS is well suited for detector testing and characterization, as well as small- to medium-scale experimental setups, offering a versatile platform adaptable to evolving research needs.
Speaker: Aliakbar Ebrahimi (University of Zurich (CH)) -
29
Quality Control of the Phase-2 CMS Inner Tracker Modules for the HL-LHC
The Phase-2 upgrade of the CMS experiment at the LHC foresees a complete replacement of the Inner Tracker to cope with the harsh operating conditions of the High-Luminosity LHC, including unprecedented radiation levels and pileup. The performance and long-term reliability of the upgraded tracking system critically depend on the quality of its detector modules, making an extensive and systematic quality control (QC) program essential during large-scale production.
We present the current status of the quality control procedures for the Phase-2 CMS Inner Tracker modules. The QC workflow covers all production stages, from individual component verification to full module characterization, and combines electrical, mechanical, and functional tests. Key measurements include sensor and front-end electronics validation, high-voltage behavior, noise and gain characterization, as well as checks of module assembly integrity and environmental stability.
An overview of the testing infrastructure, data acquisition systems, and analysis tools used in the QC process is provided, together with a summary of the results obtained so far. Correlations between different QC measurements are discussed, with the aim of enabling early defect identification and efficient feedback to production sites.
Finally, the effectiveness of the current QC strategy in providing timely and valuable input for optimizing module production and ensuring the required performance of the CMS Inner Tracker is evaluated.
Speaker: Amrutha Samalan (Paul Scherrer Institute (CH)) -
30
Spatial distribution of displacement damage in silicon diodes under neutron and high-energy proton irradiation
Radiation-induced displacement damage in silicon sensors critically affects detector performance in high-energy physics experiments, in particular through increased leakage current and charge carrier trapping. Understanding the spatial distribution and nature of defect production is therefore essential for the development of radiation-tolerant detector structures.
In this work, abrupt n$^{++}$/p$^{+}$ silicon diode geometries with total thicknesses of $250~\mu\mathrm{m}$ and $525~\mu\mathrm{m}$ are studied using Geant4 simulations. The structures include a highly doped n$^{++}$ layer ($\sim 1 \mu{\rm m}$, phosphorus up to $5 \times 10^{18}\,\text{cm}^{-3}$) and boron-doped p$^{+}$ substrates representative of two experimental sample types. Irradiation scenarios corresponding to 1 MeV neutrons (TRIGA-like) and 24 GeV protons (CERN-like) are considered. A dedicated analysis framework is implemented to extract recoil information and construct voxelized damage maps based on an NRT formalism, providing an estimate of the spatial distribution of primary displacement damage. Depth-dependent NRT profiles, voxel-wise damage distributions, and two-dimensional spatial maps are presented for both scenarios, together with a quantitative separation of damage contributions in the n$^{++}$ and p$^{+}$ regions. Although the present study does not include defect evolution or annealing effects, it provides insights into the different microscopic damage patterns induced by neutrons and high-energy protons and their potential impact on detector performance and constitutes a basis for future coupling to device-level modeling.Speaker: Andrea Danu (Institute of Space Science subsidiary of INFLPR (RO)) -
31
Identification of Sensor Cleavage in ITk Pixel Quad Modules
Mechanical cleavage of planar ITk pixel quad sensors has been identified in 44 production modules, corresponding to approximately 1.2% of the total quad module production. Since some affected devices show no evident optical signature during routine inspection, the analysis of IV characteristics suggests that the true number of mechanically compromised modules may be higher. This work investigates whether standard electrical quality-control measurements can provide an early electrical indicator of mechanical damage. The study focuses on 39.5 mm × 41.1 mm, 150 µm-thick planar sensors and includes a representative module characterized before cleavage, after separation of the sensor halves, and after reassembly through successive IV measurements.
After cleavage, the IV characteristic develops a reproducible bias-dependent distortion that is well described by a quadratic parameterization of the temperature-normalized leakage current, I(V) = a·V² + b·V + c. This criterion successfully identifies known cleavage reference samples and can trigger targeted follow-up visual inspections. In two representative cases, modules initially classified as intact was later confirmed to exhibit mechanical failure after detailed optical inspection prompted by this analysis method.
Additional discrimination methods are under investigation to reduce false positives, which are more frequently observed when IV measurements are performed around −15 °C. Experimentally, mechanically cleaved sensors exhibit higher leakage currents at low temperature. The current operational mitigation strategy therefore compares the leakage currents measured at 20 °C and −15 °C at the highest common bias voltage.
The parabolic behaviour is consistent with a transport regime compatible with space-charge-limited conduction, providing a qualitative interpretation of the emergent quadratic component. Because IV shapes can evolve with time and test conditions, we treat the method as an operational indicator rather than a definitive classifier. This workflow is intended to enhance early detection, streamline triage, and reduce the risk of propagating mechanically compromised modules through ITk pixel production.Speaker: Saverio D'Auria (Università degli Studi e INFN Milano (IT)) -
32
Electrical Quality Control Testing of Barrel Strip Modules for the ATLAS Inner Tracker Upgrade for the HL-LHC
The ITk strip detector is part of the ATLAS inner tracker upgrade for the High Luminosity (HL) -LHC era. Its production is a globally coordinated effort currently underway. 13 sites in the UK, US, and China are involved in building and testing 11k barrel modules, while 20 sites in Canada, Europe, and Australia are producing 7k end-cap modules with different designs.
The modules consist of large 300 um thick planar silicon sensors of ~100 cm^2 in size. Several flexible circuit boards housing the custom powering and readout electronics are glued directly onto the sensor and wirebonded to the capacitively coupled sensor strips. All modules have to fulfill tight assembly and performance specifications. Their conformity and consistency is checked by Quality Control (QC) tests at every step of the production process and results are collected in a global database. As part of the electrical QC the finished modules undergo thermal cycling between +20 C to -35 C in dedicated test stands exposing them to stresses comparable to their operation environment. At each cycle their performance is closely monitored and analyzed.
The testing methodology for the final modules will be presented including a number of setup and detector specific challenges encountered during production testing and lessons learned. An overview will be shown of QC results and variations from building and testing of the first ~2000 production grade barrel detector modules.
Speaker: Botho Paschen (Lawrence Berkeley National Lab. (US)) -
33
TCAD Simulation Study of Radiation Damage Effects on LGAD performance under Neutron Irradiation
Low Gain Avalanche Detectors (LGADs) are being extensively studied due to their unique charge amplification capability arising from the high electric field region created by the gain layer. Owing to their excellent timing and tracking performance, these detectors are expected to play a crucial role in the harsh radiation environments of current and future generations of high-energy physics (HEP) experiments. However, the charge multiplication characteristics of LGADs are significantly affected by the unprecedented fluences of hadrons encountered in such environments. Experimental investigations have shown that the thick LGADs (300 µm) gradually lose their charge multiplication advantage at the neutron fluences of the order of 10^15 n_eq " " cm^(-2).
In the present work, the Silvaco TCAD simulation framework is used to investigate the performance of both non-irradiated and neutron-irradiated LGADs with various detector thicknesses and different gain layer design parameters. The performance of these device configurations is evaluated through the analysis of their charge collection (CC) behaviour as well as the electrical responses, including the current–voltage (IV) and capacitance–voltage (CV) characteristics.
To account for the effects of neutron irradiation in simulations, a recently developed comprehensive neutron radiation damage model is implemented. In addition to incorporating fluence-dependent parametric values for the impact ionization coefficients, specifically optimized for LGADs, the model also describes the acceptor removal mechanism in the gain layer along with the bulk damage effects induced by the neutron irradiation.
The reported study provides useful insights into the radiation tolerance and optimization of LGAD designs and can serve as a valuable reference for the development of radiation-hard silicon detectors for present and future high-energy physics and collider experiments.Speaker: Chakresh Jain -
34
High Resolution Characterisation of Pristine and Irradiated Silicon Carbide PIN and LGAD Radiation Detectors Using Two- and Three-Photon Absorption Transient Current Techniques
We report on the application of non-linear optical Transient Current Techniques --- Two-Photon Absorption (TPA-TCT) and Three-Photon Absorption (3PA-TCT) --- to the three-dimensional characterisation of silicon carbide (SiC) radiation detectors. Silicon carbide is a wide-bandgap semiconductor of growing interest for operation in harsh radiation environments, owing to its low leakage current, high thermal conductivity with respect to silicon. The large bandgap of SiC makes non-linear optical excitation a natural route to achieve depth-resolved charge injection within the device bulk, enabling true three-dimensional characterisation with sub-micrometre spatial resolution.
The TPA/3PA-TCT technique generates excess carriers within a localised three-dimensional voxel by exploiting the nonlinear intensity dependence of multi-photon absorption processes. Scanning the laser focus across the device volume enables spatially resolved measurements of the depletion width, internal electric field profile, carrier mobility, and charge collection efficiency, without the need for ion beams or destructive sample preparation.
We demonstrate the method on three classes of 4H-SiC devices: pristine p-in-n diodes, neutron-irradiated p-in-n diodes at fluences up to 1×10¹⁵ n_eq cm⁻², and Low Gain Avalanche Detectors (LGADs). For irradiated samples, analytical modelling of the z-scan charge profiles allows the simultaneous extraction of electron and hole trapping times, revealing a pronounced asymmetry consistent with preferential hole trapping by neutron-induced deep-level defects. Notably, TPA-TCT z-scan measurements on forward-biased neutron-irradiated diodes provide the first direct observation of hole multiplication near the n+ contact, attributed to the enhanced electric field in that region in combination with the strong hole trapping characteristic of neutron-damaged SiC. Results are validated against ion beam-based measurements (AR-IBIC, TRIBIC), confirming the reliability of the optical approach. Taken together, these results establish TPA/3PA-TCT as a versatile, non-destructive, in operando platform for the advanced characterisation of SiC-based semiconductor devices, with potential implications for the engineering of radiation-hard detectors with intrinsic signal amplification.
