Fast timing for nuclear structure and applications - FAST'26

27 Apr 2026, 09:00 → 29 Apr 2026, 19:00 Europe/Bucharest

Training and Conference Center (CCI) ( Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH))

Razvan Lica (Horia Hulubei National Institute of Physics and Nuclear Engineering (RO)), Luis M Fraile (CERN), Agnieszka Barbara Korgul (University of Warsaw (PL))

Following the successful 2025 edition in Madrid, the FAST'26 workshop is aimed at sharing the latest developments in instrumentation and methods for fast timing measurements, their use in fundamental physics research and their application to other fields such as medical imaging.

The meeting will be held at the Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), Magurele-Bucharest, Romania from 27^th to 29^th April 2026.

The scientific programme includes:

• New detector technologies, including scintillators and photosensors
• Fast front-end and readout electronics
• Time pick-up methods, optimization, and AI processing
• Large scintillator and hybrid arrays for fast-timing measurements
• Nuclear structure from fast-timing measurements: decay and reactions
• Other methods for the measurement of nuclear state lifetimes (RDDS, DSAM, etc.)
• Fast scintillators for time-of-flight PET and other imaging modalities
• Fast response and high count rate detectors for technology and applications

 

Registration and Fees

To attend the workshop, registration is required. The standard fee of €150 covers coffee breaks and lunches (April 27–29) and the workshop dinner on the evening of Tuesday, April 28.

Fee waivers and free accommodation at the IFIN-HH Student Dormitory will be available for a limited number of MSc, PhD students and Postdocs (up to 2 years post-defense). To apply: During registration, submit a request for financial support by including a CV and a recommendation letter from your supervisor.

 

The FAST'26 workshop will be followed by the ISOLDE Decay Station (IDS) collaboration meeting, at the same venue in the afternoon of April 29^th 2026.

 

 

 

FAST26-poster_v3.pdf

FAST26-timetable.pdf

FirstCircular_FAST26.pdf

Monday 27 April

10:00 → 12:00 Registration

12:00 → 13:00 Lunch

13:00 → 15:05 Day 1: Large Scintillator and hybrid arrays (I)

Convener: Razvan Lica (Horia Hulubei National Institute of Physics and Nuclear Engineering (RO))

13:00 The ROSPHERE array at IFIN-HH

Speaker: Sorin Gabriel Pascu (Horia Hulubei National Institute of Physics and Nuclear Engineering (RO))

ROSPHERE_talk_Pascu.pptx

13:25 Fast-Timing Spectroscopy with FATIMA: Status, Highlights, and Future Directions

In this talk, the current status of the FATIMA array will be presented. Recent highlights from experiments performed at GSI Helmholtz Centre for Heavy Ion Research will be discussed, demonstrating the performance of the array under in-beam conditions. Ongoing efforts to upgrade the array, including developments in the data acquisition system and detector technology, will be outlined. Future planned experiments involving FATIMA as part of the IDATEN array will also be presented. Finally, several ideas for further applications and developments of the array will be discussed.

Speaker: Vassil Karayonchev

FAST26_Karayonchev_FATIMA.pdf

13:50 Lifetime measurements at FIPPS

Nuclear lifetimes are one of the key observables providing a direct access to the structure of excited states. The commonly used technique that allows for their extraction is the fast-timing method which benefits from the use of fast scintillators. However, it also requires large datasets collected by highly granular setups. This limitation can be overcome by using a strong flux of thermal neutrons with a high gamma-detection efficiency setup. This enables population of excited states either by a thermal neutron capture or in fission.
In my talk I will present FIPPS, Fission Product Prompt gamma-ray Spectrometer, a permanent gamma-ray detection setup at the Institut Laue-Langevin in Grenoble, France. I will discuss its capabilities, results from recent experimental campaigns and future plans. The particular focus will be put on the preliminary results from the most recent fast-timing campaign.

Speaker: Dr Marek Stryjczyk (Institut Laue-Langevin (FR))

2026_04_28_Stryjczyk_FAST_workshop_FIPPS.pdf

2026_04_28_Stryjczyk_FAST_workshop_FIPPS.pptx

14:15 Lifetime measurements in exotic fission fragments at Lohengrin

In this work, we present recent results obtained in different neutron-induced fission campaigns at Lohengrin (ILL), using a hybrid setup made of HPGe clover detectors and LaBr3 scintillators. The latter were employed to measure lifetimes, down to a few ps, using γ-ray fast-timing techniques [1]. In particular, results on $^{131}$Sb [2] and $^{96}$Rb [3] will be discussed. In the first case, the lifetime of the 11/2$^+$ state was measured, yielding T$_{1/2}$ = 3(2) ps, the first such result in neutron-rich antimony nuclei and one of the shortest ever measured in beam with this experimental technique. Consequences on the origin and development of collectivity in the vicinity of the doubly magic $^{132}$Sn nucleus will be presented in the framework of the shell model. In the second case, particular emphasis will be given to the observation of a retarded E2 transition deexciting the 4− state in 96Rb. This γ ray connects the strongly deformed band above 450 keV with near-spherical low-lying states. Its impact on the shape-coexistence phenomenon in this exotic mass region around N=60 will be addressed.

[1] J.-M. Régis et al., Nucl. Instrum. Methods Phys. Res., Sect. A 955, 163258 (2020).
[2] S. Bottoni et al., Phys. Rev. C 107, 014322 (2023).
[3] E. R. Gamba, S. Bottoni et al., Phys. Rev. C 108, 064301 (2023).

Speaker: Simone Bottoni (Università degli Studi e INFN Milano (IT))

Bottoni_FAST26.pdf

14:40 A review of measurements using halide scintillators at the National Physical Laboratory UK

For over a decade, the National Physical Laboratory in Teddington UK has used novel scintillators for nuclear metrology within the laboratory for measurements of industrial application as well as more fundamental blue-sky research. The high light yield, possibility for low internal background, suitable energy resolution and low cost of the devices make them attractive counters for coincidence counting in the metrological regime and beyond.
Currently these measurements are made on the second generation National Nuclear Array (NaNA) device [1,2], which utilises up to 20 CeBr$_3$ in a 3D printed spherical geometry allowing for auxiliary detectors such as HPGe, Si and TDCR (liquid scintillation) counters to be added to the system for individualised experimental setups. This improvement has shown promise in the metrological context from the previous version comprised of 12 LaBr$_3$ detectors which contributes more internal background leading to more uncertainty in count rate for coincidence counting. Measurements on both generations of the device will be presented from primary standardisations: i.e. the realisation of the Becquerel – in the case of the $\gamma$-$\gamma$ emitting $^{60}$Co [3] and $\gamma$-X emitting $^{125}$I, to measurements of nuclear structure – validation of the $2^+\rightarrow0^+$ lifetime in $^{166}$Er - and measurements regarding the lifetime of positronium in different media.
These works, and other smaller scale studies with other different scintillator detectors at NPL have created expertise that have allowed the Nuclear Metrology Group to be involved in a fleet of experiments and collaborations worldwide. This talk will provide an overview of the work done at the NPL site and in outside experiments, as well as future work planned with these detectors.

[1] Shearman, R., et al, 2017. Commissioning of the UK NAtional Nuclear Array. Radiation Physics and Chemistry 140, 475–479. https://doi.org/10.1016/j.radphyschem.2017.02.007
[2] Regan, P.H., et al, 2015. Development of NANA: A Fast-Scintillator, Coincidence Gamma-ray Array for Radioactive Source Characterisation and Absolute Activity Measurements at the UK National Physical Laboratory. J. Phys.: Conf. Ser. 620, 012005. https://doi.org/10.1088/1742-6596/620/1/012005
[3] Collins, S.M., et al, 2018. Investigation of γ-γ coincidence counting using the National Nuclear Array (NANA) as a primary standard. Applied Radiation and Isotopes 134, 290–296. https://doi.org/10.1016/j.apradiso.2017.07.056

Speaker: Rob Shearman

FAST26_260427.pdf

15:05 → 15:30 Coffee Break

15:30 → 17:20 Day 1: Large Scintillator and hybrid arrays (II)

Convener: Agnieszka Barbara Korgul (University of Warsaw (PL))

15:30 Experiments with large volume LaBr3(Ce) and CeBr3 detectors at the IFIN-HH 9MV Tandem facility

While the $\gamma$-ray beams at ELI-NP are still under implementation, the instrumentation for nuclear structure and reaction studies at the $\gamma$-ray beam facilities are already completed and operational. Some of the scientific cases at ELI-NP will be the measurement of electromagnetic dipole response and strength distribution in different nuclei, pygmy dipole resonance excitations and decay, giant dipole resonance excitations and decay, photoinduced reactions for astrophysics and several other topics.

To initiate the ELI-NP scientific program already in this stage a set of campaigns with the large volume LaBr$_{3}$:Ce and CeBr$_{3}$ detectors [1] for large efficiency of high-energy $\gamma$ rays have been performed as a joint collaboration with the nuclear physics department at the 9MV Tandem accelerator facilities at IFIN-HH. These experimental campaigns from 2022-2025 have already proved very successful with several publications on multiple topics related to, among many other, light nuclei, statistical properties, collective motion and astrophysics [2-7]. Here we will give an overview of these campaigns.

