MPGD 2026

Aug 31, 2026, 8:00 AM → Sep 4, 2026, 6:00 PM Europe/Prague

Masarykova Kolej Congress Centre, Czech Technical University in Prague

Hugo Natal Da Luz (Czech Technical University in Prague)

 

Announcement

Deadline extension of the early registration fee: 14th of July

 

Welcome to the 9^th International Conference on Micro-Pattern Gaseous Detectors, MPGD2026. This year's edition will be hosted by the Institute of Experimental and Applied Physics at the Czech Technical University in Prague, Czech Republic, from August 30 to September 4, 2026.

 

Following an already long series of very exciting and proficuous gatherings which started in Crete, Grece (2009) and continued in Kobe, Japan (2011), Zaragoza, Spain (2013), Trieste, Italy (2015), Philadelphia, USA (2017), La Rochelle, France (2019), Rehovot, Israel (2022) and Hefei, China (2024), we are pleased to welcome you in Prague, a city of science, music, culture and art.

 

Plenary sessions of contributed talks will be preceded by invited talks that will give a broad perspective of MPGD in the realm of gaseous detectors and also other technologies. A poster session will also take place, offering a further opportunity to present research work.

 

The topics covered in the conference include

● Simulation and software

● Detector physics

● MPGD technologies

● Applications

● Electronics

● Production techniques

 

The proceedings will be published in the Journal of Instrumentation. The submission procedure will start after the conference and will be managed by JInst.

Important dates:

• Early registration and call for abstracts: 1 December
• Abstract submission deadline: 24 April
• Announcement of abstract acceptance: 22 May
• Early registration closes: 14 July (extended from 1 July)
• Registration closes: 14 August

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Latest news

22 May 2026

Abstract acceptance announced.

10 April 2026

Invited speakers:

• Stanislav Pospišil (CTU) - opening session, detector development at the Institute of Experimental and Applied Physics
• Jerry Va'vra (SLAC, ret.) - timing detectors
• Michael Campbell (CERN) - detectors with readout of the Timepix family
• Rui de Oliveira (CERN) - MPGD production techniques
• Jochen Kaminski (Uni. Bonn) - the GridPix
• Paolo Soffitta (INAF-IAPS) - X- and gamma-ray polarimetry in space
• Gregor Kramberger (Jožef Stefan Institute) - Silicon detectors with gain
• Oliver Kortner (MPP Munich) - the FCCee

1 December 2025

Registrations are open. Click here to register.

Abstract submission is open. Click here to submit an abstract.

Partners

Sponsors

 

 

MPGD2026_3rdAnnouncement.pdf

MPGD2026_FirstAnnouncement.pdf

MPGD2026_SecondAnnouncement.pdf

Poster_A3.pdf

Mon, August 31

Arrival and registration

Conference opening session

Invited session: Stanislav Pospišil

Convener: Stanislav Pospišil (CTU in Prague)

1 Invited speaker: Stanislav Pospišil

Speaker: Stanislav Pospišil (CTU in Prague)

Plenary Session

2 Development of the FATIC front-end electronics for the Muon detector at the LHCb Upgrade II

In order to exploit the physics opportunities of the HL-LHC era, the LHCb Collaboration is proposing the Upgrade II of the apparatus. The Muon system, currently exposed to particle rates below 100kHz/cm2, aims at sustaining increased rates up to about 1MHz/cm2 under the operating conditions expected for the Upgrade II. Therefore, for the most exposed inner regions, new detectors with high rate capability based on the μRWELL (micro-Resistive WELL) technology are under study. The readout electronics is based on the FATIC (FAst Timing Integrated Circuit) ASIC, providing charge and timing measurements with 100ps resolution. First prototypes of the FATIC chips have been produced and tested in 2024 and 2025 at the at PS T10 beam line with both μRWELLs and hybrid chambers (GRWELLs), composed of μRWELLs integrated with a GEM foil. Promising performance in terms of both time resolution and particle detection efficiency have been observed. An intensive R&D is currently underway in order to reduce the FATIC dead time to 100ns, satisfying the requirements for the LHCb Upgrade II. This contribution presents the state of the art and future perspectives of the project.

Speaker: Dr Liliana Congedo (INFN Bari (IT))

3 The Stabilized Voltage Divider – A Rate-Capable HV-Scheme for GEMs

Triple-GEM detectors are widely used as tracking detectors in modern particle physics experiments. Typically, a Passive Voltage Divider (PVD) is used to define the electrode potentials from a single input. This circuit generates the required potentials through a resistor chain and limits the current in case of a shorted segment through its high output impedance on the order of MΩ. Under high-rate conditions, the large number of charges moving inside the detector leads to non-negligible potential drops over the bias resistors. This results in a reduction of gain and therefore tracking efficiency, calling for improvements of the high-voltage supply.

The newly developed Stabilized Voltage Divider (SVD) is a MOSFET circuit that provides the nominal potentials with a low output impedance of 100 kΩ during normal operation. This enables stable gain, even at particle rates of several MHz/cm². In the event of a permanent short circuit in a GEM segment, the drawn current is limited by a MOSFET to 20 µA, leaving the other segments unaffected. Strong emphasis was put to ensure the adequate response of the SVD to discharges, minimizing the risk of damage to the detector and its readout.

A detailed explanation on the working principle of the SVD will be given and test beam and lab measurements demonstrating the superior rate capability and safe discharge behavior in triple-GEM detectors will be presented.

Speaker: Jakob Quentin Krauss (University of Bonn (DE))

11:05 AM Coffee break

Plenary Session: Plenary session

4 Progress on the design and testing of the Lateral and Central modules of large area Micromegas for AMBER experiment

The Apparatus for Mesons and Baryon Experimental Research (AMBER, NA66) is a high-energy physics experiment at CERN’s M2 beam line at the Super Proton Synchrotron (SPS). Its broad physics program extends beyond 2032. Measurements of the anti-proton production cross-section on He, proton, and Deuterium to support the dark matter searches, the charge-radius of the proton to contribute to the solution of the puzzle in the values and the Kaon and Pion PDFs using Drell-Yan process are already approved for the initial part of the experiment. For this new apparatus we are designing together with the CERN MPT workshop both a resistive bulk MICRO-MEsh GAseous Structure (MM) detector and a new custom 64 channel fully digital front-end ASIC ToRA (Torino Readout for AMBER) for timing and energy measurements. The MM detector composed of three independent modules with an active area of 1x0.5 m² will cover a total acceptance of 1x1.5 m². Each module includes two readout planes in a face-to-face configuration enabling XUV coordinate measurements, the cathodes are implemented on a thinner common central PCB. For Lateral modules a uniform 10 MΩ/sq Diamond-Like Carbon (DLC) resistive layer is applied on top of the readout strips whereas the Central module is planned with a double DLC resistive configuration. The ToRA ASIC is closely tailored to the specifications of the MM but also suited to equip the existing Wire type detectors to make them compatible with the future trigger-less Data Acquisition system (DAQ) of AMBER. We must face the challenges of detecting 1.5-2.5 fC signals from AMBER Micromegas modules that will have a ~1.2x0.5 m^2 size with ~1.2 m long strips of up to ~500 pF capacitance and expected rates of up to 100-200 kHz/strip. The power consumption of the 65nm ToRA ASIC is expected to be around 10 mW/ch.

We present the results obtained from the first Lateral module both with TIGER ASIC based and ToRA ASIC based readouts in laboratory and beam test conditions. Design considerations and production challenges of the Central module will be discussed. Considerations on the ToRA v2 ASIC now in design phase will be presented.

Speaker: Maxim Alexeev (Universita e INFN Torino (IT))

5 The SALSA versatile readout ASIC for MPGD detectors

The Sao Paulo University and the CEA Saclay IRFU teams are developing a new readout ASIC for MPGD detectors, named SALSA. This ASIC is meant to be versatile and adapted to different kinds of MPGD applications like tracking, time projection chambers or photon detection. The 64-channel chip, designed in the TSMC 65nm technology, will integrate preamplifier and shaper front-ends with 12-bit per channel ADC able to reach 50 MS/s sampling rate. The front-end part will be able to manage large capacitance readout electrodes up to 1 nF, with four configurable amplitude ranges from 0-50 fC to 0-5 pC, and 8 peaking times up to 500 ns. An integrated data processing block will take in charge baseline corrections, zero-suppression and feature extraction before to format the data in packets to be transmitted by up to four gigabit links.

The SALSA project was launched in the framework of the EIC project for the readout of ePIC experiment MPGDs. Different prototypes were produced since 2022 to evaluate front-end and ADC blocks, as well as the phase-locked loop (PLL) block that generates internal clocks. A larger prototype, SALSA1, was then produced in 2024 to validate and measure the performance of the front-end - ADC chain, as well as of service blocks. The SALSA2 prototype, which will include the data processing functionalities of the final ASIC but with 32 channels only, is presently under development. It will be submitted in the second half of 2026, and tested from the beginning of 2027. The final pre-series prototype is expected in 2028, for a series production in 2029. After a presentation of the project and the target specifications of the ASIC, major results on the performance of the SALSA1 prototypes will be shown. Then the ongoing development of SALSA2 will be presented, as well as the major steps of the project.

Speaker: Damien Neyret (CEA IRFU, Université Paris-Saclay (FR))

6 Modular and scalable DAQ system for GEM detectors

This contribution presents the development of a new data acquisition (DAQ) system dedicated to the readout of Gas Electron Multiplier (GEM) detectors. The system is an evolution of a previously developed FPGA-based readout architecture [1], which has been successfully used in various applications with GEMs. Due to the obsolescence and unavailability of the FPGA device employed in the original design, a complete reorganization of the firmware, control infrastructure, and hardware migration was required.

The new system is built around the Enclustra MARS AX3 module, based on an AMD/Xilinx Artix-7 FPGA. To accommodate the new FPGA module, a dedicated base board was carefully designed. The board hosts the FPGA module, ADC circuitry, Ethernet interfaces and other supporting components. It is electrically and mechanically interfaced with a dedicated ASIC board, which connects directly to the GEM detector and performs the front-end signal processing using a dedicated readout ASIC.

A key novelty of the system is the completely redesigned firmware architecture, which was adopted and successfully adapted from our other project [2]. In particular, the system uses XFCP (eXtensible FPGA Control Platform), an open-source framework for FPGA control and communication that uses a source-routed packet-switched bus over AXI Stream and supports operation over UDP, together with a Python-based control framework. In the presented DAQ, XFCP serves as a main communication layer between the FPGA firmware and the host software. In parallel with the hardware redesign, the DAQ control system was also modernized by developing a new communication layer based on the Python language.
Another leap forward is system scalability, now it could readout as many channels -- therefore detectors as needed. The independent FPGA addressing and reliable time synchronization made it possible.

The contribution will discuss in detail the firmware architecture and XFCP integration, the readout hardware design, the data transmission path, and the upgraded DAQ control system. Preliminary measurement results illustrating the correct operation and functionality of the developed DAQ and detector readout will be presented as well.

The authors would like to acknowledge: M. Kopeć, S. Koperny, W. Dąbrowski

References

[1] B Mindur et al 2013 JINST 8 T01005
[2] B. Mindur et al 2025 JINST 20 P06040

Speaker: Bartłomiej Łach (AGH University of Krakow)

7 High Granularity Readout Time Projection Chamber R&D for Future Circular e+e- Collider

The Circular Electron Positron Collider Technical Design Report (TDR), as a Higgs and high luminosity Z factory, has been released in 2023 and 2025 at Institute of High Energy Physics, CAS in China. The baseline design of a detector concept consists of a large 3D tracking system, which is a high precision (about 100μm) spatial resolution Time Projection Chamber (TPC) detector as the main track embedded in a 3.0T solenoid field, especially for the accelerator operating at High luminosity Tera-Z. TPC requires the longitudinal time resolution <100ns) and the physics goals require PID resolution (<3%).
In this talk, we will present the feasibility and progress of the high-precision TPC technology for the Circular Electron Positron Collider (CEPC), even at low-luminosity Tera-Z operation. The fundamental parameters—such as spatial resolution, PID with good separation power using cluster counting, and drift velocity—were studied through simulation and measurement using a TPC prototype with 500 mm drift length. Compared with pad readout in simulation, the high-granularity readout TPC option (hundred-micrometer level) achieves better spatial resolution for single electrons, balanced against power consumption, with very high detection efficiency, excellent tracking, and good PID performance (less than 3σ). Track reconstruction performance and dE/dx results will be presented. In addition, we will report on the ongoing R&D of TPC readout modules based on the TEPIX chip(v1), which represents a key step towards integrated, low-power front-end electronics for future TPC systems. We will review these results and summarize the next steps towards TPC R&D for tracker detectors in future e+e- colliders.