Speaker: Cristian Quintana San Emeterio (Universidad de Cantabria and CSIC (ES)) -
35
Electrical simulation and S-parameter measurements of all-silicon CMOS monolithic pixel modules
Silicon pixel detectors offer high spatial and temporal resolution with a low material budget. Traditional multi-chip modules add material through bump-bonding, flexible PCBs, cooling, and support structures. A new approach explores post-processing monolithic wafers with redistribution layers interconnecting multiple chips, enabling thin and lightweight structures based on low-power monolithic CMOS sensors. A current concept used in all-silicon modules foresees four future-generation monolithic active pixel sensors (MAPS) in a row, which reduces component count and supports low-material designs suitable for future collider environments. The research focuses on the electrical performance of the signal and data interconnections at high transmission speeds. Current structures target the first use-cases, lower speeds up to 320 Mbps, but want to push as much as possible to at least 1 Gbps, more if possible. Prototype measurements covering impedance, signal integrity, S-parameters, and electrical simulations of differential trace geometry, dielectric layers, and vias are used to optimize the design for higher data-rate operation.
Speaker: Darshil Girishbhai Vagadiya (Universitaet Siegen (DE)) -
36
The MUonE Test Run 2025: DAQ Development and Tracking Performance
The MUonE experiment seeks to directly measure the hadronic contribution to the anomalous magnetic moment of the muon, providing an opportunity to resolve the tension between differing theoretical predictions for g-2. This will be achieved through the measurement of the angular distribution of high-momentum muons elastically scattering off electrons in a fixed target. Whilst the proposed full-scale experiment will run after the Long Shutdown of CERN scheduled for this year, a number of pilot runs with scaled versions of the detector have been performed in recent years using the high-intensity M2 muon beam, located in the North Area of CERN, culminating in a long duration data-taking run in 2025. In this run, three tracking "stations" were installed, comprising each of 6 tracking planes, using the 2S module designed for the Phase-II upgrade of the CMS detector, alongside an electromagnetic calorimeter, muon detector, timing detector and two further tracking stations located upstream to provide momentum information. This apparatus allowed for the accurate measurement of both the incident muon as well as its products as a result of a scattering event within one of the two targets installed. The run lasted for 2 months over the summer of 2025, recording over 500 billion scattering candidate events.
In this contribution, the development of the novel triggerless DAQ system used in 2025 will be presented, alongside preliminary results for the performance of the tracking system both in resolution and efficiency, as well as projections for physics results to come from the data recorded.
Speaker: Dr David Gabriel Monk (Northwestern University (US)) -
37
Laboratory Characterization of Embedded TDCs in Prototype ASICs for Ti-LGAD and MAPS Pixel Timing Applications
High-precision timing is increasingly vital in modern particle physics instrumentation, providing a crucial temporal dimension to resolve complex physical processes. Whether isolating simultaneous interaction events in high-energy particle colliders or accurately measuring particle decay lifetimes, precise sub-nanosecond time-tagging is a fundamental requirement. Consequently, integrating dedicated Time-to-Digital Converters (TDCs) into readout ASICs has become a critical design priority. In this context, we present the laboratory characterization of the embedded TDC blocks featured within two distinct, custom-designed ASICs tailored for these applications, namely LIGHT01 and PANTHER01.
LIGHT01 is a 8x8 pixel prototype designed in a 28nm CMOS technology for the readout of Trench-isolated Low Gain Avalanche Diodes (Ti-LGAD) sensors in ultra-fast timing applications. It contains a TDC per pixel, targeting a 30 ps timing resolution per channel. Conversely, PANTHER01 is a prototype ASIC fabricated in a 150 nm CMOS Monolithic Active Pixel Sensor (MAPS) technology that targets a timing resolution between 200 and 300 ps. It contains a 48x42 pixel matrix with 3 different analog front-ends; however, unlike LIGHT01, its TDC architecture is implemented in the column periphery.
The laboratory characterization of the two chips is currently underway. Initial experimental TDC performance results for LIGHT01 and PANTHER01 will be presented, alongside a comparison with previous architectures.Speaker: Ennio Monteil (Paul Scherrer Institute (CH)) -
38
Novel Self-Suppression Breakdown Phenomena in High-Aspect-Ratio 3D Silicon Detectors for Extreme Radiation Environment and Fast Timing
As next-generation high-energy physics experiments scale to unprecedented luminosity frontiers, such as the High-Luminosity LHC (HL-LHC), silicon detectors must withstand extreme radiation fluences exceeding 10^{16} neq/cm2. While conventional 3D column and trench-electrode designs mitigate radiation-induced performance degradation by reducing electrode spacing, scaling down cell size traditionally introduces severe non-homogeneous electric fields and early breakdown risks.
This contribution presents a comprehensive performance evaluation of novel 3D silicon detector geometries fabricated on 30 microns thick wafers using an 8-inch CMOS process. We investigate two distinct architectures: a 35 x 35 x 30 um3 3D Trench-column device, and cylindrical 3D multi-pixel fan-structures with cell diameters of 10 and 20 mu featuring an ultra-fine central electrode (0.5 um to1 um diameter, respectively).
Using Multi-Photon Absorption Transient Current Technique (MPA-TCT) characterization, both non-irradiated and irradiated (up to 5e15 neq/cm2) devices were evaluated. We present spatially and depth-resolved measurements of charge collection efficiency, internal gain, and timing performance.
Crucially, we report an unexpected self-stabilizing breakthrough feature: despite the sub-micron diameter of the central electrode, which conventionally exacerbates electric field peaks, the devices remain highly stable close to breakdown. This phenomenon is attributed to geometric self-suppression of gain near the electrode tip, fundamentally contradicting trends observed in ATLAS and CMS 3D designs (where larger problem was uncontrollable gain with breakdown at the electrode tip). This hypothesis is further validated by a uniform breakdown bias observed across both studied geometries (with charge uniformity variation of 20%- 25% only across the cell), offering a promising new paradigm for ultra-radiation-hard, high-precision timing detectors, with controllable (self-stabilized) gain near breakdown bias.
Moreover, study on 3D cylindrical devices enabled us to investigate the impact ionisation at high fluency in silicon.
Speaker: Prof. Gordana Lastovicka Medin (Faculty of Natural Sciences and Mathematics, University of Montenegro (ME)) -
39
Lookup table based vertex digitisation for accurate sensor response simulation and detector layout optimisation at FCC-ee
Precise and efficient vertex reconstruction is essential for the FCC-ee physics programme. Full end-to-end simulation provides a robust estimate of the detector performance. A key component in full simulation is the digitiser, which transforms Geant4 energy deposits into realistic signals in silicon pixel sensors. This can provide a direct link from sensor R&D to detector optimisation and physics performance. We present a digitisation algorithm that captures sensor-specific behaviour and delivers inputs for both sensor development and detector-level studies.
Accurately simulating the vertexing performance at FCC-ee requires a detailed digitiser that captures differences between sensor types and layouts by modelling charge sharing and signal generation at the sensor level. In a workflow refined within the DRD3 OCTOPUS project, TCAD and Allpix Squared are used to simulate the sensor behaviour. The resulting information is stored in a lookup table, which encodes the probability for a deposited charge to be collected by a given pixel in its vicinity. In FCC-ee full simulation in the Key4hep framework, the digitisation algorithm then generates pixel hits according to this mapping, inherently accounting for hit position and angle.
The simulated cluster size is validated by comparing grazing-angle measurements from the H2M sensor prototype with corresponding Key4hep simulations. Based on this, first results obtained with the algorithm are presented. Incoherent pair creation in beam-beam interactions drives the vertex detector hit rate, which in turn defines the readout requirement for candidate sensor technologies. By using lookup tables for various sensor layouts, realistic cluster sizes and thus pixel hit-rates are estimated. Finally, an outline is given on how this algorithm will provide input for systematic detector layout optimisation studies based on the achievable spatial resolution on hits as a function of hit position in the integrated detector model.
Speaker: Jona Dilg (University of Zurich (CH)) -
40
Inter-pixel Distance Characterization of TI-LGAD Sensors of Different Thickness
Low Gain Avalanche Diodes (LGADs) have demonstrated excellent time resolution, making them a well-established technology for precision timing applications in high-energy physics. However, their segmentation into fine pixels is traditionally limited by the presence of a no-gain region between pads. To overcome this limitation, Trench-Isolated LGADs (TI-LGADs) have been developed, where physical trenches are introduced to electrically isolate neighboring pixels.
In this work, we focus on the characterization of TI-LGAD sensors with an active thickness of 275 µm, with complementary measurements performed on thinner devices (45 µm and 55 µm). Different device layouts, including variations in trench depth and fabrication process, are also considered to assess their influence on charge sharing and pixel isolation. The analysis is based on experimental measurements of the Inter-Pixel Distance (IPD) using an infra-red laser in a Transient Current Technique (TCT) setup.
The results of this study will contribute to the optimization of TI-LGAD designs. Sensors with an active thickness of 275 µm are of particular interest for X-ray detection, providing an additional application beyond high-energy physics.
Speaker: Juan Ignacio Carlotto (Fundazione Bruno Kessler) -
41
Nanowire-Based Thermal Interconnects for Enhanced Thermal Management in High-Density Silicon Pixel Modules
The increasing integration density of silicon pixel sensors, together with emerging applications such as module-level power conversion and enhanced on-detector signal processing, significantly raises the demand for advanced thermal management solutions. Efficient heat removal at the module level is becoming a critical requirement for ensuring stable and reliable operation. In this work, we demonstrate the use of nanowire-based interconnects to improve the thermal coupling between a silicon die and a heat sink, achieving superior performance compared to conventional thermal interface materials such as conductive pastes.
Two bonding approaches for nanowire integration, adhesive bonding and sintering, are presented and systematically compared in terms of thermal efficiency, bonding process requirements, and bonding process demands. The advantages and constraints of each method are discussed, highlighting their suitability for different integration scenarios. Furthermore, we demonstrate that these bonding technologies can be employed not only to enhance thermal conduction but also to mechanically mount silicon pixel sensors onto supporting structures. This dual functionality provides both improved heat dissipation and robust mechanical stability using minimal material.