[1] S. Aogaki, et al., Nucl. Instrum. Meth. A 1056 (2023) 168628
[2] A. Kuşoğlu, et al. Phys. Rev. Lett., 133 (2024) 072502
[3] P.-A, Söderström, et al., Phys. Scr., 100 (2025) 075301
[4] P.-A, Söderström, et al., Phys. Rev. C 112 (2025) 024327
[5] A. Giaz, et al., Phys. Lett. B 868 (2025) 139653
[6] K. Sakanashi et al., Phys. Lett. B 870 (2025) 139893
[7] O. Wieland, et al., Acta Phys. Pol. B Proc. Suppl. 18 (2025) 2-A33

This work was supported by the ELI-RO program funded by the Institute of Atomic Physics, Măgurele, Romania, contract number ELI-RO/RDI/2024-002 (CIPHERS)

Speaker: Pär-Anders Söderström (ELI-NP/IFIN-HH)

soderstrom_fast26_corrected.pdf

15:55 Fast-Timing at the GRIFFIN Facility

Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) is a high-efficiency gamma-ray spectrometer designed for use in decay spectroscopy experiments with low-energy radioactive ion beams provided by TRIUMF’s Isotope Separator and Accelerator (ISAC-I) facility in Vancouver, Canada. The 16 Compton suppressed HPGe clover detectors are complemented by a fast-timing array consisting of 8 cerium-doped lanthanum bromide detectors (LaBr$_{3}$(Ce)) and a fast $\beta$ plastic scintillator mounted at 0° to the beam axis. With a hybrid digital-analog DAQ, the system has been shown to achieve a $\gamma$-$\gamma$ timing resolution of $\approx$ 330 ps FWHM, with a time walk of $\pm$ 60 ps across the 244–1299 keV energy range [1]. The setup enables simultaneous application of both the Advanced Time-Delayed $\beta\gamma\gamma(t)$ (ATD) method and the Generalized Centroid Difference Method (GCDM) to $\beta$-decay studies, providing access to nuclear excited state lifetimes down to the picosecond range [2-5]. Recent developments include the commissioning of ARIES (Ancillary Detector for Rare-Isotope Event Selection), a high-efficiency $\beta$-particle detector combining ultra-fast plastic scintillators and Silicon Photomultipliers (SiPM) that will broaden the scope of the fast-timing program at GRIFFIN. This talk will give an overview of the current and future capabilities of the fast-timing array, followed by a discussion of recent results.

[1] A.B. Garnsworthy et al. In: Nucl. Inst. Meths. A 918 (2019), pp. 9–29
[2] H. Mach, R.L. Gill, and M. Moszyński. In: Nucl. Inst. Meths. A 280 (1989), pp. 49–72.
[3] M. Moszyński and H. Mach. In: Nucl. Inst. Meths. A 277 (1989), pp. 407–417.
[4] H. Mach et al. In: Nucl. Phys. A 523 (1991), pp. 197–227.
[5] J.-M. Régis et al. In: Nucl. Inst. Meths. A 726 (2013), pp. 191–202.

Speaker: Ms Rashmi Umashankar (TRIUMF/UBC)

FAST26_Rashmi.pdf

FAST26_Rashmi.pptx

16:20 Portable African Neutron-Gamma Laboratory for Innovative Nuclear Science

The Portable African Neutron-Gamma Laboratory for Innovative Nuclear Science (PANGoLINS) [1] project aims to investigate measurements of both gamma rays and neutrons which forms an important component part on site or in transit and the detection of both fissile material for the use in decarbonised energy sources or disposal thereof. A core component of the project is to miniaturize the weight of the gamma ray detection device and associated infrastructure so that it can be loaded on an unmanned aerial vehicle to enable access to and enhance performance of radiation monitoring measurements at remote sites leading to autonomous operations.

PANGoLINS incorporates commercial detector assemblies of LaBr3(Ce), SrI2(Eu) and/or CLYC(Ce) for spectroscopy. In addition, the project encompasses the instrumentation of other scintillation detectors with silicon photomultiplier technologies. The coupling of these to readout devices such as high-density ADC readout are planned for applications for nuclear science, medical imaging [2] or astronomy.
An overview of the project, its progress and potential outcomes will be presented.

References
[1] Jones, P. et al., IEEE Nuclear Science Symposium (2025) DOI: 10.1109/NSS/MIC/RTSD57106.2025.11286641
[2] Hart, S. et al., IEEE Nuclear Science Symposium (2025) DOI: 10.1109/NSS/MIC/RTSD57106.2025.11287197

Speaker: Dr Pete Jones (iThemba LABS, National Research Foundation (ZA))

Fast26_Jones_Presented.pdf

16:40 Development and Current Status of the FLASH Campaign at HIL Warsaw

The EAGLE array (European Array for Gamma Levels Evaluations) [1] is a multi-configuration detector setup for in-beam nuclear spectroscopy studies at the Heavy Ion Laboratory (HIL) of the University of Warsaw. It can accommodate up to 30 Compton-suppressed HPGe detectors.

Building on this foundation, a new campaign, FLASH (Fast-Timing LaBr$_3$ Array for Spectroscopy at HIL), is planned to expand the experimental capabilities of the EAGLE array. By incorporating up to 15 LaBr$_3$(Ce) detectors, the setup will enable advanced fast-timing measurements, opening a possibility for precise lifetime measurements of excited nuclear states.

The present status of development of the enhanced experimental setup will be reported along with the planned timeline for installation and strategies to mitigate issues such as Compton scattering, which posed challenges during the previous attempt. Additionally, the collaborative efforts with other research groups and their experimental ideas will be highlighted.

[1] A. Mierzejewski et al., Nucl. Inst. & Meth. Phys. Res. Sec. A 659 84 (2011).

Speaker: Andrej Špaček (Heavy Ion Laboratory at the University of Warsaw)

Spacek_FAST26_workshop.pdf

17:00 HISTARS: A High-Performance Detector for Nuclear Excited-State Lifetimes at HIE-ISOLDE

The ISOLDE facility at CERN is one of the most versatile and prolific facilities worldwide for the production of exotic isotopes using the Isotope Separation On-Line (ISOL) method. The HIE-ISOLDE project has realized a cutting-edge superconducting post-accelerator capable of delivering radioactive ion beams with energies up to 10 MeV/u, making ISOLDE a unique facility worldwide to accelerate medium and heavy isotopes within this energy range.

To exploit the vast possibilities offered for research in nuclear structure, nuclear astrophysics and other fields at ISOLDE, the HIE-ISOLDE Timing Array for Reaction Studies (HISTARS) project aims at building a detection device for the measurement of lifetimes of excited states populated in reactions. Nuclear excited-state lifetimes are essential to have direct access to electromagnetic transition rates, which are sensitive to the details of nuclear wavefunctions.

HISTARS combines a charged particle inner detector system with enhanced capabilities for reaction tagging with excellent timing response and an external gamma fast-timing array based on LaBr$_3$(Ce) detectors. The system aims to benefit from recent advancements in instrumentation and electronics, utilizing improvements in digital signal processing and innovative analysis techniques based on genetic algorithms. The project will expand research opportunities for the large community of accelerated beam users at ISOLDE.

The presentation will address the HISTARS conceptual design, the technical design study including Monte Carlo simulations, and the performance evaluation of fast-scintillator systems for gamma rays and charged particles. Test physics cases to showcase the potential of the instrument will be also introduced.

Speaker: Nikita Bernier (Universidad Complutense (ES))

Nikita_HISTARS_FAST2026.pdf

Tuesday 28 April

09:10 → 10:20 Day 2: Nuclear Structure from fast-timing measurements (I)

Convener: Sorin Gabriel Pascu (Horia Hulubei National Institute of Physics and Nuclear Engineering (RO))

09:10 Some aspects of fast timing measurements and background considerations

With the advent of relatively high-energy resolution (around 2-3 %) fast scintillators the use of fast timing techniques has had a revival in the past two decades, and led to a large number of efforts in instrumentation and development of techniques in almost all laboratories for nuclear spectroscopy. This includes stable beam facilities as well as the most advanced rare-isotope facilities.

In this presentation i will not even try to cover all these efforts, but will focus on a few points and more or less recent examples on measurements of the lifetimes of low-lying excited states, and how these (potentially precision) data can impact nuclear structure research.

Nowadays widely-accepted methods to analyze fast timing (or formerly called fast-electronics szintillaion timing [FEST]) data have been developed into a new "standard", e.g., with the introduction of the generalized centroid-shift method and ways to deal with so-called "time background". The latter can pose a huge challenge and needs to be dealt with, generally, case by case. Examples from a very low statistics data set, as well as a very high statistics set will be given, offering different ways (or besser necessities) for background considerations.

Speaker: Volker Werner (TU Darmstadt)

vw_fast26.pdf

09:35 Are the medium-mass odd-A Ag nuclei shell-model systems?

j-1 anomaly remains a mystery [1] 60 years after the first observations that something is not quite right with the low-energy poitive-parity states in the odd-A medium-mass Ag nuclei. Within the Shell model, nuclei with three particles or holes on g9/2, should have 9/2+ as their lowest-lying state. Instead, these nuclei have 7/2+ at even lower energies, which is considered to be anomalous behaviour. Such ordering of the states of the πg9/2-3 multiplet can not be easily explained within the state-of-the-art theoretical models. Also, within the Shell model, the single-j occupation leads to forbidden M1 transitions between the multiplet members. Thus, E2 transition rates should dominate the Ag structure [2]. Hence, the electromagnetic transition rates can provide a stringent test to the purity of the wave functions. However, to obtain them experimentally we need lifetimes and mixing ratios data [3]. Unfortunately, such data are available only for very few nuclei of the 16 odd-A Ag nuclei, spanning the region between the 97Ag and 129Ag, which is not enough to track the structureral changes throughout the silver isotopic chain. Therefore, three years ago we started a campaign of plunger life-time measurements in the πg9/2-3 multiplet members. This research will be completed with Fast-timing data that we plan to take in future experiments at IFIN and elsewhere.

Bibliography
[1] S.Lalkovski, S.Kisyov, Evolution of the j-1 anomalous states of the j-3 multiplets, Phys.Rev.C106 (2022)064319
[2] S.Lalkovski, S.Kisyov, O.Yordanov, j-1 anomalous states and the electromagneti transition rates in the neutron mid-shell Ag nuclei, Acta Physica Polonica B55 (2024) A2
[3] S.Kisyov, S.Lalkovski, Structure of the odd-A Ag isotopes via algebraic approaches, Symmetry 17 (2025) 1276

Speaker: Dr Stefan Lalkovski (Sofia University)

2026_04_28_FAST26_SL.pdf

10:00 Fast-timing lifetime measurements in the 176Yb and 178Yb isotopes

All rare-earth isotopic chains are known to undergo a transition from spherical to deformed shapes between the magic neutron number N = 82 and the neutron mid-shell region around neutron number N = 104. Both $^{176}$Yb and $^{178}$Yb isotopes (with N = 106 and 108, respectively) show signs of strong deformation, standing on the deformed side of the ytterbium isotopic chain, with R$_{4/2}$ = E$_{4^+_1}$/E$_{2^+_1}$ values close to the 3.33 benchmark value of a rigid-rotor nucleus. An experiment was carried out in the 10 MV FN Tandem accelerator of the Institut für Kernphysik at the University of Cologne to study the deformation evolution in the ytterbium isotopic chain through $\gamma$-spectroscopy and lifetime measurements in $^{176}$Yb and $^{178}$Yb isotopes. The lifetime of the E$_{2^+_1}$ excited state in $^{176}$Yb was remeasured, whereas in $^{178}$Yb it was measured for the first time. The preliminary results of the lifetime analysis, using fast-timing techniques, will be presented in this contribution together with the $\gamma$-spectroscopic findings, which set $^{178}$Yb as the most rigid-rotor-like isotope in its isotopic chain.

