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Physics Physics Instrumentation and Detectors

physics.ins-det Watch Instrumentation and Detectors

Tuesday 4 August

Instrumentation and Detectors

High Temporal and Spatial Resolution X-Ray and Gamma-Ray Imaging using an Event-Mode Scintillator-Based Detector

Alexander Wolfertz, Ondrej Zapadlik, Alex Gustschin et al. (+2 more)

LumaCam detectors are a novel type of event-mode imaging detectors based on scintillator screens that have been developed recently for neutron imaging applications. They operate in an event-mode in which individual interactions of the incoming particles with the scintillator screen are reconstructed in both space and time, providing simultaneous high spatial and temporal resolution. In this work, we demonstrate the applicability of LumaCam detectors to X-ray and gamma-ray imaging. First tests with a 120 kV acceleration voltage X-ray source show a spatial detector resolution down to 50 um and the temporal resolution is estimated to be ~1 us. This combination makes LumaCam detectors especially suitable for imaging fast processes with high spatial resolution with limited cone beam magnification. The most significant adaption of the detector from the version for neutron detection is the scintillator screen. To further investigate the potential of LumaCam detectors for high-energy photon applications, additional measurements employing different scintillator screen materials have been carried out using gamma ray sources. The results show significant improvements in the temporal resolution with values as low as ~15 ns. In addition, some scintillators also show significant energy sensitivity in the photon multiplicity spectrum, highlighting the potential of LumaCam detectors for energy-selective X-ray and gamma-ray imaging.
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All authors Alexander Wolfertz, Ondrej Zapadlik, Alex Gustschin, Adrian Losko, Andrei Nomerotski

Instrumentation and Detectors

A table-top few-femtosecond broadband extreme-ultraviolet absorption spectrometer with cryogenic cooling

Sheng-Chih Lin, Alfred Zong, Emma Berger et al. (+5 more)

We present a table-top cryogenic ultrafast broadband XUV absorption spectroscopy (c-UBXAS) beamline designed for temperature-dependent and time-resolved investigations of quantum materials. The instrument combines a broadband high-harmonic generation source spanning 22-73 eV with automated image registration and cryogenic sample control down to 20 K, enabling element-specific measurements under both equilibrium and nonequilibrium conditions. The beamline provides sub-50-meV energy resolution and a sub-10-fs instrument response function, while maintaining long-term stability suitable for extended, ultrasensitive measurements. Benchmark experiments on NiI$_2$, a van der Waals multiferroic, reveal temperature-dependent spectral evolution across its magnetic phase transitions, demonstrating the ability to identify element-specific contributions to the ground state and its transient response in the femtosecond regime. This instrument introduces the opportunity to unravel the very first response of a solid-state material during light-matter interaction, paving the way for understanding the complex phase space of nonequilibrium dynamics and emergent states in strongly correlated systems where the few-femtosecond electronic response has eluded most other types of time-resolved techniques.
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All authors Sheng-Chih Lin, Alfred Zong, Emma Berger, Bailey R. Nebgen, Marcus Hui, Shuaiwei Pan, Jackson McClellan, Michael W. Zuerch

Instrumentation and Detectors · Cross-listed from physics.optics

AOM-based ultra-low noise laser intensity control up to the MHz range

Christian Partes, Jonas Auch, Eduard Heidt et al. (+3 more)

High-power laser sources that exhibit low relative intensity noise and allow simultaneous dynamic control of their light level are required for a broad range of applications in various fields of physics. Acousto-optic modulators (AOMs) are widely used for active power stabilization and regulation due to their simple drive electronics requirements and high optical power handling capability in free-space. However, the rather slow propagation speed of the sound wave within the AOM crystal typically limits their control bandwidth to a few hundred kHz. In this work, we present a novel AOM-based control system that is capable of significantly suppressing intensity noise of high-power lasers up to the MHz range. By combining two standard feedback loops with one feedforward control branch and optimizing the beam path in the AOM crystal, ultra-low relative intensity noise levels down to $-155\, \text{dB}\,\text{Hz}^{-1}$ even at several hundred kHz are achieved. Our results are relevant for applications that require ultra-low intensity noise at Fourier frequencies up to the MHz range, such as optical lattice experiments with light ultracold atoms.
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All authors Christian Partes, Jonas Auch, Eduard Heidt, Kirill Karpov, Florian Kiesel, Christian Groß