Together, the presented thermal and mechanical bonding strategies offer a scalable pathway to enhance module-level thermal stability, supporting the performance and longevity of future high-density detector systems and related applications.Speaker: Julian Weick (CERN) -
42
Advanced Radiation Damage Modelling of Neutron-Irradiated Thin Low Gain Avalanche Detectors
Thin Low Gain Avalanche Detectors (LGADs) are among the most promising sensors for precision timing applications in the High-Luminosity Large Hadron Collider (HL-LHC) era. Owing to their intrinsic charge-multiplication capability, thin LGADs can achieve timing resolutions of ~15 ps even under high pile-up and intense-radiation conditions. However, measurements have shown that the gain of the LGADs progressively degrades with increasing irradiation fluence, mainly due to acceptor removal in the gain layer. Therefore, robust device modelling and optimization are essential to ensure reliable operation of LGADs in future harsh hadron collider environments.
Recent results from our group have demonstrated that the two-trap neutron radiation “DELHI” model can be successfully extended to thick (300 μm) LGADs within the Silvaco TCAD framework by separately tuning the impact ionization parameters for different irradiation fluences, together with gain layer degradation modelling and two-level bulk neutron damage model. In the present work, we extend and refine this approach for thin LGADs by implementing the DELHI radiation damage model along with gain layer degradation modelling, while employing a more effective radiation-fluence based impact-ionisation framework rather than independently tuning the ionisation parameters for each irradiation condition. This provides a more consistent and predictive modelling strategy for irradiated LGAD operation.
Using measurements from the thin LGADs, this study aims to reproduce the electrical characteristics of non-irradiated and irradiated devices, including capacitance–voltage (C–V), current–voltage (I–V), and gain–voltage behaviour. The overall objective is to establish a reliable Silvaco-based simulation framework for thin LGAD optimization, which can be used to guide and improve future device designs.
Speaker: Kalpna Tiwari (CDRST, Department of Physics & Astrophysics, University of Delhi (IN)) -
43
Global MaPSA Production and Testing for the CMS Phase-II Outer Tracker Upgrade: Status and Readiness for HL-LHC
The High-Luminosity LHC (HL-LHC) upgrade will increase the instantaneous luminosity by up to a factor of five beyond the current LHC design, imposing strict requirements on the CMS tracking system. The Phase-II Outer Tracker will employ novel silicon Pixel-Strip (PS) modules capable of performing transverse momentum discrimination for the Level-1 trigger. A key component of the PS module is the Macro-Pixel Sub-Assembly (MaPSA), which integrates a pixelated silicon sensor with dedicated readout ASICs.
A distributed network of CMS institutes worldwide carries out the production and quality assurance of MaPSAs. A common testing framework has been established to ensure uniform electrical characterisation, threshold tuning, and noise evaluation, among other assessments across all production sites. Continuous optimisation of assembly and testing procedures has led to significant improvements in yield and process stability.
This contribution presents an overview of the global MaPSA production effort, including testing methodologies, quality control metrics, yield evolution, and current production status.Speaker: Leticia Braga Da Rosa (Deutsches Elektronen-Synchrotron (DE)) -
44
Progress on the MALTA CMOS Sensor: Edge-TCT Measurements for Parametric Pixel Simulation
MALTA2 is a monolithic active pixel sensor, developed in 180 nm CMOS technology for radiation-hard applications in high-rate environments. This contribution summarizes recent progress on the MALTA2 sensor characterization and simulation developments. Test-beam measurements at the CERN SPS are used to study hit efficiency, charge collection, and timing performance before and after irradiation up to $5\times10^{15} \mathrm{n_{eq}/cm^{2}}$.
In addition, Edge-TCT measurements of the MALTA2 sensor on epitaxial silicon have been performed using both analog and digital readout. The front-end time-walk is characterized with dedicated analog monitoring pixels. For the first time, the charge collection is studied through digital Edge-TCT, reconstructing charge solely from binary hit data. The digital readout gives access to the full edge of the pixel matrix instead of just the monitoring pixels. Combined with test-beam measurements, these studies result in a 3D pixel parameterization of the charge collection.
The measured sensor response serves as input to a fast parametric pixel simulation developed for chip design optimization and system-level studies. Applications of the resulting simulation model to MALTA2 detector studies are discussed.
Speaker: Lucian Fasselt (DESY) -
45
A Dual-Gain Front-End Channel with Time-over-Threshold Digitization for Hybrid Pixel Detectors in Photon Science Applications
Hybrid pixel detectors, where the sensor and the readout electronics are fabricated independently and interconnected via bump-bonding, have become the standard technology for X-ray detection at synchrotron beamlines and FEL facilities. They enable independent optimization of sensor and readout electronics, where advanced in-pixel processing can be integrated.
Several state-of-the-art detectors for FEL applications, such as AGIPD and JUNGFRAU, leverage adaptive gain front-ends, in which different gain blocks can be enabled depending on the amount of the charge delivered by the sensor. However, these designs typically rely on architectures with shared analog-to-digital converters (ADCs), where the transmission of analog data through different regions of the chip could potentially lead to data corruption and signal integrity issues.
In this work, a proof-of-concept, 28 nm CMOS front-end that combines a dual-gain charge sensitive amplifier (CSA) architecture together with Time-over-Threshold (ToT) digitization is discussed as a compact alternative to standard ADC-based readout. While ToT conversion has been widely adopted in high-energy physics readout chips (as for RD53), its extension to X-ray science has been less explored.
The developed channel features a CSA gain switching mechanism that preserves single-photon sensitivity at low signal levels while extending the upper range to around 4000 photons at 9 keV. The CSA output is processed by a comparator, whose output pulse duration is digitized by means of an 8-bit counter running at 1 GHz, yielding a conversion window of around 250 ns (compatible with the inter-pulse spacing at most existing and planned FEL facilities). A 1-bit gain flag is stored together with the 8-bit ToT value to unambiguously identify the active gain mode. A minimum SNR of 8 has been obtained from the characterization of one sample of the front-end channel.
The design and the characterization of the front-end channel will be discussed in detail in the conference paper.Speaker: Luigi Gaioni (University of Bergamo (IT)) -
46
Results from the pre-series production of the loaded module cells for the upgrade of the new Inner Tracker of the ATLAS experiment
The ATLAS Experiment is preparing for the Phase 2 upgrade. Leading the upgrade program is the replacement of the current Inner Detector with an all-silicon Inner Tracker (ITk) designed to operate during High-Luminosity LHC with an average of 200 proton-proton interactions per bunch crossing. The ITk will consist of a Strip detector and a Pixel detector. The five layer Pixel detector will be constructed from three sub-systems. One system occupying the central three outermost layers, called the ITk Pixel Outer Barrel, will use carbon-fiber local supports with steel pipes that provide CO2 cooling and services for 4472 loaded module cells. A loaded module cell combines an ITk pixel hybrid module with four front-end chips and a thermo-mechanical structure called bare cell. The bare cell is made of aluminium graphite block and pyrolithic graphite tile for precise positioning and thermal coupling respectively.
The contribution will share experiences from the pre-production qualification campaign for loaded module cell assembly and quality assurance carried out last year. Collaborating institutes loaded onto bare cells and thoroughly characterized 134 modules to verify the production procedures, loading accuracy, electrical integrity, and thermal performance at each site. The pre-production campaign demonstrated reliable assembly and testing capabilities in a large-scale production chain, and it identified an insulation issue between the module and the bare cell, allowing corrective actions before large-scale production.
This contribution presents the developed site production equipment, the homogenization process of the equipment, and common production rules between sites. The entire cell loading workflow and qualification procedures will be explained, as well as the results, and systematic studies of the pre-production run will be shared. Ultimately, the contribution will show lessons learned to produce components for the best possible tracking detector.Speaker: Matej Repik (Universite de Geneve (CH)) -
47
ITk Pixel 3D Modules: Final Test Beam Results Ahead of Production
The High-Luminosity upgrade of the Large Hadron Collider (LHC) will push the ATLAS tracking system into an unprecedented experimental environment, with particle densities and radiation levels far beyond those faced by the current LHC configuration. To meet these challenges, ATLAS is replacing its tracking system with the all-silicon Inner Tracker, ITk. Following the successful completion of prototyping and pre-production, the project has now entered the full-scale production phase.
The ITk pixel detector will employ hybrid pixel modules. Different sensor technologies are used across the detector volume to match the expected radiation environment: highly radiation-tolerant 3D pixel sensors are selected for the innermost layer, where fluences up to $1.7\times10^{16}$\,n$_\mathrm{eq}$/cm$^2$ are expected; planar pixel sensors will instrument the outer layers.
Test-beam campaigns were carried out at CERN in 2025 and 2026 to qualify the module performance before and after irradiation. A key milestone was the first test-beam operation of an ITk pixel production module, equipped with the final readout chip that will be installed in the detector. It provides Time Over Threshold readout, enabling an indirect measurement of the charge deposited by traversing particles and playing a crucial role in optimising spatial resolution. This talk will present the tracking performance of 3D sensors assembled in production modules after irradiation to fluences between $1.0\times10^{16}$ and $1.7\times10^{16}$\,n$_\mathrm{eq}$/cm$^2$. It will also discuss the operability of the final front-end electronics under realistic irradiation conditions, with particular emphasis on Time-over-Threshold (ToT) to charge calibration. The results will include current–voltage characteristics, hit efficiency, noisy-pixel occupancy, and the performance of the readout electronics at different operating points, defined by threshold settings and ToT-to-charge calibrations. In addition to these laboratory characterisations, a simple Monte Carlo toy model has been developed to interpret charge sharing within the pixel cell, taking into account the experimental track-intercept resolution and non-perfectly perpendicular particle incidence.Speaker: Simone Ravera (INFN e Universita Genova (IT)) -
48
Efficiency of the Microstrip Silicon Detector in the FOOT experiment
In the field of applied nuclear physics the FOOT (FragmentatiOn Of Target) experiment has a relevant role in both medical physics, with oncological treatments based on Hadrontherapy, and Radiation Protection in Space (RPS). It aims to measure double differential cross-sections of nuclear fragmentation processes as a function of the emission angle and the kinetic energy of the fragments, with a precision better than 5$\%$.