This work is supported by the German Research Foundation – 539757749.

Speaker: P. Koseoglou (Department of Physics, National and Kapodistrian University of Athens, Zografou Campus, GR-15784 Athens, Greece)

FAST26_koseoglou.pdf

10:20 → 10:40 Coffee Break

10:40 → 12:30 Day 2: Nuclear Structure from fast-timing measurements (II)

Convener: Prof. Luis M Fraile (CERN)

10:40 Enhanced collectivity observed through the first $0^+_3$ lifetime measurements in $^{118,120}$Sn using the fast-timing technique

The semi-magic Sn nuclei, extending beyond the $N=50$ and $N=82$ shell closures, present one of the most-studied isotopic chains on the nuclear chart. $^{118}_{50}$Sn$_{68}$ and $^{120}_{50}$Sn$_{70}$ lie in the neutron mid-shell, where shape coexistence was proposed with the signature of deformed excited $0^+$ states intruding into the seniority-like spherical yrast bands. However, transition strengths studies were hindered because only limits were available in the literature on the lifetimes of the excited $0^+_3$ states. Notably, the lack of electric monopole strengths between the $0^+_3$ and $0^+_2$ states, $\rho^2(E0;0^+_3\rightarrow0^+_2)$, obscured the shape difference and mixing amplitudes between the excited $0^+$ states.

These $0^+_3$ lifetimes were recently measured for the first time in a thermal-neutron capture experiment at the Institut Laue-Langevin. The world's highest-flux thermal neutron beam of $10^8$~neutrons/cm$^2$/s was delivered onto enriched $^{117}$Sn and $^{119}$Sn targets, respectively. Low-spin states in $^{118,120}$Sn were populated up to the $\approx 9$-MeV neutron separation energies, and the decaying gamma-ray cascades were detected with the Fission Product Prompt Gamma-ray Spectrometer (FIPPS) comprised of eight Compton-suppressed HPGe clovers coupled to an array of 15 LaBr$_3$ fast scintillation detectors.

In total, $\approx 4\times10^9$ counts were recorded in the $\gamma\gamma\gamma$ cube for each isotope, where two LaBr$_3$ events were in coincidence with one HPGe.

Monopole transition strengths from the lifetime measurements for the $0^+_3$ states in $^{118,120}$Sn will be presented along with theoretical interpretations employing MR-CDFT calculations without adjustable parameters.

Speaker: Frank Wu (Simon Fraser University)

FAST2026_FW.pdf

11:05 Fast-timing measurements in actinide nuclei

The atomic nuclei in the actinide region exhibit some of the most striking examples of collective structure in the nuclear chart, including strong quadrupole deformation, octupole correlations, and the emergence of reflection-asymmetric (pear-shaped) configurations. These phenomena give rise to enhanced electric dipole (E1) and octupole (E3) transition strengths, parity doublets, and low-lying collective excitations that challenge microscopic descriptions of nuclear structure. Of particular interest is the role of octupole deformation in amplifying symmetry-violating effects, making certain actinide nuclei prime candidates for searches for permanent electric dipole moments (EDMs) in atoms and molecules. Precision measurements of electromagnetic transition rates and lifetimes in these systems therefore provide critical input for both nuclear structure theory and fundamental symmetry tests.

This contribution will present an overview of recent fast-timing studies in selected actinide nuclei, drawing on both previously published results and ongoing analyses. The presentation will highlight how modern fast-timing techniques provide access to lifetimes and electromagnetic transition strengths in complex, highly collective systems, and will discuss how these measurements inform our understanding of octupole correlations and shape coexistence in this region.

Speaker: David O'Donnell

FAST26_workshop_2026.pdf

11:30 Enhanced octupole correlations in 148Dy

Octupole correlations are a form of nuclear collectivity that break reflection symmetry, giving rise to pear-shaped nuclei. They appear as static deformation or dynamic vibrations, with a key probe of this behavior being the reduced electric-octupole strength, B(E3), with large values pointing strong octupole correlations. The clearest evidence for static octupole deformation is found in Ra isotopes, while neutron-rich Ba isotopes were also prime candidates; however, recent precision measurements favor an octupole-vibrational interpretation, leaving stable deformation unresolved.
We report direct evidence for enhanced octupole collectivity in the neutron-deficient $^{148}$Dy through a lifetime measurement of the 3$_{1}$$^{-}$ state using fast-timing techniques. Excited states in $^{148}$Dy were populated via the β$^{+}$/EC decay of the $^{148}$Ho isomer at the TRIUMF ISAC-I facility and studied with the GRIFFIN spectrometer and its LaBr$_{3}$(Ce) array, PAELLA. This nucleus was investigated as part of an experimental campaign on Dy isotopes spanning $^{148-172}$Dy, carried out in December 2025.

In this contribution we present prelimiary values from the measured lifetime and branching ratio establishing $^{148}$Dy as a key nucleus and showing that the trend of increasing octupole strength extends beyond Z=64.

Speaker: Victoria Vedia (CERN)

V_Vedia_FAST'26.pdf

11:50 Fast-timing study of shape evolution around N≈60 in the 98-102Rb β-decay chain

The region around N≈60 with Z≤40 has generated considerable interest as it features the most abrupt shape transition known to date in the nuclear chart, when crossing from N=58 to N=60 [1]. This transition is closely linked to shape coexistence [2], a phenomenon where two or more states with different intrinsic shapes coexist within the same nucleus at low excitation energy and within a narrow energy range. Specifically, the abrupt change arises from the inversion of two distinct quantum configurations of nucleons, each corresponding to different nuclear shapes. These shifts are interpreted as quantum phase transitions [3], indicating a fundamental transformation in nuclear properties. This phase transition emphasizes the importance of nuclear deformations and the variety of shapes present in neutron-rich nuclei such as strontium, yttrium and zirconium.
To investigate the evolution of nuclear structure across this region, a fast-timing experiment (IS622) was performed at the ISOLDE Decay Station [4]. The experimental setup combined high-purity germanium (HPGe) detectors for precise γ-ray spectroscopy with fast LaBr$_{3}$(Ce) scintillators optimized for high-resolution timing measurements. Excited states were populated through the β decay of neutron-rich $^{98–102}$Rb isotopes, populating nuclei along the decay chain including Sr, Y, and Zr isotopes. The fast-timing method [5], based on both β–γ and γ–γ coincidences, enables the measurement of lifetimes from the nanosecond to the picosecond range.
The results provide updated and newly determined lifetimes for several excited states of interest in nuclei around N≈60. These lifetimes allow the extraction of transition strengths sensitive to nuclear deformation and collectivity, offering a more systematic view of structural evolution across the Sr–Y–Zr region and contributing to a better understanding of shape coexistence in neutron-rich nuclei.
[1] R. Rodriguez-Guzman, P. Sarriguren, and L. M. Robledo. Shape evolution in yttrium and niobium neutron-rich isotopes. Phys. Rev. C 83, 044307 (2011).
[2] A. Poves. Shape coexistence in nuclei. J. Phys. G: Nucl. Part. Phys. 43, 020401 (2016).
[3] T. Togashi, Y. Tsunoda, T. Otsuka, and N. Shimizu. Quantum Phase Transition in the Shape of Zr isotopes. Phys. Rev. Lett. 117, 172502 (2016).
[4] ISOLDE Decay Station, CERN. Available online: https://isolde-ids.web.cern.ch/. Accessed on March 6, 2026.
[5] J.-M. Régis, G. Pascovici, J. Jolie, M. Rudigier. The mirror symmetric centroid difference method for picosecond lifetime measurements via γ–γ coincidences using very fast LaBr$_{3}$(Ce). Nucl. Instrum. Methods Phys. Res. A 622, 83–92 (2010).

Speaker: Jesús Sánchez Prieto (Consejo Superior de Investigaciones Cientificas (CSIC) (ES))

FAST26 Jesús Sánchez Prieto.pdf

12:10 Nuclear structure of neutron-rich Ge isotopes

Abstract

The region around the doubly-magic $^{78}\mathrm{Ni}$ ($Z = 28$ and $N = 50$) is crucial for nuclear structure studies since it provides an ideal testing ground to investigate shell evolution and the interplay between single-particle and collective effects. Currently, many experimental and theoretical efforts are dedicated to investigate this region of the nuclear chart [1-3], aiming to understand the robustness of nuclear shells far from stability and the emergence of collective effects when nucleons are added. The interaction among valence nucleons may be capable of attenuating the magic nature of a nucleus very close to shell closures [4]. From this perspective, isotopes of Ge ($Z = 32$) are of interest to understand the evolution of the $N = 50$ gap.

In a recent experimental campaign, neutron-rich Ge isotopes were investigated via beta-decay spectroscopy of neutron-rich Ga using the ISOLDE Decay Station. Ga beams were produced at the ISOLDE facility at CERN by fission on a thick $\mathrm{UC}_x$ target by fast neutrons produced in a proton-to-neutron converter by the PSB proton beam. High production yields were achieved for isotopes such as $^{83-85}\mathrm{Ga}$, populating $^{82-85}\mathrm{Ge}$ through $\beta$-decay and $\beta$-delayed neutron emission.

The high yields and the 40 High Purity Germanium crystals in clover configuration at the ISOLDE Decay Station enabled the identification of new transitions and levels and provide the capability to perform angular correlation measurements for spin-parity assignments. In addition, two $\mathrm{LaBr}_3\mathrm{(Ce)}$ and three fast beta detectors were used to perform lifetime measurements of excited states in the sub-nanosecond range via fast-timing techniques.

In this contribution the extended level schemes of $^{85,84}\mathrm{Ge}$ and lifetime results will be presented. Furthermore, a theoretical interpretation of the nuclear structure of $^{84}\mathrm{Ge}$ based on the Projected Generator Coordinate Method using the Gogny D1S force and quadrupolar constraints with cranked HFB wavefunctions [5, 6] will be shown and compared to the experimental results.