Instrumentation and Detectors

Real-Time Smart Self-Mixing Interferometry Sensor With Embedded Neural Network

Pierre-Emmanuel Novac, Laurent Rodriguez and Stéphane Barland

Self-mixing interferometry is a measurement ap- proach in which a laser beam is re-injected into the emitting laser itself after reflection on a target. Information about the position of the target can be obtained from monitoring the voltage across the laser. However, analyzing this signal is difficult. In previous works, neural networks have been used with great success to process this data. In this article, we present an updated prototype of an integrated sensor based on self-mixing interferometry with embedded neural networks. It consists of a semiconductor laser (acting both as light emitter and detector) equipped with an embedded platform for data processing. The platform includes an ADC (Analog-to-Digital Converter) and an STM32U575ZI microcontroller. The microcontroller runs a residual neural network in charge of reconstructing the displacement of a target from the interferometric signal entering the ADC. We assess the robustness of the neural network to unwanted signal amplitude variations, the impact of different network weights quantization choices required to run the network on the microcontroller, and the energy consumption of the system. Finally, we provide a demonstration of target displacement reconstruction fully running on the embedded platform in real-time. Our results pave the way towards robust, low power and versatile sensors based on self-mixing interferometry and embedded neural networks.
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Instrumentation and Detectors

Organic liquid scintillator neutrino detector experiment, theoretical modeling, and computational simulation

Xi Liu and Wenxi Fang

The Liquid Scintillator Neutrino Detector (LSND) experiment aimed at investigating neutrino oscillations, particularly the transformation of muon-type antineutrinos (\(\overline{\nu}_\mu\)) into electron-type antineutrinos (\(\overline{\nu}_e\)). This phenomenon challenges the Standard Model's assumption of massless neutrinos. The LSND employed a large organic liquid scintillator (LS) to detect low-energy neutrino interactions, enhanced by the addition of metal ions such as gadolinium (Gd) for improved signal sensitivity and noise suppression. Theoretical modeling and simulations are used in this paper to accurately interpret experimental results. The FLUKA Monte Carlo code was employed to simulate particle interactions and transport in the detector. Key processes modeled included neutrino interactions (\(\overline{\nu}_e + p \to e^+ + n\)), neutron capture (\(n + p \to d + \gamma\)), and the corresponding light output in the scintillator. The simulations accounted for quenching effects using Birks' law, enabling precise predictions of light yield and detector response to secondary particles. Neutrino fluxes from decay-at-rest (DAR) and decay-in-flight (DIF) processes were calculated, capturing the energy spectra of neutrinos generated by pion and muon decays. Pion production cross-sections and light output efficiency for various particles were also modeled to understand detector performance comprehensively. The theoretical modeling and simulation framework validated the experimental observations and provided insights into the detector's sensitivity and limitations. The LSND results hinted at deviations from the Standard Model, stimulating further investigations into neutrino oscillations and the potential existence of sterile neutrinos.
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Instrumentation and Detectors · Cross-listed from cond-mat.mtrl-sci

Picometre-scale real-time drift correction in TEM and STEM by dynamic control of the specimen stage for atomic-resolution imaging

Christophe Gatel, Julien Dupuy, Teresa Hungria et al. (+1 more)

In this work, we show how the specimen drift can be actively compensated by controlling the stage with precision down to the picometre scale. We do this by dynamic control, a generic real-time feedback framework designed to actively stabilize electron microscopy experiments by continuously monitoring an experimental variable from the detector data stream and compensating its evolution during acquisition. The framework, applicable to a broad range of controllable experimental instabilities, includes automated calibration procedures, operates in parallel with image acquisition and is implemented as a software plugin without requiring any hardware modification of the microscope. Results for live drift correction are shown for a selection of TEM and STEM instruments using conventional mechanical stages as well as piezoelectric stages. Experimental results are presented for medium resolution TEM, high-resolution TEM, HR-STEM and in situ observations. With piezoelectric stages, specimen stabilization down to the picometre scale was achieved allowing drift-corrected atomic-resolution imaging. Specimen stage-based stabilization significantly improves long-exposure imaging and in situ experiments by increasing the effective exposure time, preserving the field of view, maintaining identical optical conditions and eliminating the need for numerical alignment of large datasets. Beyond the specific application presented here, dynamic control provides a versatile framework for real-time regulation of electron microscopy experiments and opens new perspectives for quantitative imaging, automated in situ studies and multimodal acquisitions.
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All authors Christophe Gatel, Julien Dupuy, Teresa Hungria, Martin J. Hytch

