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Physics Physics Instrumentation and Detectors

physics.ins-det Watch Instrumentation and Detectors

Monday 17 August

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

In-situ measurements of space plasma: recent progress and future challenges

Daniel Verscharen

Space plasmas like the solar wind or the Earth's space environment offer unique opportunities to observe fundamental plasma processes and their impact in situ. With modern space instrumentation, we measure the velocity distribution function of the plasma particles as well as the electromagnetic fields at high resolution and with minimal perturbation of the observed plasma systems. Plasma measurements like this are often not possible in laboratory settings on Earth. This review article focuses on modern diagnostic methods for the in-situ detection of plasma particles in space. It presents the detection principle of top-hat electrostatic analysers and highlights recent examples of scientific discoveries based on data from the heliospheric space missions Parker Solar Probe and Solar Orbiter. These examples demonstrate the capabilities of modern space plasma instrumentation. The article then discusses future directions in space plasma physics as well as the involved challenges in terms of the required plasma diagnostics. These new developments include, for example, upcoming and proposed space missions such as the operational space-weather mission Vigil, the multi-spacecraft mission HelioSwarm, the Mars mission M-MATISSE, and the electron-astrophysics mission Debye.
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Instrumentation and Detectors

The ASD2 Chip for the Upgrade of the ATLAS MDT Chamber Readout at HL-LHC

S. Abovyan, A. Baschirotto, V. Danielyan et al. (+8 more)

Upgrading the ATLAS detector for operation at the High-Luminosity LHC requires a new, more se-lective trigger scheme to control the readout of MDT drift-tube chambers by incorporating RPC trigger information. This necessitates replacing the MDT readout electronics, including the front-end boards that house the ASD amplifiers and the custom-designed TDC. The latter buffers timing measurements for transmission to a chamber-mounted data concentrator (CSM), which, in turn, communicates with the MDT Data Processor, where MDT tracking data are combined with RPC timing information, to specifically identify high-energy muon tracks. In this article, we report on the new ASD2 preamplifier, discussing its architecture, design details, functionality and measured performance. We also present test results for chips from MPW runs, the engineering run and the volume production of 80,000 chips. Unlike the ASD1 preamplifier, currently used for MDT readout, which relies on 500 nm chip tech-nology, the ASD2 is manufactured using the more advanced 130 nm technology. This offers a range of technical improvements that enhance critical performance parameters such as signal rise time, noise levels, and the reproducibility of threshold settings across a chip's channels. Comparative measurements are presented to verify this improved performance. Finally, we discuss the robust-ness of ASD2 against environmental conditions like radiation exposure and potential high-voltage discharges within the MDT drift tubes.
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All authors S. Abovyan, A. Baschirotto, V. Danielyan, M. Fras, O. Kortner, S. Kortner, H. Kroha, M. de Matteis, F. Resta, R. Richter, Y. Zhao

Instrumentation and Detectors

TARDIS Lab: infrastructure for characterization and assembly of highly granular silicon calorimeter modules for LUXE and future Higgs Factories

Melissa Almanza-Soto, César Blanch, Shan Huang et al. (+2 more)

The TARDIS Lab has been established at IFIC (CSIC-UV) to develop infrastructure and expertise in high-granularity silicon calorimetry. The laboratory provides an ISO7 clean-room environment and dedicated instrumentation for silicon sensor characterization and ultra-thin calorimeter module assembly. It supports developments of silicon-based high-granularity calorimetry concepts pursued within CERN DRD Calo (DRD6) and the FCAL Collaboration. These developments serve not only as technological prototypes of the electromagnetic calorimeters and luminometers at future Higgs-factory proposals (FCC-ee, Linear Collider Facility at CERN, International Linear Collider, etc.) but are also essential for the strong-field QED program of the LUXE experiment. We describe the laboratory infrastructure, assembly workflows and DESY test-beam validation of fully assembled calorimeter modules. The assembled ECALp modules have an average thickness of approximately 760~$\mu$m, while laboratory tests of 4352 channels identified connectivity problems in only 0.5% of them. For the two SiWECAL modules assembled in 2025, connectivity problems were observed at the level of approximately $10^{-3}$ of the instrumented pads, with no mechanical failures or sensor delamination after transport and beam operation. We also present ongoing infrastructure upgrades and production milestones for 2026-2027.
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All authors Melissa Almanza-Soto, César Blanch, Shan Huang, Adrián Irles, Carlos Orero

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

Highly Efficient 3-in-1 FPGA-Based Unit Combining an ADC, DAC, and Multichannel Pulse Generator for Pulsed EPR Spectroscopy