References

[1] R. Yokoyama et al., $\beta$-delayed neutron emissions from N > 50 gallium isotopes, Physical Review C 108 (2023) 064307.
[2] K. Sieja et al., Laboratory versus intrinsic description of nonaxial nuclei above doubly magic $^{\mathrm{78}}$Ni, Physical Review C 88 (2013) 034327.
[3] C. Delafosse et al., Pseudospin Symmetry and Microscopic Origin of Shape Coexistence in the $^{\mathrm{78}}$Ni Region: A Hint from Lifetime Measurements, Physical Review Letters 121 (2018) 192502.
[4] A. Huck et al., Beta decay of the new isotopes $^{\mathrm{52}}$K, $^{\mathrm{52}}$Ca, and $^{\mathrm{52}}$Sc; a test of the shell model far from stability, Physical Review C 31 (1985) 2226.
[5] J. Berger et al., Microscopic analysis of collective dynamics in low energy fission, Nuclear Physics A 428 (1984) 23–36.
[6] L. M. Robledo et al., Mean field and beyond description of nuclear structure with the Gogny force: a review, Journal of Physics G: Nuclear and Particle Physics 46 (2018) 013001.

Speaker: Pablo Gonzalez-Tarrio Vicente (Universidad Complutense (ES))

FAST26_Slides_PGTV_v2.pptx

12:30 → 13:30 Lunch

13:30 → 14:30 Day 2: Instrumentation (Sponsors)

Convener: Simone Bottoni (Università degli Studi e INFN Milano (IT))

13:30 Fast scintillators from LUXIUM

Speaker: Fabien Dubar (LUXIUM SOLUTIONS)

2026-04-27 FAST bucarest.pdf

14:00 Compact and Scalable Electronics for Sub-10 ps Timing in Particle and Nuclear Physics

High-precision time measurements are crucial for both high-energy physics experiments and advanced medical imaging applications, such as Positron Emission Tomography (PET). Future detector systems require readout electronics that combine sub-10 ps timing resolution with scalability, compactness, and efficient multi-channel integration.
The CAEN A5203 module, part of the FERS 5200 system, integrates the high-performance picoTDC ASIC from CERN, enabling precise Time of Arrival (ToA) and Time over Threshold (ToT) measurements. The unit features 3.125 ps LSB precision over 64 channels and can be coupled with a leading-edge discriminator stage. In this configuration, it achieves ~7 ps RMS timing resolution for constant-amplitude signals and ~20 ps RMS for variable-amplitude signals. The walk effect is corrected via ToT, which also enables signal amplitude reconstruction and background noise suppression.
Successfully deployed in a high-resolution PET imaging system, the A5203 has demonstrated its capability for large-scale applications, supporting continuous, dead-time-free acquisition from thousands of channels. In high-energy physics, the FERS architecture, combined with the picoTDC’s performance, is well-suited for integration with advanced front-end electronics, such as Weeroc’s Radioroc and Psiroc ASICs, enabling precise energy and time measurements with Silicon-based detectors. These features make the FERS system a powerful and flexible solution for next-generation applications in both fundamental research and applied physics.

Speaker: Mr Yuri Venturini (CAEN SpA)

PicosecondTimingMeasurements_FAST26_Venturini_CAEN.pptx

14:30 → 15:20 Day 2: Flash poster presentations

Convener: Agnieszka Barbara Korgul (University of Warsaw (PL))

14:30 Probing the chiral geometry in $^{126}$La using the ROSPHERE array

Chirality is one of the most intriguing phenomena observed in atomic nuclei. It has been extensively reported in doubly odd nuclei within the mass region around A ≈ 130 [1]. A vital test for confirming the presence of chirality in nuclei involves examining the behavior of their in-band transition probabilities [2]. Given this context, precise lifetime measurements of excited states are essential. This is evident in the case of Lanthanum isotopes [3,4], where the nearly energy degenerates bands are observed but their respective transition probabilites do not follow the predicted behavior. Chiral vibration has been observed in $^{130}$La [5] but not in $^{132}$La [2], although both nuclei exhibit nearly degenerate energy bands. To explore the presence of chirality on the more neutron-deficient side of lanthanum isotopes, we have conducted an experiment to populate high-spin states and measure the lifetimes of excited states in $^{126}$La, with the aim of investigating its chiral character. The experiment has employed the $^{112}$Sn($^{16}$O, pn)$^{126}$La reaction at a beam energy of 68 MeV. The ROSPHERE array, consisting of twenty-two Compton-suppressed HPGe detectors arranged in multiple angular rings, has been used for γ-ray detection. We have successfully populated the main band and its partner bands and have observed Doppler-shifted γ-ray line shapes. The extraction of lifetimes from these line shapes is currently under investigation.

[1] K. Starosta, T. Koike, C. J. Chiara, et al., Phys. Rev. Lett. 86, 971 (2001).
[2] E. Grodner, J. Srebrny, A. A. Pasternak, et al., Phys. Rev. Lett. 97, 172501 (2006).
[3]  K.Y. Ma, J.B. Lu, D. Yang, H.D. Wang, et al., Phys. Rev. C 85, 054306 (2012).
[4]  K.Y. Ma, J.B. Lu, S.P. Ruan, D. Yang, et al., Phys.Rev. C 88, 057302 (2013).
[5] M. Ionescu-Bujor, S. Aydin, N.Marginean, et al., Phys. Rev. C98, 054305 (2018).

Speaker: Himanshu Kumar Singh

126La_HKSingh.pdf

14:35 Recent Advances in the β-Decay Spectroscopy of $^{118}$Pd

The study of $\beta$-decay properties of neutron-rich nuclei in the A $\approx$ 120 region provides key insights into nuclear-structure evolution and serves as a critical benchmark for modern theoretical models, as well as for astrophysical r-process simulations. In this context, the $\beta$-decay of $^{118}$Pd ($Z$ = 46, $N$ = 72), populating excited states in $^{118}$Ag, has been investigated at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyväskylä.

The $^{118}$Pd isotope was produced via proton-induced fission of uranium and subsequently purified and mass-separated using the JYFLTRAP system to ensure high isotopic purity. The decay spectroscopy setup consisted of three high-purity germanium detectors for $\gamma$-ray detection, a plastic scintillator for β tagging, and a movable tape-transport system for activity collection and removal.

A comprehensive analysis of $\beta-\gamma$ and $\gamma-\gamma$ coincidence data has led to a substantial revision of the previously established decay scheme of $^{118}$Pd [1]. Several new γ transitions and previously unreported excited states in $^{118}$Ag have been identified. Furthermore, a cascade of transitions indicative of a new isomeric state [2] has been proposed.

Ongoing work focuses on the extraction of $\beta$-feeding intensities and log ft values, which are essential for constraining spin–parity assignments and refining theoretical descriptions of $\beta$-decay strength distributions in this mass region.

The presented results contribute to the systematic investigation of neutron-rich palladium and silver isotopes, offering improved understanding of nuclear structure in the vicinity of N ≈ 70 and providing valuable experimental input for r-process nucleosynthesis models. A summary of the latest findings will be presented and discussed.

[1] Z. Janas, J. Äystö, K. Eskola, P.P. Jauho, A. Jokinen, J. Kownacki, M. Leino, J.M. Parmonen, H. Penttilä, J. Szerypo, J. żylicz,
Gamow-Teller decay of 118Pd and of the new isotope 120Pd,
Nuclear Physics A,
Volume 552, Issue 3,
1993,
Pages 340-352,
ISSN 0375-9474,

[2] B. van den Borne, M. Stryjczyk, R. P. de Groote, A. Kankainen, D. A. Nesterenko, L. Al Ayoubi, P. Ascher, O. Beliuskina, M. L. Bissell et al.
Binding energies, charge radii, spins, and moments:
Odd-odd Ag isotopes and discovery of a new isomer

Speaker: Michał Młynarczyk (Faculty of Physics, University of Warsaw, PL-02-093 Warsaw, Poland)

Mlynarczyk_Michal_FAST2026.pdf

14:40 Investigation of Excited States in 124Sn Populated in β Decay of 124In

Over the past several years, extensive studies have been devoted to the structure of neutron-rich tin isotopes, which possess a closed proton shell, with ¹³²Sn being a doubly magic nucleus. For this reason, these nuclei play a particularly important role in testing the validity of the nuclear shell model and serve as a benchmark for theoretical predictions. Information obtained in this region of the nuclear chart is essential for developing reliable extrapolations toward even more neutron-rich isotopes.

In the experiments studied, the tin nuclei are produced by the β− decay of indium isotopes and via the emission of β− delayed neutrons or, in some cases, two β− delayed neutrons [1, 2]. Data from this mass region are also highly relevant from an astrophysical perspective, as they contribute to a better understanding of the r-process nucleosynthesis responsible for the formation of heavy elements in the universe.

In the present study, we focus on the excited states in 124Sn populated in the β− decay of 124In investigated in an experiment performed at the ISOLDE Decay Station (IDS). In addition to the aforementioned motivations, an additional driving factor for studying the structure of this nucleus is the possible occurrence of the rare two-neutrino double beta decay (2β−) in 124Sn. Although
124Sn is a stable nucleus and the single β− decay is energetically forbidden, the 2β− decay is allowed and has been the subject of several investigations [3–5]. A better understanding of the nuclear structure of 124Sn will improve the reliability of theoretical predictions for this process
and may help identify excited states that are more likely to be involved in the transition.

The current analysis of the β− decay of the two isomeric states of 124In includes β–γ, β–γ–γ and γ–γ coincidence spectra. A detailed comparison of the previously established decay scheme with the new experimental data led to the reassignment of six γ transitions to different positions in the level scheme. These changes were reinforced by finding new gammas that fit the changed scheme very well. To sum up the preliminary analysis, 21 new transitions were identified and included in the scheme and 17 new excited levels were obtained.