2608.03344 · 4 Aug · 27 pages, 9 figures. Submitted to Ultramicroscopy Christophe Gatel: Writing original draft, Software, Methodology, Investigation, Data treatment, Conceptualization, Resources, Funding acquisition. Julien Dupuis: Software, Conceptualization, Methodology. Teresa Hungria: STEM experiment, Review & editing. Martin Hytch: Review & editing, Data treatment, Resources, Funding acquisition

Abstract PDF $ALIGN ×1$DATA ×1$EVO ×1$MMOD ×1

Instrumentation and Detectors

Spectacular - A Modular DAQ System for Microdosimetry

Matthias Knopf, Simon Waid, Daniel Radmanovac et al. (+8 more)

Particle therapy using light ions like protons, helium ions or carbon ions enables precise tumor targeting with enhanced biological effectiveness while minimizing damage to healthy tissue. Successful treatment planning depends not only on the absorbed dose but also on quality of the radiation, as quantified by the linear energy transfer (LET). Microdosimetry provides a direct experimental determination of such quantities by measuring the energy deposited per incoming particle in micrometer-sized solid-state detectors representing the relevant biological scales. However, the small signal amplitudes and high particle rates in therapeutic ion beams challenge existing readout systems, which are not sufficiently optimized for reliable operation with respect to pileup and signal-to-noise ratio (SNR). To address this, a modular data acquisition (DAQ) system was developed to accelerate the design of custom readout electronics and sensor characterization in microdosimetry and related spectroscopic applications. Centered around a Xilinx Zynq system-on-chip, it combines real-time processing, high-bandwidth streaming, and high-resolution digitization (16 bit at 100 MSas$^{-1}$) to enable advanced digital signal processing. The platform integrates programmable power supplies, a bias-voltage filter, test-pulse generators, and flexible I/O. Detector and preamplifier front-ends are hosted on interchangeable daugtherboards connected via a standardized interface, allowing different hardware configurations and readout algorithms to be evaluated on the same platform. The Spectacular DAQ system was successfully tested at the MedAustron ion therapy facility with custom charge-sensitive amplifiers and a diamond microdosimeter. First results demonstrate the feasibility and provide a proof-of-concept for potential future applications in clinical practice.
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All authors Matthias Knopf, Simon Waid, Daniel Radmanovac, Sebastian Onder, Richard Thalmeier, Peter Fischer, Stefan Gundacker, Claudio Verona, Edoardo Domenicone, Thomas Bergauer, Albert Hirtl

Monday 3 August

Instrumentation and Detectors

Imaging performance of a Single-Plane Readout Compton Camera

Om Prakash Dash, Tomislav Bokulić, Damir Bosnar et al. (+1 more)

This work presents the design, development, and characterization of a compact Compton camera employing a novel single-plane readout architecture. The proposed concept simplifies conventional multilayer Compton cameras by optically coupling the scatterer and absorber into a single compact detector element using a light guide, enabling readout exclusively from one side with silicon photomultipliers. The system was validated through Monte Carlo simulations, prototype construction, and experimental characterization using standard gamma-ray sources. Detector performance for 511~keV and 662~keV photons was optimized using simulations based on the Geant4 framework, by guiding event selection strategy. Event reconstruction relied on coincidence detection consistent with Compton scattering kinematics, while image reconstruction was performed using maximum likelihood expectation maximization algorithm. The prototype comprises 64 detector elements arranged in an $8\times8$ matrix, read out by an $8\times8$ silicon photomultiplier array. Each element consists of two GAGG:Ce scintillators coupled by a 20 mm long light guide. Measured energy resolutions were $8.9\%\pm1.9\%$ and $10.8\%\pm1.6\%$ for the front and back layers, respectively. Successful gamma-ray imaging was demonstrated for Na-22 and Cs-137 sources, achieving angular resolutions of $12.4^\circ$–$14.3^\circ$ at 511~keV and $14.3^\circ$–$16.8^\circ$ at 662~keV, confirming the feasibility of the proposed single-plane architecture for compact and cost-effective gamma-ray imaging applications.
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All authors Om Prakash Dash, Tomislav Bokulić, Damir Bosnar, Mihael Makek