FOOT works with two different setups, the Emulsion Spectrometer, with an angular acceptance around the beam axis bigger than 70° in order to detect fragments with Z $\leq$ 3, and the Magnetic Spectrometer, with 10° angular acceptance in order to detect fragments with Z $\geq$ 2.One of the detectors involved in the magnetic spectrometer is the Microstrip Silicon Detector (MSD). The MSD provides fragment tracking together with the Vertex and Inner Tracker detectors, enabling momentum reconstruction, and it also measures the fragments' energy loss for Z identification (Zid), which can be matched to the ToF Wall Zid.
The MSD detector, consists of three planes spaced by $\sim$ 2 cm along the beam direction (positive Z-axis) and each plane is built from two orthogonal single‑sided silicon sensors for X–Y hit reconstruction. Each sensor has an active area of $\sim$ 10 x 10 cm$^2$, a thickness of 150 $\mu$m, and for each one 640 strips are read by ten IDE1140 ASIC chips.The response of the sensors to ionizing radiation has been characterized through several data‑taking campaigns and in particular this work presents the results obtained in 2024 and 2025 at the CNAO (National Center for Oncological Hadrontherapy) in Pavia using proton and carbon‑ion beams.\The study shows that the detection efficiency of the single sensor exceeds 95$\%$ for minimum‑ionizing particles, and that the measured spatial resolution is consistent with the expected theoretical performance.
Speaker: Sofia Mazzolani (Istituto Nazionale di Fisica Nucleare) -
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Scaling up test-beam measurements of detector material via multiple scattering with the MONSTAR telescope
A reliable description of material in particle detectors is a key ingredient for precision measurements, particularly in tracking systems where both momentum determination and hit resolution depend crucially on the material content. In many experiments, this information is derived from simplified detector models estimated from design specifications. In practice, such models can deviate significantly from reality due to incomplete knowledge of components or construction effects, leading to material uncertainties that can exceed O(10%). Incorporating direct measurements of radiation length during the development stage of new detectors enables better-informed design decisions and improved detector modelling.
In this talk, a measurement approach based on the multiple scattering of electrons in test beams is presented. Central to this method is the lightweight MONSTAR tracking telescope, developed specifically to minimise its own material impact whilst maintaining high angular resolution. The interplay between telescope performance, beam energy, and the range of measurable material thicknesses is examined using simulation studies.
The methodology is illustrated using data from an experimental campaign at the PSI PiM1 beamline, where the material content of a wide variety of samples—including detector modules, support elements, and services from ATLAS, CMS and Mu3e—was measured, along with dedicated calibration targets, amounting to more than 500 cm$^2$ of scanned material. The talk will outline the analysis strategy, discuss different modelling approaches to multiple scattering (theoretical and data-driven), and highlight the potential of this technique for broader use in future detector R&D and validation.Speaker: Sophie Rohletter (ETH Zurich (CH))
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19:30
Dinner
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TimingConvener: Valentina Sola (Universita e INFN Torino (IT))
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TI-LGAD: current status and future directionsSpeaker: Anna Macchiolo (University of Zurich (CH))
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Recent Developments in AC-LGADs for Timing-Capable Tracking Detectors
AC-coupled Low-Gain Avalanche Diodes (AC-LGADs) are a versatile sensor technology for future particle detectors requiring simultaneous precision timing and spatial measurement. By separating the gain layer from the readout segmentation, AC-LGADs allow flexible electrode design with 100% fill factor while preserving the excellent timing performance characteristic of LGAD-based devices.
This contribution will present recent progress in AC-LGAD development along two complementary directions: the realization of fine-pitch electrodes for high-occupancy hadron collider environments, and the use of coarser electrode geometries in which hit positions can be reconstructed from charge sharing and signal ratios among neighboring channels. These studies highlight the broad design flexibility of AC-LGADs while maintaining precise timing capability.
Radiation tolerance will also be discussed. Gain-layer modifications, including carbon co-doping, have been investigated in collaboration with Hamamatsu Photonics K.K. (HPK) using DC-LGAD structures to improve tolerance against acceptor removal after irradiation. Comparative studies of the radiation-induced behavior of AC-LGAD and DC-LGAD structures will also be presented to assess whether the mitigation trends established in DC-LGADs are applicable to AC-LGADs.
Speaker: Koji Nakamura (KEK High Energy Accelerator Research Organization (JP)) -
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Status and perspectives of DC-coupled Resistive Silicon Detectors.
Thin silicon sensors combining resistive readout and internal gain, known as Resistive Silicon Detectors (RSDs), represent a highly promising technological solution for future 4D tracking detectors.
These sensors are based on LGAD technology and provide, along with increased signal-to-noise ratio, a built-in intrinsic charge sharing that enables excellent space resolution while maintaining reduced granularity.
In particular, the DC-coupled Resistive Silicon Detectors (DC-RSDs) exploits the benefits of a resistive DC-coupled read-out with controlled charge sharing.
The first production of such devices, fabricated at FBK, comprises pixel matrices with a broad range of geometries and pitches, as well as multiple technological implementations of the electrode layout and resistive layer. This variety allows for a systematic and quantitative investigation of device performance as a function of fabrication parameters and design choices.
In this work, we present the RSD design concept and its evolution, together with a comprehensive characterization of the FBK DC-RSD production. We present the spatial and temporal resolution, response uniformity, and detection efficiency achieved across different sensor designs, demonstrating the potential of this technology for high-precision 4D tracking. Measurements were performed in test beam campaigns at DESY and CERN facilities and complemented by dedicated laboratory studies. The devices were also subjected to irradiation campaigns to o assess their radiation tolerance.
Finally, we discuss recent developments in reconstruction techniques, as well as the sensor design optimization studies providing key insights for the next DC-RSD production.Speaker: Roberta Arcidiacono (Universita e INFN Torino (IT))
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50
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10:30
Coffee break
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TimingConvener: Fabian Huegging (University of Bonn (DE))
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53
Characterisation of Silicon electron multiplier structures
Silicon sensors for the future generation of collider physics experiments will require high performances on spatial (< 10 μm) and time resolution (20-50 ps ) with a radiation tolerance up to fluences of 1017neq. To meet these challenges, an innovative silicon sensor architecture achieving internal gain without relying on doping is proposed: the Silicon Electron Multiplier (SiEM). In contrast to LGADs or APDs sensors, where the gain region is induced by doping, the amplification in the SiEM is achieved by applying an electric potential difference in a composite electrode structure embedded within the silicon bulk using MEMS fabrication techniques. Since no gain-layer deactivation is expected with radiation damage, such a structure could withstand fluence higher than 1016neq/cm2. SiEM structures produced by HPK were characterised and it was shown gain
can be achieved and behavior roughly follow the expectation from simulation. Since those results were presented, the structures were further investigated in testbeam and first results of their response after irradiation will be presented.Speaker: Federico De Benedetti (Universidade de Santiago de Compostela (ES)) -
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3D integrated sensing solutions
Highly granular precision timing detectors are required to achieve scientific breakthroughs across HEP, NP, BES, and FES applications, and their critical need has been highlighted by the US DOE BRN, European Strategy for Particle Physics, and Snowmass processes. We will present the recent results from our project on the development towards 3D-integrated sensors. We developed LGAD sensors using a 12'' commercial CMOS process, and the readout ASICs in 28nm technology node. Details of their designs, and characterization of prototypes will be presented.
Speaker: Shuoxing Wu (Fermi National Accelerator Lab. (US)) -
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Developments and latest results from the IGNITE project on 4-dimensional vertex detectors
The INFN IGNITE project is developing technical solutions in CMOS 28-nm technology for the next generation of trackers at colliders, which require high time resolution at the pixel level (<50 ps RMS), pixel size around 50 µm, and system power density below 1-2 W/cm2, depending on the specific cooling technique adopted.
We present test results about a prototype ASIC, the Ignite64, featuring a matrix of 64x64 pixels, equipped with 1 TDC per pixel, and conceived to test prototype silicon sensors of 55 µm pitch, developed within the AIDAInnova initiative in recent years. The Ignite64 is designed according to a modular architectural concept which is being replicated in the large-area ASIC, named the IgnitER (320x256 pixels, 45 µm pitch, die size 1.6x1.4 cm2), now close to submission.
The Ignite64 implements solutions for accurate power and clock distribution, which are key to obtain high and uniform performance in timing. Different solutions for the Analog Front End have been designed and tested, to accurately characterize their response concerning performance vs power.
At 1 fC input charge and 10 µW per pixel, typical measured time resolution is around 20 ps (AFE + TDC) at 0 input capacitance, which increases to around 35 ps RMS when a 3D silicon sensor is connected (100 fF typical pixel capacitance). Value dispersion on the the distribution of resolutions per pixel is kept under control, showing around 5 ps RMS error on the full matrix. This demonstrates the success of the adopted architecture and circuital solutions for powering (localized LDO).
These and other results from the Ignite64 tests are precious indications for the design of the IgnitER. The architectural choices adopted for the IgnitER, and its expected performance, as obtained from IgnitER post-layout simulations, are also illustrated.Speaker: Adriano Lai (Universita e INFN, Cagliari (IT))
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12:00
Lunch
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TimingConvener: Dominik Dannheim (CERN)
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The path to the extreme fluences via the nLGAD sensors
The results from an innovative batch of Low-Gain Avalanche Diodes (LGADs) produced by the Fondazione Bruno Kessler (FBK, Italy) will be presented.
The sensors are p-in-n LGADs, where the high-concentration implant that generates charge-carrier multiplication is provided by an n-type dopant (nLGAD). The nLGADs are produced on thin epitaxial n-type substrates, with an active thickness of 55 $\mu$m. A completely new design for the p$^{++}$ ohmic contact and the n$^+$ gain implant has been developed, with careful consideration of dopant activation and diffusion during production. Furthermore, extensive R&D on peripheral structures optimised for n-type thin substrates has been incorporated into the batch, resulting in 10 guard ring designs. Fourteen wafers are produced with different diffusion and implant depths, using Boron on the p$^{++}$ contact and two different dopants, namely Phosphorus and Arsenic, for the n+ implant.