References
[1] M. Piersa, A. Korgul et al., Phys. Rev. C 99, 024304 (2019).
[2] M. Piersa-Siłkowska, A. Korgul et al., Phys. Rev. C 104, 044328 (2021).
[3] A. S. Barabash, Ph. Hubert et al., Nucl. Phys. A 807, 269281 (2008)
[4] M. Horoi, A. Neacsu, Phys. Rev. C 93, 024308 (2016)
[5] D. Patel, P. C. Strivastava et al., Nucl. Phys. A 1042, 122808 (2024)

Speaker: Pawel Wakuluk (University of Warsaw (PL))

Pawel_Wakuluk.pdf

14:44 A desktop digital TDPAC spectrometer based on a CAEN DT5730S digitizer and the PACIFIC² Python analysis suite

Advancements in low-cost FPGA-integrated digitizers are reshaping timing techniques in nuclear spectroscopy, enabling compact digital solutions for coincidence measurements. In this work, we present a fully digital time-differential perturbed angular correlation (TDPAC) spectrometer based on a commercial CAEN DT5730S digitizer (8 channels, 14-bit ADC, 500 MS/s) combined with PACIFIC², an in-house Python framework for flexible online and offline γ–γ coincidence analysis. [1]

The system allows efficient processing of list-mode data and reconstruction of coincidence spectra in multi-detector configurations. Experimental validation was performed using metallic indium and layered perovskite samples probed with $^{111}$In and $^{111m}$Cd isotopes. The results demonstrate reliable real-time acquisition and processing of γ–γ coincidence events.

Time resolution optimization was investigated using 511–511 keV γ–γ coincidences from positron–electron annihilation in a $^{22}$Na source, detected with LaBr$_3$:Ce scintillators coupled to Hamamatsu R2083 photomultiplier tubes. After optimization of the digitizer's digital constant fraction discriminator parameters, a coincidence time resolution of approximately 450 ps FWHM was achieved with the 500 MS/s digitizer. [1]

The PACIFIC² framework also enables flexible coincidence analysis strategies, including ongoing developments aimed at evaluating γ₁–γ₂ correlations detected within the same detector channel, which may further extend the applicability of digital timing methods.

These results demonstrate that compact multi-channel digitizers combined with modern data-analysis frameworks provide an accessible and versatile platform for timing-based nuclear spectroscopy and hyperfine interaction studies.

Acknowledgments:
This work was supported by the Portuguese Foundation for Science and Technology (FCT) under projects UIDB/04968/2025, UIDP/04968/2025, LA/P/0095/2020, and CEECIND-2023.07340.CEECIND/CP2833/CT0006.

References:
[1] Rocha-Rodrigues et al., NIM A 1087 (2026) 171440, https://doi.org/10.1016/j.nima.2026.171440

Speaker: Pedro Miguel Da Rocha Rodrigues (Universidade do Porto (PT))

PACIFIC2_poster.pdf

14:48 l-forbidden M1 transitions in N=50 isotones

Regions near closed shells in areas of the nuclear chart far from stability are very interesting from the point of view of nuclear structure, since a shell model description based on single-particle states can be challenged by collective effects. One of the most interesting regions is the one around the doubly-magic $^{78}$Ni nucleus, with $Z = 28$ and $N = 50$ [Taniuchi2019].

Odd-$A$ $N = 50$ isotones are particularly well suited to probe proton single-particle configurations outside the $^{78}$Ni core. The low-lying structure of the $^{79}$Cu to $^{89}$Y isotones, with $Z = 29$ to $Z = 39$, is expected to arise from the progressive filling of the proton $pf$ shell, involving the $f_{5/2}$, $p_{3/2}$ and $p_{1/2}$ single-particle orbitals and giving rise to low-lying $5/2^{-}$, $3/2^{-}$ and $1/2^{-}$ states. The occurrence of single-particle states experimentally observed as the ground state and low-lying first-excited states with dominant $p_{3/2}$ and $f_{5/2}$ configurations leads to magnetic dipole M1 $\Delta l = 2$ connecting transitions between them, which are $l$-forbidden in the extreme shell model picture [Sachs1951,Govil1964].

This is so because magnetic dipole isovector operator does not change the orbital angular momentum. Nonetheless, such transitions are still experimentally observed, although with rates that are generally much lower than those of allowed transitions, or even below the single-particle limit. It is expected that these transitions result from the breakdown of $l$-forbiddenness, influenced by other nuclear dynamic effects, such as core polarization [Horie1954] and meson exchange mechanisms [Andrejtscheff1981].

Therefore, the investigation of $l$-forbidden M1 transitions may provide insight into the role of these effects within the atomic nucleus.

In this work we aim at extending the systematics of M1 transitions to constrain the underlying proton configurations and try to clarify the origin of the $l$-forbidden M1 hindrance. To this end, two complementary experiments were performed at the ISOLDE (CERN) facility and ILL reactor in Grenoble, France. In the former the structure of $^{83}$As was investigated via the $\beta$ decay of $^{83}$Ga at the ISOLDE Decay Station, while in the second excited states in $^{85}$Br, $^{87}$Rb where populated in the $\beta$ decay $^{85}$Se and $^{87}$Kr, which were transported and analyzed using the LOHENGRIN spectrometer. Lifetimes of excited states in nuclei of interest investigated by fast-timing techniques.

The presentation will address the experimental methodologies and the data analysis procedures. The results will be discussed in the context of other available data for the region, completing the systematics from $^{81}$Ga to $^{87}$Rb where the dominant single-particle configurations are due to the $p_{3/2}$ and $f_{5/2}$ orbitals in the $28$-$50$ proton shell. Based on these measurements the systematics of $l$-forbidden M1 transitions in $N = 50$ isotones will be described.
Andrejtscheff1981] W. Andrejtscheff et al., Nuclear Physics A 351 (1981) 54.
[Govil1964] I.M. Govil and C.S. Kurana, Nuclear Physics 60 (1964) 666.
[Horie1954] Horie and Arima, Prog. Theor. Phys. 11 (1954) 509.
[Sachs1951] R.G. Sachs and M. Ross, Phys. Rev. 84 (1951) 379.
[Taniuchi2019] Taniuchi et al., Nature 569 (2019) 53.

Speaker: Gabriel Garcia De Lorenzo (Universidad Complutense (ES))

Flash-FAST-2026.pdf

Flash-FAST-2026.pptx

14:52 Optimization of time-stamping methods in digital acquisition systems for $\gamma$ detection

In recent years, nuclear spectroscopy experiments have progressively replaced traditional analog setups with compact and affordable digital data acquisition systems. These systems reduce size and electronic complexity while maintaining adequate performance for a wide range of applications.

More recently, digital Time Differential Perturbed Angular Correlation (PAC) spectroscopy setups have been implemented at ISOLDE/CERN and at IFIMUP (Porto, Portugal) using CAEN DT5730s digitizers operating at a sampling rate of 500 MS/s with 14-bit ADC resolution. For PAC experiments employing probes such as $^{111m}$Cd and $^{111}$In, whose probe state has a half-life of 84 ns, the digital systems are fully operational and provide results equivalent to those obtained with conventional analog electronics.

However, PAC studies using probes with much shorter probing half-lives, such as $^{199m}$Hg (2.46 ns) and $^{181}$Hf (10.8 ns), remain limited. These experiments require an effective time stamp resolution significantly smaller than the digitizer sampling period of 2 ns, which cannot be achieved through hardware-based digital processing alone. This limitation can nevertheless be addressed through post-processing of the detector output signals, taking advantage of the high 14-bit ADC resolution.

In this work, the recorded waveforms are fitted with approximate analytical functions to refine the determination of event timestamps. Preliminary results obtained from 511 keV - 511 keV photon coincidences following the $\beta^{+}$ decay of $^{22}$Na show a clear improvement in time-stamping resolution. The method becomes effectively insensitive to sub-2 ns delays between the arrival times of the two photons.

These results indicate that cost-effective digitizer units can be employed in modern $\gamma$-detection experiments while preserving good timing performance and eliminating the need for precise channel synchronization.

Acknowledgements
The authors acknowledge FCT for the projects 2024.00223.CERN; 2023.01884.BD; 2023.07340.CEECIND/CP2833/CT0006; 2022.04845.CEECIND/CP1719/CT0008; LA/P/0095/2020; UIDB/04968/2025; and UIDP/04968/2025.

Speaker: Antonio Duarte Neves Cesario (Universidade do Porto (PT))

FAST26-Oral-Pres-Poster-final-final.pdf

FAST26-Oral-Pres-Poster-final-final.pdf

poster-FAST26-final.pdf

14:56 Testing results of a novel front-end readout ASIC with precise timing capabilities for next generation LHCb RICH detectors: the FastRICH

The LHCb Ring Imaging Cherenkov (RICH) sub-detectors will undergo a major upgrade of their opto-electronics chain in the next decade. The upgrade will take place in two steps and will start first with the electronics chain upgrade during the LS3 Enhancement program for RUN 4, followed by a sensor replacement for Upgrade II during RUN 5. A novel front-end ASIC, the FastRICH, was designed to fulfill the requirements of the next generation RICH fast-timing readout chains with single-photon operation regime.
The FastRICH is a collaboration effort between CERN EP-ESE department and University of Barcelona and features a radiation-hard with digital-on-top design in a 65 nm CMOS technology node. It provides 16 single-ended input channels that can be configured to allow working either in positive or negative polarity. Due to its wide input dynamic range between 50 μA to 5 mA, it allows the coupling of various single-photon sensitive sensors such as: Multi-Anode Photomultiplier Tubes (MaPMTs), Silicon Photomultipliers (SiPMs), or Micro-Channel Plate sensors (MCPs). Every channel includes two discrimination processing paths: leading-edge discriminator (LED) and constant-fraction discriminator (CFD). The LED is based on direct discrimination of the input signal with a threshold value. It allows measuring time-of-arrival (TOA) with 24.41 ps bins and time-over-threshold (TOT) bins of 390.62 ps and up to a maximum range of 100 ns. The CFD allows for time walk correction and gives only the corrected signal TOA information. Overall, the recovery time for the analog processing part is better than 10 ns. The timing information is obtained with a built-in 16-channel time-to-digital converter (TDC) with performances down to 24.41 ps bins (ultrafine mode) and per channel auto-calibration capabilities. A hardware gate is implemented to filter out the data from the TDC outputs. Within a 25 ns window, the gate can be precisely set with configurable start time in 195.32 ps steps, and up to 6.25 ns length in steps of 24.41 ps. The ASIC is compatible with the LHCb readout framework by supporting Experiment Control System (ECS) for configuration over I2C protocol and Timing and Fast Control (TFC) for synchronization. An event-driven readout protocol is used for transmitting the data and it dynamically adapts to the number of hits that may arrive in the same bunch crossing event. Data is encoded with the commercial Aurora 64b/66b protocol, and it can be sent through serializers with a configurable speed between 0.32 Gbps and 5.12 Gbps. The power consumption has been optimized for less than 16 mW/channel with the ASIC powered at 1.2 V nominal voltage. Finally, the FastRICH will be integrated in a 10 mm x 10 mm plastic molded QFN88 package.
The ASIC was submitted to the foundry for a MPW run in February 2025 and the first naked dies have been received in May 2025. In parallel, massive efforts have been put together to characterize the ASIC with a dedicated FPGA-based and in-house designed system. The lab characterization tests have been carried out with the ASIC wire-bonded to a test board and without a sensor coupled to its inputs. So far, all the blocks inside the ASIC are working as expected. The analogue blocks inside the ASIC behave according to simulations. The linearity measurements of the digital-to-analogue (DACs) periphery blocks are matching the simulation results. The ASIC embeds a built-in threshold scan functionality that allows to scan the noise levels in the channels over the ECS and without relying on the full readout path. This is done by counting the number of discriminator rising edges (LED and CFD) that are triggered by the electronic noise. The results show consistent noise σ values across all 16-channels. The output jitter of the internal Phase-Locked Loop (PLL) has been optimized to ~5.81 ps, being very close to the expectations and in response to an external reference clock with ~1.5 ps jitter. The TDC blocks proved to have very good linearity. The standard deviation of the differential non-linearity (DNL) value was measured to be below 6 ps, while the integral non-linearity (INL) was obtained to be in the range of +/- 24 ps. All the interfaces are working as expected. Tests with external triggered test pulse injection and with the full readout chain have been performed with success. The power consumption was measured to be between 11 - 13 mW/ch, being strongly dependent on the configuration and on the hit rate.
The FastRICH ASIC and its pre-production validation campaign represents a very important milestone to achieve in the timeline of the future LHCb RICH upgrade programs. More results regarding the characterization of the FastRICH in the lab will be presented at the workshop.