Speaker: Huirong Qi (Institute of High Energy Physics, CAS)

12:45 PM Lunch break

Invited session: Jerry Va'vra

Convener: Dr Jerry Vavra (SLAC)

8 Development of high-resolution timing technique in the past 25 years

The talk describes the progress in high-resolution timing, rate capability and aging performance over past 25 years. It concentrates on recent developments in MCP, SiPM, LGAD, 3D trench Si and SiEM detectors and compares them to gas detectors.

Speaker: Jerry Va'vra (SLAC ret.)

Plenary Session

9 Optical readout of MPGDs with SiPMs

Scintillation light recording is a versatile readout approach for MPGDs which exploits the high granularity of pixellated imaging sensors or the high sensitivity and time resolution of photomultiplier tubes (PMTs). As an alternative to camera- or PMT-based optical readout, we report on the optical readout of GEMs and Micromegas with silicon photomultipliers (SiPMs). The compact dimensions, high sensitivity and good time resolution of SiPMs enable novel readout approaches when combined with MPGDs.
An array of 16 SiPMs was used for optical readout of a triple GEM detector. The signal waveforms from each individual sensor were recorded with a digitiser and signal amplitudes and integrals were extracted during offline analysis. A centre-of-gravity algorithm utilising weights determined from the amplitudes of SiPM signals was used to reconstruct the position of events. Different detector geometries are investigated to improve optical signal sharing across multiple readout channels.
To demonstrate the time resolution achievable with SiPM-based readout of MPGDs, an array of four SiPMs was used to optically read out a glass Micromegas detector in a PICOSEC Micromegas configuration. This detector is characterised by a thin drift region of 200 µm used for preampfification and a bulk Micromegas integrated on a transparent substrate coated with indium tin oxide (ITO). The possibility to reconstruct hit locations was investigated and the time resolution achievable with this combination of a precise timing detector with SiPM readout was measured.
To complement the abovementioned studies of optical readout with SiPMs, scintillation light spectra were measured for a range of gas mixtures based on Ar and He combined with CF$_{4}$ and other quenchers. While CF$_{4}$-based mixtures emit ample visible light which can be directly recorded with conventional SiPMs, the UV light emitted in other gas mixtures can be converted to the visible range with wavelength shifters (WLSs). Optical readout with different gas mixtures is demonstrated, illustrating the versatility of this readout approach.

Speaker: Florian Maximilian Brunbauer (CERN)

10 Optical time projection chamber measurements with an intensified sCMOS camera

Camera-based readouts for time projection chambers (TPCs) are an appealing means of measuring low-energy particle tracks, with low cost per channel, high resolution, and isolation of the readout from the gas volume. We have recently developed an optical TPC with an intensified camera-based readout, called CYGNUS-n, as a test platform for rare-event physics TPCs and other TPC measurement applications. The addition of an image intensifier yields excellent signal-to-sensor-noise performance, allowing measurements of low-energy tracks. The fast switching of the intensifier also allows gating on sub-microsecond transient effects that are not possible with typical camera-based readouts, which are limited to millisecond-scale acquisitions. This talk will discuss the development and initial performance tests of CYGNUS-n, along with reconstruction methods developed for processing intensified camera images.

Speaker: Dr Lindsey Bignell (Department of Nuclear Physics and Accelerator Applications, The Australian National University)

11 Optimization of optical readout micromegas detectors for spatial resolution with X-rays and beta imaging

Conventional Micromegas detectors are typically based on charge readout, which requires a complex electronic chain and becomes increasingly demanding for large-area and high-granularity requirements. As an alternative, optical readout Micromegas detectors use cameras and optical elements to record the scintillation light produced during avalanche multiplication.

Such detectors have demonstrated promising performance for the imaging of X-rays, neutrons, and beta particles. In neutron imaging, the aim is real-time operation in high-radiation environments for applications related to radioactive waste and nuclear fuel characterization. In beta imaging, these detectors are being developed to investigate low-activity radiolabelled samples, with the long-term objective of imaging isotope distributions at the cellular scale. Specifically, this approach could support the development of more effective anti-cancer therapies by enabling the characterization, in pre-clinical models, of the intracellular accumulation of dual labelled antibody–drug conjugates (ADCs). These ADCs would incorporate a tritiated (3H) drug and a 14C-labelled protein component, allowing their distribution to be tracked within individual tumour cells.

In this context, optimizing the optical imaging system to achieve high spatial resolution and sensitivity is a central aspect of this work, with performance determined by both the detector design and the optical chain, including the lens and the camera. An X-ray generator was used to compare detectors with different characteristics, including a non-reflective black mesh, a standard mesh, and a detector incorporating a wavelength shifter (WLS). Spatial resolution was evaluated using a dedicated target with line patterns of varying spatial frequencies. The black-mesh detector operated with an Ar/CF4 gas mixture delivered the best performance, due to reduced light reflections, whereas the WLS-based detector showed degraded resolution as a result of diffusion in the Ar/isobutane gas mixture. In addition, optimization of the optical chain through the use of different lenses made it possible to image X-ray beams with dimensions down to a few tens of micrometres.

For beta imaging, 3H-labelled glucose samples with activities ranging from 10 Bq to 0.01 Bq were studied, and dedicated analysis made it possible to detect drops with activities down to 0.1 Bq. A triple gas mixture of Ar/CF4/Isobutane showed very promising performance, improving detector stability while maintaining sufficient light yield even without the use of a wavelength shifter. In addition, 14C-labelled and 3H-labelled glucose with the same activity were measured simultaneously, demonstrating the feasibility of discriminating between the two isotopes. Imaging of cells constitutes the next step of this work and is currently underway.

Speaker: Elisavet Fasoula (Université Paris-Saclay (FR))

12 Optical Readout of Particle Beam Profile with MPGD

Scintillation light recording is a versatile readout approach for MPGDs which exploits the high granularity of pixelated imaging sensors and can provide additional feedback for beam monitoring applications.
As an alternative to wirechamber-based beam profile and position monitoring, we report on the readout of GEM-based detectors using CMOS- and CCD cameras.
This approach enables semi-online readout of beam parameters for fast feedback and can offer novel live beam profiling.

In this work, we present the progress and results achieved during testbeams with different particles, intensities and conditions, covering muon-, pion- and proton beams as well as electron-flash conditions.
During this period, a secondary detector has been built to supplement the main vacuum-chamber based one, focusing on the reduction of primary scintillation and reflexions within the chamber to optimise for high-intensity beams.

The utilization of a high-speed camera alongside a slow camera allows detection of single ionisation events and building a beam profile from those, as well as long exposition over the spill time which provides an integrated beam profile.

Upcoming studies include further tuning of the detector and camera in muon and pion beams as well as exploration of different image transmission methods for high-radiation environments, allowing for more flexible placement of sensitive readout devices.
Further testbeam campaigns are also planned, both within CERN and external to gather more information about the detectors response to already tested particles and conditions as well as new ones where the focus will lie on flash conditions.

The results demonstrate the viability of optical readout for beam profiling for various beam conditions and type of ionising particles.

Speaker: Bernd Schoenfelder (Technische Universitaet Wien (AT))

Flash talks

3-minutes long flash talks by poster authors.

4:30 PM Coffee break

Plenary Session

13 Studies on the effects of THGEM rim-width on charge accumulation and avalanche to streamer transition by numerical modelling

Radiation dosimetry and radiation therapy are closely related because precise therapy requires precise measurement of the interaction of radiation with biological tissues. Early attempts to understand cellular radiation effects recognized that knowledge of the energy distribution at a scale comparable to the structures affected by irradiation was essential. It turned out that the microscopic distribution of energy deposition in volumes of lineal cellular and sub-cellular dimensions is of critical significance in biological damage. This realization led to the development of micro- and nano-dosimetry.
Among other measuring instruments, Tissue-Equivalent Proportional Counters (TEPC) play an important role in investigations related to these fields. Traditionally, TEPC designs have relied on single wire counter and parallel plate chamber configurations. However, recent studies [1] have indicated that it is important to fabricate TEPCs with very small cavity and avoid pile-up in high intensity beam, that is difficult using single-wire configuration. Use of Micro-Pattern Gaseous Detectors (MPGD), such as Gaseous Electron Multiplier (GEM), Thick GEM (THGEM) simplifies the construction of (i) a miniature counter with a small sensitive volume that reduce pile-up effects and (ii) multi-element counter configurations to increase the sensitivity of the TEPC to measure very low radiation field intensities. Despite such improvements, TEPCs based on MPGDs also suffer from problems related to efficiency, non-uniformity, space and surface charge accumulation. This is especially true for MPGDs such as GEM / THGEM, since they have a significant amount of insulating surface, made of materials such as Kapton, FR4, exposed to the active gas volume. In this presentation, we report results of recent numerical investigations on accumulation of space and surface charge in generic gaseous ionization detectors, which are based on THGEMs, and their effects on device response. Accumulation of surface and space-charge in gaseous ionization detectors are known to influence avalanche to streamer transition [2], onset of inefficiency and response non-uniformity [3]. While the former is delayed by the introduction of a THGEM rim, the latter can remain in control only if the charging up, and space charge accumulation, are entirely uniform, or below a reasonable threshold.
Numerical modelling of these phenomena using particle models faces insurmountable problems due to the fact that charge accumulation occurs over a large number of events and incorporation of space / surface charge effects through all these events becomes computationally intensive [4,5]. Fluid modelling such as those pursued in [6,7], on the other hand, misses important aspects related to statistical fluctuations. In this presentation, we will make an attempt to assess the pros and cons of using both the approaches. Standard HEP software such as Geant4 and Garfield++ will be used for particle modelling, while commercial FEM packages, such as COMSOL, will be used for modelling charge transport as a process described by drift-diffusion. Devices based on THGEMs, with and without rims, will be studied in reasonable detail using both models to understand what effect rim has on the detector response and avalanche to streamer transition from the perspective of charge accumulation on surface, and in the device volume.

Speakers: Abhijit Pal (Adamas University), PURBA BHATTACHARYA (Adamas University, Kolkata, India)

14 Experimental and Numerical Studies of Resistive and Non-Resistive Micromegas for Muon Imaging

Micromegas detectors are a cornerstone of modern high-rate tracking and imaging applications, including muon tomography, where precise spatial resolution and stable operation are essential for accurate trajectory reconstruction. While conventional (non-resistive) Micromegas detectors offer excellent signal localization, they are susceptible to discharges under high-rate conditions. Resistive Micromegas, incorporating a resistive anode layer, provide intrinsic spark protection but introduce charge-spreading effects that can influence position resolution.

In this work, we present a comparative study of resistive and non-resistive Micromegas detectors in the context of muon tomography. The study is based on ongoing experimental efforts involving the characterization of a high-granularity resistive Micromegas prototype alongside available non-resistive Micromegas. The experimental workflow focuses on absolute gas-gain and spatial-resolution measurements using standard radioactive sources.

To support and interpret the measurements, simulations are performed using the Garfield++ framework coupled with an enhanced neBEM (nearly exact Boundary Element Method) solver. The simulations focus on modeling the electric-field configuration, signal induction, and the influence of accumulated space charge on detector response. By combining experimental observations with simulation-based outcomes, this work aims to establish a consistent framework for evaluating the trade-offs between spark tolerance and spatial resolution in Micromegas detectors. The outcomes of this study are expected to provide useful insights for the optimization of Micromegas-based tracking systems in muon tomography and related applications.

Speakers: Shubhabrata Dutta (Atomic, Nuclear and High Energy Physics Group, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF Block, Bidhannagar, Kolkata 700064, West Bengal, India.), Saikat Ghosh (Atomic, Nuclear and High Energy Physics Group, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, 1/AF Block, Bidhannagar, Kolkata 700064, West Bengal, India.)