The NLGAD sensors will provide unique information on the donor-removal mechanism at a concentration of about 10$^{16}$ atoms/cm$^3$. This study will provide fundamental knowledge for the design of p+–n+ compensated LGADs on the path to extreme fluences. Moreover, nLGAD sensors are valuable tools for detecting low-energy photons.
Preliminary results on the sensor characterisation on the wafer and after dicing will be presented and discussed.
Speaker: Valentina Sola (Universita e INFN Torino (IT)) -
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Development of 4D (5D) pixel detectors at PSI
Precise timing information in pixelated detectors is becoming increasingly important for future particle physics experiments. This need arises from two main application areas. In environments with extremely high track densities, such as the High-Luminosity LHC (HL-LHC), timing measurements can significantly improve tracking performance by associating detector hits with the correct interaction vertices. Such applications require time resolutions at the level of a few tens of picoseconds. In addition, timing capabilities can enable direct measurements of the lifetimes of unstable particles, such as pions and muons.
At the Paul Scherrer Institute (PSI), an R&D program is underway to develop dedicated readout ASICs addressing both classes of applications. The LIGHT project focuses on the development of a readout chip for hybrid pixel detectors employing Trench-isolated LGAD sensors (Ti-LGAD), targeting future HEP applications. The design of the first prototype ASIC will be presented together with initial measurement results.
A second development line, PANTHER, is a depleted monolithic pixel detector with integrated timing capabilities, targeting a time resolution of 200–300 ps. The chip is intended for experiments with relatively low particle rates and moderate radiation levels, as commonly encountered in PSI in-house experiments. A first prototype has been fabricated and is currently under evaluation. The detector architecture will be described and first experimental results will be presented.
Speaker: Hans-Christian Kaestli (Paul Scherrer Institute (CH)) -
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Performance of MiniCACTUSV2: A Monolithic HV-CMOS Sensor for Precision Timing
The MiniCACTUS prototypes are large fill-factor monolithic demonstrator sensors optimised for timing measurement of charged particles in future high-energy physics large-scale timing detectors. They are designed in 150 nm LFoundry HV-CMOS process and produced on high resistivity p-type silicon substrates with a deep n-well acting as collecting electrode.
The MiniCACTUSV2 is the latest iteration of the chip featuring pixel structures with different implant sizes ranging from $1.0\times1.0$ $mm^{2}$ down to 50 × 50 µm with dedicated analog front-ends and discriminators implemented at the column level.
The chips are thinned down to 150, 175 and 200 µm active thickness and processed for backside biasing.Detection efficiency and time resolution of these prototypes have been studied in testbeam experiments at SPS CERN using high energy pion beams. Best performance has been observed for the $0.5\times0.5$ $mm^{2}$ structures reaching less than 50 ps resolution when operated with bias voltage above 300 V.
While these results have been obtained on pixels without gain layer, first prototypes of pixel diodes with intrinsic gain have been recently produced at LFoundry on both 150 µm high resistivity substrates and 30 µm epitaxial active silicon layers.
In this presentation, we provide an overview of the MiniCACTUSV2 testbeam characterisation results, along with the initial characterisation of the gain-layer diodes.
Speaker: Stefano Terzo (IFAE Barcelona (ES)) -
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Time Resolution and Radiation Hardness of monolithic pixel sensor with PicoAD
The MONOLITH H2020 ERC Advanced project aims at producing a monolithic silicon pixel ASIC with 50 µm pixel pitch and picosecond-level time stamping. The two main ingredients of the project are fast and low-noise SiGe BiCMOS electronics and a novel sensor concept, the Picosecond Avalanche Detector (PicoAD). The PicoAD uses a patented multi-PN junction to engineer the electric field and produce a continuous gain layer deep in the sensor volume. The result is an ultra-fast current signal with low intrinsic jitter in a full fill factor and highly granular monolithic detector.
The first proof-of-concept PicoAD prototype demonstrated full detection efficiency and an average time resolution of about 17 ps for minimum-ionising particles, with values ranging from 13 ps at the pixel centre to 25 ps near the pixel edge. A new monolithic PicoAD prototype, produced in 2024 using improved front-end electronics, was recently characterised in a CERN SPS test beam with 120 GeV/c pions. At a sensor bias voltage of 180 V, corresponding to an electron gain of about 50, and at a front-end power density of 2.6 W/cm², the prototype reached an efficiency of (99.99 \pm 0.01)% and a time resolution of (12.1 \pm 0.3) ps after time-walk correction.
To assess the suitability of the PicoAD concept for operation in harsh radiation environments, samples from the same production have been irradiated up to fluences of $1 \times 10^{16}~ \mathrm{n_{eq}/cm^2}$. Preliminary results from the 2026 SPS test beam campaign show that, at a front-end power density up to 1.0 W/cm², the detector maintains a detection efficiency compatible with 99.8% and a time resolution compatible with 14 ps up to fluences of $1 \times 10^{15}~ \mathrm{n_{eq}/cm^2}$. The evolution of detection efficiency and timing performance after irradiation will be presented as a function of fluence, sensor bias voltage and front-end operating conditions.
Speaker: Théo Moretti (Universite de Geneve (CH)) -
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LHCb VELO Upgrade II - 4D Tracking at HL-LHC
LHCb is planning to upgrade its detector for 2035 to operate at luminosities of $1.0 \times 10^{34} cm^{-2}s^{-1}$ ($5\times$ increase on current operation), accumulating over 300 fb$^{-1}$. This luminosity will produce ~30 interactions per bunch crossing, resulting in approximately 1500 charged particles within acceptance. LHCb physics relies on exclusive reconstruction of events, including primary and secondary vertices. To achieve this in the high-occupancy environment, LHCb's VErtex LOcator (VELO) must be upgraded. New techniques will assign $b$-hadrons to their origin vertices and perform real-time pattern recognition, involving a new 4D hybrid pixel detector with advanced rate and timing capabilities as well as high-radiation tolerance up to $3 \times 10^{16} n_{eq}$cm$^{-2}$.
Prototype front-end ASICs are under design in 28nm technology which must handle extreme hit rates as well as added timing information. The sensor must provide time measurements with less than 50ps resolution and resist high fluence while keeping the spatial resolution below 10 $\mu$m. New silicon photonics technology will provide on-chip electrical-optical conversion, enabling a readout bandwidth of up to 100 Gbps per ASIC. The mechanical design will minimize the module material, with thinned sensors and ASICs combined with a lightweight cooling structure and optimised electronic design. This will ensure a total material budget of $x/X_0 < 10\%$ for tracks in the VELO, maximising vertexing performance which underpins LHCb physics. The ongoing redesign of the RF shield, required for wakefield protection due to the inner-sensors nearing 6mm radial distance from the beam, is a vital factor towards this.
This presentation will highlight the progress on the different components of the VELO Upgrade II design, focusing on the close relationship established between simulation and the sensor/ASIC/mechanics/electronics groups. This has enabled rapid physics evaluation of proposed solutions and ensured that material budget constraints are met, utilising a flexible geometry framework.
Speaker: Dan Thompson (University of Birmingham (GB))
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We leave at 16:20!!!! in front of the hotel
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Excursion and social dinner
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MonolithicConvener: Ben Kilminster (University of Zurich (CH))
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Tracking and Vertexing at FCC-ee
The first phase of the Future Circular Collider (FCC) program aims to deliver electron–positron collisions at unprecedented luminosities, enabling a precision physics program that places stringent requirements on detector performance and reconstruction algorithms.
This contribution presents the current status of tracking and vertexing developments for FCC detectors, with a focus on gaseous tracking systems based on drift chambers and straw tubes. These detectors introduce specific challenges, including the intrinsic left–right ambiguity in drift measurements, which must be properly addressed during pattern recognition and track fitting.
Modern machine learning approaches, such as Geometric Graph Track Finding, are being investigated to improve pattern recognition by incorporating detector information at early reconstruction stages. At the fitting level, the GenFit2 framework with the Deterministic Annealing Filter provides a robust and detector-independent solution to this ambiguity, enabling precise track parameter estimation.
A key aspect of these developments is their detector-agnostic design, which is essential in the FCC context where detector concepts are expected to evolve significantly over time. This flexibility allows reconstruction algorithms to be reused across different geometries, reducing maintenance effort and ensuring long-term stability of the software framework.
The contribution will also discuss tracking performance studies for FCC-ee detectors, as well as the impact of beam-induced background.
Finally, the current status of vertexing developments for FCC detectors is reviewed, focusing on ongoing efforts to establish robust primary and secondary vertex reconstruction in the FCC-ee environment.
Speaker: Andrea De Vita (CERN & Università di Padova) -
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Vertex detectors at the FCC-ee – Requirements, layouts, and link to MAPS R&D
The electron–positron Future Circular Collider (FCC-ee) is the European particle physics community’s plan A for succeeding the LHC as the world’s premier collider facility. Precise reconstruction of primary and secondary interaction vertices is central to the FCC-ee physics programme, enabling measurements of rare flavour processes and of Higgs and Z boson decays to bottom, charm and strange quarks and to τ leptons. Vertex detectors therefore sit not only at the geometric core of the experiment, but also at the core of its physics programme.
To understand the ongoing effort in developing vertex detectors for the FCC-ee, this contribution shortly reiterates the stringent requirements on FCC-ee vertex detectors, including excellent impact parameter resolution and high hit detection efficiency, while maintaining an low material budget of 0.3% $X_0$ per layer or less. The constraints imposed by the intense collision environment are briefly discussed, as they drive requirements on radiation tolerance, readout, and timing. Monolithic active pixel sensors (MAPS) are the prime candidates to fulfil all of these requirements simultaneously.
Current FCC-ee vertex detector layouts, as developed for the CLD, IDEA, and ALLEGRO detector concepts, are reviewed and compared. Building on these baselines, progressively lighter and more ambitious layouts are explored and their performance evaluated in full simulation, with emphasis on impact parameter resolution and acceptance as functions of first layer radius and intrinsic sensor resolution. Moving beyond these layouts, the FCC-SEED vertex detector concept is presented, which employs overlapping, thin, and curved MAPS to combine very low material budget with high geometrical acceptance, achieving the best impact parameter resolution so far. The associated technological and integration challenges are outlined.