N. P. Isaev, A. R. Melnikov, A. V. Vedkal et al. (+4 more)

A hardware and software system for pulsed electron paramagnetic resonance (EPR) spectroscopy is presented, built around a single PCI Express (PCIe) card that combines a 16-bit digital-to-analog converter (DAC) with a 10 GS/s effective sample rate, a 2.5 GS/s 14-bit analog-to-digital converter (ADC), and an 11-channel pulse generator on board. Custom firmware reloads the pulse-generator and DAC buffers and streams the digitized data in parallel with a running experiment, so that no time is lost on data input or output. The unit is integrated into the open-source Atomize software and controlled at the level of pulse sequences through a high-level Python application programming interface (API). Benchmarking with a four-pulse double electron-electron resonance (DEER) sequence shows that the card reaches close to 100% time efficiency for accumulation times of a few milliseconds per pulse sequence, even for demanding arbitrary waveform generator (AWG) protocols. Although demonstrated for a single sequence, the efficiency proved insensitive to the number of pulses, the number of measurement points, or the phase-cycling depth, so that comparable performance is expected for any protocol whose shot repetition time exceeds the ~2 ms reprogramming time of the card. The on-the-fly reprogramming, which makes every successive sequence fully independent, also enables nonuniform sampling and acquisition. The system design, its firmware, the Python API, and its performance in pulsed EPR applications are described.
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All authors N. P. Isaev, A. R. Melnikov, A. V. Vedkal, A. S. Ishchenko, A. M. Sokolov, E. A. Voronkov, S. L. Veber

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

Exact spherical-wave forward model for radio reflection from stratified media and implications for the anomalous-polarity events observed by ANITA

Paramita Dasgupta

Radio detection of ultra-high energy particles relies on the propagation and reflection of broadband radio pulses at boundaries between natural media. In the Sommerfeld–Weyl treatment, a spherical wave is decomposed into plane-wave components and their reflection from a single homogeneous interface is calculated exactly. We extend that treatment to an arbitrary number of laterally uniform spherical layers. Both the spherical-wave decomposition of the source and the spherical geometry of the boundary are retained, while the reflection and transmission coefficients of the plane-wave components are replaced by the exact characteristic-matrix coefficients of the layered medium, evaluated at the local incidence angle on the spherical boundary. When the layer contrast is removed, the formalism recovers the single-boundary result to machine precision, and it reproduces the published spherical-surface reflectivity calculation to better than $1.1\%$ at ten HiCal-2 elevation angles, with a mean deviation of $0.6\%$. We reproduce the measured HiCal-1 reflected pulses from their measured direct partners, with a best signed correlation of $0.83$ and a median of $0.70$ across $106$ pairs, of which $101$ show the expected polarity inversion. Applied to the six reported ANITA anomalous-polarity event geometries, the buried-layer refractive index required for a sign change of the reflection coefficient ranges from $1.68$ at the steepest event to $3.8$–$5.4$ at the four near-horizon events. The full waveform calculation gives no non-inverted reflected pulse at any of these angles, showing that shallow, laterally uniform firn layering does not account for the polarity of the anomalous ANITA events. Because the formalism depends only on the complex refractive index of the medium, it applies more generally to isotropic, nonmagnetic stratified media, including ice, lunar regolith, and conducting layers.
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Sunday 16 August

Instrumentation and Detectors · Cross-listed from cond-mat.supr-con

Identification and electrothermal modeling of persistent current switch operating regimes in a Siemens MRI magnet using external electrical measurements

Volodymyr Pupkov

The persistent current switch (PCS) closes the superconducting loop of an MRI magnet. During ramping it is commonly treated as a binary element: with the heater on, the PCS branch is assumed effectively open; after heater turn-off, it is assumed superconducting. Field measurements with an MPS2 service power supply (Digit Systems) on a Siemens MAGNETOM Avanto show that the PCS remains electrically active and that its resistive state can persist after heater turn-off through Joule self-heating. Dedicated maneuvers identified two resistive regimes. With the heater on, the low-voltage resistance is nearly constant; after heater turn-off, self-heating produces a power-law voltage dependence. Both are described by a single effective electrothermal relation, $R_{sw}=C\,(P_h h+V_{node}^2/R_{sw})^a$, where $h$ is the recorded heater state, spanning a 690-fold resistance range. Final-hold data from 17 Siemens magnet sessions confirmed the voltage dependence of effective PCS resistance. Since branch-current relaxation follows $\tau=L/R_{sw}$, the required hold time depends on switch state rather than a fixed delay; the median margin after source settling was $3.6\,\tau$. The intersection of the PCS characteristic with the external-circuit load line defines the boundary of self-sustained resistive operation. For Avanto, the predicted 0.062 V threshold lay between superconducting recovery at 0.06 V and resistive-state persistence at 0.07 V, and retrospectively classified all 24 archived segments correctly. Including both PCS resistive regimes in the dynamic model reproduced the observed current redistribution: RMSE decreased from 1.449 to 0.154 A, a factor of 9.4. This improvement required explicit representation of heater state.
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Instrumentation and Detectors · Cross-listed from physics.med-ph