15 Development of a large area DMM-based photodetector for the RICH detector in STCF

The Super Tau-Charm Facility (STCF) is the next-generation electron-positron collider proposed by China, featuring a center-of-mass energy range of 2-7 GeV. To meet the high-precision particle identification requirements of the STCF, Ring Imaging Cherenkov (RICH) detectors have been extensively studied. The photodetector for the RICH system is required to possess high gain and large-area coverage. A novel RICH detector based on a double micro-mesh structure (DMM) integrated with a photocathode was developed, leveraging its advantages of high gain, large-area scalability, and potential for good time resolution.
In this study, Garfield++ simulations were employed to optimize the mesh parameters, electric field settings, and working gas of the DMM detector. Reflective Cesium Iodide (CsI) photocathodes with a thickness of approximately 500 nm were successfully deposited on the top mesh. The quantum efficiency of the CsI photocathode deposited on the stainless steel mesh was verified to be consistent with that on the gold-plated PCB surface. Prototypes with a sensitive area of 32 cm × 32 cm achieved a gain exceeding 1 × 10⁵ (tested with 5.9 keV X-rays), with a gain uniformity better than 15%. Cosmic ray and beam tests were performed to study the performance of the DMM-based photodetector, as well as the performance of the Cherenkov radiator and the CsI photocathodes. The results confirmed that the prototypes are capable of meeting the requirements for single photoelectron detection. These results demonstrate the feasibility and promising performance of the DMM-based RICH detector, indicating its great potential as a high-performance photodetector solution for the STCF and experiments.

Speaker: Xu Wang (University of Science and Technology of China (CN))

16 PICOSEC Timing with Graph Neural Networks

PICOSEC MicroMegas (PICOSEC-MM) is a high precision timing Micro Pattern Gaseous Detector (MPGD) developed to reach time resolutions on the order of a few tens of picoseconds. Its operation is based on detecting Cherenkov light generated in a crystal radiator. The ultraviolet photons produced are converted into photoelectrons by a photocathode, and the signal is subsequently formed through a two stage amplification process.

Test beam studies using muon beams have shown that PICOSEC-MM prototypes can achieve a time resolution of about $ \sigma_t \approx $ 10ps when the avalanches from all photoelectrons are collected on a single pad; this is referred to as the intrinsic resolution. In addition, the signal formation mechanism in PICOSEC-MM detectors has been thoroughly investigated and modeled, providing a detailed understanding of their timing behavior, including resolution and systematic time offsets.

However, maintaining this level of precision becomes significantly more challenging in multi pad PICOSEC-MM detectors, where photoelectrons are distributed across multiple anode pads. Traditional signal reconstruction methods, based on combining individual pad signals, suffer from systematic errors. These effects are particularly pronounced for non central tracks, i.e., when the muon track crosses the detector near pad boundaries. Such systematic time offsets are difficult to model and typically require large calibration datasets for proper parameterization.

In this work, we present a novel signal reconstruction framework based on Graph Neural Networks (GNNs). We demonstrate that this approach can provide unbiased, high precision estimates of the particle arrival time using raw digitized waveforms as input. By representing the detector’s multi pad signals as a graph, the network learns both spatial correlations and signal sharing effects. Moreover, by employing a Gaussian Negative Log Likelihood (NLL) loss function, the model simultaneously performs regression of the particle arrival time ($t_{GNN}$) and estimation of its uncertainty ($\sigma_{GNN}$) on a track by track basis.

Our results, based on muon beam data, show that the GNN architecture effectively recovers the intrinsic timing resolution (within $\sim$ 1 ps), even in cases where photoelectrons are shared across pad boundaries. In addition, the model’s self estimated uncertainty is shown to be a consistent and unbiased measure of the true timing resolution. Finally, the computational efficiency of the GNN framework enables fast inference, offering a scalable solution for real time particle timing.

Speaker: Ioannis Karakoulias

17 Simulation and Reconstruction of e+ and e- Trajectories in a Time Projection Chamber with Orthogonal Fields

In this work, we describe the development of track- and energy-reconstruction algorithms for atypical Time Projection Chambers (TPCs) that will be used at the Institute of Experimental and Applied Physics, Czech Technical University in Prague, to search for the ATOMKI anomalous internal pair–creation phenomenon. These chambers operate with an inhomogeneous toroidal magnetic field oriented orthogonally to the electric field; we therefore refer to them as Orthogonal-Fields TPCs. Although this configuration distorts the drift inside the chamber and complicates the resulting electron and positron trajectories, it also offers several advantages. We present the most effective of several tested approaches, which employs a simulated ionization-electron drift map for track reconstruction and a Runge–Kutta–based fit for energy reconstruction. Finally, using simulations, we demonstrate that—assuming an ideal charge readout with no amplification and no noise, and with known initial track positions and directions—it is possible to achieve a fitted sigma better than 1% for both electrons and positrons after applying corrections for systematic effects dependent on track parameters.

Speaker: Martin Vavřík (IEAP CTU)

Reception

Tue, September 1

Invited session: Michael Campbell

Convener: Michael Campbell (CERN)

18 Invited speaker: Michael Campbell

Speaker: Michael Campbell (CERN)

Plenary Session: Plenary session I

19 A new design of secondary electron detector for low-energy radioactive ion beam

New facilities like FAIR at GSI or SPIRAL2 at GANIL, will permit to provide radioactive ion beams at low energies (less than 10 MeV per nucleon). Such beams have generally a large emittance, which requires the use of beam tracking detectors to reconstruct the exact trajectories of the nuclei. To reduce the angular and energy straggling that classical beam tracking detectors would generate in the beam due to their thickness, we propose the use of SED (Secondary Electron Detectors). The detector studied in this work consists in a low pressure gaseous chamber (below 10 mbar) placed outside the beam coupled to an emissive foil in the beam. Different low pressure gaseous detectors (wire chambers and micromegas) have been constructed and tested for several years at GANIL. The performances achievable at very low pressure are similar or even better than at atmospheric pressure. The fast charge collection leads to excellent timing properties as well as high counting rate capabilities even for a wire chamber. The spatial, temporal and counting rate performances of the final detector were measured both with radioactive source and a 238U beam. The results demonstrate the good functioning of the detection system as well as its suitability and adaptability to the detectors to which it will be coupled. Time and spatial resolutions below 150 ps and 0.5 mm, have been achieved, respectively, even at high counting rates. A comparison of CF4 and iC4H10 was also performed, including systematic gain measurement, providing new insights concerning the behavior of these gases at very low pressure.

Speaker: Julien PANCIN (GANIL)

20 Low pressure and low energy studies of μ-RWELL in planar and cylindrical geometries

The micro-Resistive WELL (μ-RWELL) is a state-of-the-art Micro-Pattern Gaseous Detector combining high gas gain with intrinsic spark-suppression in a single amplification stage. Its design versatility and robust performance make it well suited for use in various fields of study such as nuclear, particle, and dark matter physics, as well as medical and nuclear security applications. This work details the integration of flexible μ-RWELL detectors as the gas amplification stage for TACTIC (TRIUMF Annular Chamber for Tracking and Identification of Charged particles), a cylindrical Active-Target Time Projection Chamber designed for studies of astrophysically relevant nuclear reactions.
We evaluate the performance of large-area μ-RWELL detectors in both planar and cylindrical geometries across various gas mixtures. Key parameters including gas gain and energy resolution achievable are investigated using alpha and 55Fe X-ray sources. Particular emphasis is placed on the characterisation of μ-RWELL in helium-based gas mixtures, motivated by the use of helium as the most common target gas in Active-Target detectors for studying alpha-induced nuclear reactions. We also present comparative charging up studies in planar and cylindrical geometries at gas pressures as low as 0.2 atm. Furthermore, we demonstrate sub-keV energy detection capability and an energy resolution of 9%, highlighting the sensitivity to low-ionising charged particles for ion beam experiments. Finally, we report the successful in-beam experiments with TACTIC at TRIUMF, demonstrating for the first time the implementation of μ-RWELL detectors in a curved geometry for such applications.

Speaker: Soham Chakraborty

21 Developments for Spherical Proportional Counters

NEWS-G is an experiment searching for dark matter using Spherical Proportional Counters (SPCs). SPCs are low capacitance detectors which allow the detection of gas ionisation with very low (single electron) thresholds. It consists in a grounded metal sphere with a small sensing anode at the center, creating a radial electric field. Its low capacitance, and the possibility to use low mass target gases such as neon, helium and methane, make it an interesting candidates to detect low mass dark matter. It also has potential for the detection of low energy neutrinos through coherent nucleus elastic scattering (CEvNS).

Due to the simple design, drift and amplification fields are entangled.
A multi-anode system (dubbed achinos) was developed to improve the drift field. Building such structures with a surface resistivity that allows stable operation has been a challenge. I will show the challenges and the solutions that were found, and how 3D printing with novel materials could allow to explore new geometries and improve the detectors capabilities at lower cost.

I will also discuss some recent results on the effects of oxygen contamination on SPC operation. Attachment on oxygen has been found to be a significant source of background for the NEWS-G experiment. Work is ongoing to correctly describe the effect in simulations.

Speaker: Philippe Gros

Flash talks

3-minutes long flash talks by poster authors.

11:10 AM Coffee break

Plenary Session: Plenary session II

22 µ-RWELL R&D activities for the IDEA muon system at FCC-ee

The ongoing R&D program focuses on optimizing both the detector and the readout electronics to meet stringent system requirements. Various readout architectures are currently under investigation, including a novel µ-RWELL layout featuring a double DLC layer, designed to increase the charge spread by leveraging a lower resistivity while keeping an high resistivity to quench the discharges. Concurrently, a comparative analysis of the TIGER and APV-25 front-end electronics is being conducted to improve integration with the detector, with a strong focus on noise reduction. These studies are validated by test-beam campaigns at the CERN SPS.

Simulation tools are extensively leveraged to model the integration of the µ-RWELL with new electronic stages and to guide the design of a dedicated ASIC. Furthermore, the full implementation of the µ-RWELL muon system within the IDEA DD4HEP framework allows for a precise evaluation of the detector's performance in the FCC-ee environment.

This contribution presents the latest updates on detector R&D, electronics characterization, and simulation studies, outlining the roadmap toward the final µ-RWELL configuration for the IDEA muon system.

Speaker: Emma Di Fiore (Universita e INFN, Ferrara (IT))

23 Performance of cylindrical μRGroove in magnetic field

The μRGroove is a novel micro-pattern gaseous detector with a resistive micro-groove amplification structure. A cylindrical μRGroove (c-μRGroove) detector was developed for inner tracking application in future electron-position collider experiments, such as the Super Tau-Charm Facility. Its spatial resolution in strong magnetic field is a key figure of merit for evaluating tracking performance. Beam tests were carried out of the detector at the CERN SPS H4 to characterize its performance in magnetic field. The c-μRGroove detector operated stably in a 1 T magnetic field. A spatial resolution better than 130 μm and a detection efficiency exceeding 95% were achieved for the detector in the magnetic field with the micro-TPC reconstruction algorithm. A detailed simulation with full detector response was performed to reproduce the test beam results. The detector design was optimized based on the simulation. The optimization indicated that increasing the effective gas gain, reducing avalanche gain fluctuations, and improving the measurement precision of the T₀ timing can further enhance the position reconstruction performance of the detector. These results demonstrate that the c-μRGroove detector is a promising solution for inner tracking in future electron-position collider experiments.

Speaker: Qixuan Huang (University of Science and Technology of China (CN))

24 The CGEM-IT detector of the BESIII experiment

The CGEM-IT detector is the new inner tracker of the BESIII experiment, hosted at IHEP, Beijing. Developed by an international collaboration led by INFN, it consists of three layers of cylindrical triple-GEMs, and its $\sim10000$ channels are read out by an innovative electronics based on TIGER/GEMROC. After the installation in late 2024, the CGEM-IT underwent a commissioning run with cosmics and beams, taking data with the BESIII detector at the psi(2S) peak energy until February 2026. This presentation will report on the operations during commissioning and present the first preliminary results on performance.