Speaker: Vlad-Mihai Placinta (Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH RO))

15:00 Investigating shape-effects of neutron deficient Sr-82 with safe multi-step Coulomb Excitation

Neutron deficient nuclei in the A=80 mass region present a rich-nuclear structure where subshell effects give rise to sudden shape changes, from highly deformed nuclides in the N≤40 region to spherical isotopes near N=50. Systematics of low-lying states and transitions in neutron-deficient strontium isotopes show a steady reduction in excitation energies and a corresponding increase in reduced transition probabilities as one look to more neutron-deficient isotopes. The reduced transition probability ratio B is found to increase towards the axial rotor limit for more deformed neutron-rich nuclei. A significant deviation from this trend is found for ${}^{82}$Sr [1], with the ratio rising above the vibrational limit, indicating that more complex phenomena is occurring at low excitation energies. Shape coexistence and triaxial degrees of freedom may explain this deviation as both phenomena are common in the A=80 region.

Shape effects in ${}^{82}$Sr have been investigated through the safe multi-step Coulomb excitation using the TIGRESS spectrometer at TRIUMF [2], with the aim of measuring B(E2) and spectroscopic quadrupole moments $Q{}_{s}$. This was done by impinging ${}^{82}$Sr nuclei onto ${}^{196}$Pt and ${}^{208}$Pb targets. The Coulomb excitation code GOSIA [3] was used to extract multiple E2 matrix elements, from which the B(E2) and $Q{}_{s}$ values were determined and, using Kumar-Cline sum rules [4][5], deduced the intrinsic shape invariant quantities, establishing the deformation and axial symmetry of the nucleus. In this presentation, the results of the analysis will be presented and compared with the triaxial rotor empirical model to determine the nuclear axial asymmetry or triaxiality γ [6], and beyond mean-field calculations.

References
1. Evaluated Nuclear Structure Data File (ENSDF), NNDC
2. G. Hackman and C. E. Svensson, Hyperfine Int. 225 (2014) 241
3. D. Cline et al., Gosia User Manual for Simulation and Analysis of Coulomb Excitation Experiments, http://www.pas.rochester.edu/~cline/Gosia/Gosia_Manual_20120510.pdf, Rochester, NY, US, 2012
4. K. Kumar, Phys. Rev. Lett. 28 (1972) 249
5. D. Cline, Ann. Rev. Nucl. Part. Sci. 36 (1972) 249
6. E. A. Lawrie and J. N. Orce, Atom. Data Nucl. Data Tables 164 (2025) 101730

Speaker: Manfred Jaftha (University of the Western Cape)

Manfred.pdf

15:04 Investigating shape coexistence using β+/EC decay spectroscopy in 80Sr and 118Te

Nuclides in the A ≈ 80 mass region provide an important testing ground for shape coexistence driven by sub-shell gaps and configuration mixing. The nucleus ⁸⁰Sr is predicted to exhibit coexisting shapes at low excitation energy [1], but experimental information on non-yrast states and excited 0⁺ levels remain limited. The first excited 0⁺ state has been tentatively assigned near 1 MeV in evaluated data (NNDC) [2], based on the ⁷⁸Kr (³He, n) two-proton transfer reaction [3].β-decay spectroscopy provides complementary information needed to confirm these assignments.
The collective structure of ⁸⁰Sr is investigated using β⁺/EC decay of ⁸⁰Y. The data were obtained at the ISOLDE Decay Station (IDS) at CERN, during requested yield measurements preceding the approved experiment on ⁸⁰Y and ⁸²Y decays. The setup included eight HPGe clover detectors for γ-ray spectroscopy, LaBr₃(Ce) detectors for fast timing, a plastic scintillator for β detection, and a geometry suitable for γ–γ angular correlation measurements. These data allow β–γ–γ coincidence analysis, angular correlation and lifetime measurements of excited states. The SPEDE electron spectrometer was part of the approved proposal [4] but was commissioned only in October 2025, and the full experiment will be performed when beam time becomes available.
Gamma-ray transitions were identified and coincidence relationships established to search for low-lying non-yrast states, and a partial level scheme of ⁸⁰Sr has been constructed. Contamination from ¹¹⁸I decay was observed, and a partial level scheme for ¹¹⁸Te was therefore built, with several previously unreported transitions and levels assigned to this nucleus.
Ongoing work includes γ–γ angular correlation analysis and lifetime measurements in ⁸⁰Sr to determine spins and multipolarities. Participation in the planned workshop will provide essential training in angular-correlation and fast-timing techniques required to complete this analysis.

References:
[1] J. Döring, K. Heyde, M. Hannawald, et al. Low-spin states from decay studies in the mass 80 region. The European Physical Journal A 7(4) (2000) 507–515. https://doi.org/10.6028/jres.105.006
[2] National Nuclear Data Center (NNDC). Chart of Nuclides & Level Schemes (2023). Brookhaven National Laboratory. https://www.nndc.bnl.gov
[3] W.P. Alford, J. Cerny, B.G. Harvey, et al. A study of the (3He, n) reaction on isotopes of Krypton, Nuclear Physics A 330 (1979) 77–90. https://doi.org/10.1016/0375-9474(79)90538-4
[4] Proposal to the ISOLDE and Neutron Time-of-Flight Committee https://cds.cern.ch/record/2731976/files/INTC-P-586.pdf

Speaker: Geneva Anelska April (University of the Western Cape (ZA))

Geneva.pdf

15:08 Fusion-fission yield measurements: Current gamma-ray spectroscopy and prospective ToF upgrades

Prompt and delayed gamma-ray spectroscopy of fission products is a robust method for measuring fragment yields in fusion-fission reactions. Currently, the analysis of $\gamma$-$\gamma$-$\gamma$ cascades and decay curves enables the extraction of absolute independent fragment yields, as demonstrated in recent studies on heavy-ion induced fission of the $^{215}$Fr and $^{194}$Hg systems at high excitation energies performed with the $\nu$-ball-2 set-up at the ALTO facility (IJCLab) [1, 2].

Ongoing work focuses on analysing data from the May 2024 EAGLE–NEDA–DIAMANT campaign at Heavy Ion Laboratory (University of Warsaw), studying the $^{32}$S + $^{112}$Sn reaction. This setup combines HPGe detectors with the NEDA liquid scintillator array for neutron/gamma-ray separation, and the DIAMANT detector for alpha-proton discrimination.

This poster presents both previous and ongoing experiments and introduces preliminary calculations on the possible use of fast-timing instrumentation in planned fusion-fission studies at HIL. The integration of additional detectors with the EAGLE array is being evaluated. In particular, diamond detectors are considered for time-of-flight-based fragment mass-ratio tagging. These detectors offer high radiation hardness and intrinsic resolution; they can achieve mass resolution useful for fission-fragment detection and potentially unlock new capabilities for fusion-fission studies at HIL.

[1] K. Miernik et al., "Fission of $^{215}$Fr studied with $\gamma$ spectroscopic methods" In: Physical Review C 108, 054608 (2023). DOI: https://doi.org/10.1103/PhysRevC.108.054608
[2] K. Miernik et al., "$\gamma$ spectroscopy of fission fragments from the ${}^{12}$C + ${}^{182}$W fusion-fission reaction", In: Physical Review C, Accepted 31 March, 2026, DOI: https://doi.org/10.1103/78t8-cycj

Speaker: Piotr Michal Garczynski (University of Warsaw (PL))

garczynski_fast26_poster_ad.pdf

15:12 Heterostructured scintillators for enhanced timing resolution in ToF PET imaging

In between modern technologies for precise tumor diagnosis at early stages, the positron emission tomography (PET) scanner is the most informative and “sensitive” tool used in medicine. The goal is to develop a new series of ultrafast (time resolution < 100 ps) scintillation detectors for time-of-flight positron emission tomography (ToF-PET) scanners oriented to replace the conventional PET systems. Along with the commercial application, the goal is also to accomplish a missing theory gaps in scintillation detectors design for medical imaging. Now we are faced with the physical barrier of detector performance; all other parts, like fast electronics, mathematical processing, AI image reconstruction, and machine learning, could easily handle it, even with femtosecond fast signal processing. Compared to the classic scintillation detectors, the research question is to create a new scintillation material combining the high stopping properties in the 511 keV energy range, with the high light yield (>10000 ph/MeV), along with fast rise (< 1ns) and decay time (< 10 ns) light feedback. A promising heterostructured material, like bismuth germanate (BGO), in combination with ZnO: Ga microwire coatings, could accelerate scintillation signal response.