Low-rank modal endpoints from beat-resolved retinal arterial Doppler holography velocity waveforms characterize the response to flicker provocation

Sienna O'Shea, Maxime Boy Arnould, Adrien Gordon et al. (+3 more)

Conventional retinal flicker endpoints quantify changes in diameter, mean velocity, or flow but do not capture the modal concentration of the cardiac velocity waveform during neurovascular stimulation. Here, beat-resolved retinal Doppler holography and low-rank modal decomposition are combined to derive compact arterial endpoints from unfiltered arterial segment-velocity waveforms sampled across beats and vessel locations. For each acquisition, locally centered waveforms are assembled into a common matrix and decomposed by singular-value decomposition (SVD). Robust summaries quantify total pulsatile scale, modal amplitude, residual amplitude, mean-to-pulsatile balance, and singular-spectrum dimensionality; the same construction can also be applied descriptively to individual beats. We demonstrate the framework using 33 temporally ordered Baseline~1/Flicker/Baseline~2 acquisitions from one eye. Relative to the pooled baselines, 13-Hz flicker was associated with lower centered-waveform RMS scale $R_0$ and leading-mode amplitude $A_1$, and with higher robust residual-amplitude ratios $\rho_1$ and $\rho_2$, mean-to-pulsatile ratio MPR, effective rank, and participation ratio; these contrasts showed exploratory within-session separation after Holm adjustment. No evidence of differences in the absolute residual amplitudes $R_1$ and $R_2$ was detected; together, these observations are consistent with reduced concentration in the leading acquisition-specific arterial pulse mode rather than an increase in absolute residual pulsatility.
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All authors Sienna O'Shea, Maxime Boy Arnould, Adrien Gordon, Yann Fischer, Zacharie Auray, Michael Atlan

Saturday 15 August

Instrumentation and Detectors

Development of a 10 mol% Rubidium-doped CsI Crystal for $^{87}$Rb Beta-Spectroscopy and Sterile Neutrino Searches

W. K. Kim, K. W. Kim, L. T. Truc et al. (+3 more)

The third-forbidden non-unique beta-decay of $^{87}$Rb to $^{87}$Sr (Q$_\beta = 282.275(6)$ keV) has long served as an important benchmark for understanding forbidden beta-decay. To investigate this, we have developed a novel CsI scintillator with a 10 mol% Rb concentration using the Bridgman method. The incorporated $^{87}$Rb serves as an intrinsic radioactive source, enabling a source-in-detector configuration with high detection efficiency and minimal energy loss for low-energy electrons from beta-decay. We investigated both Rb doped and Tl co-doped CsI crystals and characterized their scintillation properties, including light yield, energy resolution, and non-linear response. We report distinct scintillation characteristics for the CsI:Rb and CsI:Tl,Rb crystals, with light yields of $1.38\pm0.01$ and $4.73\pm0.13$ PE/keV, respectively. Using the measured $^{87}$Rb beta-spectrum, we search for a keV-scale sterile neutrino admixture through the characteristic kink-like distortion induced by a heavy neutrino mass eigenstate. This study provides a basis for future sterile neutrino searches using rubidium doped CsI crystal.
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All authors W. K. Kim, K. W. Kim, L. T. Truc, H. S. Lee, H. J. Kim, Y. D. Kim