Speaker: Michela Greco (INFN-UniTO)

25 Micromegas Performance in the ATLAS Muon Spectrometer New Small Wheel: First Four Years of Operation

With the transition to Run 3 and in preparation for the High-Luminosity LHC, the ATLAS muon system has undergone major upgrades, most notably the installation of the New Small Wheel (NSW), replacing the innermost endcap stations of the Muon Spectrometer. Installed during the 2020–2021 Long Shutdown and commissioned in 2022, the NSW has now been fully operational for over three years.
The NSW introduces two novel detector technologies in ATLAS: small-strip Thin Gap Chambers (sTGC) and resistive-strip Micromegas (MM), the latter constituting the largest MPGD system ever deployed in a high-energy physics experiment, with more than 1200 m² of active area.
This presentation reports on the performance of the NSW using Run 3 data collected between 2022 and 2025. The focus is on the Micromegas system, covering its stability over the first four years of operation and its integration into the ATLAS muon tracking and Level-1 trigger systems. Current performance is presented, together with planned improvements for the HL-LHC.
An overview of the sTGC system status and performance will also be provided.

Speaker: Valerio D'Amico (Ludwig Maximilians Universitat (DE))

12:50 PM Lunch break

Invited session: Rui de Oliveira

Convener: Rui De Oliveira (CERN)

26 Invited speaker: Rui De Oliveira

Speaker: Rui De Oliveira (CERN)

Plenary Session: MPGD technologies

27 The G-RWELL: a high-rate resistive MPGD for the LHCb Upgrade II Muon system

Future high-energy experiments require advanced gaseous detectors combining excellent spatial and time resolution with high-rate capability and robustness in harsh radiation environments. The μ-RWELL, a single-stage resistive Micro-Pattern Gaseous Detector (MPGD) developed by the authors, achieves typical gas gains of 2×10^4, spatial resolution better than 100 μm, and time resolution in the 5-6 ns range. To meet increasingly stringent performance requirements, particularly in view of the LHCb muon system Upgrade II, we have developed the G-RWELL detector, an hybrid MPGD layout that integrates a single GEM pre-amplification stage on top of a standard μ-RWELL, forming thus a two-stage amplification MPGD.

The G-RWELL has been characterised through extensive laboratory and beam tests conducted in 2024 and 2025, demonstrating improved gain and timing performance compared to the standard μ-RWELL. Efficiency and time resolution were measured at the CERN PS-T10 beamline using 5 Gev/c muons and a dedicated front-end electronics system (FATIC3), confirming the advantages of the two-stage amplification scheme. A detailed comparison was performed for detectors with active areas ranging from 10×10 to 25×60 cm². In addition, transfer gap distances of 2 and 3 mm were investigated, enabling a comprehensive characterisation of the detector over a broad range of amplification, transfer and drift field settings.

The present design significantly enhances detector performance, ensuring stable operation at gas gains up to 10^5 and achieving time resolutions better than 5 ns. These results satisfy the LHCb muon system Upgrade II requirement of identifying particles within a single bunch crossing.

These results establish the G-RWELL as a robust and high-performance detector concept for the next-generation of high-rate experimental environments.

Speaker: Francesco Debernardis (Universita e INFN, Bari (IT))

28 Performance of the Full-scale Prototype for ePIC's G-RWELL Endcap Tracker

ePIC will be the first experiment at the upcoming Electron-Ion Collider (EIC) at Brookhaven National Laboratory. It will enable precision studies of nucleon and nuclear structure, addressing key open questions on confinement and on the behaviour of QCD in the non-perturbative regime.

The ePIC detector is designed to ensure large acceptance and excellent tracking performance. In the endcap regions, the G-RWELL technology, a hybrid of Gas Electron Multiplier (GEM) and micro Resistive Well ($\mu$-RWELL), has been chosen to provide precise tracking and good timing at pseudorapidity $|\eta|>2$.
The detector must satisfy stringent requirements in terms of material budget of about $1\%~X_0$ per disk, efficiency, $\sim 97\%$ per layer, time resolution better than $20$ ns, and spatial resolution of $150~\mu$m.

A dedicated test beam campaign was carried out at CERN in November 2025 at the H4 beamline to validate full-scale G-RWELL Engineering Test Article quadrants with $140$ GeV muon beams. Two detectors were tested, featuring a 2D strip readout with a pitch of $600~\mu$m. The data was collected using APV25 front-end electronics coupled to the Scalable Readout System and controlled by mmDAQ3. Reconstruction and analysis were tackled using custom libraries developed for strip-based MPGD detectors within the Corryvreckan framework.

Early results from the H4 test beam are promising, with detector efficiencies approaching requirements and spatial and time resolutions within the design specifications. This contribution will introduce the detector's design, the experimental setup, and the first performance estimates obtained with full-scale G-RWELL quadrants, demonstrating the suitability of this technology for the ePIC endcap tracker.

Speaker: Elena Sidoretti

29 An Overview of Large-area MPGDs for Upcoming Physics Programs at Jefferson Lab

Large-area Micro-Pattern Gas Detectors (MPGDs) are key components of major upcoming physics programs at Jefferson Lab (JLab). Various large-area GEM trackers have been developed and constructed for two highly ranked experimental programs at JLab: PRad-II/X17 in Hall B and MOLLER in Hall A. By combining high-granularity tracking with transition radiation capabilities for particle identification, the GEM-based Transition Radiation Detector (GEM-TRD) has become an essential component for improving electron–pion separation in the GlueX experiment in Hall D. Due to their excellent position resolution, low material budget, and simple mechanical construction, large-area Micro-Resistive Well detectors have emerged as highly promising candidates for upgrading the CLAS12 forward tracking system to support operations at luminosities as high as $\mathrm{2\times 10^{35}\ cm^{-2}s^{-1}}$ in Hall B.
This talk will discuss the challenges in the design, fabrication, and operation of large-area GEM-based detectors at JLab, as well as ongoing R&D efforts on large-area uRWELL and GEM-TRD technologies for future JLab experiments.

Speaker: Prof. Huong Nguyen (University of Virginia (US))

4:20 PM Coffee break

Poster session

Social events: Open session: MPGD to Czech community

Social events: Cocktail

Wed, September 2

Invited session: Jochen Kaminski

Convener: Jochen Kaminski (University of Bonn (DE))

30 Invited speaker: Jochen Kaminski

Speaker: Jochen Kaminski (University of Bonn (DE))

Plenary Session: Plenary session V

31 The CYGNO experiment

We are going to present the CYGNO experiment whose goal is the development of a high precision optical readout gaseous TPC for directional Dark Matter search and solar neutrino spectroscopy, to be hosted at Laboratori Nazionali del Gran Sasso (LNGS). CYGNO (a CYGNus TPC with Optical readout) fits into the wider context of the CYGNUS proto-collaboration, for the development of a Galactic Nuclear Recoil Observatory at the ton scale with directional sensitivity. CYGNO peculiar features are the use of sCMOS cameras and PMTs coupled to GEM amplification of a helium-based gas mixture at atmospheric pressure, in order to achieve 3D tracking with head tail capability and background rejection down to O(1) keV energy. The 50 L prototype LIME, located in the underground laboratories at LNGS, has been taking valuable data in a realistic environment for rare event searches
for two years. At the same time, the collaboration is starting the construction of a detector
demonstrator of 0.4 m3 with the goal of demonstrating the scalability of the technology and physics reach. We will discuss the status of the CYGNO experiment focusing on the most relevant results attained with LIME prototype. Furthermore, we will describe the design and status of the CYGNO-04 detector, highlighting the improvements with respect to previous prototypes.

Speaker: Stefano Piacentini

32 Gas Pixel MPGD for Migdal Effect Observation

We present a dedicated gas pixel micro-pattern gaseous detector (MPGD) developed for the direct observation of the Migdal effect. This detector integrates a gas microchannel plate (GMCP) and a high-resolution charge-sensitive pixel chip, using a He-DME gas mixture as the working medium. It features low noise, outstanding position resolution, and precise track and vertex imaging performance, which provide key advantages for identifying rare Migdal events in neutral particle-induced nuclear scattering. We also introduce the ongoing research progress on next-generation detector optimization and front-end electronics upgrading, which will further boost detection sensitivity, lower energy thresholds, and advance the application of this MPGD in light dark matter detection and other rare-event physics studies.

Speaker: Qian Liu

33 TREX-DM: a TPC with GEM+Micromegas detection system for low mass WIMP searches

The TREX-DM experiment is a high-pressure Time Projection Chamber, located at Canfranc Underground Laboratory (LSC), designed for the direct search of WIMPs in the low-mass region. For the detection of these rare interactions, ultra-low background levels and a low energy threshold are required. TREX-DM meets these criteria by operating a TPC filled with neon- (or argon-) based mixtures with a large radiopure microbulk Micromegas readout plane.
TREX-DM has successfully implemented a GEM as a preamplification stage to further improve the low-energy threshold, demonstrated the potential to go down to the single-electron ionisation detection.
A description of the detector specifications is discussed along with the latest improvements of the experiment and the current status of the high-pressure data taking campaigns, highlighting the performance of the GEM+Micromegas detection system.

Speaker: Ana Quintana García

34 Status of C/N-1.0: Large gaseous detector for direction-sensitive dark matter search

The sensitivity of the direct dark matter search is being improved by various energy-sensitive experiments, such as dual-phase liquid xenon TPCs. In parallel, direction-sensitive dark matter searches are designed and taken place to reveal properties of the dark matter particle after its discovery or to explore beyond the neutrino fog.
NEWAGE is a direction-sensitive WIMP search with a micro-pattern gaseous detector based on the micro pixel chamber (μ-PIC) strip readout, operated at a low gas pressure of 0.1 atm. To further improve the experimental sensitivity, a large-scale detector upgrade is under development. We have developed C/N-1.0, a next-generation detector with an active volume of approximately 1 m³ for future underground dark matter searches at Kamioka Underground Laboratory. The detector is designed to install up to 18 modular detectors. Prior to its underground deployment, we conducted a performance evaluation in a surface laboratory using multiple modular detector units. Using these modular detectors, we confirmed that three-dimensional track reconstruction is feasible in C/N-1.0.
In this talk, we report the results of these detector characterization studies and discuss the readiness of C/N-1.0 for forthcoming underground operation.

Speaker: Ryota Namai (Kobe University)

11:00 AM Coffee break

Plenary Session: Plenary session VI

35 Development of a hadronic calorimeter read out by resistive micro-pattern gaseous detector for future collider experiments

Experiments at proposed future Higgs factories, such as the FCC-ee and the Muon Collider, will require excellent energy resolution to discriminate hadronic decays of W/Z and Higgs bosons effectively. To meet this target, calorimeters must feature a high granularity readout, essential for Particle Flow reconstruction. We present progress on the development of a hadronic calorimeter (HCAL) read out by resistive micro-pattern gaseous detectors (MPGDs). Resistive MPGDs have shown promising performance for the high-rate environment of future colliders thanks to their excellent space resolution (of the order of 100 µm), rate capability (up to tens of MHz/mm2) and longevity (up to integrated charges of 8 C/cm2) and good time resolution of the order of a few ns.
A MPGD-HCAL prototype cell of 1 radiation length made of 12 readout layers between µ-RWELLs and resistive MicroMegas has been assembled and tested. We describe the performance of the readout detectors - of transversal size 20x20 cm2 and 50x50 cm2 - measured in test beam at CERN SPS with high-energy muons, focusing on their efficiency, space resolution and response uniformity. We also present the energy response of the MPGD-HCAL prototype measured with low-energy pions (up to 10 GeV) at the CERN PS; additionally, we show the preliminary results of a joint test of the prototype together with a semi-homogeneous electromagnetic calorimeter to evaluate the energy response of the integrated system of the two detectors. The results are compared with a Geant4 simulation of the tested detector as well as a simulated full-scale prototype to compare their shower containment, response linearity and energy resolution. The evaluation of different readout electronics solutions is discussed, focusing on the performance achievable with analog, digital and semi-digital readout and the integration of the present prototype with the VMM3a-SRS front-end.