Finally, ongoing work improving the interconnection between detector layout optimisation and MAPS R&D is highlighted, providing a path towards quantitatively linking sensor design choices to physics performance.
Speaker: Armin Ilg (University of Zurich) -
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Design and status of the ePIC Silicon Vertex Tracker detector for the Electron-Ion Collider
The Electron-Ion Collider (EIC) is a new accelerator facility under construction at the Brookhaven National Laboratory to investigate the internal structure and dynamics of strongly interacting matter. Starting in the mid-2030s, the EIC will collide polarized electrons with polarized protons and light ions, as well as with unpolarized heavy ions, across a wide range of center-of-mass energies, at high luminosity. Key to the delivery of the EIC science program is a detector able to provide high precision charged-particle tracking and vertexing. To this aim, a large acceptance, high resolution Silicon Vertex and Tracking (SVT) subsystem is under development for the EIC project detector, ePIC. The SVT will be instrumented with low power, high granularity Monolithic Active Pixel Sensors (MAPS), combined with lightweight technologies for power distribution, data transmission, cooling, mechanical support. This contribution will present the design and ongoing development of the SVT, focusing on prototypes of its ASICs, inner-barrel layers with curved wafer-scale sensors, as well as the outer barrel and disk layers.
Speaker: Laura Gonella (University of Trieste and INFN) -
65
4D Semiconductor Tracking Detector R&D for CEPC
The Circular Electron–Positron Collider (CEPC), designed to operate at center-of-mass energies up to 360 GeV, aims to enable precision studies of the Higgs boson and searches for physics beyond the Standard Model. Its silicon tracker, with an active area of approximately 100 m², is designed to provide high-precision charged-particle tracking over a wide momentum range from below 1 GeV to above 100 GeV, supporting both isolated high-momentum tracks and dense jet reconstruction, with a target momentum resolution at the 10⁻³ level. In addition, it will serve as a precision time-of-flight system with a single-layer timing resolution of about 50 ps. This talk presents the development of a 4D tracking system based on advanced semiconductor timing detectors, aiming at picosecond-level timing resolution and micrometer-level spatial resolution for next-generation high-energy physics experiments. The R&D focuses on low-gain avalanche detectors (LGADs), targeting large-area semiconductor sensors achieving better than 40 ps timing resolution and ~10 μm spatial resolution. In parallel, a dedicated fast-timing readout ASIC (LATRIC) is being developed, featuring low power consumption, high precision, and large-scale channel integration. Recent progress on silicon-based LGADs, SiC-based fast timing detectors, and the LATRIC ASIC will be presented, together with prospects for their application in CEPC and other future experiments.
Speakers: JIA JIAN TEOH (中国科学院高能物理研究所(IHEP)), Jia Jian Teoh (Chinese Academy of Sciences (CN))
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62
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10:20
Coffee break
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MonolithicConvener: Laura Gonella (University of Trieste and INFN)
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66
ARCADIA fully-depleted CMOS sensors for future vertex and silicon trackers
The detection of charged particles and photons with high efficiency, excellent spatial resolution, and precise timing represents one of the most demanding challenges in the design of modern semiconductor detectors. Fully depleted CMOS monolithic sensors address these requirements by integrating sensor, readout, and signal processing electronics within a single silicon substrate while enhancing the signal collection efficiency via the complete depletion of the bulk material. Building on a proprietary process developed in collaboration with LFoundry on high-resistivity n-type wafers processed with a 110 nm CMOS node, the ARCADIA program delivered a broad portfolio of results spanning IP cores, ASICs, and dedicated data acquisition systems. Pixel architectures targeting a spatial resolution of 5 $\mu$m have been demonstrated together with readout solutions achieving a power density below 20 mW/cm$^2$, a combination that positions these devices as compelling candidates for vertex and tracking detectors at future leptonic colliders. The introduction of a shallow p-type gain implant beneath the collection electrode yields a monolithic CMOS LGAD whose intrinsic timing capability is projected to surpass 20 ps r.m.s. in thin-substrate configurations, offering a route to precise time-of-flight measurements in four-dimensional tracking systems. At the opposite end of the thickness spectrum, sensors with active layers reaching 700 $\mu$m provide the stopping power required for efficient detection of gamma rays and X-ray photons, making them directly relevant to medical imaging modalities such as nuclear medicine, proton therapy monitoring, and spectroscopic X-ray imaging. Together, these achievements establish the ARCADIA technology as a versatile and mature platform connecting frontier physics instrumentation with high-impact applications in the medical and applied science domains.
Speaker: Matteo Barbagiovanni -
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Performance Studies of the CASSIA Monolithic Sensors with Internal Amplification
The CASSIA (CMOS Active SenSor with Internal Amplification) project is focused on developing monolithic active pixel sensors (MAPS) with internal signal gain in the Tower 180nm CMOS process.
An internal amplification enables the simplification of the in-pixel electronics while simultaneously improving the signal to noise ratio for radiation hardness and offering the potential for excellent timing performance for future 4D tracking applications.
This presentation will focus on measurements of the first prototype sensors (CASSIA1) that have been fabricated to demonstrate the feasibility of the gain layer implementation into the Tower Semiconductor 180nm CMOS process. Currently the second iteration of a new prototype (CASSIA2) is in production, which implements the in-pixel electronics alongside the sensor structure with gain, to operate them in either low-gain (LGAD) or high-gain (SPAD) mode.In this presentation charge collection, gain and time resolution measurements utilising the Transient Current Technique will be presented, comparing the four different matrices with varying gain-layer designs for sensors produced in the epitaxial and in the Czochralski process. Additionally, the waveforms are evaluated to investigate the effects of the different gain layer sizes.
Furthermore, first results of a recent beam test at CERN SPS will be shown to further explore the sensor performance and compare to the TCT results.Speaker: Leena Diehl (University of Zurich (CH)) -
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Characterisation of pixel chip prototypes for ALICE 3
A major upgrade of the ALICE experiment is foreseen for Run 5 of the LHC. The new retractable Vertex Detector (VD) is a crucial component of the upgraded experiment and will achieve an unprecedented pointing resolution owing to its close proximity to the interaction point, with three layers installed inside the beam pipe, in combination with a low material budget. Monolithic active pixel sensors (MAPS) are ideally suited, yet require significant research and development to meet the combined requirements in position and time resolution as well as radiation hardness, all while limiting the power consumption. In addition, the desired position resolution of 2.5 µm and, thus, a pixel pitch of 10 µm requires an unprecedented integration density. To this end, small pitch prototypes are characterised in view of charge collection properties to pave the way towards a pixel chip targeting the requirements of the ALICE 3 vertex detector. A second variant of the pixel chip is adapted to the needs of the tracker layers (barrel and forward disks) surrounding the VD up to a radius of 80 cm.
In this contribution, the pixel chip requirements and design concepts for the VD and outer layers will be presented. Particular focus will be given to the characterisation of prototypes to validate the required technological steps towards ALICE 3, including laboratory measurements and testbeam campaigns.Speaker: Elena Dall'Occo (CERN) -
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Status of the OCTOPUS project
The OCTOPUS project focuses on the simulation, development, and evaluation of fine-pitch monolithic pixel sensors produced in the 65 nm TPSCo process. All activities are pursued within the DRD3 collaboration on solid-state detectors. The key final development goals target the requirements of vertex detectors for future lepton-collider experiments. They include a single-point resolution of 3 µm, a time resolution below 10 ns, a hit-rate capability of up to 100 MHz/cm², thinning to 50 µm, an average power consumption below 50 mW/cm², a minimal inactive periphery area, and a sensor architecture scalable to a large-area detector system. The development of new high-resolution sensors for beam telescopes is foreseen as an intermediate target, with relaxed power-consumption (<500 mW/cm²) and timing requirements (100 ns). This contribution introduces the project and presents the current status and plans in the areas of technology evaluation, simulations, sensor and ASIC design.
Speaker: Dominik Dannheim (CERN) -
70
Monstera - status and latest developments of CMOS strips
Large tracking detector volumes for next generation particle physics experiments require scalable technologies at moderate costs and at highest possible integration levels to reduce system complexity. The Monstera project investigates fully integrated strips developed in LFoundry 150nm HV-VMOS, based on previous successful testing of passive strips. The design profits from the exiting readout and configuration scheme that has been implemented for example in the LHCb Mighty tracker upgrade. The contribution will recap on previous passive strip testing and simulation, introduce the current design status within a shared DRD3 submission and give a preview on planned tests for the active strip sensor when returning from the foundry.
Speaker: Marta Baselga (Technische Universitaet Dortmund (DE))
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66
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12:30
Lunch
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Other applicationsConvener: Roberta Arcidiacono (Universita e INFN Torino (IT))
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71
Hybrid detectors for synchrotrons and XFELs
Detectors for photon science inherit concepts and technologies originally developed for vertex detectors in high-energy physics, driven by shared demands for high granularity, low noise, radiation tolerance, and fast frame rates. While the underlying sensors and readout chips show strong commonality, the experimental requirements differ fundamentally: unlike HEP vertex systems, photon-science detectors do not perform particle tracking due to the point-like absorption of X-rays, but instead focus on precise photon counting, imaging, spectroscopy, and operation across an extreme dynamic range. To meet these needs, photon-science instrumentation has developed advanced readout techniques to achieve both single-photon sensitivity and very high dynamic range. While single-photon counting revolutionized science at synchrotrons, charge-integrating detectors with dynamic gain switching are essential to achieve a dynamic range of 10^4 photons at X-ray Free Electron Lasers (XFELs). The rapid increase in source brilliance at synchrotrons and in repetition rate at X-ray free-electron lasers creates challenges analogous to those faced in collider experiments, particularly regarding data throughput, power density, and frame-rate capability.
From the sensor side, while planar silicon pixel sensors, as used in vertex detectors, are the standard choice, current research explores the customization of Low Gain Avalanche Detectors (LGADs) for soft X-ray detection, exploiting their internal gain to detect low-energy X-rays with improved signal-to-noise performance. At higher photon energies, compound semiconductor materials such as CdTe and GaAs can provide superior stopping power compared with silicon, and current research aims at developing materials with improved homogeneity and charge-collection properties.