Instrumentation and Detectors

Mitigating warp divergence in GPU optical photon Monte Carlo: an order of magnitude speedup with Shader Execution Reordering

Gabor Galgoczi

In high energy, nuclear, and medical physics, optical photon transport Monte Carlo is a frequent bottleneck in detector simulation. GPU ray tracing accelerates photon propagation, but one thread per photon megakernels suffer from SIMT execution divergence when photon lifetimes vary widely. Short-lived photons leave inactive lanes while a few long-lived photons delay warp completion. We evaluate NVIDIA Shader Execution Reordering (SER) in an OptiX based optical photon transport kernel and use it to regroup surviving photons during propagation. In a 14.7 kton liquid argon time projection chamber benchmark with ~61 million photons from a 2.5 GeV electromagnetic shower, SER capable execution reduces propagation kernel cycles by 16.55(23)x and end-to-end optical simulation time, including transfers and initialization, by 14.72(30)x with bit-identical hit output. We decouple the speed-up into a 3.2x contribution from the launch configuration changes introduced when SER is enabled and a further 5.1x from executing the reorder. Profiling identifies active lane recovery as the dominant mechanism, while branch efficiency and memory bandwidth change little. A volume coherent SER hint enables an analytic navigation fast path in bulk argon, adding a further 1.13x wall-time speedup. Utilizing SER resulted in a ~90% reduction in GPU energy per simulated event.
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Instrumentation and Detectors

Cryogenic Mechanical Loss of GaAs/AlGaAs Crystalline Coatings

Nicholas A. Didio, Steven D. Penn, Satoshi Tanioka et al. (+3 more)

Optical coatings with minimal thermal noise are essential for high-precision, laser-based metrology experiments. Substrate-transferred crystalline GaAs/Al$_{0.92}$Ga$_{0.08}$As coatings have the lowest thermal noise for high-reflectivity mirror coatings with $\lambda =900$ nm – 12 $\mu$m. Time-frequency stabilization experiments have demonstrated that GaAs/AlGaAs mirror coatings have a lower noise floor than amorphous mirror coatings. These mirrors are now being developed at sizes $\ge 300$ mm for gravitational-wave detectors. In order to understand the coating's fundamental loss mechanisms, which cause thermal noise, we have performed the first measurement of the mechanical loss at cryogenic temperatures using a cryogenic, multimodal, gentle nodal suspension system, which operates from 12 K to room temperature. This initial measurement used a silicon substrate whose asymmetry produced excess friction with the nodal support. Accounting for this friction and Akhiezer loss in the substrate and coating, the mechanical loss agrees well with the thermal noise observed in experiments using cryogenic fixed-cavities with GaAs/AlGaAs mirrors.
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All authors Nicholas A. Didio, Steven D. Penn, Satoshi Tanioka, Elenna M. Capote, Garrett D. Cole, Stefan W. Ballmer

Instrumentation and Detectors

An Open Source RFSoC-based Readout Electronics System for Arrays of Kinetic Inductance Detectors and Superconducting Resonators

Cody Roberson, Nia McNichols, Jack Sayers et al. (+12 more)