Speaker: Antonello Pellecchia (Universita e INFN, Bari (IT))

36 The Micromega detectors of the PADME experiment

The PADME experiment (Positron Annihilation into Dark Matter Experiment), at the Laboratori Nazionali di Frascati
Beam Test Facility,
is designed to search for light dark sector particles in positron-on-target interactions.
Among its physics goals is the investigation of anomalies in leptonic final states, such as the excess in the
e+e− → e+e− channel seen in the data collected in the fall of 2022 at an invariant mass of about 17 MeV/c^2.
A new data-taking campaign has been carried out between June and October 2025, whose major upgrade consisted in the installation
of a tracking detector based on Micromegas technology, aiming to significantly improve neutral background rejection.
The detector consists of a resistive Micromegas chamber with two 5 cm drift regions separated by a floating mesh acting as
a cathode, and two-dimensional readout planes with a strip pitch of 1.2 mm. The enlarged drift gap allows the detector to be operated as
a Time Projection Chamber (TPC). Precise timing information and high granularity of the readout allow the reconstruction
of particle tracks in three dimensions. Given the large drift distance, a fast gas mixture Ar:CF4:iC4H10 = 88:10:2 has been adopted.
The detector geometry is optimised to provide high spatial resolution in track reconstruction without the need
for a multi-layer tracking system, reducing the material budget. Furthermore, the detector has been designed to be able to monitor
the positron beam position as well as the number of positrons during the data taking.
The construction of the detector, the results of validation studies with cosmic rays prior to installation, and the preliminary
results on its performances obtained during the commissioning of the experiment are presented.

Speaker: Fabio Bossi

37 Performance of the new T2K High Angle TPCs

As a part of the upgrade of ND280, the off-axis detector of the T2K experiment, two new gaseous Time Projection Chambers (TPCs) have been installed above and below the active target to enhance the tracking of particles emitted at a large angle with respect to the beam direction. The two TPCs are equipped with 16 Encapsulated Resistive Anode Micromegas (ERAMs) each. The upgrade was completed in spring 2024 and, since then, it has been running stably. Commissioning with cosmic rays and data taking with neutrino beam confirmed that the design requirements were met; a spatial resolution better than 800 $\mu m$ and ionization energy loss ($dE/dx$) resolution below 10\% are achieved, as well as a gain stability over the run period within few percent. This talk presents the highlights of the upgrade project, the challenges that were faced and the techniques to ensure stable operations.

Speaker: Daniele D'Ago (Universita e INFN, Padova (IT))

38 Double Micro-Mesh (DMM) detectors for low-pressure TPC applications in the direct measurement of 12C+12C reaction at stellar energies

Low-pressure time projection chambers (TPCs) are essential for precision measurements of low-cross-section nuclear reactions in nuclear astrophysics, as they enable excellent tracking, particle identification, and background suppression. However, conventional TPCs face challenges under low-pressure and high-rate conditions, including insufficient gain, severe ion backflow (IBF), and space-charge distortion. To address these issues, we developed a double micro-mesh (DMM) detector integrated into a low-pressure TPC for the direct measurement of 12C+12C reaction at stellar energies. The two-stage amplification structure achieves high gas gain while strongly suppressing IBF ratio under low-pressure operation.
Prototypes with a sensitive area of 13 cm × 23 cm have been fabricated. Systematic X-ray characterization demonstrates stable gain performance in both He-based and Kr-based gas mixtures at around 90 mbar. An IBF ratio of 6 × 10-4 is achieved with optimized mesh configurations, maintaining the gain-IBF product below 5 under typical experimental conditions. Studies of high beam intensities at about 30 p𝜇A show that substantial X-rays are generated by beam interaction on the carbon target and the resulting challenge of large space charge distortions is successfully resolved by using DMM-TPC in the He/Ar working gas. In the 12C+12C measurement at Ec.m. < 3 MeV with a current of 50 p𝜇A, the detector enables clear 3D track reconstruction and efficient particle identification for protons and α particles. The DMM-TPC exhibits long-term stability, high rate capability, and low IBF, making it a promising solution for precision measurements of low-cross-section astrophysical fusion reactions.

Speaker: Prof. Zhiyong Zhang (USTC)

12:40 PM Lunch

Invited session: Astronomical X-ray Polarimetry via the Photoelectric Effect in Gas: From IXPE to Future Opportunities

Convener: Paolo Soffitta

39 Astronomical X-ray and Gamma-ray Polarimetry: From IXPE to Future Opportunities

After more than 10 attempts to fly an X-ray polarimeter, aimed at revitalizing the field, with early efforts based on Bragg diffraction and Thomson scattering and yielding a single positive (and fundamental) result in the mid-1980s, the innovative use of the photoelectric effect in gas detectors led to the development of the Gas Pixel Detector, specifically designed for astronomical polarimetry.

Finally, NASA approved IXPE in January 2017, and the NASA–ASI Small Explorer mission was successfully launched in early December 2021. IXPE is still in operation, providing a wealth of scientifically outstanding results across all classes of X-ray–emitting celestial sources.

The next step beyond IXPE requires significant improvements in several key areas: larger mirror effective area and enhanced angular resolution, a broader energy band to access a wider range of physical phenomena through polarimetry, and a substantially faster repointing capability to capture the polarization of transient sources.

This vision is embodied in Europe by EXPO (Enhanced X-ray Polarimetry Observatory) a proposed M-8 mission waiting for selection outcome for phase-0 by ESA and in USA by Lynx2030 under consideration for angular resolution at the 1–2 arcsecond level and mirror effective areas on the order of square meters. In China the enhanced X-ray Timing-Polarimetry mission (eXTP) with a projected launch in 2030 will augment the number of sources observed by IXPE being sensitive in the same energy band.

At higher energies indeed, Compton Scattering takes the role and while at lower energies photoelectric effect allows for fine imaging polarimetry this is not possible above about 20-30 keV. Anyhow the use of new generations of ASICs coupled to solid state detectors may overcome the situation. XL-Calibur, AstroSat-CZTI, XPOSAT-POLIX and the future Polar-2 and COSI are making (or will) use of Compton/Thomson scattering for non-imaging polarimetry.

In this talk, I will present the main scientific results obtained by IXPE, discuss its limitations, and outline how these can be overcome by EXPO and Lynx 2030. I will also discuss Compton polarimeters highlighting also the astrophysical potential enabled by this new generation of high-throughput X-ray missions.

Speaker: Paolo Soffitta

Plenary Session: Simulation and software

40 Micro-Pattern Gas Detectors for Low-Energy Nuclear Physics: Status and Prospects at FRIB

We present recent advances in novel gas avalanche detector concepts developed for applications at the Facility for Rare Isotope Beams (FRIB). We report on the development of Multi-layer Thick Gas Electron Multiplier (M-THGEM) structures as readout systems for the tracking detector at the focal plane of the S800 spectrometer, alongside the design of an enlarged drift chamber for the upcoming High Rigidity Spectrometer (HRS) project. Additionally, we detail the integration of the Scalable Readout System (SRS) as a data acquisition (DAQ) solution for wire-based heavy-ion tracking detectors.
Furthermore, we highlight the latest developments in a low-pressure, heavy-ion 2D imaging system employing the novel Multi-Mesh THGEM (MM-THGEM) readout architecture, targeting fission and fission-like reaction studies. We present the operational principles and characterize detector performance, including sub-nanosecond timing resolution (σ < 1 ns), sub-millimeter spatial resolution (σ < 1 mm), and long-term operational stability. Experimental results obtained with a low-energy rare isotope beam are presented and discussed.

Speaker: Marco Cortesi (Michigan State University (US))

41 µRWELL detectors for the MUSHROOM spectrometer at ISIS

The MUSHROOM instrument is a novel low energy indirect geometry neutron spectrometer being developed at the ISIS Neutron and Muon Source within the Endeavour Programme. It aims to deliver a significant gain in neutron flux and detection efficiency for studies of low energy excitations, placing stringent requirements on detector technology in terms of efficiency, spatial resolution, rate capability, and scalability. This contribution presents the proposed integration of µRWELL detectors as the baseline detection solution for MUSHROOM and discusses the corresponding mechanical, electrical, and material challenges.
The detector system is based on a modular geometry comprising 28 detector modules arranged around the sample position, divided equally into upper and lower circular arrays. Each module contains eight trapezoidal detector units, each with 48 one dimensional pixels at 3mm pitch. Such a detector will have a total area of 2.3 m2 and almost 11,000 readout channels. This configuration provides the required angular coverage while maintaining compactness within the detector vessel.
To meet the efficiency target of approximately 80% at a neutron wavelength of 4.3 Å, the detector has an active volume 20mm thick, pressurised to 2.5 bar with ³He. The 3 mm position resolution will be achieved by adding up to 1bar of CF4 to the gas mixture. The anticipated rate capability is demanding, with localised rates reaching 1–2 MHz per pixel during intense peaks that transiently propagate across the detector’s area, while most pixels operate at a few kHz.
The integration of µRWELL foils inside a pressurised vessel introduces several technical challenges. These include the mechanical attachment of the foils to neutron-absorbing backing materials such as boron nitride or sintered boron carbide, the routing of signal traces beneath readout pads while controlling crosstalk, and the optimisation of resistive-layer properties, targeting surface resistivities of around 20 MΩ/□.
The total ³He inventory required for the full detector system is estimated at approximately 220 L, which will be almost entirely recovered from old neutron detectors. The planned development path foresees several prototype iterations, with manufacturing readiness targeted for the first half of 2028. The successful deployment of µRWELL technology for MUSHROOM would represent a major step forward in high-rate, high-efficiency neutron detection for next-generation spectrometers at spallation sources.

Speaker: Davide Raspino

42 A prototype neutron spectrometer based on MICROMEGAS detector for solar physics

The SONGS (SOlar Neutron Gaseous Spectrometer) project aims to develop an innovative fast neutron spectrometer based on proton tracking within a Micro-Pattern Gaseous Detector (MPGD), with potential application as a solar physics probe in Low Earth Orbit.
Solar fast neutrons, produced by interactions between solar energetic particles and the solar atmosphere, provide a direct probe of particle acceleration mechanisms during impulsive events such as solar flares and coronal mass ejections, with important implications for space weather. Existing space-based detectors, typically based on scintillator arrays or fiber trackers, are mainly limited to neutron flux measurements and lack accurate spectroscopic and directional capabilities, while also featuring relatively small effective areas.
To overcome these limitations, we propose a detector that exploits the technique of double elastic neutron–proton scattering in hydrogen-rich materials, enabling the reconstruction of both the energy and direction of the incident neutrons. The concept combines a large-volume (2-3 dm3) MICROMEGAS (MM) detector with high-granularity readout and an array of thin plastic scintillator tiles, readout by silicon photomultipliers, inserted into the gas cell as active targets to induce neutron scattering. Recoil protons escaping from the scintillator travel through the gas between the tiles, producing ionization tracks extending over several centimeters, which are reconstructed in three dimensions via time and position measurements on the MM anode plane.
A preliminary simulation of the SONGS prototype was developed using GEANT4 interfaced with Garfield++ to optimize the detector design and identify the configuration that maximizes energy and angular resolution as well as the effective area. The results of simulations indicate that this approach can outperform existing neutron fiber trackers systems.
This contribution presents the detector concept, detailed simulation studies, and the first experimental validation from beam tests performed at the CERN SPS. The measurements were carried out using a MICROMEGAS prototype with a 10 cm-thick drift region and a field cage integrated along the lateral side of the active volume to ensure stable and uniform electric field conditions. The readout system is based on SRS/VMM3a electronics. Preliminary results focus on tracking performance, including spatial resolution and initial assessment of angular reconstruction capabilities.
Future work will focus on integrating plastic scintillator tiles within the MICROMEGAS drift volume, optimizing their geometry and compatibility with the electric field configuration. An overview of these ongoing and future developments will be presented.