The significant advances achieved in photon-science detector development can now provide valuable feedback to the vertex detector community, particularly through the characterization, the operational experience and the development of novel concepts and technologies, highlighting the importance of continued exchange and collaboration between the two communities.Speaker: Anna Bergamaschi -
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Improving spatial resolution in Transmission Electron Microscopy using the sub-ns timing sensitivity of Timepix4
We report on the use of Timepix4 as a detector for Transmission Electron Microscopy, and the rapidly growing demand for hybrid silicon detectors in this field. We discuss the benefits and limitations of thick hybrid silicon detectors such as the timepix4 in this use case, and present measurement results demonstrating how the sue of post processing can improve the spatial resolution of the detector at 100 keV and 200 keV electron energies.
Specifically, we explore the use of the additional temporal and energy information available from the Timepix4 compared to electron counting or integrating detectors. This allows us to reconstruct individual electron hit-clusters and estimate the actual sensor interaction point to sub pixel resolution. We present Modulation Transfer Function (MTF) knife edge resolution measurements carried out at the Rosalind Franklin Institute (RFI) in collaboration with RFI team and Quantum Detectors Ltd that show substantial improvements for various post-processing methods, and tie these to the expected electron trajectories at different energies. These methods include using the sub-ns time resolution available in the Timepix4 to measure the charge drift in a thick silicon sensor to form a pseudo-solid-state-TPC, and reconstructing the sensor entry point on an event-by-event basis. We compare this quantitatively to currently used detection methods. Additionally, we discuss the hardware requirements needed to operate the Timepix4 in this quite challenging very high electron rate, vacuum environment and the engineering involved in this system.
We also look forward to the incorporation of these techniques into production microscope systems and examine the integration challenges in dealing with the large data rates and fast processing involved in a non-Particle Physics setting.Speaker: Richard Plackett (University of Oxford (GB)) -
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Hardware Demonstration of Level-1 Vertexing with the Track Finder for the CMS Phase-2 Upgrade
The High-Luminosity LHC will require the CMS Level-1 (L1) trigger to operate in an environment with up to 200 simultaneous proton–proton interactions per bunch crossing. To maintain efficient event selection under these conditions, the CMS Phase-2 upgrade introduces real-time tracking and vertex reconstruction at L1.
In this work, we present a hardware demonstration of L1 vertex reconstruction using the CMS Phase-2 Track Finder. The system is realised as a multi-board demonstrator at CERN, in which track reconstruction and vertexing are implemented on separate FPGA-based platforms. A dedicated Apollo board executes the Track Finder chain to produce tracks at L1, while a Serenity board performs vertex reconstruction, together forming a complete end-to-end L1 tracking-to-vertexing pipeline.
The demonstrator is operated using an integrated online software framework for control and configuration across multiple hardware components. Realistic input data are provided via test vectors derived from simulated $t\bar{t}$ events overlaid with an average pileup of 200 interactions, generated within the CMS offline software framework.
These results demonstrate the feasibility of real-time vertexing in hardware and validate key components of the CMS L1 trigger upgrade strategy. The implications for L1 trigger performance in the Phase-2 era are discussed.
Speaker: Andrew Mastronikolis (Imperial College (GB)) -
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Advanced muon spin spectroscopy using silicon-pixel vertex reconstruction at PSI
Muon spin rotation, relaxation and resonance (μSR) is a powerful local-probe technique for studying magnetism, superconductivity and spin dynamics in quantum materials. However, conventional continuous-beam μSR spectrometers are intrinsically limited by the requirement that only one muon is present in the sample during the measurement time window. This constrains the usable stopped-muon rate and makes measurements on small, inhomogeneous or spatially patterned samples particularly challenging.
At the Paul Scherrer Institute, we are developing Advanced Muon Spectroscopy (AMS), a new μSR concept based on ultra-thin monolithic silicon-pixel detectors and vertex reconstruction. By tracking both the incoming muon and the decay positron, the stopping position of each muon can be reconstructed and correlated with the time-dependent spin asymmetry. This enables vertex-reconstructed μSR (vx-μSR) spectra, opening the path to measurements on millimetre-scale samples, and providing a route towards substantially higher data-acquisition rates at continuous muon sources.
In this contribution, we present the detector concept, reconstruction strategy and first experimental demonstrations of silicon-pixel-based μSR at PSI. We discuss the requirements imposed by low-energy charged-particle tracking close to the sample, including material budget, multiple scattering, timing, hit-rate capability and integration with μSR sample environments. We also outline ongoing developments towards high-rate, position-resolved and triggerless data acquisition, with the longer-term goal of enabling triggerless pump-probe vx-μSR measurements of transient magnetic and electronic states.
AMS illustrates how technologies and methods developed for vertex detectors can enable qualitatively new capabilities in condensed-matter spectroscopy. It therefore provides a concrete example of cross-fertilisation between high-energy detector instrumentation and applications in quantum materials research.
Speaker: Dr Zaher Salman (The Paul Scherrer Institute)
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15:20
Coffee break
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System integration: Mechanics/ElectronicsConvener: Wolfram Erdmann (Paul Scherrer Institute (CH))
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Low-Mass Mechanics for Vertex and Tracker Detectors at Future Colliders: Challenges and Perspectives
Future collider experiments such as FCC-ee, EIC and the ALICE ITS3 upgrade require ultra-light vertex detectors with extremely low material budget, high mechanical stability and detector layers positioned very close to the interaction point. These requirements pose significant mechanical and integration challenges, particularly for large-area ultra-thin MAPS sensors operated with air cooling and minimal support material.
This work presents the development and validation of lightweight mechanical architectures for next-generation vertex detectors based on stitched ultra-thin MAPS sensors integrated on carbon-foam and carbon-fibre support structures. Different mechanical solutions are investigated, including fully curved self-supporting geometries and planar low-mass staves for FCC-ee detector concepts. A systematic programme of engineering prototypes has been carried out to study sensor integration, structural rigidity, service routing, airflow cooling and vibrational behaviour. Dedicated experimental setups and CFD studies have been developed to characterise airflow distribution, thermal performance and aeroelastic stability under realistic operating conditions.
The results demonstrate material budgets below 0.1% X/X₀, sub-micron mechanical displacements under airflow and efficient air-cooling operation without liquid-cooling infrastructure, validating the feasibility of mechanically stable ultra-light detector structures for future high-precision collider experiments.
Speaker: Gherardo Ammirabile (Universita & INFN Pisa (IT)) -
76
Advanced Cooling Concepts for Vertex and Tracker Detectors at Future Colliders
The next generation of high-energy physics experiments demand thermal management solutions to balance power densities with ultra-low material budgets. Within the DRD8 (Mechanics) framework, research is focused on advancing silicon- and ceramic-based microchannel cooling. By placing the coolant in direct proximity to the heat source, these technologies achieve highly efficient heat removal. Current developments emphasize CMOS-compatible fabrication, active interposers for electrical integration, and low-cost silicon processes using hyperbaric bonding, all while aiming for a material budget as low as $0.2\% X_0$.
One of the primary drivers for these innovations is the LHCb VELO Upgrade 2, which serves as a benchmark for high-power scenarios. This detector requires stable operation in a vacuum while sustaining power dissipations of approximately $2\text{ W/cm}^2$ and resisting radiation doses up to $10^{17} \text{ MeV n}_{eq}/\text{cm}^2$. To meet these needs, current designs utilize evaporative $\text{CO}_2$ cooling which requires validation to high pressure (186 bar).
Building on the success of the large-scale $\text{CO}_2$ systems currently being commissioned for ATLAS and CMS, new research is exploring supercritical $\text{CO}_2$ (sCO$_2$) for electronics operating between $+35^\circ\text{C}$ and $+40^\circ\text{C}$. As an electrically non-conductive fluid with low viscosity and high heat transfer coefficients, sCO$_2$ allows for smaller, lighter piping and microchannel integration. This is particularly advantageous for detector regions with confined spaces.
For future detectors requiring Ultra-Low-Temperature (ULT) operation potentially down to $-140^\circ\text{C}$ (in a 2 stage approach), research has shifted toward Krypton (R784). Since $\text{CO}_2$ freezes at $-56.6^\circ\text{C}$, Krypton offers a promising evaporative candidate for the colder environments. Unlike $\text{CO}_2$, Krypton requires a specialized transcritical cooldown cycle to prevent thermal shock during liquefaction. This talk will review the principles of these sustainable cooling architectures and present the latest experimental results designed for future collider applications.
Speaker: Javier Fernandez-Tejero (Institut de Microelectrònica de Barcelona (IMB-CNM, CSIC) (ES)) -
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Data transmission technologies for future Vertex and Tracker detectors
The increasing integration density, channel count, and resolution of tracking and vertex detectors continue to drive the requirements for detector readout systems. In parallel with the demand for higher data bandwidth, improved power efficiency is also becoming increasingly important, motivating ongoing research to meet the needs of future detectors. The DRD7.1 activity coordinates a variety of efforts toward these goals, developing optical links based on silicon photonics technologies as well as wireless data transmission links. Radiation tolerance, low mass, and compatibility with detector integration are key considerations guiding these developments. This contribution summarizes the ongoing efforts within DRD7.1 and presents the current development status of the proposed solutions.
Speaker: Stefan Biereigel (CERN) -
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Timing distribution for future 4D tracking detectors
In the High-Luminosity Large Hadron Collider (HL-LHC) environment, precise timing information will be essential to disentangle events under extreme pile-up conditions. This places stringent requirements on timing distribution systems, which must deliver a stable and accurate bunch clock to thousands of front-end chips within detector experiments.
These systems are typically implemented using FPGA-based high-speed serial optical links, which transport a synchronous clock to radiation-tolerant front-end electronics. However, timing instabilities can arise at multiple levels in the distribution chain. These include fast phase fluctuations (jitter), as well as longer-term effects such as wander, temperature-dependent variations, and limited phase reproducibility. In complex, multi-stage distribution architectures, such effects can accumulate and significantly impact the overall timing performance.
This talk provides a comprehensive overview of the timing challenges associated with the HL-LHC, along with a review of current technologies for high-precision timing distribution.