Friday 14 August

Instrumentation and Detectors

Muon Bulb: A Cosmic-Ray Detector Inside a Light Bulb

Yuvaraj Elangovan

Cosmic-ray muons are among the most abundant high-energy particles reaching Earth's surface, with a flux of approximately one muon per square centimeter per minute at sea level, yet they remain entirely invisible to the naked eye, posing a persistent challenge for public engagement in particle physics. We present the Muon Bulb, a self-contained cosmic ray muon detector built within the enclosure of a standard commercial LED bulb, designed to produce a vivid and immediate visible light flash upon the passage of a cosmic-ray muon. The detector integrates a plastic scintillator tile coupled to a Silicon Photomultiplier (SiPM) for efficient detection of scintillation photons produced by ionizing muons. The SiPM signal is processed by a compact analog front-end comprising an amplifier and a leading-edge discriminator, which isolates genuine muon-induced pulses from background. Validated trigger signals are passed to an ESP32/RP2350 microcontroller, which drives an internal LED, causing the bulb to flash visibly in real time. The readout additionally enables wireless data transmission for real-time monitoring of muon event rates and flux measurements. The Muon Bulb is designed to serve as a high-impact outreach instrument across science museums, planetariums, K-12 classrooms and public science festivals without requiring specialized infrastructure. Its wireless capability enables networked classroom activities where multiple Muon Bulbs can be operated simultaneously, allowing students to collaboratively measure muon flux and engage in genuine data-driven scientific inquiry. The Muon Bulb transforms a commercial house hold item into a powerful tool for particle physics, making the invisible universe visible to everyone.
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Instrumentation and Detectors · Cross-listed from physics.optics

Angular displacement readout of a mechanical oscillator with a guided mode resonance

Diego Torres-Barajas, Oscar Angulo, Aman R. Agrawal et al. (+2 more)

Measuring the angular displacement of a mechanical oscillator is a ubiquitous task; however, the multimode nature of angular optomechanical coupling makes coherent signal enhancement challenging. Here we demonstrate coherently enhanced angular displacement readout with an integrated guided mode resonance (GMR) structure, applying it to precision readout of a nanomechanical oscillator. Specifically, we fabricate subwavelength gratings into 100-nm-thick Si$_3$N$_4$ membranes and record their vibration by direct transmission measurements. The narrow linewidth $\approx 2.5\;\text{mrad}$ of the GMR enables a shot-noise-limited displacement imprecision of $ 10^{-9}\;\text{rad}/\sqrt{\text{Hz}}$ with nanowatts of optical power, sufficient to resolve the thermal motion of a $Q\approx 10^6$ torsion mode with a signal-to-noise ratio of 47 dB. Control experiments based on polarization and wavelength detuning confirm that the measured signal arises from GMR-mediated transduction. These results establish guided-mode resonance as an on-chip approach to angular displacement readout in quantum optomechanical sensors.
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All authors Diego Torres-Barajas, Oscar Angulo, Aman R. Agrawal, Mohamed ElKabbash, Dalziel J. Wilson

Instrumentation and Detectors · Cross-listed from cs.RO

Effect of Twisted-Yarn Architecture on Pressure and Proximity Sensing Characteristics of Textile Capacitive Sensors for Robotic Skin

Ishtia Zahir, Eslam Saleh, Maryam Rezayati et al. (+2 more)

Textile-integrated capacitive sensors offer flexible and conformable tactile sensing for wearable electronics and human-robot interaction; however, the influence of yarn-level architecture on capacitive transduction characteristics remains insufficiently quantified. This work presents a textile capacitive sensing platform based on silver-coated yarns coated with polydimethylsiloxane and assembled into one-, two-, and four-layer twisted configurations. The influence of effective electrode overlap area and inter-fiber separation on the capacitive response is systematically investigated, enabling architecture-dependent tuning of pressure and proximity sensing characteristics. Pressure was calculated using the localized single-fiber contact area, corresponding to stresses of 0.4-3.9 MPa. Increasing the layer number improved mechanical strength and sensing performance: elongation at break increased from 37.5% to 62.5% and 85.0%, while the maximum load increased from 23.3 to 42.7 and 89.7 N. Sensitivity increased with layer number and frequency, reaching 0.1331 MPa$^{-1}$ for the four-layer sensor at 100 kHz. The four-layer configuration also exhibited low hysteresis, minimal thermal drift from 25 to 90 $^\circ$C, and stable operation over 15,000 cycles. Proximity detection ranges of 60, 50, and 40 mm were obtained for the one-, two-, and four-layer sensors, respectively, revealing an architecture-dependent sensitivity-range trade-off. A 4$\times$4 textile sensing array enabled spatial contact mapping, while robotic-arm integration demonstrated real-time touch and proximity detection with an end-to-end robotic system latency (from detection to robot reaction) of 403 ms. The results establish yarn architecture as a tunable design parameter governing the measurement characteristics of textile-integrated capacitive sensing systems.
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All authors Ishtia Zahir, Eslam Saleh, Maryam Rezayati, Güunter Grabher, Gaffar Hossain

Instrumentation and Detectors

Variable-Path-Length FTIR of E. coli in Aqueous Media

Jonathan Matsuura, Andrew Huang, Jaehyeon Kim et al. (+3 more)