Speaker: Prof. Paolo Maestro (Universita & INFN Pisa (IT))

43 Gaseous Detectors for Hard X-ray Polarimetry: from EXPO to Wide-Field Hard X-ray TPCs

We report on gaseous detector developments for hard X-ray polarimetry in space, on two complementary fronts. First, we present the status of the EXPO (Enhanced X-ray Polarimetry Observatory) payload, a proposed ESA M-class mission extending IXPE's heritage with a 2–35 keV broadband polarimetric capability. EXPO employs five GridPix photoelectric polarimeters — two Low Energy Polarimeters (Ne/DME, 1 bar) and three Medium Energy Polarimeters (Ar/DME, 3 bar) — all based on an InGrid amplification stage read out by the Timepix3 ASIC, enabling dead-time-free 3D track imaging with modulation factors of 34% at 3 keV and 49% at 17.4 keV. We also discuss the assessment of the instrumental background and the potential application, in an orbital astrophysics context, of background-rejection techniques originally developed for underground dark-matter experiments, which may prove decisive in optimizing the final detector configuration. Second, we present a wide-field Time Projection Chamber for hard X-ray polarimetry, derived from directional dark-matter search technology. The prototype (3.7 cm radius, 6 cm drift, triple-GEM + sCMOS optical readout) achieves ~15° angular and 10–15% energy resolution in the 5–50 keV band. Polarized beam calibrations yield modulation factors exceeding 0.4 at 17 keV. We outline next-generation R&D on gas mixtures, ML-based onboard data reduction, and background simulations for LEO deployment targeting GRBs, magnetar flares, and Galactic sources above ~100 mCrab.

Speakers: Davide Fiorina (GSSI & INFN LNGS), Stefano Piacentini

Flash talks

3-minutes long flash talks by poster authors.

4:30 PM Coffee break

Plenary Session: Electronics

44 Quality Management for the Mass-production of GEM Foil

Since 2011, Korea-CMS (KCMS) has received GEM Foil production technology transfer from CERN RD-51 and has collaborated with Mecaro Co., Ltd. on Research and Development. A large GEM foil, ranging in size from 10 cm² to over 1 meter in length, was produced and supplied to the laboratory. In recognition of these achievements, a Memorandum of Understanding was signed with CERN CMS in 2019 to provide the GEM foil required for the construction of the GEM detector system for the Phase-2 upgrade.
Korea-CMS prepared facilities for mass production in 2020 and, from 2021, began producing GEM Foil. Initially, low production yield and electrical instability were issues, prompting Korea-CMS to implement a Quality Management (QM) system to address them. The problematic foil was selected through Quality Control (QC), and the cause of the problem was analysed using Electron Dispersive Spectroscopy (EDS) and an optical lens. Based on the analysis findings, the Quality Assurance (QA) team improved the production process to enhance product quality. Consequently, the product's performance improved, and the initial low production efficiency of less than 20% increased to more than 80%. Thanks to its successful Quality Management activities, Korea-CMS successfully mass-produced high-quality GEM foil from 2021 to 2026.

Speaker: Dr Dong Hyun Kim (University of Seoul & Kyungpook National University (KR))

45 From CMS GEM Mass Production to microRWELL R&D: Status of the Korean MPGD Infrastructure

As one of the few facilities globally capable of large-area GEM production alongside CERN MPT, the Korean MPGD infrastructure has recently achieved a major milestone. Late last year, we successfully completed the mass production of 1,040 high-quality GEM foils as the second supplier for the CMS Phase-2 upgrade. Building upon this extensive experience in large-scale manufacturing and quality control, our facility is now expanding its technological expertise toward the development of microRWELL detectors.

The decision to expand into microRWELL development was strategically motivated by its production process being fundamentally analogous to that of GEM foils, allowing for an efficient leverage of our existing infrastructure and technical expertise. To mitigate current global supply bottlenecks, we are conducting comprehensive R&D focused on streamlining fabrication steps. Key areas include establishing domestic production of DLC-sputtered FCCL in collaboration with a Korean company and the development of a shadow-mask-based DLC patterning method to enhance mass-production yield. Furthermore, we are investigating wellization via polyimide etching using monoethanolamine, characterized by its lower inhalation toxicity, through collaboration with an industrial partner.

In parallel with these technological developments, a significant organizational restructuring is underway. The MPGD production infrastructure, formerly operated under Korea CMS—a consortium of Korean universities collaborating in the CMS experiment at CERN—is being integrated into the Institute for Rare Isotope Science (IRIS). This transition marks the establishment of a centralized MPGD production and R&D hub in Korea, well-positioned to contribute to future international collaborations. The current status and results of our R&D activities, as well as the progress of the organizational restructuring, will be presented.

Speaker: Inseok Yoon (Seoul National University (KR))

46 Suppressing GEM-Foil Creep-Induced Gain Nonuniformity in the NinjaSat-2 LCP-GEM Detector

Liquid-crystal-polymer gas electron multipliers (LCP-GEMs) have been used in X-ray astronomy missions. We developed the Xe-based GEM detector Gas Multiplier Counter (GMC) for the 2–50 keV CubeSat X-ray observatory NinjaSat. For the successor mission NinjaSat-2, we investigated pre-launch GEM-foil creep during thermal-cycle testing as a possible cause of foil deformation and geometry-induced position-dependent gain variation.
In space gas detectors, adhesives are restricted because of outgassing. Thus, the conventional method of tensioning and gluing the GEM foil to a frame cannot be used. In the GMC onboard NinjaSat, the GEM foil was clamped between flat frames. We conducted thermal-cycle tests from −30 °C to +60 °C on a sealed GMC to simulate the in-orbit temperature range. After the thermal cycles, the gain became position dependent, with variations of up to 31%, and the energy resolution degraded. We infer that the GEM foil underwent creep within the frame during the pre-launch thermal-cycle tests, making it more susceptible to temperature-induced deformation. The resulting change in the GEM-to-readout distance and the produced gain variation was caused by detector geometry rather than intrinsic GEM nonuniformity.
For NinjaSat-2, we introduced a knife-edge frame in the GMC. This frame locally supports the GEM foil, suppresses creep, and maintains foil flatness under thermal stress. To evaluate the new frame, we performed mapping measurements with a compact 4.5 keV Ti X-ray source using a test-chamber GMC before and after thermal cycling from −30 °C to +60 °C. Thermal cycling changed the gain distribution by only ~3%. The spatially averaged energy resolution showed no degradation, changing by only 0.14–0.19 percentage points. Fe-55 irradiation tests conducted with the chamber interior temperature controlled between −10 °C and +40 °C showed no significant temperature dependence of the energy resolution. These results support our interpretation that GEM-foil creep is caused by geometry-induced apparent gain variations and demonstrate that the knife-edge frame effectively suppresses this effect.

Speaker: Satoko Iwata (Tokyo University of Science / RIKEN)

47 New developments in MPGD manufacturing with the MPT Magnetron Sputtering Machine

The CERN MPT workshop operates a magnetron sputtering machine to develop thin-film resistive and metallic coatings for Micro-Pattern Gaseous Detectors (MPGDs). The three main base materials are: DLC, DLC+ (DLC/Ti/Cu), and double-sided DLC++. Process optimisation has recently replaced Cr with Ti as an adhesion layer, improving etching control and reproducibility. At the end of 2025, the first DLC++ foils with matched resistivity on both sides were successfully produced, enabling full in-house fabrication of MPGD base materials.
The talk will focus on different facets of the production processes for base materials and the development of new manufacturing processes for resistive and chemically resistant layers.
A key focus is the uniformity of resistivity across large-area foils. Systematic studies show that gas distribution strongly influences plasma density and film properties. Optimised gas outlet configurations significantly improved uniformity, enabling full-area usage and increased yield. This is essential for the production of large-area detectors.
Reproducibility is ensured by calibrating the C₂H₂ amount at the start of each deposition series. Small variations allow controlled tuning of surface resistivity from a few MΩ/□ to several tens of MΩ/□.
These developments support MPGD R&D towards improved detector stability and rate capability. While higher resistivity enhances stability, it limits rate performance in single-layer designs, motivating multilayer concepts such as double-DLC structures with vertical charge evacuation.
In parallel, new materials (e.g. B₄C) and processes, including deposition on PMMA and PCB substrates and lift-off patterning of multilayer films, are being developed, extending the flexibility of MPGD base material production. In this context, lift-off processes are currently being developed to pattern DLC, enabling the fabrication of fully DLC-based MPGDs, such as double-sided DLC-GEMs.

Speaker: Karl Jonathan Floethner (CERN)

48 Development of Large-Area Resistive Micromegas Detectors for the MX17 Experiment at n_TOF

The search for the hypothetical X17 boson has motivated the design of the MX17 experiment at the CERN n_TOF facility. To accurately reconstruct the coincident e+ e- pairs associated with this search, we have developed a large-area Micromegas detectors at CEA Saclay. These detectors feature a 40 x 40 cm² active area and are designed to provide good spatial resolution while operating under the constraints of a limited number of DREAM-based electronics channels.
To optimize the channel count without sacrificing performance, we implemented a high-granularity XY pixel-strip pattern. In this configuration, pixels are interconnected to internal strips, a technique evolved from the CAST experiment. Each pixel is surrounded by eight neighbors connected to different strips to enhance charge sharing. Achieving this design required the fabrication of a 300µm thick PCB containing 262,144 metallized holes, successfully produced by the CERN Workshop.
Key technical features of the detector include:
Charge Sharing & Spark Protection: A resistive layer was applied via screen printing at the Saclay MPGD workshop using Saral paste of 4 MΩ/sq. Two patterns were evaluated: a plain resistive center with high-resistance "buried" HV connections and a strip-only resistive pattern.
Detector Construction: The Bulk process utilized Dynamask layers and an ASADA 45/19 mesh. To ensure mechanical planarity, the readout PCB is reinforced with a 5 mm Rohacell backing. The Bulk is design to have a floating mesh that can be grounded or optional charge injected.
Modular Readout: Connectivity is handled via GZS connectors on the readout PCB, avoiding direct welding. This interface leads to exchangeable multiplexing cards (M1, M2, and M4 schemes) allowing for 2048, 1024, or 512 channels per detector to match the DREAM Front End Unit availability.
µTPC Capability: The detector features a 30 mm drift gap enclosed in an aluminum frame with a 30µm Mylar window. A field cage using high-value resistors ensures field uniformity, enabling operation in µTPC mode for 3D track reconstruction.
Of the six detectors to be manufactured at CEA Saclay, four are designated for the final MX17 experimental setup. This presentation will report on the performance of the first two production modules, including results from the Saclay cosmic test bench regarding spatial resolution, tracking efficiency, and gain stability.

Speaker: Stephan Aune (CEA Saclay)

Thu, September 3

Invited session: Gregor Kramberger

Convener: Gregor Kramberger (Jozef Stefan Institute (SI))

49 Invited speaker: Gregor Kramberger

Speaker: Gregor Kramberger (Jozef Stefan Institute (SI))

Plenary Session: Plenary session VIII

50 Development of wavelength-shifting MPGD structures for ultra-cold Argon applications

In this work we report the initial results of for a ultra-cold argon gas Time Projection Chamber (Ar-TPC) demonstrator developed at Astrocent, instrumenting both primary (S1) and secondary (S2) scintillation signals using a single optical readout plane, blind to Ar scintillation. This milestone represents a significant step forward in the development of compact, high-performance Ar-TPC technology for direct dark matter searches.

The novelty of this work lies in the use of wavelength-shifting optical amplification structures (MPGD-based) in ultra-cold Ar gas (about -180 C). By integrating a wavelength shifter directly into these optical amplification structures it is possible to convert the vacuum ultraviolet (VUV) scintillation produced by argon (peaked at 128 nm) into the visible region, improving the detection efficiency of Ar scintillation by standard blue-sensitive silicon photomultipliers (SiPMs). These structures combine optical amplification with wavelength shifting capability, allowing to improve the signal collection efficiency, reaching scintillation yields similar to the ones originated in detectors using a uniform-field electroluminescence region, using meshes.

For this initial characterization of the setup, an alpha-particle source was used. Results demonstrate the wavelength-shifting FAT-GEM's capability to efficiently convert and collect scintillation signals originated in ultra-cold Ar in a single readout plane. This solution, apart from simplifying the optical readout, enables the development of back-to-back TPC solutions. In addition to the detailed description of the proof-of-concept demonstrator, we will present the initial results of the characterization of these novel optical amplification structures highlighting its potential for dark matter searches.

The results presented serve as a stepping stone for a wider research programme aiming at demonstrating the wavelength-shifting MPGD-based technology as a promising and scalable solution for dual-phase liquid TPCs, aiming at tonne-scale.