We present a novel readout electronics system for large arrays of superconducting electromagnetic resonators, such as kinetic inductance detectors (KIDs), based on a Radio Frequency System on Chip (RFSoC) architecture. Each channel in the readout system is designed for frequency division multiplexing of up to 1024 high quality factor resonances placed on a single microwave transmission line at unique frequencies within a 512 MHz bandwidth. We describe the design of the digital and analog signal processing chains for the implementation of a two-channel 2048-resonator system on the Xilinx ZCU111 RFSoC evaluation board in combination with a custom intermediate frequency (IF) system to convert the RFSoC band to higher frequencies up to 4 GHz. We also detail an associated software interface that provides a range of tools commonly utilized for characterizing KID resonators and for operating them as part of a photometric millimeter-wave imager. We additionally provide noise characterizations of the individual readout components, along with the complete readout system in isolation and in operation to readout KID resonators.
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All authors Cody Roberson, Nia McNichols, Jack Sayers, Sean Bryan, Daniel Cunnane, Peter K. Day, Fabien Defrance, Simon Hempel-Costello, Tracee Jamison-Hooks, Bradley R. Johnson, Maya Lee, Philip Mauskopf, Adrian Sinclair, Liam C. Walters, Eric Weeks

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

A diagnostic system of 5.7 keV muon beam for muon accelerator

M. Wada, M. Kimura, S. Aritome et al. (+28 more)

Realization of a low-emittance muon beam through the acceleration of keV-scale muons requires the injection of a suitably matched beam into an accelerator, since beam mismatch can lead to emittance growth and reduced acceleration efficiency. In one such scheme, muons are first thermalized to room temperature and then injected into a linear accelerator. Non-destructive diagnostics are challenging because of the low energy and low intensity. We developed a compact low-energy muon diagnostic system compatible with the accelerator under construction at J-PARC. The system is designed to evaluate beam conditions required for precise tuning prior to acceleration. Commissioning with low-energy muon sources shows the system's capability to identify low-energy muon signals and measure beam profiles.
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All authors M. Wada, M. Kimura, S. Aritome, E. Cicek, K. Futatsukawa, K. Hirai, M. Hoshiai, T. Iijima, Y. Imai, K. Inami, K. Ishida, S. Kamioka, Y. Kawase, A. Kondo, Y. Kondo, M. Lyu, T. Mibe, Y. Nagatani, Y. Nakazawa, S. Ogawa, Y. Oishi, M. Otani, N. Saito, K. Shimomura, K. Suzuki, T. Takayanagi, K. Ueda, S. Uetake, S. Yamamoto, T. Yamazaki, M. Yang

Instrumentation and Detectors · Cross-listed from quant-ph

Nanohertz Pendulum toward Macroscopic Entanglement under Structural Damping

Azusa Sawada, Hina Nakano, Kanta Watanabe et al. (+3 more)

Pendulums are attractive for macroscopic quantum control because gravity dilution reduces mechanical loss, while the $1/f$ force-noise spectrum associated with structural damping allows nearly lossless trapping to suppress the thermal noise sampled at an upward-shifted resonance. The same $1/f$ spectrum, however, produces a low-frequency tail that penalizes entanglement. With $10\%$ detection loss, we find that this tail raises the required back-action-to-thermal force-noise ratio by about $50\%$, corresponding to a required suspension gain $G_{\rm req}=1.49$. To overcome this structural-noise penalty, we realize a $7$-mg pendulum suspended by a stepped fused-silica fiber, with an energy-decay rate $\Gamma/2\pi=361(39)$ nHz ($Q\equiv\omega_0/\Gamma=7.3(8)\times10^6$) at $\omega_0/2\pi=2.63$ Hz. The reduction in $\omega_0\Gamma$ yields a measured gain $G_q\simeq2.5$ relative to the previous monolithic device, exceeding the requirement.
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All authors Azusa Sawada, Hina Nakano, Kanta Watanabe, Gaku Ohashi, Shota Okumura, Nobuyuki Matsumoto

Instrumentation and Detectors

Performance and prospects of polyurethane-based scintillators for neutron and gamma radiation detection

Olga Maiatska, Torsten Duennebacke, Roland Hillebrands et al. (+6 more)