In addition, it will present ongoing research within the DRD7 R&D programme, focusing in particular on DRD7.3c (Timing Distribution Techniques) and DRD7.3b (Strategies for Characterization and Calibration of Timing Uncertainties). These efforts aim to support the development of future 4D detectors.
Speaker: Eduardo Brandao De Souza Mendes (CERN) -
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Powering Next Generation Detector Systems: The DRD7.1b Project
Future particle physics experiments will require detectors with a much larger number of channels, higher data rates, and the ability to operate in extreme radiation and temperature conditions. This trend is already being observed in current detector upgrades, where increasing detector granularity, faster readout electronics and more complex front-end systems are leading to higher power demands. As a result, power delivery systems represent one of the key engineering challenges for the next generation of experiments. Project DRD7.1b is part of the ECFA DRD7 collaboration, and its goal is to develop power distribution schemes, voltage and current regulators, and power converters suitable for future detector applications, from neutrino experiments to high-luminosity collider detectors.
The project investigates two complementary powering approaches: parallel powering, based on DC-DC conversion, and serial powering, where a chain of modules shares a common constant current.
For parallel powering, a two-stage conversion scheme is being developed. The first stage handles conversion from 48 V down to an intermediate voltage, with CERN developing a GaN-based converter and TalTech exploring an alternative single stage topology. The second stage, targeting on-chip regulation down to 0.9V in 28nm CMOS technology, is being addressed in parallel by FH Dortmund and a CERN–UniUD team, each exploring different converter architectures. RWTH Aachen contributes by integrating the bPOL48V converter into CMS Phase-2 Outer Tracker modules to characterise its noise impact.
For serial powering, a similar two-stage scheme is being developed. ITA is working on a COTS-based 48 V input GaN current source focused on embedded filtering, low-noise operation and modular scalability. In parallel, FH Dortmund is developing next-generation Shunt-LDO regulators in 28 nm technology for on-chip current-to-voltage conversion. INFN, together with the University of Milan, is building a demonstrator to characterise serially powered monolithic pixel modules.
Results and progress from all these efforts will be presented.Speaker: Alvaro Pradas Luengo (Aragon Institute of Technology Itainnova (ES)) -
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A Combined Serial Powering Approach for the ATLAS and CMS HL‑LHC Trackers
The High-Luminosity phase of the Large Hadron Collider (HL-LHC) poses unprecedented challenges to the inner tracking detectors of the ATLAS and CMS experiments, particularly in terms of channel density, power consumption, material budget, and radiation tolerance. Within this context, serial powering has been identified as a key technology to efficiently distribute power while significantly reducing cable mass and associated material. This contribution presents a combined serial powering approach developed through coordinated efforts between ATLAS and CMS. The proposed scheme integrates local regulation, active protection mechanisms, and common control strategies to ensure stable and robust operation at the system level. After reviewing the main HL-LHC requirements and the motivations for serial powering, the talk will focus on the architectural choices of the combined approach, addressing critical aspects such as fault tolerance, voltage distribution along the chain, and electromagnetic compatibility. Experimental results obtained from laboratory setups and detector-representative prototypes will be discussed, demonstrating system performance under realistic load conditions and irradiation environments. The experience gained highlights how a coordinated strategy between the two experiments helps mitigate risks, consolidate design choices, and accelerate the validation of key powering technologies for next-generation vertex and tracking detectors.
Speaker: Antonio Cassese (INFN, Firenze (IT))
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19:30
Dinner and announcement of poster prize winner
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New DevelopmentsConvener: Stefano Terzo (IFAE Barcelona (ES))
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Recent developments in Allpix Squared
The Allpix Squared Simulation Framework is a versatile, open-source simulation framework for semiconductor pixel detectors. Its eases the implementation of detailed simulations for single sensors as well as more complex structures with multiple detectors, and small experiments. Over the past decade, it has been used in many projects in high-energy physics as well as medical imaging, synchrotron light sources, and satellite-based detectors. It is capable of simulating a wide range of detector types for various application scenarios, e.g. through its interface to Geant4 to describe the interaction of particles with matter, and the different algorithms for charge transport and digitization. The simulation chain is arranged with the help of intuitive configuration files and an extensible system of modules, which implement the individual simulation steps. Detailed electric field maps imported from finite-element TCAD simulations can be used to precisely model the drift behavior of the charge carriers, bringing a new level of realism to the Monte Carlo simulation of semiconductor particle detectors.
Currently, Allpix Squared is undergoing several improvements to its core framework in preparation of a new major release. and new simulation modules for effects such as self-interaction of charge carriers are being worked on, further extending the application range. This contribution provides an overview of the framework and its components, highlighting recent applications for vertex detector simulations.
Speaker: Naomi Davis (ATLAS) -
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Progress of SiC and GaN as particle detector
Wide band-gap (WBG) semiconductors such as SiC and GaN are desirable material for charged particle spectroscopy in high temperature, high radiation environments. SiC PIN, Schottky and LGAD devices have been fabricated in the past few years. Detector response such as spatial and temporal resolution at higher temperatures and irradiation environments have been investigated by several groups. For GaN, a variety of homoepitaxial Schottky diode test structures have been fabricated and characterized by I–V and C–V measurements to determine the Schottky barrier, the low background (unintentional) doping, and the room-temperature leakage current. In addition, UV illumination combined with DLTS is used to evaluate carrier collection efficiency and to identify deep-level trap states. Temperature-dependent electrical measurements are further performed to analyze design-dependent leakage mechanisms, providing guidance for optimizing radiation detector performance.
Speaker: Valentina Sola (Universita e INFN Torino (IT)) -
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Progress in 3D Diamond detector characterisation and design
3D diamond detectors for ionising radiation can be produced with femto-second laser systems and beam shaping techniques, allowing feature sizes of micron precision inside the bulk diamond.
Diamond is a proven radiation hard material, while the 3D electrode geometry reduces the drift length to produce a signal and this enhances the detector tolerance to radiation damage.
We report about the latest progress in prototyping 3D diamond detectors to be used in the ATLAS for the phase-2 upgrade and for future particle physics experiments at the Future Circular Collider. New electrode geometries have been tested to improve the uniformity of the detector response as well as the timing resolution and radiation hardness.
Prototypes have been build and tested with the two photon absorption technique, test beams at CERN and micro-proton beams at RBI, Zagreb. The results show promising performance in terms of charge collection efficiency, superior to conventional planar diamond detectors.Speaker: Alexander Oh (The University of Manchester (GB))
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Coffee break
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New DevelopmentsConvener: Martin Kocian (SLAC National Accelerator Laboratory (US))
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Talk by the poster prize winnerSpeaker: Jona Dilg (University of Zurich (CH))
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Quantum sensors for forward detectorsSpeaker: Ben Kilminster (University of Zurich (CH))
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Modern interconnection technologies for pixel detectors
In this presentation an overview of interconnection technologies for hybrid pixel detectors as used in HEP experiments is given. Since more than twenty years the classical fine-pitch bump bumping with solder (SnAg, Cu pillars) and indium with pitches down to 50 µm or below is the state-of-art technology for hybrid pixel detectors in use for example at all LHC and HL-LHC experiments. But since a decade more modern technologies such as die-to-wafer, wafer-to-wafer bonding in connection with metal direct or polymer-metal-hybrid bonding and 3D integration techniques (TSV, backside RDL) come into the focus which would allow significant improvements in terms of performance, scalability and costs. With such technologies finer pitches down to 10µm or below could be achieved while the material budget of the pixel detectors could be kept very low due to post bonding thinning capabilities. Additional 3D integration features of TSV and RDL enables more integrated module concepts with four-side buttable chips and integrated services chains. On the other hand also more flexible, fast and low cost integration techniques of pixel detectors are investigated for prototyping and small-scale projects. Among possible solutions are in-house techniques like anisotropic conductive film or paste bonding (ACF/ACP) which combine a simple deposition process for the conductive film/paste with high precision flip chip processes usable for fine-pitch application.
In this presentation the advantages, disadvantages, possibilities and problems of these integration technologies are reviewed and discussed not only for larger projects like future vertex detectors at electron or hadron colliders but also for smaller projects and R&D purposes.Speaker: Fabian Huegging (University of Bonn (DE)) -
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NEUROPix: Spiking Neural Networks fo pixel detector data processing
Advances in edge computing for future high energy physics experiments, electron microscopy, and neutron imaging demand state of the art hardware and software solutions. Modern experimental environments require rapid data handling and real time processing, including precise and consistent particle identification and characterization at nanosecond timescales. The high data rates typical of these systems further necessitate approaches that minimize or eliminate long term data storage.
The NEUROPix project aims to address these challenges by integrating spiking neural networks into FPGA based firmware and charting a pathway toward neuromorphic computing ASICs capable of processing raw outputs from high throughput event based cameras. As with all machine learning approaches, the foundation of this effort is the development of a large, realistic, and detailed training dataset, generated using Allpix2.
This presentation will outline the strategies employed in dataset creation, discuss the constraints associated with spiking neural network based processing, describe the training methodology, and highlight potential applications at ORNL. Future directions for the NEUROPix project will also be presented, along with an invitation to the community for input on additional machine learning applications.Speaker: Mathieu Benoit (Oak Ridge National Laboratory (ORNL)) -
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Smart pixels: on-chip data reduction with machine learning
High-granularity pixel detectors at the LHC and beyond must operate in extreme collision environments and satisfy stringent constraints on power consumption and read-out bandwidth. Current-generation pixel detectors produce too much data to read out for every collision, and the future experiments will face even bigger challenges due to smaller pixel pitch and more complex beam backgrounds. Edge machine learning (ML) algorithms implemented in the pixel front-end readout electronics can reduce the amount of data that must be read out, and sufficient reduction would enable full-collision analysis of every event. Smart pixels is a coordinated effort to co-design ASICs and ML algorithms suited to this task. I will present the status of ongoing work in smart pixels, including an overview of the algorithms designed and the testing of the first 28nm ASIC implementation.
Speaker: Jennet Elizabeth Dickinson (Cornell University (US))
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Closure
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CloseoutSpeaker: Anna Macchiolo (University of Zurich (CH))
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