Speaker: Mr Diego Rodas Rodriguez (Astrocent /CAMK PAN)

51 Advances in photocathode development for PICOSEC Micromegas precise-timing detectors

The PICOSEC Micromegas detector is a precise-timing gaseous detector based on a Cherenkov radiator, a semi-transparent photocathode and a Micromegas amplification structure, targeting a time resolution of tens of picoseconds for minimum ionising particles. Single-pad prototypes have demonstrated excellent timing performance and ongoing developments aim to adapt the concept for physics applications by building robust, tileable multi-channel modules for large-area systems requiring precise timing.

Conventional photocathodes such as Cesium Iodide (CsI) provide high quantum efficiency and strong ultraviolet sensitivity, but are limited by their sensitivity to ion backflow, as well as humidity. These constraints motivate the development of more robust alternatives. While several materials have been previously explored, a comprehensive comparison of metallic and carbon-based photocathodes in terms of both time resolution and photoelectron yield was still missing.

This contribution presents a systematic study of photocathodes aimed at improving robustness while preserving excellent timing performance. Four materials with varing thcknesses - CsI, Titanium (Ti), Boron Carbide (B₄C) and Diamond-Like Carbon (DLC) - were produced at the CERN Thin Film and Glass and Micro-Pattern Technologies workshops. The photocathodes were characterised by combining laboratory measurements of their optical and resistive properties with beam tests using 150 GeV/c muons.

Although CsI is not suitable as a long-term solution, it remains a useful reference for detector and electronics studies. Investigations of few-nm CsI layers, supported by scanning electron microscopy measurements, show a grain-like morphology with grain size increasing with film thickness. For the beam measurements, the best result is obtained with a 5 nm CsI photocathode, achieving a time resolution of σ = 10.9 ± 0.3 ps with more than 30 extracted photoelectrons. Among the alternative materials, Ti and B₄C show the most promising outcome, reaching σ ≈ 30 ps with approximately 5 photoelectrons. Current work focuses on exploring alternative photocathode configurations, enabled by the versatility of magnetron sputtering.

The results demonstrate that improved robustness can be achieved while maintaining excellent time resolution, supporting the feasibility of using the PICOSEC Micromegas concept in future experiments.

Speaker: Marta Lisowska (CERN)

52 Visible light gas-PMT based on triple Micromegas

Gaseous photomultiplier tubes (gas-PMTs) based on micro-pattern gaseous detectors for visible light detection have been widely investigated due to their compelling advantages. These include cost-effective large-area coverage, high spatial and time resolution, and resistance to magnetic fields. However, visible light photocathodes are highly chemically reactive and suffer from severe degradation when subjected to excessive ion bombardment.
To address these challenges, we designed a triple micromesh gaseous structure (TMM) capable of achieving an unprecedented ion backflow (IBF) ratio of 3×10^−5 at gas gains exceeding 1×10^5. Based on this structure, a novel visible light gas-PMT prototype coupled with a bialkali photocathode was developed. This was achieved by exploring fabrication techniques relying entirely on inorganic materials, such as ceramics and metals, and utilizing a ppb-level gas purification system. We measured the gain and quantum efficiency (QE) of the prototype, and evaluated the long-term stability of the photocathode in a gaseous environment.

Speaker: Kunyu Liang

Flash talks

3-minutes long flash talks by poster authors.

11:10 AM Coffee break

Plenary Session: Plenary session IX

53 Study of a new ecofriendly gas mixture for the PICOSEC-Micromegas detector

Picosec-Micromegas (Picosec-MM) is a precise-timing Micro-Pattern Gaseous Detector (MPGD) designed to achieve a time resolution at the level of tens of picoseconds. Its performance relies on the detection of Čerenkov light produced in a crystal radiator. The emitted UV photons are converted into photoelectrons by a photocathode, and the resulting signal is produced through a two-stage amplification process.
Test beam campaigns at the CERN SPS with a muon beam have demonstrated that a single-pad prototype can reach a time resolution of approximately σₜ ≈ 10 ps, improving the time resolution of MPGDs by about two orders of magnitude. The standard gas mixture for this technology consists of Neon (Ne), ethane (C2H6), and tetrafluoromethane (CF₄). The latter has a high Global Warming Potential (GWP), defined as the ratio between the greenhouse effect of a given compound and that of carbon dioxide (CO₂). This represents a significant challenge for the deployment of this detector in future experiments, both due to environmental concerns and to cost and supply constraints, especially in light of European Union regulations foreseeing the phase-out of fluorinated gases.
Alternative mixtures based on neon and using isobutane (iC₄H₁₀) as a quencher have been tested in different proportions. These mixtures allow achieving a time resolution comparable to that of the standard gas, while completely eliminating fluorinated components, thus reducing the GWP by about three orders of magnitude. Moreover, a potential advantage of these mixtures lies in the high achievable gain and improved detector stability over a wider voltage range, enabling optimal time resolution without operating at the limit of the stability region. Additional mixtures based on other noble gases, such as helium (He) and argon (Ar), have also been investigated, yielding promising results, particularly for helium-based mixtures. These options could significantly reduce the operational costs associated with gas consumption.
In this contribution, results obtained with the different gas mixtures will be presented, highlighting their strengths and potential drawbacks, together with the planned next steps of this study, which is crucial for the application of this technology in future experiments.

Speaker: Matteo Brunoldi (Pavia University and INFN (IT))

54 CF4 Reduction Studies for µRWELL Detectors

The µRWELL detector, a novel Micro-Pattern Gaseous Detector (MPGD) technology, uses a gas mixture of Ar/CO$_2$ (3:1) and 40% CF$_4$, where CF$_4$'s high electron drift velocity enables time resolution in the order of nanoseconds (ns). CF$_4$ is a potent greenhouse gas, with a Global Warming Potential (GWP) ~7,000 times that of CO$_2$, and is subject to the EU F-Gas Regulation, with a phase-down that implies increased procurement costs and limited availability.

This study evaluates the µRWELL detector operated with different CF$_4$ concentrations and with alternative gases, to reduce and replace CF$_4$ in the gas mixture while maintaining acceptable performance. The experimental performance was studied with a setup installed at CERN's SPS H4 beamline, during several beam campaigns, using the DRD1 Thermal-bonded MicroMegas Telescope for data acquisition. The telescope can also be rotated for cosmic test outside beam times. Several gas mixtures were tested, systematically quantifying the effects of reduced CF$_4$ concentrations on the detector's performance and of CF$_4$ alternatives.

Between the two detectors tested, preliminary results consistently show that mixtures spanning 0% to 50% CF$_4$ have a time resolution difference of 2.5 ns. Notably, a 20% fraction of CF$_4$ limits the maximum time resolution by 1.3 ns relative to the mixture with 40% of CF$_4$. This change reduces emissions by 50%, significantly lowering CF$_4$ consumption and costs. Detection efficiency was compatible across the tested gas mixtures, with losses attributed to the DLC groove sectorisation and geometrical acceptance of the tested µRWELL prototype. Possible alternative gases, such as N$_2$, He, i-C$_4$H$_{10}$, and R-1234ze, are also under investigation.

Speaker: Stefania Juks (Université Paris-Saclay (FR))

55 Searching for X17 at n\_TOF with Large Area Micromegas Detectors in $\mu$TPC Mode

The X17 is a hypothetical light boson (${\sim}17\,\text{MeV}/c^2$) proposed to explain anomalous $e^+e^-$ pair excesses observed in nuclear de-excitation decays at ATOMKI. No independent experiment has yet definitively confirmed or refuted the anomaly. We present the first search for X17 using a neutron beam, conducted at CERN's n_TOF facility (EAR2). Neutron capture on a pressurized $^3\text{He}$ target produces excited $^4\text{He}^*$ at ${\sim}20\,\text{MeV}$, which may de-excite via X17 production. The subsequent decay to MeV-scale $e^+e^-$ should be kinematically peaked at an opening angle of around $120^\circ$, making precise and efficient MIP tracking the central detector requirement.
The experimental setup relies on four $40 \times 40\,\text{cm}$ resistive Micromegas detectors developed at CEA Saclay, arranged to detect coincident $e^+e^-$ pairs. These detectors feature a novel pad-strip readout geometry with 512 channels per axis. A top layer of pads are connected by vias to $X$ and $Y$ strip layers below to facilitate equal charge sharing. With a $3\,\text{cm}$ drift gap, the detectors are designed for $\mu$TPC mode operation to provide full 3D track reconstruction --- to our knowledge, the first application of Micromegas in $\mu$TPC mode for a dedicated physics experiment. Performance characterized with cosmic muons has demonstrated high detection efficiency, uniform response, and an angular resolution better than $2^\circ$ for track inclinations above $5^\circ$, validating the $\mu$TPC approach for precise vertex and angular measurements.
Operating these detectors in the n_TOF EAR2 environment presents significant challenges, primarily the intense ``gamma-flash'' produced when each proton bunch strikes the lead spallation target, which can generate sufficient charge to saturate the readout electronics. To mitigate these effects, we explore a range of gas mixtures to minimize photon and neutron sensitivity while preserving high efficiency for Minimum Ionizing Particles (MIPs). Additionally, we describe the implementation of an adjustable drift window designed to tune the active volume, reducing the charge produced from the prompt flash.

Speaker: Dylan Neff (The University of Manchester (GB))

56 Performance of Low-Material Budget Metallic Micromegas Trackers for the P2 Experiment

The P2 experiment at MESA (Mainz) aims to measure the weak mixing angle at low momentum transfer via parity-violating electron scattering off protons at an unprecedented precision. A key experimental challenge is the characterization and suppression of backgrounds in the backward-scattering regime, dominated by photon-induced signals in the 50–150 keV range. The BASKET tracker — a dedicated Micromegas-based backward tracker — addresses this by reconstructing backward-scattered electron tracks and exploiting hit coincidences across detector layers as the primary tool for background rejection, a capability that is central to the physics reach of the experiment.
The BASKET consists of three detection layers, each housing 7,680 pads ($\sim$23,000 channels total), designed for trigger-less streaming readout at hit rates of 15–20 kHz per pad and an overall backward-scattered particle rate of ~100 MHz. The low-material metallic Micromegas design imposes tight constraints on construction, requiring careful control of mesh geometry, pad uniformity, and assembly procedures across large detector areas. Construction challenges and quality assurance strategies are discussed.
The VMM3a ASIC has been selected as the readout frontend, offering an adjustable dynamic range of 62 fC–2 pC and sub-2.5 ns timing resolution, well matched to the expected signal of $\sim$21 fC with pad capacitances of 75–170 pF. The final readout architecture foresees a 128-channel streaming front-end board based on an FPGA aggregating multiple VMM3a ASICs in zero-suppressed timestamped mode.
This contribution presents results from a first test beam campaigns at the SPS H4 beam line at CERN using a size-1 prototype detectors. The objectives include detector characterization, systematic exploration of gain and peaking time configurations of the VMM3a readout, and signal-to-noise ratio estimation at the optimal operating point. Rate dependence studies were also performed across different beam intensity configurations. A proof-of-concept demonstration of hit coincidences between detector layers — the key discriminating observable for background rejection in the full experiment — is among the primary goals of the beam test programs. The full analysis is ongoing; the results presented here constitute an important first validation of the detector and electronics design ahead of full BASKET construction.

Speaker: Alexandra Kallitsopoulou (CEA / IRFU / Université Paris-Saclay (FR))

12:50 PM Lunch

Tours: Scientific tour

Social events: Night event

Fri, September 4

Invited session: Gaseous Ionization Detectors in the FCC-ee Era

Convener: Oliver Kortner (Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut) (D)

57 Gaseous Ionization Detectors in the FCC-ee Era

In recent years, gaseous ionization detectors have gradually been displaced in the LHC experiments and were mainly considered for muon systems because of their cost advantage for instrumenting large detector areas. However, in the context of future high-intensity and high-energy electron–positron colliders, these technologies are currently experiencing a renaissance. They are being considered for the instrumentation of virtually all detector subsystems: an ultra-light drift chamber, an ultra-light straw-tube tracker, and a time projection chamber for the inner detector to maximize momentum resolution and provide particle-identification capabilities; RPCs and MPGDs for particle-flow calorimeters, where high granularity and excellent time resolution are required; and finally, conventional gaseous detectors such as drift tubes and RPCs, as well as MPGDs, for muon systems providing large-area muon tracking and the capability to search for long-lived particles.