Speaker: Dr Ivan Yakymenko (V.N. Karazin Kharkiv National University (UA))

Poster fast 2026.pdf

Poster fast 2026.pptx

15:20 → 15:30 Coffee Break

15:30 → 17:00 Poster Session

19:00 → 22:00 Workshop Dinner (Direct bus leaving from ELI-NP Gate at 18:00)

We will have the pleasure to invite you to the Workshop Dinner taking place at https://hanumanucrestaurant.ro/ in the Old City Centre. A bus will take everyone to the restaurant at 18:00 from the main gate of ELI-NP.

Wednesday 29 April

09:20 → 10:40 Day 3: Nuclear structure from fast-timing measurements (III)

Convener: Volker Werner (TU Darmstadt)

09:20 Fast-timing measurement of the $2^+_1$ state lifetime in $^{106}\mathrm{Pd}$

The neutron-deficient region around the $Z=50$ major shell closure provides fertile grounds for nuclear structure studies, as single-particle degrees of freedom compete with collective phenomena to form several of the observed spectroscopic properties. Pd isotopes, sitting 4 protons below the shell closure,present especially attractive study cases, with recent theoretical and experimental work highlighting their complex structure. Evidence for shape coexistence appears in the neutron region $N=60-66$, while substantial triaxiality is predicted for $N=56-74$. The overlap of these phenomena points to a rich interplay between nuclear shapes, collectivity, and phase transitions. Motivated by the above, an experiment was conducted at the 9 MV Tandem Accelerator Laboratory of IFIN-HH, aimed at investigating the nuclear structure of $^{106,108}$Pd through measurements of lifetimes and $B(E2)$ reduced transition probabilities of low-spin states. A proton-pickup reaction with a 35~MeV $^{11}$B beam impinging on a $^{nat}$Ag target was used to populate excited states in $^{106,108}$Pd. The $\gamma$ rays de-exciting these levels were detected by the ROSPHERE array, in its mixed 15 HPGe + 10 LaBr$_3$(Ce) detector configuration. Additionally, the SORCERER particle detector array was coupled to ROSPHERE, enabling the study of $p-\gamma$ and $p-\gamma-\gamma$ coincident events. The lifetime of the $2^+_1$ state in $^{106}$Pd was determined with the fast electronic scintillation timing (FEST) technique, and compared to theoretical predictions, to probe quadrupole collectivity in the $^{106}$Pd nucleus.

Speaker: Dr Polytimos Vasileiou (Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH))

PVasileiou_FAST26_presentation.pdf

09:40 In-flight $\gamma$-ray spectroscopy and $T_{1/2}$ measurements of low-lying excited states in $^{129}In$ and $^{128}Cd$

The region "south-west" of $^{132}$Sn is of interest for both theoretical and experimental efforts to comprehend nuclear shell structure in the vicinity of proton (Z=50) and neutron (N=82) shell closures. The half-lives of excited nuclear states are a crucial source of information on nuclear shell structure, and advanced experimental methods had to be developed to obtain the necessary data. Since possible half-lives, even taking into account only fast-timing spectroscopy, span over a few orders of magnitude from sub-picosecond up to nanosecond scale, the challenge for experimental nuclear physics becomes even more demanding. Due to the difficulties in studying such exotic nuclei, experimental data in the aforementioned region remain limited. This abstract will present the benefits and practical problems. In-flight $gamma$-ray spectroscopy will be discussed based on experimental data on $^{129}$In and $^{128}$Cd obtained during the HiCARI campaign in November 2020 at RIKEN (Japan). Nuclei of interest were produced via nucleon knock-out reactions from $^{130}$In projectile impinging with velocity of approximately 0.55c on 6mm $^{9}$Be target following induced, in-flight fission of $^{238}$U primary beam. HiCARI, an array comprised of 3 different types of segmented HPGe detectors aimed at detecting prompt gamma rays emitted after the knock-out reaction, was located in close proximity to the target. Based on the reconstructed velocity of ions and position of $\gamma$-ray emission during their de-excitation event-by-event, $\gamma$-ray spectra were obtained for each reaction channel. The line shape of identified transitions carries information about their energy ($E$) and half-life ($T_{1/2}$). Taking into account precisely measured HiCARI geometry, the response function of every HPGe crystal to the $\gamma$-ray of given $E$ and $T_{1/2}$ was simulated using the Geant4 package. However, line shape is in general influenced by the contaminant $\gamma$-rays emitted in the rest frame. The origin of these $gamma$-rays is connected with the projectile energy loss, and the response function to this kind of radiation was also taken into account. Finally, $E$ and $T_{1/2}$ of the excited states were extracted by minimizing $\chi^{2}$ of response functions fitted to the experimental data. The method allows access to short half-lives ranging from single ps to a few hundred ps, making it a perfect tool to study low-lying excited states of the nuclei in the vicinity of $^{132}$Sn. Moreover, knock-out reactions populate short-lived states directly, in contrast to methods that require a nuclear isomer. Thanks to this, previously unobserved states can be discovered. Results will be interpreted employing state-of-the-art shell model calculations.

Speaker: Michal Mikolajczuk

fas26_Wed_Mikolajczuk.pdf

10:00 New Results in 115Rh β-decay spectroscopy

The astrophysical rapid neutron-capture process (r-process) is responsible for producing approximately half of the heavy elements in the Universe; however, its quantitative modeling remains limited by the scarcity of experimental knowledge of the structure of neutron-rich nuclei far from stability. In particular, nuclei in the $A \approx 115$ region provide an important benchmark for nuclear models used in r-process calculations, as their decay properties and level structures directly influence $\beta$-decay strength distributions and feeding patterns. The study of $\beta$-decay in this mass region allows for detailed exploration of low-lying states, spin–parity assignments, and the interplay between ground and isomeric configurations, which are essential for reliable theoretical predictions.

The present work focuses on the $\beta$-decay of $^{115}$Rh populating excited states in $^{115}$Pd, investigated at the IGISOL-4 facility at the JYFL Accelerator Laboratory (University of Jyväskylä, Finland). A high-purity beam of $^{115}$Rh was obtained using the JYFLTRAP Penning trap. The detection setup consisted of a $\beta$-plastic scintillator, three HPGe detectors, and a tape station. Excited states in $^{115}$Pd were investigated using $\gamma$-$\gamma$ and $\beta$-$\gamma$-$\gamma$ coincidence techniques, resulting in a substantially expanded and revised decay scheme. More than 98 previously unobserved $\gamma$ transitions and 25 new excited states were identified, extending the level scheme up to 1605 keV and significantly improving its completeness. For the first time, reliable absolute $\gamma$-ray intensities and $\beta$-feeding distributions have been determined, providing new insight into the structure of low-lying states.

A new half-life value of $T_{1/2} = 1.072(16)$ s was extracted, representing a significant improvement in precision compared to the previously adopted value ($T_{1/2} = 0.99(5)$ s [1]). Additionally, internal conversion coefficients for selected low-energy transitions were estimated using a $\beta$-$\gamma$-$\gamma$ versus single-$\gamma$ comparison method, enabling tentative multipolarity assignments for several key transitions. These results, combined with $\gamma$-branching ratios and $\log(ft)$ calculations, have led to revised spin–parity assignments for several states in $^{115}$Pd.

The presented findings provide important constraints for nuclear-structure models, particularly concerning the predicted shape evolution in Pd isotopes around N = 69 [2], and offer new insight into the band structure of $^{115}$Pd [3]. Additional knowledge of lifetimes, obtained by fast-timing techniques of excited states in $^{115}$Pd, will greatly expand and complement the presented results.

[1] J.Äystö et.al. “Identification and decay of new neutron-rich isotopes 115Rh and 116Rh”. In: Physics Letters B 201.2 (1988), pp. 211–214. issn: 0370-2693. doi: 10.1016/0370-2693(88)90214-6.

[2] J. Kurpeta, W. Urban. et. al. “Excited states in 115Pd populated in the $\beta$−decay of 115Rh”. In: Phys. Rev. C 82 (2 Aug. 2010), p. 027306. doi: 10.1103/PhysRevC.82.027306.

[3] J.O. Rasmussen, Y.X. Luo. et. al. “New insights into the nuclear structure in neutron-rich 112,114,115,116,117,118Pd”. In: Nuclear Physics A 919 (2013), pp. 67–98. issn:0375-9474. doi: 10.1016/j.nuclphysa.2013.10.002.

Speaker: Krzysztof Albert Solak (University of Warsaw (PL))

FAST_115Rh.pdf

10:20 Fast-timing lifetime measurements in $^{83}$Se and $^{83}$Br

Low-lying 1/2$^+$ and 5/2$^+$ states, interpreted as resulting from 1p-2h excitation through the N=50 shell gap, have been observed in several neutron-rich N=49 nuclei. In particular, charge radii measured for the ground state and the 1p-2h 1/2$^+$ isomer in $^{79}$Zn provide evidence for a deformed character of the latter [1].
In this context, fast-timing measurements have been performed to investigate the nuclear structure of $^{83}$Se and $^{83}$Br, with the aim of studying the evolution of collectivity and possible shape coexistence in the vicinity of the $N = 50$ shell closure.

The experiment was carried out at the LOHENGRIN recoil mass separator at the Institut Laue-Langevin. Neutron-induced fission products were separated and implanted, and $\gamma$ rays were detected using a fast-timing setup based on LaBr$_3$(Ce) scintillators. Lifetimes were extracted using both Generalized Centroid Difference (GDC) and Advanced Time-Delayed (ATD) techniques, providing sensitivity in the picosecond range.

Three lifetimes were measured for the first time. In $^{83}$Se, the lifetime of the $3/2^+$ state at $E = 963.4$ keV, was determined to be $\tau = 13 \pm 3$ ps using the GDC method and $\tau = 17 \pm 6$ ps using ATD. The corresponding B(E2; $3/2^+ \rightarrow 5/2^+$) transition strength indicates that the $3/2^+$ state is not associated with the deformed structure, while the low B(E1; $3/2^+ \rightarrow 1/2^-$) value makes it impossible to draw any conclusions regarding octupole collectivity in $^{83}$Se.