Organic scintillators have been used for decades to detect gamma rays or fast neutrons at low cost. Despite extensive efforts it is still difficult to combine stability, ruggedness, high light yield, and decent pulse-shape discrimination (PSD) in a single scintillator material. We took the unusual approach of embedding phosphors and wavelengths shifters in a solid polyurethane matrix, trying to combine the robustness of a common construction material with scintillating properties and PSD performance. The plastic scintillators resulting from years of research ultimately meet these intentions. Moreover, the production process is less demanding and less complex than that of conventional plastic scintillators. It allows to directly integrate light sensors or electronics into the scintillator. This opens the door for the construction of extremely compact and robust plastic detectors for the simultaneous detection of fast neutrons and gamma rays. This paper presents basic recipes and properties of scintillators based on this novel conception and discusses first applications in neutron imaging and personal radiation protection.
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All authors Olga Maiatska, Torsten Duennebacke, Roland Hillebrands, Achim Kreuels, Martin Kreuels, Guntram Pausch, Falko Scherwinski, Andreas Wolf, Juergen Stein

Instrumentation and Detectors

Spectroscopic study of argon electroluminescence light with a wavelength-sensitive particle detector

R. Santorelli, V. Pesudo Fortes, G. Vera Díaz et al. (+5 more)

We present a spectroscopic study of argon electroluminescence (EL) light in a gaseous time projection chamber (TPC). Using a compact detector equipped with photomultiplier tubes with different spectral sensitivities, we measure the light emission in two nominal wavelength regions, approximately [110, 160] nm and [160, 650] nm, at different gas pressures. In addition to the well-known 128 nm emission of the second continuum, significant emission is observed in the [160, 650] nm band, with a prompt, nanosecond-scale response indicating that photon production closely follows the transit of drifting electrons across the high-field EL region. In contrast, the [110, 160] nm emission displays a markedly slower time evolution, dominated by excimer formation and de-excitation dynamics, with the light output governed primarily by the long-lived triplet component of the argon second continuum emission. We demonstrate that the full VUV pulse shape can be reproduced by convolving the fast UV3 response with excimer formation and decay functions, providing a coherent phenomenological interpretation of the observed signals. Our results provide new insights into the spectral and temporal properties of argon electroluminescence and have direct implications for the design and optimization of next-generation rare-event detectors based on gaseous TPCs. Further studies are underway to characterize this emission more precisely and to investigate its potential for particle discrimination.
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All authors R. Santorelli, V. Pesudo Fortes, G. Vera Díaz, C. K. Guérard, R. López Manzano, L. Luzzi, J. Martínez Morales, L. Romero

Instrumentation and Detectors · Cross-listed from cond-mat.mtrl-sci

Physics-Informed Neural Networks for Sparse Strain-Field Reconstruction in 4D-STEM

Roberto dos Reis, Gabriel T. dos Santos, Yukun Liu et al. (+2 more)

Quantitative strain mapping using four-dimensional scanning transmission electron microscopy (4D-STEM) typically requires densely sampled scans that can damage beam-sensitive specimens. We develop a physics-informed neural network (PINN) for sparse 4D-STEM strain reconstruction that embeds elastic equilibrium and Saint-Venant compatibility in the training loss through automatic differentiation. The architecture combines a coordinate-based implicit representation, sine activations with stable second derivatives, frozen residual-scale normalization, an exponential physics-weight ramp, and residual-based adaptive collocation. We apply a sine-activated residual network to an experimental $180\times400$-pixel strain map of domain-structured PbGeSnSe$_{1.5}$Te$_{1.5}$. Across $1$-$75%$ sampling ($720$-$54{,}000$ probe positions), $R^2$ for $\varepsilon_{xx}$ reaches $0.80$ at $10%$ sampling and saturates near $0.86$ by $25%$; the chevron strain-band morphology is recovered from $10%$ of probe positions. At $10%$ sampling, the PINN reduces mean absolute error by approximately $26%$ relative to compressed sensing and $22%$ relative to Gaussian-process regression. An ablation against an equal-capacity data-only SIREN shows that the PDE prior improves accuracy at extreme sparsity and consistently improves physical self-consistency, but biases the reconstruction when data are abundant. Monte Carlo dropout and mean-field variational inference provide per-pixel epistemic uncertainty maps correlated with reconstruction error. With an appropriate constitutive model, the framework is adaptable to strain mapping across diverse material systems.
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All authors Roberto dos Reis, Gabriel T. dos Santos, Yukun Liu, Xiaobing Hu, Vinayak P. Dravid