This presentation will provide an overview of the technologies under investigation and discuss their respective advantages and limitations.

Speaker: Oliver Kortner (Max Planck Society (DE))

Plenary Session: Plenary session XII

58 Development of a charge-sharing Micromegas detector with a pixel-strip hybrid readout

MICRO MEsh GAseous Structure (Micromegas) detectors are micro-pattern gaseous detectors with excellent spatial resolution due to their small scale readout pitch and high rate capability due to small amplification gaps and the fast evacuation of positive ions. However, large-scale detectors with pixel-readout need thousands of readout channels, which leads to increased cost, power consumption, and significant heat generation,
often requiring dedicated cooling systems.

This talk explores a way to reduce the number of readout channels by orders of magnitude without compromising position accuracy by the use of charge-sharing pixel anodes coupled to a strip readout with up to 4-fold strip information. Three layers of pixels are stacked, where the pixel layer next to the resistive DLC anode has a typical pitch of 0.4 mm x 0.4 mm and the successive layers have a factor of 2 larger structures. The position information using the charge distribution created by a muon traversing the detector is contained in the layers.

The readout pixels are lithographically segmented into substructures that are coupled to the readout electronics using galvanic vias and copper readout lines. The X,Y,U,V strips connect each quarter of the pixel: the X strips in the horizontal direction, the Y strips in the vertical, the U strips at +45 degrees, and the V strips at -45 degrees. The incidence of multiple simultaneous particles becomes hereby unambiguous.

Two prototypes of this detector were tested at CERN's SPS beam of 120 GeV muons and pions. The results of the performance and efficiency of these detectors will be presented. Comparison with the simulation results using the method of weighting fields with the help of ANSYS and Garfield++ will also be discussed.

Speaker: Eshita Vinay Kumar (Ludwig Maximilians Universitat (DE))

59 A Monolithic Gas Pixel Detector with on On‑Chip Micro‑Gap Amplification

We report on the development of a monolithic Gas Pixel Detector featuring an on‑chip integrated charge multiplication stage. The detector is built around a custom CMOS ASIC with 100,000 pixels arranged in a 50 µm‑pitch hexagonal matrix, providing fine spatial granularity and uniform charge collection. Gas amplification is implemented through micro‑patterned structures integrated directly on the readout chip using post‑processing techniques, thereby eliminating the need for external multiplication elements such as GEMs or Micromegas.

In this work, we present the experimental characterization of three different charge‑multiplication geometries, in both one- and two-dimensional flavors, all based on the micro‑gap amplification concept. The tight integration between amplification and readout enables operation at low gas gain, taking advantage of the low pixel noise of approximately 30 electrons. Measurements performed with an $^{55}$Fe source demonstrate an excellent energy resolution at 5.9 keV, down to better than 12% FWHM. These results demonstrate the feasibility of on‑chip integrated micro‑gap gas multiplication and highlight its potential for compact, highly integrated MPGD architectures.

Speaker: Luca Baldini

60 μ-RWELL Technology: Practical Rules for Design, Manufacturing and Safe Operation

Among single-stage resistive MPGD technologies, the μ-RWELL, developed at the Laboratori Nazionali di Frascati (LNF), has evolved into a versatile detector concept with multiple layouts optimized for both low and high-rate applications. It is currently proposed for the upgrade of the innermost regions of the LHCb muon system at the LHC, as well as for tracking applications in several regions of the EPIC experiment at the EIC. Recent R&D activities have also demonstrated the potential of μ-RWELL operated with He-based gas mixtures (3He and 4He) for thermal neutron detection and nuclear astrophysics applications, respectively. In addition, a growing number of groups are approaching the technology for a variety of novel use cases.
Based on more than a decade of R&D, this contribution aims to provide a comprehensive overview of the key design rules and operational procedures required to ensure robust and reliable detector performance. Extensive work carried out in close collaboration with the CERN MPT Workshop has enabled the fine tuning of several critical parameters, including DLC resistivity, DOCA, PEP-DOT and grounding grid geometries for high-rate layouts, prepreg thickness for the coupling of the amplification stage, optimization of pad readout PCB routing, and selection of cathode frame materials. These aspects are crucial to maximize detector stability and performance under demanding conditions. Ongoing efforts addressing remaining critical issues, in collaboration with other partners, will also be discussed.
Finally, standard procedures for detector preparation and operation will be presented, including pre-conditioning and quality assurance protocols developed at the CERN MPT Workshop (e.g. hot cleaning), as well as best practices for detector commissioning in the laboratory. These include humidity control, high-voltage settings (maximum voltage, current limits), and the design of HV filters to ensure stable operation at high rates.
This work aims to define the operational and construction parameter space of the μ-RWELL detector, providing a reference framework for both developers and users, and supporting its reliable deployment in next-generation experiments.

Speaker: Marco Poli Lener (INFN e Laboratori Nazionali di Frascati (IT))

10:40 AM Coffee break

Plenary Session: Plenary session XIII

61 Development of GEM-based detectors to study of X-rays emission during in-vacuum discharges at the High Voltage Padova Test Facility

The Neutral Beam Test Facility in Padova, Italy, is the site where the development of the Neutral Beam Injector (NBI) for the ITER tokamak is being carried out. In this context, the Megavolt ITER Injector and Concept Advancement (MITICA), the full-scale prototype of the NBI, is currently in the installation and commissioning phase. The system aims at producing neutrals with energies up to 1 MeV to be injected into the plasma, through the acceleration and subsequent neutralization of a negative ion beam. The accelerator is based on a multi-grid, multi-aperture system, where high-voltage holding in vacuum over long distances represents one of the most critical challenges for reliable operation. In-vacuum discharges and breakdowns can interrupt operations and potentially damage the system. These phenomena are investigated at the High Voltage Padova Test Facility (HVPTF), which consists of a cylindrical vacuum vessel equipped with two electrodes that can sustain voltage differences up to 800 kV DC. In HVPTF, several electrode configurations have been tested, including needle-to-plane, plane-to-plane, and sphere-to-plane geometries, in order to study the dependence of discharge behavior on the electric field topology. During operation, current and voltage are monitored for the two independent power supplies, together with the pressure inside the chamber, while multiple lines of sight allow complementary diagnostics. The dynamics of the discharges have been studied using cameras operating in the visible, UV, and IR spectral ranges. Particular attention has been devoted to X-ray emission from the vacuum chamber, generated by bremsstrahlung processes associated with energetic electrons interacting with the electrodes and the chamber walls during discharge events. The emitted radiation spans a broad energy range, from a few keV up to approximately 800 keV. Initial measurements were performed with inorganic scintillators; however, the extremely high X-ray fluxes involved, exceeding 10^6 photons/cm2⋅s, severely limit the applicability of scintillator or solid-state detectors due to saturation effects, pile-up, and loss of linearity. In this regime, the use of Micro-Pattern Gaseous detectors such as a GEM becomes essentially mandatory. Their intrinsically low detection efficiency to high energy x-rays, combined with a very high rate capability, allows them to operate reliably under such intense flux conditions, avoiding saturation while preserving temporal resolution. This makes GEM detectors uniquely suited for studying the fast time dynamics of X-ray emission associated with discharge events in HVPTF. Different GEM-based detectors have been developed and tested on the HVPTF facility, demonstrating their capability to significantly improve both the temporal and spatial characterization of the X-ray emission. Their implementation has enabled a more detailed investigation of the discharge dynamics, providing enhanced resolution in tracking the evolution of the radiation in both time and space. A strong correlation has been observed between the current signals from the power supplies and the X-ray signals measured with GEM detectors, indicating that X-ray diagnostics can provide valuable insight into the physics of discharges. This opens the possibility of using such measurements for the characterization of breakdown phenomena and for the development of mitigation and prevention strategies.

Speaker: Gabriele Croci (Universita & INFN, Milano-Bicocca (IT))

62 Construction and test of a µRGroove based transition radiation detector prototype

We propose a transition radiation detector (TRD) prototype based on a µRGroove detector for electron/hadron separation at the EIC. The µRGroove detector is a micropattern gaseous detector (MPGD) with excellent gain uniformity, high rate capability, discharge robustness, and good spatial resolution. The TRD uses a µRGroove detector with a 10 × 10 cm² active area and a 4 cm drift gap. Signals from two dimensional readout strips with a 400 µm pitch are read out by SAMPA electronics. A 4 cm thick ROHACELL HF71 foam radiator is used to produce sufficient TR photons.
Conventional TRDs typically identify electrons by applying a one dimensional (1D) likelihood analysis to the total energy deposit. In this work, a two dimensional (2D) likelihood method exploits the spatial correlation of transition radiation (TR) photon absorption: TR photons are preferentially absorbed near the drift electrode, while ionisation energy loss is position independent. Primary charge clusters are reconstructed via a least squares inversion of the induced waveforms, yielding joint energy–drift time distributions that serve as probability density functions for particle identification.
Beam tests were performed with a Xe/Ne/isobutane mixture (48.85% Xe) at the CERN PS using 3–5 GeV/c mixed electron/hadron beams. GARFIELD++/GEANT4 simulations show good agreement with experimental results. The 2D likelihood analysis significantly improves electron–pion discrimination over conventional 1D methods. For a four layer TRD configuration at 90% electron efficiency, the pion misidentification probability is <1.5% at 3–5 GeV/c. Simulations give a misidentification probability of 3.4% at 15 GeV/c, meeting the EIC requirement. Simulations also indicate that a higher Xe content (85%) allows comparable performance with only two TRD layers.
This work provides a compact, high performance solution for electron–hadron separation at future facilities like the EIC.

Speaker: Guofeng Song (University of Science and Technology of China)

63 The MultiStrip Proportional Chamber: a MWPC-inspired new detector based on MPGD techniques

The Multi Wire Proportional Chambers (MWPC) have found wide application due to their ability to instrument large areas, with a rate capability of up to a few hundred kHz/cm^2. While MWPCs remain a robust solution today, their scalability is limited by the time-consuming wire-stringing process and the decreasing availability of expertise. This significantly increases production cost for large systems, such as muon detectors at future $\textrm{e}^{+}\textrm{e}^{⁻}$ colliders. MicroStrip Gas Chambers (MSGCs) introduced photolithographic techniques for detector construction, paving the way for Micro-Pattern Gaseous Detectors (MPGDs) and enabling the transition from manual assembly to industrial fabrication.

The MultiStrip Proportional Chamber (MSPC) is a novel detector concept that combines the MWPC principle of operation with MSGC-inspired photolithographic fabrication. It is designed to simplify construction and enable industrial-scale production while maintaining MWPC-like performance.

The MSPC active volume is defined between a cathode PCB and a flat electrode hosting the amplification stage. The latter consists of metallic strips photolithographically patterned on a resistive substrate (glass or Diamond-Like Carbon (DLC)), replacing the wire structure of MWPCs. Two configurations have been implemented: anodic (sense) strips ($\sim30\ \mu m$), or alternating anodic (sense) and cathodic (field) strips ($\sim100\ \mu m$), both with $2\ mm$ pitch. The sense electrode width provides stable proportional amplification and the sense-field distance suppresses streamer formation. The resistive substrate enables charge evacuation during avalanches and reduces charging-up effects. A backplane electrode on the opposite side of the substrate shapes the electric field and improves charge collection.

The use of DLC as a resistive substrate represents a key advancement with respect to traditional MSGCs based on resistive glass ($10^9-10^{11}\ \Omega\cdot cm$). The lower DLC resistivity ($10^6-10^{9}\ \Omega/\Box$) can be tuned to optimize charge evacuation, mitigating further charging-up effects while preserving stable operation and improving the rate capability.

In 2026, a first batch of $5\times6\ cm^2$ prototypes was produced and tested, operating with Ar:CO$_2$ gas mixtures (90:10 and 70:30). Results for both configurations will be presented in terms of detection efficiency and stability over time. These results indicate that the MSPC offers a scalable, wire-free alternative to MWPCs for mid-rate applications, reducing assembly complexity while maintaining comparable performance. This approach is well suited for large-area detector systems, where production cost and manpower are critical constraints.

Speaker: Matteo Giovannetti (INFN e Laboratori Nazionali di Frascati (IT))

Prize ceremony

Invited session: Oed Prize winner

64 Oed Prize talk

Closing session

1:10 PM Lunch