In $^{83}$Br, the GDC analysis yielded $\tau = 12 \pm 2$ ps for the $5/2^-$ state at $E = 356.7$ keV,and $\tau = 7 \pm 3$ ps for the $7/2^-$ state at $E = 866.9$ keV, with compatible values obtained using ATD. While a regular excitation-energy pattern observed for these states could suggest that they belong to a collective structure built on the $3/2^-$ ground state, the newly obtained B(E2) and B(M1) values undermine this interpretation. Instead, our data combined with the literature lifetimes of the $11/2^-$ and $13/2^-$ states in $^{83}$Br [2] suggest that these four states can be understood as arising from the coupling of a proton hole in the $p_{3/2}$ or $f_{5/2}$ orbitals with neutron configurations of the type $(g_{9/2})^{-2}$, coupled to total angular momenta $J^\pi = 0^+, 2^+, 4^+, 6^+$.

[1] X.F. Yang {\it et al.}, Phys. Rev. Lett. 116, 182502 (2016).

[2] R. Schwengner {\it et al.}, Nucl. Phys. A 584, 159 (1995).

Speaker: LUDOVICO LAPO LUPERI (CEA Paris-Saclay)

LUPERI_PresentationFast26Keynote_PDF.pdf

10:40 → 11:00 Coffee Break

11:00 → 12:40 Day 3: Instrumentation

Convener: James Cubiss (The University of Edinburgh (GB))

11:00 Fast front-end amplifiers for time-of-flight PET

The evolution of the technical design in the PET scanning industry aims to reduce the radiation dose and shorten the scanning time. To achieve this ambitious goal, it is essential to develop a PET experiment and test benches for the characterization of new scintillation materials.
One important part of the readout path is a fast-amplifying stage that decouples a high-capacity photosensor array from the acquisition electronics. The goal of this work is to design a low-noise amplifying stage with a high bandwidth. The low-distortion differential amplifier could be utilized for a PET application. A practically implemented readout board for MPPC based on ADA4960-1 demonstrates a promising performance. The best combination of slew rate, bandwidth, and broadband distortion. These attributes allow it to drive a wide variety of MPPC arrays.

Speaker: Dr Ivan Yakymenko (V.N. Karazin Kharkiv National University (UA))

fast_front_end_fast2026_short_intro.pdf

fast_front_end_fast2026_short_intro.pptx

11:20 Sum-Amplifier Circuit For Fast Timing With Large Area SiPM Arrays

The HYPATIA (HYbrid Photon detector Array To Investigate Atomic nuclei) [1] is an array under construction at the RIBF that consists of GAGG and CeBr3 scintillator crystals coupled to large area SiPM photosensors. In particular, the Hamamatsu S14161-6050HS-04 4x4 SiPM array. Excellent timing response from HYPATIA is important for reducing the non-prompt background induced by particles emitted during nuclear reactions, and for performing fast-timing lifetime measurements. Connecting SiPM pixels in parallel results in a large total capacitance, broadening the signal’s rise time and degrading the time resolution. Therefore, careful consideration needs to be paid to how the pixel signals are summed. Several methods have been successfully used to achieve fast timing with SiPM photosensors [2,3]. However, they typically produce a slow and a fast signal, requiring two DAQ channels per detector and introducing additional complexity. Other methods for summing have also been developed using multiple op-amps to sum the signals, such as in [4]. However, the use of many op-amps requires a large PCB and produces heat. To address this, a fast-timing circuit has been developed using a sum-amplifier circuit with a single op-amp and a single output. In this contribution, we will present the circuit's performance with a small LaBr3 detector in comparison to a simple circuit with the pixels connected in parallel. In addition, the results from GAGG and CeBr3 detectors will be presented.

[1] P. Doornenbal, et al. The HYPATIA Project, RIBF NP-PAC-24, (2023)
[2] S. Dolinsky, et al. IEEE NSS/MIC, (2013), 1-6
[3] C. Mihai, et al. NIM A, 953, (2020), 163263
[4] C. M. Lavelle, et al. AIP Advances, 9, (2019), 035123

Speaker: William Marshall (University of York)

SiPMBoardFAST26-13.pdf

11:40 Intrinsic coincidence time resolution of candidate data acquisition systems for the HISTARS project

The HIE-ISOLDE Timing Array for Reaction Studies (HISTARS) array is being developed for the measurement of lifetimes of excited nuclear states produced in reactions at HIE-ISOLDE (CERN). It is based on fast particle and gamma scintillator detectors that will require a fast data acquisition system capable of handling more than 60 channels with good time and energy resolution. Digitizing the fast scintillator signals will allow for a flexible signal processing, while preserving the pulse time structure, and potentially enabling high-precision timing.
In this work we measure the intrinsic time resolution of several digitizer systems for data acquisition and processing of data stemming from fast scintillators, such as LaBr₃(Ce). A very promising high-performance candidate is the CAEN 2751 digitizer, providing 14-bit, 1 GS/s, 16 channels, a 500 MHz bandwidth, and embedded FPGA/ARM processing for advanced waveform acquisition and digital pulse processing via USB or Ethernet.
The DRS4 Evaluation Board uses the DRS4 switched-capacitor array chip developed at Paul Scherrer Institute with 4 input channels, sampling rates of 0.7 to 5 GS/s with 1024 sampling cells (roughly 200 ns acquisition window at 5 GS/s), and an analog bandwidth of 700 MHz at 12-bit resolution. The board has a FPGA-based readout control with USB data transfer. The CAEN DT5742B is a 16-channel switched-capacitor digitizer based on the same DRS4 chip, thus providing 12-bit resolution and up to 5 GS/s sampling rate. It includes a fast trigger channel for timing, multiple trigger modes, event buffers, and USB or optical-link readout.
The CAEN DT5751 is a desktop waveform digitizer with 2 or 4 channels, 10-bit resolution, and sampling rate of 2 GS/s (interleaved) or 1 GS/s per channel. It has 500 MHz analog bandwidth and 1 Vpp input range with programmable DC offset.
An in-house custom microcontroller-based data acquisition system, still in development, capable of analog pulse integration and timestamp assignment based on a bespoke time to amplitude converter (TAC), will also be included in the comparison. This comparison will guide the choice of the data acquisition system for the HISTARS project and determine its baseline contribution to the timing capabilities of the array.

Speaker: Victor Martinez Nouvilas (Universidad Complutense (ES))

FAST26-VMN.pdf

12:00 Performance evaluation of GaGG(Ce) crystals coupled to different photosensors

In the framework of the HIE-ISOLDE Timing Array for Reaction Studies (HISTARS) project at ISOLDE/CERN, a detector system is being developed to measure lifetimes of excited nuclear states populated in reactions at HIE-ISOLDE. For particle detection, plastics or fast inorganic scintillators such as GAGG(Ce) and YSO(Ce) are promising candidates due to their non-hygroscopic nature, high density, high light yield, and fast scintillation decay time [Wang2020, Tsuchida1997]. These detectors are intended to be combined with LaBr₃(Ce) crystals for gamma detection, which are well established for their excellent time and energy resolution [Vedia2017].
In this work, thin square GaGG(Ce) crystals (20 × 20 × 1 mm³) were coupled to two different photosensors: a customized version of the 2-inch, 8-stage bialkali photocathode R9779 PMT (assembly H10570), and an array of five SiPMs (Hamamatsu 14160-6075, 6 × 6 mm²) using a custom-designed circuit. This was used in combination with a cylindrical LaBr₃(Ce) detector (1″ height × 1″ diameter) coupled to the same customized version of the R9779 PMT. Two data acquisition systems, a CAEN 2751 desktop digitizer and a DRS4 waveform digitizer, were employed.
We report on the comparative performance of both readout coupling methods, specifically focusing on Pulse Shape Discrimination (PSD) capabilities, energy resolution, and alpha-gamma/gamma-gamma coincidence time resolution (CTR). These results will help define the final architecture of the HISTARS particle array.

References
[Wang2020] Z. Wang, H. Guo, S. Qian, Y. Zhu, P. Hu, Q. Wu, P. Chen, L. Ma, S. Peng, L. Zhang, Z. Ning, Z. Zhang, J. Instrum. 15, C06031 (2020)
[Tsuchida1997] N. Tsuchida, M. Ikeda, T. Kamae, M. Kokubun, Nucl. Instrum. Methods Phys. Res. A 385, 290 (1997)
[Vedia2017] V. Vedia, M. Carmona-Gallardo, L.M. Fraile, H. Mach, J.M. Udías, Nucl. Instrum. Methods Phys. Res. A 857, 98 (2017).

Speaker: Miriam Caballero Rodriguez (Universidad Complutense (ES))

MCR-PerfEvalGaGG.pdf

12:20 Development of perovskite-based scintillator films for fast timing applications

In recent years, perovskites have been widely studied as materials for the development of fast scintillators [1]. Due to their excellent carrier dynamics and excitonic behavior—particularly when present as nanocrystals—perovskites can emit light between 20 and 1,000 times faster than other semiconductors [2]. These properties make them promising candidates for fast-timing applications such as positron emission tomography (PET) [3].
Lead halide perovskites, such as cesium lead bromide (CPB), have been the most extensively studied. However, our group is investigating alternative oxide perovskites, including barium zirconate (BZO) [4]. Preliminary studies show promising radioluminescence from nanostructured BZO, suggesting its potential use as a scintillator material for detector development.
In this work, thin films are produced and deposited on plastic or glass substrates and coupled to a SiPM. This technique can be reproduced with different materials, enabling a direct comparison of their detection performance.
Experiments carried out at our laboratory aim to evaluate the particle detection capability of these thin films. The coincidence time resolution was also investigated through beta–gamma coincidence measurements, allowing to compare the fast response of BZO with other materials.
Ongoing work focuses on optimizing the electronics, data acquisition (DAQ), and analysis techniques to further improve time resolution. Additional efforts include exploring new detector geometries and combining the films with commercial scintillators. The final objective is the development of a combined detector array with spatial resolution and good particle discrimination for fast-timing applications in nuclear physics and medical instrumentation.

[1] Wibowo, A. et al. Commum Mater 4 (2023)
[2] Becker, M. et al. Nature 553 (2018)
[3] Pagano, F. et al. Adv. Materials Interfaces 11 (2024)
[4] M.L. Moreira et al. Scripta Materialia 64 (2011)

Speaker: Juan Francisco Gonzalez Linares (Instituto de Estructura de la Materia - CSIC)

FAST26_JuanFGonzalez.pdf

12:40 → 13:30 Lunch

13:30 → 15:00 Visit of IFIN-HH facilities: ELI-NP and the 9MV Tandem Accelerator

Conveners: Vlad Vasilca (Extreme Light Infrastructure - Nuclear Physics (ELI-NP)), Andrei Turturica (Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH))