Peer Revenue Publish or profit

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Physics Instrumentation and Detectors

physics.ins-det Watch Instrumentation and Detectors

Thursday 3 September

Instrumentation and Detectors · Cross-listed from physics.geo-ph

Estimating subsurface water mass changes with ground-based gravimetry

Isabelle Schmidt, Jackson Ang'ong'a, Peter Bauer-Gottwein et al. (+10 more)

Gravitational force is proportional to the mass of an attracting body; therefore, changes in subsurface mass can be detected using gravimetry. In the near subsurface, mass variations are primarily driven by changes in water storage, meaning that gravity measurements provide direct information on variations in water mass. Traditionally, groundwater and soil water dynamics are monitored using point-scale instruments that require direct installation into the subsurface. In contrast, gravimetry is a non-invasive method that integrates signals over a larger spatial extent. Recent advancements in gravimeter technology have significantly improved measurement accuracy and long-term stability under field conditions, thereby expanding their potential for hydrological applications. This review summarizes recent developments in gravimetric instrumentation and provides essential background on gravimeters used for ground-based measurements and their application in hydrology, aiming to facilitate their broader use. In addition, it presents an overview of studies in hydrology and hydrogeology that have successfully applied gravimetry to quantify subsurface water storage changes, estimate hydrological parameters, and constrain numerical models. A perspective on future advancement in gravimetry and resulting potential applications is given.
Read the full abstract

All authors Isabelle Schmidt, Jackson Ang'ong'a, Peter Bauer-Gottwein, Stephan Costabel, Christian Freier, Bastian Leykauf, Tina Lundgren, Miguel Martinez-Dorantes, Achim Peters, Ernst Rasel, Enrico Vogt, Gregor Willkommen, Vladimir Schkolnik

Instrumentation and Detectors

Monitoring antiproton numbers with a CMOS detector in a dense-track environment

C. Regenfus, P. Adrich, I. Belosevic et al. (+42 more)

The production of antihydrogen by the GBAR experiment at AD/ELENA requires good knowledge of the number of incident keV antiprotons, which can be problematic. We have used a commercial CMOS digital camera mounted around the experimental vacuum chamber to determine antiproton numbers from ionising particles created in the annihilation process on the surface of microchannel plate detectors which are used for beam imaging. We show that the multiplicity of emerging charged particles is as expected for individual annihilations of antiprotons with nucleons at rest, taking into account the surrounding material budget. Most of those particles are in the minimal ionising regime, but can be detected with nearly 100% efficiency in the CMOS pixel detector, while due to the thin depletion layer the device is insensitive to background gammas. Thanks to the high granularity and small pixel size millions of antiproton annihilations can be reconstructed in a dense tracking environment over a large dynamic range with good resolution. From cluster length studies of non perpendicular tracks the thickness of the depletion zone and effective detection area was estimated. The cluster length also allows for a monitoring of track angles. Antiproton numbers are determined from the number of reconstructed clusters in the CMOS sensor by means of the covered solid angle relative to a calibration measurements with well known beam intensities at the most upstream location of the GBAR apparatus. Material effects on the emerging annihilation products were estimated by Monte Carlo (Geant4) calculations, while annihilation artefacts on the complex surface of a microchannel plate are cancelled out in this approach. This method minimises largely systematic uncertainties, leading to a final error of roughly 10% for the reconstruction of absolute antiproton numbers.
Read the full abstract

All authors C. Regenfus, P. Adrich, I. Belosevic, F. Benkel, M. Chung, P. Cladé, P. Comini, P. Crivelli, P. Debu, A. Douillet, S. Geffroy, S. Guellati-Khelifa, P. Guichard, P.-A. Hervieux, L. Hilico, P. Indelicato, S. Jonsell, J.-P. Karr, B. Kim, S. Kim, E.-S. Kim, N. Kuroda, B. Lee, L. Liszkay, D. Lunney, G. Manfredi, B. Mansoulié, V. Martimort, M. Matusiak, V. Nesvizhevsky, F. Nez, K. Park, N. Paul, E. Perez, P. Pérez, C. Roumegou, J.-Y. Roussé, F. Schmidt-Kaler, K. Szymczyk, T. A. Tanaka, B. Tuchming, D.-P. van der Werf, D. Won, S. Wronka, P. Yzombard

Instrumentation and Detectors

Testbeam characterization of a 3D silicon sensor read out by Timepix4

E. Chatzianagnostou, M. J. Madurai, K. Akiba et al. (+15 more)

Testbeam results from a $300\,\mu\mathrm{m}$-thick 3D silicon sensor bump-bonded to a Timepix4 ASIC, are presented. The hit detection efficiency, spatial resolution, and timing performance of the 3D sensor are studied for several track angles, bias voltages and charge thresholds. The time measurements are corrected for Timepix4 clock-frequency variations and timewalk, while for the spatial studies, nonlinear charge-sharing corrections are determined. At perpendicular incidence, the time resolution of the 3D detector is equal to $245\,\mathrm{ps}$ with a $97\%$ hit detection efficiency. An optimal angle of $8^\circ$ with respect to the beam direction of the 3D detector was found, in which the time resolution improves by $6\%$ compared to normal incidence, while the hit detection efficiency reaches above $99\%$ and the spatial resolution is approximately $7\,\mu\mathrm{m}$. Intrapixel studies show that a time resolution of $153\,\mathrm{ps}$ at the most probable value of the signal charge can be achieved for hits between the electrodes at normal incidence, while the timing performance of these best-performing regions deteriorate upon sensor rotation. The timing properties at different depths of the 3D sensor have been investigated with tracks at grazing-angle incidence, revealing a dependence of the time resolution along the sensor depth.
Read the full abstract

All authors E. Chatzianagnostou, M. J. Madurai, K. Akiba, D. Bacher, R. Bates, M. van Beuzekom, T. Bischoff, V. Coco, R. Dumps, T. Evans, K. Heijhoff, D. Johnson, U. Krämer, E. Lemos Cid, D. Oppenhuis, T. Pajero, E. Rodríguez Rodríguez, D. Rolf

Instrumentation and Detectors · Cross-listed from physics.optics

Cavity Ring-Down Spectroscopy at Benchmark-Level Sub-Permille Accuracy Enabled by a System-Level Detection Transfer Function

Rajesh Chell, Marcin Gibas, Szymon Wójtewicz et al. (+3 more)

Cavity ring-down spectroscopy (CRDS) is widely used for sensitive optical absorption measurements, but its quantitative accuracy can be limited at the few-percent level by systematic distortions originating in the CRDS detection system, particularly at short ring-down times. These limitations can restrict demanding spectroscopic applications requiring sub-permille accuracy, including atmospheric sensing, tests of ab initio theory and fundamental physics, and quantum-based optical gas standards. Here we develop a methodology based on a system-level detection transfer function describing the complete CRDS detection-system response, including detector, electronics, and digitization stages, and use it to correct previously unaccounted-for instrumental distortions in retrieved absorption. We demonstrate the method on a CO absorption line measured down to very short ring-down times using multiple independent CRDS detection configurations, initially exhibiting line-area biases of up to 14%. After applying the transfer-function correction, all systems converge to a common value, with the bias relative to the most accurate ab initio-validated reference data reaching the sub-permille level and the accuracy improving by a factor of 41–87. The proposed framework brings well-established CRDS to the level of the most accurate reference methods without requiring specialized measurement schemes or external calibration standards, making benchmark-quality measurements more widely accessible.
Read the full abstract

All authors Rajesh Chell, Marcin Gibas, Szymon Wójtewicz, Jakub Łasocha, Daniel Lisak, Agata Cygan

Instrumentation and Detectors

Optimisation of importance sampling implementation in rare-event shielding simulations using Geant4

P. Knights, L. J. Milligan and K. Nikolopoulos

Rare-event search experiments demand ever-lower backgrounds, and the resulting radio-pure materials and suppressive shielding make related background simulations computationally expensive without event biasing. We present a method for optimising the widely used importance splitting and Russian roulette technique for rare-event searches, in which a whole number of equal-width importance layers fill the shielding geometry. Balancing relative uncertainty against execution time, we optimise the layer thickness for both $\gamma$-rays and neutrons, and across different shielding materials and thicknesses. Expressed as a multiple of the primary particle's mean free path, the optimal thickness generalises across energies for a given particle type and yields a physics-based prediction applicable to any shielding design. The same trend reveals that over-biasing is possible, with relative uncertainty worsening at high layer counts for fixed execution time. The optimal configuration gives an $\mathcal{O}$(20) gain in computational efficiency over the unbiased case.
Read the full abstract

Instrumentation and Detectors · Cross-listed from physics.atom-ph

Low stray-field ion pump configuration for cold atom experiments

Preeti Sharma, Luisa Loranca Cruz, Leonardo Ricci et al. (+1 more)

Ion pumps used in cold-atom experiments generate stray magnetic fields that can perturb magneto-optical trapping, shift Zeeman sensitive energy levels, and introduce systematic errors in precision spectroscopy. We numerically investigate a compact low-stray-field ion pump configuration designed to reduce magnetic flux leakage through the ultrahigh-vacuum port without increasing the overall pump size. Starting from a simplified magnetic model of a standard ion pump, we study two complementary modifications: auxiliary permanent magnets surrounding the original pump magnets with opposite magnetisation, and a soft-magnetic honeycomb field stopper integrated at the pump port. The resulting combined configuration strongly reduces the magnetic flux density outside the pump. In the geometry considered here, the field at 10 mm from the UHV port is reduced by 97.9%, while the calculated reduction in effective pumping speed due to the honeycomb stopper is 17.9%. These results indicate that engineered magnetic compensation and field-guiding structures can support more compact cold-atom vacuum systems while preserving pumping performance. Further work should validate the design with nonlinear magnetostatic modelling, molecular-flow simulations, and measurements on a complete pump geometry.
Read the full abstract

All authors Preeti Sharma, Luisa Loranca Cruz, Leonardo Ricci, Andrea Bertoldi

Instrumentation and Detectors

Multi-Angle Beam Scanning Transmission Electron Microscopy for Diffraction-Contrast-Free Magnetic Imaging

Akira Yasuhara, Zentaro Akase and Takumi Sannomiya

Recent development of the differential phase contrast (DPC) scanning transmission electron microscopy (STEM) technique has significantly advanced materials science supported by high-sensitivity detectors and powerful data processing. Especially the 4D-STEM technique, employing a pixelated camera as a STEM detector, enables extensive information acquisition through post-processing of large datasets. However, magnetic or electric field imaging using DPC is often disturbed by diffraction contrasts intrinsic to the crystalline material. In this paper, we demonstrate elimination of the diffraction contrasts for magnetic field imaging by using angularly distributed multiple electron beams generated by a multi-hole aperture within the 4D-STEM framework. This multi-angle beam configuration suppresses irrelevant crystalline contrast and yields direct magnetic information with high sensitivity from the specimen. Furthermore, we performed various image analysis to extract and interpret magnetic domain structures and domain walls.
Read the full abstract

Wednesday 2 September

Instrumentation and Detectors

An extensible software platform for automated operational and characterization testing of scientific cameras

Baolong Chen, Hongfei Zhang, Wei Liu et al. (+5 more)

Multi-detector programs such as Earth 2.0 (ET) require detector characterization across different technologies, operating conditions, and production batches, together with consistent procedures for operation, characterization, and device selection. Traditional laboratory workflows often distribute camera control, illumination, image analysis, and report generation across detector-specific programs and manual steps, slowing iterative development and hindering standardized characterization. We address this gap with PixelXVision, a layered software platform that combines a common camera SDK, preset-based configuration, and a runtime plugin system. Detector-specific behavior is configured through declarative presets, allowing the same host interface to operate CCD, CMOS, and infrared detectors without model-specific core changes. Characterization procedures are implemented as plugins that use a shared object manager to access camera, illumination, storage, and database services. Each run links raw frames, measured operating conditions, configuration, analysis products, and reports into a traceable archive with a queryable index. The platform supports lightweight deployment for iterative single-detector development and structured workflows for multi-detector campaigns. The platform has been applied in characterization testing across CMOS, CCD, and HgCdTe cameras, and its configurable architecture can accommodate additional camera models for subsequent CCD testing for WFST without model-specific changes to the core host software. For operational troubleshooting, the platform integrates ChatPixel, a knowledge-base assistant that provides answers with cited sources when it has relevant information.
Read the full abstract

All authors Baolong Chen, Hongfei Zhang, Wei Liu, Zihao Xia, Xin Luo, Qi Feng, Zhe Geng, Jian Wang

Instrumentation and Detectors

Toward High-Resolution Detection of Target Fragmentation: TEA-Sensitized NIT for Proton Therapy Applications

V. Boccia, T. Asada, A. Alexandrov et al. (+96 more)

Nano Imaging Trackers (NIT) are fine-grained nuclear emulsions capable of tracking charged particles with sub-micrometric spatial resolution. The DAMON (Direct Measurement of Target Fragmentation) experiment recently employed NIT to detect target-fragmentation events relevant to proton therapy in direct kinematics. These measurements showed that the small crystal size, while providing high spatial resolution, limits the reconstruction efficiency for primary proton tracks and high-energy secondary protons. This work reports an enhancement of NIT sensitivity achieved through alternative chemical sensitization methods, namely gold-plus-sulfur (Au-S) and triethanolamine (TEA), together with the use of the GR-1 developer. The detector response was evaluated with gamma-ray, carbon-ion and proton exposures, including clinically relevant proton energies.
Read the full abstract

All authors V. Boccia, T. Asada, A. Alexandrov, G. Ambrosi, S. Argirò, M. Barbanera, N. Bartosik, G. Battistoni, A. Bigot, M. G. Bisogni, G. Butella, F. Cavanna, P. Cerello, E. Ciarrocchi, N. D'Ambrosio, G. De Lellis, A. Di Crescenzo, B. Di Ruzza, M. Dondi, M. Donetti, Y. Dong, M. Durante, R. Faccini, V. Ferrero, C. Finck, E. Fiorina, M. Francesconi, M. Franchini, G. Franciosini, L. Galli, A. Iuliano, K. Kanxheri, B. Kharpuse, M. Kimura, S. Kodaira, A. C. Kraan, A. Lauria, E. Lopez Torres, T. Maggipinto, M. Magi, A. Manna, M. Marafini, S. Masci, M. Massa, C. Massimi, I. Mattei, S. Mazzolani, A. Mengarelli, A. Mereghetti, R. Mirabelli, A. Moggi, M. C. Montesi, M. C. Morone, M. Morrocchi, S. Muraro, T. Naka, N. Pastrone, V. Patera, F. Pennazio, C. Pisanti, P. Placidi, M. Pullia, F. Quattrini, S. Rabaglia, L. Ramello, C. A. Reidel, R. Ridolfi, L. Rocchetti, L. Sabatini, L. Salvi, C. Sanelli, A. Sarti, O. Sato, S. Savazzi, A. Schiavi, C. Schuy, E. Scifoni, L. Servoli, G. Silvestre, M. Sitta, K. Someya, B. Spadavecchia, R. Spighi, E. Spiriti, L. Testa, V. Tioukov, S. Tomassini, F. Tommasino, M. Toppi, G. Traini, A. Trigilio, G. Ubaldi, S. Valentinetti, M. Vanstalle, M. Villa, U. Weber, R. Zarrella, A. Zoccoli, G. Galati

Instrumentation and Detectors · Cross-listed from physics.optics

Rydberg-atom microwave angle-of-arrival detection via cylindrical vapor-cell-mediated field redistribution

Peicheng Liu, Xingchen Hu, Yong Gao et al. (+3 more)

Microwave angle-of-arrival(AoA) measurement is essential for radar, communication, and spectrum mon-itoring. Existing Rydberg-atom-based AoA schemes employ phase-difference measurements with local oscil-lators, standing-wave fluorescence imaging, or amplitude-ratio readout with internal metal reflectors. Here we demonstrate a new approach: a cylindrical glass vapor cell serving directly as an angle-encoding dielectric structure, eliminating the need for multiple apertures, local oscillators, or imaging optics. The cylindrical geometry produces angle-dependent reflection and field redistribution, mapping the incident AoA onto the effective microwave field sampled by the Rydberg ensemble. This effective field is read out optically via the Autler-Townes(A-T) splitting in the electromagnetically induced transparency(EIT) spectrum. Full-wave simulations and experiments at 11.64 GHz confirm a deterministic, geometry-mediated response over 0{\deg}-90{\deg}.Over the monotonic operating range(55{\deg}-125{\deg}), the angular resolution(minimum distinguishable increment)is 0.05{\deg}, and the angular accuracy(RMSE of repeated measurements) is 0.13{\deg} across the full range, improving to 0.05{\deg} in the optimal region(65{\deg}-115{\deg}). Occupying a sensing volume of~2.5 cm3, this method offers a compact, single-sensor pathway toward Rydberg AoA receivers.
Read the full abstract

All authors Peicheng Liu, Xingchen Hu, Yong Gao, Ao-Lin Guo, Yuan Ren, Hao Wu

Tuesday 1 September

Instrumentation and Detectors

Characterization of a low-power 3D photon-to-digital converter readout improved for system integration in meter-scale applications

Olivier Lepage, Tommy Rossignol, Nicolas Roy et al. (+5 more)

Digital silicon photomultipliers (dSiPM) are arrays of single photon avalanche diodes (SPADs) where each SPAD has its own electronic readout. To maximize the photodetection area, we developed a readout integrated circuit (ROIC) 3D-integrated to a custom-designed SPAD layer fabricated at Teledyne Dalsa (Bromont, Canada) to form a photon-to-digital converter (PDC). This paper presents an improved version of a previously demonstrated ROIC, fabricated in TSMC 180 nm technology to manage a 64 x 64 pixel architecture. This ROIC has different outputs, such as a flag output that produces a pulse whenever one of the pixels triggers and a digital sum that samples the amount of triggered SPADs. Improvements lead to a reduction of the timing jitter on the flag output from 72.0 ps RMS to 22.6 ps RMS through optimized H-tree design. A tunable hold-off circuit provides adjustable dead time from 32 ns to 18 {\mu}s, addressing both afterpulsing mitigation and SPAD-to-SPAD variations due to process defects. Power consumption is lowered by 30% at trigger rates exceeding 10 kHz through digital logic optimization and clock gating. These measurements validated that the ROIC is ready for 3D integration into a PDC for systems in medical imaging, particle physics, and quantum sciences.
Read the full abstract

All authors Olivier Lepage, Tommy Rossignol, Nicolas Roy, Gabriel Lessard, Frédéric Vachon, Lorenzo Fabris, Serge A. Charlebois, Jean-François Pratte

Instrumentation and Detectors

Radiation Hardness of Commercially Available NUV-MT Silicon Photomultipliers

T. Avgitas, M. Axiotis, Z. Balmforth et al. (+5 more)

Silicon Photomultipliers (SiPMs) based on the near-ultraviolet, metal-filled trench (NUV-MT) technology offer improved photon detection efficiency and reduced correlated noise relative to earlier designs, making them attractive for a broad range of particle- and astroparticle-physics applications. As such devices may be deployed in high-radiation environments, quantifying their performance after irradiation is essential. Commercially available Broadcom AFBR-S4N series NUV-MT SiPMs were irradiated with 1 MeV neutrons to fluences between 2x10^{9} and 1.1x10^{10} n_{eq}/cm^2 at the TANDEM accelerator facility of NCSR "Demokritos" in Athens, and characterised before and after irradiation and over successive thermal-annealing stages. Irradiation increased the dark noise by up to three orders of magnitude and degraded the single-photon resolution by up to a factor of ten, with resolution lost entirely at the highest fluence, while no shift in breakdown voltage was observed. Thermal annealing partially recovered the performance, reducing the dark noise by up to a factor of two and restoring the single-photon resolution.
Read the full abstract

All authors T. Avgitas, M. Axiotis, Z. Balmforth, I. Manthos, K. Nikolopoulos, E. Taimpiri, C. Toukmenidis, A. Ziagkova

Instrumentation and Detectors · Cross-listed from physics.optics

Multidimensional Double Refraction Microscopy

Jörg König and Christian Cierpka

Multidimensional optical microscopy - extracting 3D location, orientation, and spectral information from nanoscale emitters - is key to modern nanoscience. However, this multidimensional capability requires complex instrumental setups, demanding exceptional stability and specialized expertise in optics. Here, we overcome these barriers by introducing Double Refraction Microscopy (DRM), a passive imaging method providing a straightforward pathway to multidimensional super-resolution imaging. Based on bifocal imaging via a birefringent microscope slide, DRM splits nanoprobe light into a characteristic double image encoding 3D location, orientation, and spectral signature, while requiring zero hardware modifications to standard wide-field microscopes. To showcase its robustness, we implement DRM across three distinct slides of varying materials and thicknesses, calibrating 3D localization with 450-nm nanoparticles and demonstrating high orientation sensitivity using polarization-controlled emitters. Furthermore, we confirm spectral readout using a pinhole array acting as a grid of point emitters back-illuminated at various wavelengths to generate distinct spectral signatures. Finally, we showcase practical utility by performing a two-colour 3D localization measurement within a $10\,\mu\text{m}$ gap, utilizing the single optical pathway of a standard epi-fluorescence microscope. Ultimately, DRM provides the missing optical hardware simplicity to complement established computational tools, promising to transfer advanced super-resolution capabilities from specialized facilities to every laboratory bench.
Read the full abstract

Instrumentation and Detectors

Fabrication and characterization of lithium-diffused inverted coaxial point-contact HPGe detectors

Anupama Karki, Kunming Dong and Dongming Mei

High-purity germanium (HPGe) detectors with low capacitance, low electronic noise, and stable high-voltage operation are important for high-resolution gamma-ray spectroscopy and rare-event searches. We report the fabrication and characterization of two compact p-type inverted coaxial point-contact (ICPC) HPGe detectors, AK01 and AK02, produced from crystals grown at the University of South Dakota. Both devices use lithium-diffused $n^{+}$ outer contacts together with amorphous-Ge/Al point-contact electrodes. The principal advance is the implementation of this hybrid contact process on two independently fabricated USD-grown ICPC prototypes and the demonstration of stable electrical and spectroscopic operation. Both detectors exhibited picoampere-level leakage currents, operational depletion-voltage ranges of approximately 200–250~V (AK01) and 240–260~V (AK02), and estimated effective plateau capacitances of approximately 0.84 and 0.87~pF, respectively. Measurements with a $^{137}$Cs source yielded archived full-energy-peak FWHM values of 1.71 and 1.62~keV near 662~keV for AK01 and AK02, while AK02 yielded 1.04~keV FWHM at 59.5~keV with $^{241}$Am. Electric-field calculations reproduce the expected ICPC field configuration for the measured detector geometry. A Geant4 model of AK02 is used as a qualitative response study; its 0.8-mm Li-diffused inactive layer is an illustrative model assumption rather than a measured thickness, and its Gaussian broadening is constrained by the experimental resolution. The work therefore establishes the fabrication and operation of compact lithium-diffused ICPC prototypes while identifying quantitative inactive-layer characterization as an important next step.
Read the full abstract

Instrumentation and Detectors · Cross-listed from hep-ex

Validating a BDT-based Electron-Positron Identification Algorithm at CLAS12 with Experimental Data

Mariana Tenorio Pita, Pierre Chatagnon and Richard Tyson

This article presents a machine-learning, particle-identification algorithm for electrons and positrons in the CLAS12 experiment. The main objective was to minimize charged-pion contamination for both experimental and simulated data. We developed, evaluated and validated two BDT models with different input features, both trained on simulated samples, and conducted rigorous validation using both simulated and experimental data to ensure reliability. Our results show the effectiveness of the applied models in mitigating background contamination. By retaining more than 90% of leptons in the simulated samples, the charged-pion background is largely reduced. Performance was evaluated on experimental data, providing a framework to validate such approaches at CLAS12 and future electron-beam facilities.
Read the full abstract

Instrumentation and Detectors

Helium-Gas-Cooled Cryogenic Current Comparator Integrated with a Quantum Resistance Standard

Yuma Okazaki, Takehiko Oe and Nobu-Hisa Kaneko

We report a cryogen-free cryogenic current comparator (CCC) system for precision resistance measurements. A helium-gas chamber was developed and installed on the 4 K stage of a cryogen-free dilution refrigerator equipped with a pulse-tube cryocooler. The CCC probe was housed in this chamber and was cooled through helium gas serving as a heat exchange medium. The metrological performance of this helium-gas-cooled CCC was evaluated through precision resistance-ratio measurements and found to be comparable to that obtained under liquid-helium cooling. A quantum Hall resistance (QHR) device was also integrated into the same refrigerator, enabling QHR/100~$\Omega$ resistance-ratio measurements. The type-A uncertainty reached the 1~n$\Omega$/$\Omega$ level within an averaging time of 100~s, and the resulting resistance-ratio measurements agreed well with conventional liquid-helium-based measurements at the level of a few n$\Omega$/$\Omega$. The system provides this level of measurement performance while consuming less than 1~L of helium gas per thermal cycle.
Read the full abstract

Instrumentation and Detectors

Time performance of USTC-IME LGAD under synchrotron light source focused X-ray

Tianao Wang, De Zhang, Zheng Liang et al. (+9 more)

The time performance of Low Gain Avalanche Diodes (LGADs), designed by the University of Science and Technology of China (USTC) and fabricated by the Institute of Microelectronics of Chinese Academy of Sciences (IME), was characterized at the Shanghai Synchrotron Radiation Facility (SSRF). The experiment was conducted at the BL16B1 beamline, which delivers a focused X-ray beam with a diameter of 500 {\mu}m, a repetition period of 2 ns, and a photon energy of 10 keV. Using a fast oscilloscope, waveforms containing continuous signal pulses were recorded within a 50 ns time window. The LGAD under test successfully resolved the 2 ns period of the SSRF. To mitigate pile-up effects and extract pulse-by-pulse information from the acquired waveforms, a waveform-level global template fitting method was employed. The time resolution was then estimated using a combined profile likelihood approach, yielding a value of 126.6 ps. The effect of random photon absorption depth on the time resolution of LGADs was studied through dedicated simulations.
Read the full abstract

All authors Tianao Wang, De Zhang, Zheng Liang, Chaozhi Li, Jiaqi Luo, Yu Nie, Tianshuo Yue, Zebo Tang, Hao Liang, Tongpu Yu, Wanbing He, Yanwen Liu

Instrumentation and Detectors · Cross-listed from quant-ph

Superconducting Flux Memory for Cryogenic Applications

Gregory R. Boyd, Jeremy Clark, Mark Covington et al. (+15 more)

We report the development of flux memory for use with superconducting circuits. This technology stores persistent currents in superconducting loops on-chip to be used to provide flux biasing for superconducting circuits, like qubits. We developed three types of flux memory and draw comparisons among them for circuit design. We demonstrate the utility of flux memory by using an in-situ flux detector and characterize each approach and further demonstrate that once flux is set in a memory cell, benchtop DC control sources can be powered off, leaving the on-chip flux bias in place. We propose that flux memory can be arranged in a two-dimensional configuration to multiplex control signals and reduce how line counts scale (N^2 devices -> 2N control lines), and our experimental results pave the path to the proposed scalability. We demonstrate the use of flux memory to flux bias a transmon qubit and show the tunability of the qubit state to a target frequency which remained stable on-chip for 20 hours.
Read the full abstract

All authors Gregory R. Boyd, Jeremy Clark, Mark Covington, David G. Ferguson, Aref Fouladi, Keith D. Hillaire, Moe Khalil, John McFarland, Aaron Pesetski, Anthony J. Przybysz, John X. Przybysz, Sambarta Rakshit, Aruna N. Ramanayaka, Brian Sears, Robert Smith, Colin Stack, Robert M. Young, Tony X. Zhou

Monday 31 August

Instrumentation and Detectors

FPGA-based TDC for SiPM Timing and Amplitude Measurements

Lucas Finazzi, Felipe Soriano, Leandro Gagliardi et al. (+1 more)

Silicon photomultipliers (SiPMs) are widely used in photon-counting applications, such as positron emission tomography or particle physics, where precise timestamps and photoelectron number information are both required. In this work, a Time-to-Digital Converter with amplitude measurement capabilities was designed using an Artix-7 XC7A35T FPGA. For amplitude measurements, the internal xADC of the FPGA was chosen over other alternatives for simplicity. This design has two channels and can operate in timestamp-only mode or timestamp + amplitude mode. In turn, channels can be operated independently or in coincidence. The Integral Non-Linearity and Differential Non-Linearity of the design were studied, along with its time resolution, which is $(19 \pm 1)$ ps. Using a CAEN DT5810 pulse emulator, the design was tested further in timing-only mode, timing + amplitude mode and in coincidence mode to showcase its performance when using Poisson distributed SiPM-like pulses of various amplitudes.
Read the full abstract

All authors Lucas Finazzi, Felipe Soriano, Leandro Gagliardi, Federico Golmar

Instrumentation and Detectors

Development and characterization of a wingless ICPC HPGe detector with thin amorphous-Ge contacts

S. A. Panamaldeniya, K. M. Dong and D. M. Mei

High-purity germanium (HPGe) detectors with thin amorphous-germanium (a-Ge) contacts can provide bipolar charge blocking and surface passivation while minimizing contact-related inactive thickness. We report the fabrication and characterization of a p-type inverted coaxial point-contact (ICPC) HPGe detector using thin a-Ge contacts in a wingless geometry that avoids the protective wing structure used in our previous prototype. The detector was fabricated from a USD-grown, zone-refined HPGe crystal and has a mass of 20.0~g. At 77~K, it exhibited picoampere-scale leakage current and an operational depletion voltage of approximately 440~V. Gamma-ray spectroscopy yielded energy resolutions of 1.75~keV FWHM at 59.5~keV and 3.19~keV FWHM at 662~keV. The calibrated charge-injection method gave an absolute capacitance of 0.496~pF, with an estimated method-level relative uncertainty of 6–8%, consistent with the 0.488~pF value obtained from electrostatic modeling with SolidStateDetectors.jl. With a $^{241}$Am source positioned inside the detector bore, the detector showed a source-correlated excess current and a broad degraded-alpha continuum centered near 3558~keV, demonstrating sensitivity to near-surface interactions. Because the source encapsulation, intervening materials, and near-surface charge-collection response were not independently characterized, the continuum is not used to infer a unique dead-layer thickness or energy-loss mechanism. The principal result is successful fabrication and stable sub-pF operation of a 20-g wingless thin-contact ICPC prototype.
Read the full abstract

Instrumentation and Detectors

A general framework for disturbance compensation in airborne and seaborne gravimetry supported by machine learning

Lorenzo Iafolla, Massimo Chiappini, Roberto Carluccio et al. (+6 more)

High-accuracy measurement systems operating in complex operational environments, such as airborne and seaborne gravimetry, are severely affected by interacting external influences (disturbances) including temperature variations, inertial accelerations, and platform rotations. This work aims to develop and prove a general method for compensating such disturbances beyond the limits of conventional approaches. We present a general framework based on three pillars: a multi-sensor system, supervised machine learning, and a dedicated laboratory -training platform-. This measurement technique was investigated through two experimental case studies relevant to airborne and seaborne gravimetry: (i) temperature and thermal-gradient rejection in a high-sensitivity tri-axial accelerometer, and (ii) pitch and roll rejection for vertical acceleration estimation. The experiments highlighted that, although the general framework provides a useful guideline, its application to airborne and seaborne gravimetry is challenging and not straightforward, requiring the development of dedicated and innovative experimental solutions. This difficulty arises from the specific nature of the measurand-gravity-which cannot be easily varied under controlled conditions. In this work, we present a dedicated approach to addressing these challenges.
Read the full abstract

All authors Lorenzo Iafolla, Massimo Chiappini, Roberto Carluccio, Stefano Chiappini, Emiliano Fiorenza, Carlo Lefevre, Pasqualino Loffredo, Marco Lucente, Francesco Santoli

Instrumentation and Detectors

In-situ suppression of surface radon emanation using an HDPE barrier at the Stawell Underground Physics Laboratory (SUPL)

R.R. Marcelo Gregorio, K. Mintern-Lane, S. Rushbrook et al. (+5 more)

Radon-induced backgrounds remain a limiting factor in low-background experiments conducted in underground laboratories. The enclosed nature of these laboratories can result in elevated radon levels, with emanation from the surrounding rock representing the primary source of radon. In this work, we present an in-situ study of radon emanation from the floor of the main experimental hall at the Stawell Underground Physics Laboratory (SUPL) and investigate the use of a high-density polyethylene (HDPE) barrier to suppress emanation. Surface emanation was measured using an AIRTHINGS Corentium Pro passive detector before and after installation of the barrier. The equilibrium radon concentration within the surface emanation setup was reduced from 5840 $\pm$ 50 Bq m $^{-3}$ to 259 $\pm$ 3 Bq m$^{-3}$, corresponding to a suppression of $\sim$96%. These results demonstrate the potential to retrofit radon barriers to suppress surface emanation under realistic underground conditions, supporting their use in planned low-background infrastructure at SUPL and future applications at other underground laboratories.
Read the full abstract

All authors R.R. Marcelo Gregorio, K. Mintern-Lane, S. Rushbrook, A.G. McLean, L.J. Bignell, J.M.C. Brown, G.J. Lane, N.J.C. Spooner

Sunday 30 August

Instrumentation and Detectors

A high-speed anamorphic pupil-conjugate slit spectrograph for rapid, self-luminous sources

Matthew Vayner and Kyle D. Gilroy

We present a slit imaging spectrograph whose wavelength registration is a property of the instrument rather than of the pointing of the fore-optic or the position of the source. An internal telecentric 4f relay places the system stop within the instrument while a cylindrical lens places the slit aperture at a plane where transverse position encodes source angle only (an $A = 0$ conjugate in the ABCD matrix formulation). As a result, the lateral motion of the source or the pointing of the fore-optic does not cause the spectral image illuminating the sensor to wander, thus eliminating any non-physical registration of chemical species not present in the event and the need for on-the-fly recalibration. Additionally, the use of a high-speed CMOS camera eliminates temporally averaged spectral lines and aliasing noise. We characterize wavelength calibration (He discharge lamp, quadratic fit, RMS residual 0.12 nm, verified with Ne discharge lamp, same calibration, RMS residual 0.13 nm), spectral resolution (R $\approx$ 639, FWHM 0.92 nm at the optimal slit width setting, R $\approx$ 783, FWHM 0.75 nm at the instrument profile floor), and pointing invariance (He 587.6 nm line wander 0.29 nm RMS, 1.03 nm peak-to-peak, a nearly 100x reduction relative to the same instrument with the aperture stop at the fore-optic pupil). We perform combustion spectroscopy on ignited nitrocellulose at 10 kHz, 99 $\mu$s exposure time, identifying Na, K, Ca, CaOH, and Rb chemical species using the unchanged wavelength calibration transferred from the helium discharge lamp.
Read the full abstract

Instrumentation and Detectors

Toward Ionization Cluster Size Measurements with a Compact Nanodosimeter

Victor Merza, Aleksandr Bancer, Vladimir Bashkirov et al. (+8 more)

Nanodosimetry aims to provide measurable quantities related to the nanoscopic particle track structure, which determines the biological effectiveness of radiation. While simulated nanodosimetry has already demonstrated its potential for radiation treatment planning, the experimental realization of practical nanodosimetric detectors is still in its early stages. In this work, a nanodosimetric prototype operated with low-pressure gas was developed to count ionizations in a nanometer-equivalent sensitive gas volume. Its performance was evaluated experimentally with alpha beams from an Am-241 source in 1 mbar propane gas. The results support the further development of this compact nanodosimeter class, with potential applications in particle therapy, radiation protection, and space radiation dosimetry.
Read the full abstract

All authors Victor Merza, Aleksandr Bancer, Vladimir Bashkirov, Ana Belchior, Beata Brzozowska, Piotr Gasik, Jaroslaw Grzyb, Khaled Katmeh, Marcin Pietrzak, Antoni Ruciński, Reinhard Schulte

Friday 28 August

Instrumentation and Detectors

Design of a Lamb-Shift Polarimeter for $^3$He Ions and Atoms

N. Faatz, R. Engels, C. Kannis et al. (+2 more)

In high energy physics experiments $^3$He$^{2+}$ nucleons are suitable to test the internal structure of neutrons, which makes them the perfect substitute. Moreover, it is one of the atomic species for which high polarization values are achievable through the use of optical pumping methods. Therefore, nuclear polarized sources for $^3$He$^{2+}$ ions are currently under development. Consequently, detector systems validating their nuclear polarization value need to be established. Such a detector system, based on the Lamb-shift polarimeter, is introduced in this work. Its advantage is that it can operate at low energies in the range of 10 to 100 keV, which makes pre-acceleration unnecessary. In addition, a fast evaluation of the nuclear polarization within seconds leads to shorter disruptions for beam times. Another option of this Lamb-shift polarimeter might be that it can serve as a valuable tool for further investigation of the bound tritium decay into $^3$He atoms, similar to the hydrogen spin filter for the bound beta decay of the free neutron.
Read the full abstract

All authors N. Faatz, R. Engels, C. Kannis, S. J. Pütz, J. Steinhage

Instrumentation and Detectors · Cross-listed from cond-mat.mes-hall

Design and Modeling of the Charge Readout of a SiMOS Quantum Dot with a Single Electron Transistor and CryoCMOS

Adam Quinn, Troy England, Andrew Li et al. (+1 more)

Single electron spin qubits trapped in SiMOS quantum dots are a promising technology for scaling to thousand- or million-qubit systems due to their compatibility with mature CMOS manufacturing processes. A readout system that combines a single electron transistor with a custom cryogenic CMOS amplification and digitization chain offers key advantages by avoiding the use of bulky RF components or room-temperature interconnects. We present design techniques and simulation results for an optimized qubit-SET cryoCMOS interface, culminating in the design of the QNDR1 ASIC, the first cryogenic readout ASIC designed under the Quandarum project, which targets the development of a many-channel spin qubit based detector for use in high energy physics.
Read the full abstract

All authors Adam Quinn, Troy England, Andrew Li, Sharmila Mustari Nandita

Instrumentation and Detectors

Development of a high-granularity, high-precision timing readout electronics system for large-area MRPC detectors

J.N.Tang, W.H.Wu, Y.Q.Tan et al. (+4 more)

Multi-gap Resistive Plate Chamber (MRPC) detectors offer excellent time resolution and detection efficiency, creating a strong demand for high-precision, highly scalable timing readout systems. In this work, a readout electronics system is designed for a large-area 100*100 cm MRPC detector containing 2400 high-granularity 2*2 cm pad channels. The system consists of two Front-End Boards (FEBs), a central clock distribution module, and a back-end DAQ aggregator. Each FEB is equipped with 40 32-channel PETIROC2B ASICs mounted directly behind the sensing pads. An automated S-curve calibration procedure equalizes the baseline dispersion across all 2400 channels, reducing the FWHM of the baseline voltage distribution from 50 mV to 12 mV and establishing a uniform triggering threshold. Signal-injection measurements confirm an intrinsic single-channel electronic time resolution of 33 ps RMS, alongside inter-chip and inter-board time resolutions of 43 ps RMS and 45 ps RMS, respectively. This high-granularity, high-precision timing readout system can be widely applied to Time-of-Flight systems, cosmic-ray muon imaging, as well as other fast-timing detector systems.
Read the full abstract

All authors J.N.Tang, W.H.Wu, Y.Q.Tan, W.Zhi, H.J.Yang, Imad Laktineh, Q.P.Shen

Instrumentation and Detectors · Cross-listed from astro-ph.IM

Development, Configuration and Performance Characterization of a Scalable BETA ASIC-Based Readout System for Multi-Channel SiPM Detectors

Giulio Lucchetta, Keerthana Rajan Lathika, Benjamin Nobre Hauptmann et al. (+17 more)

We present the design, configuration, and performance characterization of a scalable readout system based on the BETA application-specific integrated circuit (ASIC), developed to meet stringent requirements on noise, linearity, dynamic range, and power consumption for multi-channel silicon photomultiplier (SiPM) detectors in spaceborne instrumentation. The readout electronics consists of modular interface boards (FIBs) hosting multiple BETA ASICs and controlled by a field-programmable gate array (FPGA), which provides configuration, data acquisition, and global trigger generation. Multiple BETA FIBs were tested in a dedicated optical setup enabling simultaneous readout of a large number of channels. The system performance was evaluated using three S13552-10 SiPM arrays manufactured by Hamamatsu for the FIT detector, a scintillating-fiber tracker developed for charged cosmic-ray particle tracking and charge measurement in the HERD mission. We describe the configuration procedures and performance measurements of the readout system, including gain calibration, linearity characterization, and threshold response. In addition, we present the development of a global internal trigger logic for the identification of ionizing particles in the FIT detector. The results demonstrate the stability, scalability, and suitability of the developed BETA-based readout system for large-scale multi-channel SiPM detector applications in space experiments.
Read the full abstract

All authors Giulio Lucchetta, Keerthana Rajan Lathika, Benjamin Nobre Hauptmann, Philipp Azzarello, Oscar Blanch, Juan Boix, Laia Cardiel, Arturo Castaño Gallardo, Albert Espinya, Jennifer Maria Frieden, David Gascon, Daniel Gubermann, Kimberly Sarah Keyser, Manel Martinez, Joan Mauricio, Marina Orta-Terré, Chiara Perrina, Javier Rico, Andreu Sanuy, Monong Yu

Instrumentation and Detectors

Full-field fluorescence computed tomography (F3CT) using a calibrated virtual cone-beam pinhole geometry

Thomas Zillhardt, Yunhui Chen, Alexander Rack et al. (+4 more)

We present F3CT, a synchrotron-based hyperspectral full-field fluorescence computed tomography technique that avoids raster scanning by combining a pinhole aperture with an energy-resolving 2D detector. A virtual cone-beam model and two-stage calibration-reconstruction workflow enable 3D elemental mapping under full-field illumination. The method is demonstrated on biological and geological specimens, resolving silver-stain distributions in zebrafish tissue and high-energy fluorescence signatures in rock cores. Phase-contrast tomograms acquired sequentially under the same experimental geometry provide co-registered structural context. F3CT provides a high-throughput route to 3D XRF imaging and establishes a foundation for correlated structural and chemical tomography, with potential for future in-situ and operando implementations.
Read the full abstract

All authors Thomas Zillhardt, Yunhui Chen, Alexander Rack, Matthew Veale, Matt Wilson, Philip J. Withers, Nicola Viganò

Instrumentation and Detectors · Cross-listed from physics.optics

Compact Variational Neural Networks for Spectral Inference from a Single Nonlinear 2D Perovskite Photodetector

Karl Jonas Riisnaes, Ned Thaddeus Taylor, Hoi Tung Lam et al. (+4 more)

Spectroscopy conventionally separates optical frequencies before detection, imposing persistent constraints on footprint, complexity and scalability. Here we establish an alternative paradigm in which the nonlinear optoelectronic dynamics of a single two-dimensional perovskite photodetector physically encode the incident optical field and machine learning performs the inverse spectral reconstruction. Using a planar fluorinated phenethylammonium lead iodide (F-PEAI) photodetector, we exploit wavelength- and irradiance-dependent current-voltage signatures arising from the coupled effects of photocarrier generation, trapping, interfacial transport and field-dependent carrier dynamics. A compact variational encoder-decoder preserves the functional and history-dependent structure of these responses by independently projecting forward and reverse voltage sweeps onto a truncated Legendre-polynomial basis before mapping them through a probabilistic latent representation to continuous spectral parameters. Trained on fewer than 400 experimental voltage sweeps, the model generalises to excitation wavelengths excluded from training, reconstructing wavelength with $R^2=0.958$ and a mean absolute error of 8.1 nm, while recovering log-normalised irradiance with $R^2=0.987$. Voltage-resolved analysis further reveals that wavelength and irradiance are encoded differently across the nonlinear device response, with distinct bias regions carrying complementary optical information. These results establish nonlinear material and interface dynamics as a computational resource for spectroscopy and point towards hardware-algorithm co-design in which materials, interfaces and inference architectures are engineered jointly to maximise information content, enabling compact spectroscopic systems without dispersive optics or detector arrays.
Read the full abstract

All authors Karl Jonas Riisnaes, Ned Thaddeus Taylor, Hoi Tung Lam, Rosanna Mastria, Francesco Saverio Difeo, Monica Felicia Craciun, Saverio Russo