Transmission infrared spectroscopy has been widely used for chemical analysis of biological samples in aqueous environments. However, its scope of applications has been limited by the path length, which is either too large or fixed, posing challenges for analyzing highly absorbing or heterogeneous samples. In this work, a mid-infrared (mid-IR) optical fiber probe was used for Fourier transform infrared (FTIR) micro-spectroscopy of aqueous Escherichia coli (E. coli) samples, providing continuous tuning of optical path length and sampling of near-surface and bulk regions. The mid-IR absorbance of the protein signal at 1548 cm-1 increased linearly with path length, consistent with the Beer-Lambert law. Path-length dependent spectra were used to calculate the spatially heterogeneous absorption coefficient of E. coli suspensions in aqueous media. The results demonstrate the ability of our fiber-based technique to resolve signals originating from different depths into the biological solution.
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All authors Jonathan Matsuura, Andrew Huang, Jaehyeon Kim, Ching-Ping Chang, Kai Zhang, Yingjie Zhang

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

CCAT: a two-octave 1.024 GHz KID readout featuring an overlap-channel polyphase synthesis filter bank on RFSoC

Ruixuan Xie, Adrian K. Sinclair, James Burgoyne et al. (+6 more)

Next-generation submillimeter instruments require gigahertz-scale readout bandwidths to support the growing detector counts of large microwave kinetic inductance detector (KID) arrays. Designed to meet the readout bandwidth and tone-capacity requirements of the CCAT Prime-Cam 850 GHz and 410 GHz instrument modules, we developed our second-generation (Gen2) KID readout system on a Xilinx ZCU111 radio frequency system-on-chip (RFSoC), based on a parallelized overlap-channel polyphase synthesis filter bank and a companion wideband receiving channelizer. This two-octave architecture reads out four independent RF networks, each with 1.024 GHz instantaneous bandwidth and up to 2048 detectors. The polyphase synthesis doubles the baseline channel count and bandwidth, and enables on-the-fly control of individual tone frequency, amplitude and phase, facilitating optimized KID biasing and providing a gateway to tone tracking. These capabilities may also be useful more broadly across Prime-Cam and in similar frequency-division multiplexed (FDM) readout systems. We present the design in DSP simulation, and measurements in RF loopback as well as with two KID test chips, one spanning the full two-octave band. Loopback measurements demonstrate comparable noise performance between the first-generation (Gen1) baseline and Gen2; preliminary on/off-resonance measurements indicate detector-noise-limited operation for the majority of channels; and the digital channel crosstalk is measured and discussed. We report FPGA resource and power utilization and assess scalability toward future large-format KID instruments.
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All authors Ruixuan Xie, Adrian K. Sinclair, James Burgoyne, Maxwell Chapman, Scott Chapman, Steve K. Choi, Anthony I. Huber, Ben Keller, Michael D. Niemack

Thursday 13 August

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

Comparative measurements of DC electrical breakdown distributions in liquid nitrogen, liquid helium, and liquid argon

N. S. Phan, S. M. Clayton, R. Gautam et al. (+4 more)

We present a comparative study of DC electrical breakdown in liquid nitrogen, liquid helium, and liquid argon using a common cryostat, electrode assembly, voltage-ramp protocol, and analysis procedure. This common experimental configuration minimizes systematic differences that often complicate comparisons among cryogenic liquids, including variations in electrode geometry, stressed area, surface finish, and gap spacing. For each liquid, breakdown was characterized as a statistical distribution rather than by a single characteristic voltage, allowing the stochastic nature of the process to be examined. Measurements were performed both near saturated vapor pressure and under modest pressurization to assess the influence of bubble formation and related thermodynamic effects. Liquid argon exhibited a non-stationary "turn-on" behavior, with breakdown voltage increasing over repeated discharges, consistent with evolution of the local impurity environment or electrode surface state. Near saturated vapor pressure, liquid helium showed a bimodal breakdown distribution, with a lower-field component consistent with bubble-mediated processes. Liquid nitrogen exhibited higher breakdown fields than liquid argon and fields comparable to those measured in pressurized liquid helium, within the observed run-to-run variation associated with surface state. Taken together, these results support a comparative framework in which breakdown strength reflects both thermodynamic stability against bubble formation and the transport properties of the dominant negative charge carrier.
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All authors N. S. Phan, S. M. Clayton, R. Gautam, T. M. Ito, L. Kadlec, C. M. O'Shaughnessy, T. J. Schaub

Instrumentation and Detectors

An Interactive, Automated 4D-STEM data acquisition and analysis routine for Scanning Electron Nanobeam Diffraction and Ptychography experiments

Mohsen Danaie, Max England, Yiming Xu et al. (+11 more)

Modern transmission electron microscopes are versatile instruments which have become indispensable tools for understanding structure and chemical composition at the nano- and atomic scale. In the physical sciences these instruments are still largely manually controlled, requiring significant operator expertise, limiting throughput, and precluding statistical analysis of large datasets. Recent technical advances in both hardware and in control software now allow for the interaction with almost every functionality of the microscope through a programming interface. This enables better experimental design and data collection automation while also reducing operator collection bias and required expertise. In this study, we present an automated data collection routine with machine-driven decision-making to enable the collection of hundreds of 4D-STEM nanobeam diffraction and ptychography data from a large distribution of size-selectively deposited Pt nanoparticles. We present a semi-automated data analysis workflow to extract pertinent information from the large volumes of collected data. For the nanobeam diffraction data, reducing each dataset to its azimuthal variance profile and combining automated crystal orientation mapping with per-particle morphology descriptors reveals the orientation, shape and phase distributions across the ensemble, including a weak {110} texture. For the ptychographic data, an automated screening pipeline identifies on-zone-axis particles and enables atomic-resolution phase imaging and lattice-strain mapping of individual grains. Together these demonstrate how automation turns instrument throughput into statistically meaningful, atomic-scale microstructural information.
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All authors Mohsen Danaie, Max England, Yiming Xu, Ruomu Zhang, Ed Darnbrough, Josh Willem De Boer, Frederick Allars, Zaeem Najeeb, Aakash Varambhia, Jinseok Ryu, Benjamin Bradnick, Damien McGrouther, Manfred E. Schuster, Christopher S. Allen

Instrumentation and Detectors

Optical Characterization Measurements of Commercial Polyvinyltoluene Scintillators for Accurate Geant4 Detector Modeling

Fergus Martin Huggins, Micah S. Johnson and Matthew Quinn Buckner

Accurate Monte Carlo simulation of plastic scintillator detectors requires precise wavelength-dependent optical properties. We present the first comprehensive measurements of wavelength-dependent refractive index $n(\lambda)$ and bulk absorption length $L_{\mathrm{abs}}(\lambda)$ for six commercial polyvinyltoluene (PVT)-based scintillators (Saint Gobain BC-400, BC-404, BC-408, BC-418, BC-422, and BC-430) across the 370-660 nm range. Using a precision refraction apparatus and variable-thickness transmission measurements, we characterize material-specific dispersion that deviates substantially from both the manufacturer specification and literature values for pure PVT. Validation simulations of a BC-422 detector demonstrate a 7.2% reduction in detected photon counts when using our measured $n(\lambda)$ compared to the constant manufacturer value, highlighting the practical importance of accurate optical property data for detector design and calibration. We successfully measure absorption lengths for BC-430 across most of the visible spectrum (2.2-12.4 mm) and for all materials at 372 nm (21-38 mm), while establishing lower bounds exceeding 750 mm for weakly absorbing formulations at longer wavelengths.
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Instrumentation and Detectors

Scan-Coil Delay Causes Anisotropic Signal Loss in Fast 4D-STEM

Vishal Kumar, Andreas Jehle, Tizian Lorenzen et al. (+4 more)

Fast pixelated detectors are driving 4D-STEM toward microsecond dwell times, a regime in which the finite response of the scan deflection coils becomes comparable to the dwell time itself. Using direct probe imaging and sub-frame diffraction analysis, we document a significant intra-dwell scan-coil delay that systematically smears the recorded signal anisotropically along the fast scan direction, with a settling timescale of several tens of microseconds. We present a phase-correlation-based sub-frame alignment procedure that measures and corrects this smearing, and we assess its impact on focused and defocused 4D-STEM reconstructions over a range of scan step sizes. The correction restores signal across a broad range of spatial frequencies, with the largest gains at the large step sizes required for low-dose biological imaging. Because it operates on existing data with no modification to the microscope, the method offers a practical route to recovering signal that would otherwise be lost to scan-coil delay.
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All authors Vishal Kumar, Andreas Jehle, Tizian Lorenzen, Julika Radecke, Knut Müller-Caspary, Massimo Kube, Henning Stahlberg

Instrumentation and Detectors · Cross-listed from physics.optics

Cyclic-Quadrature Intracavity Signal Amplification for Gravitational-Wave Detectors

Kaido Suzuki, Ryo Iden, Ken-ichi Harada et al. (+1 more)

The high-frequency sensitivity of laser-interferometric gravitational-wave detectors is limited by quantum shot noise. Increasing the circulating optical power reduces shot noise, but is constrained by thermal effects and optomechanical instabilities. We propose cyclic-quadrature intracavity signal amplification, in which an optical parametric amplifier (OPA) inside a detuned signal-recycling cavity is used as a phase-sensitive amplifier of the gravitational-wave signal quadrature. By detuning the signal-recycling cavity for $\pi$/4, the optical quadratures rotate by $\pi$/2 on each round trip, so a signal generated in the phase quadrature appears in the readout phase quadrature only after odd-numbered passes through the OPA. Successive contributions to the readout phase quadrature, which are separated by two round trips, have alternating signs, making this two-round-trip evolution anti-resonant. During each two-round-trip cycle, however, the same field experiences one amplification and one deamplification, so neither vacuum squeezing nor parametric gain accumulates. Despite the destructive interference between signal contributions separated by two round trips, the OPA increases the signal component extracted through the output coupler, thereby improving the signal-to-noise ratio. When the OPA gain is sufficiently large, the response approaches that of an interferometer with an effective power enhancement of $1/\tau^2$, where $\tau$ is the amplitude transmissivity of the quadrature-rotation mirror that forms the amplifier cavity. We apply the proposed scheme to a current gravitational-wave detector with a near-future upgrade and show that it improves the quantum-noise-limited sensitivity over a broad frequency range extending into the kilohertz band.
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All authors Kaido Suzuki, Ryo Iden, Ken-ichi Harada, Kentaro Somiya

Instrumentation and Detectors

Fine-tuned Normalizing Flows for ALICE Zero Degree Calorimeter Fast Simulation

Emilia Majerz, Jacek Otwinowski, Witold Dzwinel et al. (+1 more)

Simulating the ALICE Zero Degree Calorimeter (ZDC) neutron detector responses at the LHC is computationally expensive, requiring complex Monte Carlo chains. We develop a generative surrogate, focusing on Normalizing Flows (NFs). Through transfer learning, we pre-train on the full imbalanced dataset and fine-tune specialized models for different particle types ($\gamma$, $n$, $\Lambda$, $K_S^0$, $\Sigma^+$) using two gradual-unfreezing schemes. As standard ZDC metrics like Wasserstein distance overlook conditional structure, we introduce refined metrics: conditional weighted MAE, dispersion ratio, and Jaccard co-activation error, that better capture physics-relevant input-output dependencies and response variability. Our ensemble of fine-tuned models achieves a Wasserstein distance of $1.61 \pm 0.02$, outperforming baselines across all metrics. This work provides a generalizable NF-based framework for LHC detector simulation, combining NFs, conditional fine-tuning, and physics-motivated evaluation.
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All authors Emilia Majerz, Jacek Otwinowski, Witold Dzwinel, Jacek Kitowski

Wednesday 12 August

Instrumentation and Detectors

Ultracold Neutron Sources: An Essentially Enhanced Optimal Operation Temperature for Ortho-Deuterium-Based Superthermal Converters

Erik Walz and Christoph Morkel

There is a longstanding dogma in the physics of ultracold neutrons (UCN): The optimal temperature of ortho-deuterium based UCN-sources must not exceed $5\,\mathrm{K}$. This value has been established by the pioneering work of Golub et al. decades ago, utilizing previously established cross sections for solid ortho-deuterium. But recently, an improved calculation of the crucial 1-phonon up-scattering cross section - using the so-called corrected Incoherent Approximation - leads to a new upper limit for the optimal operation temperature of ortho-deuterium based UCN sources. After a discussion of the relevant cross sections of the \(\mathrm{D}_2\)-molecule we conclude that the optimal temperature lies between $10\,\mathrm{K}$ and $12\,\mathrm{K}$, a factor 2 higher than estimated earlier. This offers significantly relaxed cryogenic conditions for UCN experiments with solid ortho-deuterium and especially for the operation of ortho-deuterium based ultracold neutron sources.
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Instrumentation and Detectors

From Simulation to Real Scans: Anomaly Detection in Maritime Cargo with Muon Scattering Tomography

Angel Bueno Rodriguez, Christina Hrytsiuk, Maximilian Perez Prada et al. (+6 more)

Maritime cargo inspection requires imaging technologies capable of detecting concealed threats within dense, sealed containers, a role for which Muon Scattering Tomography (MST) is well suited: it images their interior through the density-dependent deflection of naturally occurring cosmic muons. However, MST remains constrained by the scarcity of labeled scans and by a cosmic muon flux that is both low and stochastic. Anomaly detection algorithms must therefore be trained on simulations, yet operate on measured scans acquired under different conditions, a sim-to-real gap that remains a central obstacle to operational deployment. We present the first end-to-end anomaly detection framework for maritime MST, from physically consistent simulations to validation on real container scans from the SilentBorder demonstration campaign. The task is cast as an out-of-distribution problem: the framework learns the spatial configurations of benign cargo and flags threats as deviations in the reconstruction error space, remaining agnostic to threat type and geometry. An attention U-Net, trained exclusively on benign synthetic scenes, preserves small-scale scattering signatures through its skip connections, and contraband consequently persists in the pixel-wise reconstruction error instead of being absorbed into the reconstructed background. A scoring function, the Homogeneity Index (HI), suppresses spatially uniform cosmic-ray statistical noise while amplifying coherent anomaly signatures: where pixel-level metrics collapse under a change of cargo configuration, HI retains its discriminative power. We evaluate three training strategies across two distinct cargo configurations under operational one-hour scan times, and test the best model on real muon cargo scans. The results for the studied scenarios indicate that the sim-to-real gap can be bridged.
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All authors Angel Bueno Rodriguez, Christina Hrytsiuk, Maximilian Perez Prada, Kaarel Tark, Felix Sattler, Jean Marco Alameddine, Madis Kiisk, Maurice Stephan, Sarah Barnes

Instrumentation and Detectors

Background decomposition of the CONUS+ run 1 data

N. Ackermann, H. Bonet, C. Buck et al. (+13 more)

The CONUS+ experiment is measuring the coherent elastic neutrino nucleus scattering (CE$\nu$NS) process using reactor anti-neutrinos as a source and four low energy threshold point-contact high-purity germanium spectrometers for their detection. It achieved the first measurement of coherent neutrino scattering at a nuclear reactor in run 1 of the experiment with a detection energy threshold of 160 eV$_{ee}$. This work presents the decomposition of the background spectra of the three detectors used in the run 1 analysis and the development of the corresponding background model with Geant4-based Monte Carlo simulations. The background model is used as the underlying input for the likelihood fit of the analysis. It is shown that reactor-correlated backgrounds are subdominant in all energy regions, specifically in the region of interest for CE$\nu$NS searches below 350 eV$_{ee}$ where their contribution is one order of magnitude below the expected CE$\nu$NS signal. Furthermore, cosmic ray muons and neutrons are identified as the dominant background source below 1 keV$_{ee}$ contributing approximately 75 - 90 % of the recorded background rate. The final background model predicts an average rate of (47.5 $\pm$ 3.2) d$^{-1}$ kg$^{-1}$ in reactor on measurement in the energy region between [0.4, 1.0] keV$_{ee}$, which is in excellent agreement with the average measured value of (48.0 $\pm$ 0.6) d$^{-1}$ kg$^{-1}$. Similar agreement is found in all energy regions of both reactor on and off measurements.
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All authors N. Ackermann, H. Bonet, C. Buck, J. Hakenmüller, G. Heusser, M. Lindner, W. Maneschg, S. Mertens, K. Ni, D. Piani, M. Rank, T. Rink, E. Sánchez García, I. Stalder, H. Strecker, J. Woenckhaus

Instrumentation and Detectors · Cross-listed from cond-mat.other

Formally Verified Lock-Free Software Transactional Memory for Scientific Measurement

Kentaro Kitagawa

Automated measurement of condensed-matter experiments requires instrument-control, data-acquisition, and user-interface threads to access shared, naturally hierarchical state concurrently. Coarse-grained locking can delay acquisition and cause sample loss, whereas fine-grained locking requires deadlock-prone lock ordering across instruments. Instead, we describe the lock-free software transactional memory (STM) that has been at the core of an open-source measurement platform for 16 years, in nuclear magnetic resonance experiments and, more recently, in optically detected magnetic resonance experiments. The STM organizes this state as a tree and provides atomic subtree updates and consistent subtree snapshots. After initial bundling, an unchanged subtree snapshot is acquired in $O(1)$ time through a custom lock-free atomic shared pointer. Within each bounded TLA+ configuration, TLC exhaustively checks the state space, establishing the safety and livelock-freedom properties specified for that configuration. Bounded executions of the atomic shared-pointer implementation are separately checked under the C11 weak-memory model. The same Snapshot and Transaction interfaces are exposed to Python scripting and AI-assisted automation.
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Instrumentation and Detectors

Usage of GPUs for ALICE Run 3 Offline Reconstruction on the GRID

David Rohr for the ALICE Collaboration

ALICE, the dedicated heavy ion experiment at the LHC, records Pb-Pb collisions at an interaction rate of up to 50 kHz. It was the first LHC experiment to leverage GPUs for online data processing during LHC Runs 1 and 2, and its Run 3 online data processing is now fully based on GPUs with more than 90% of the compute load offloaded to the accelerator. In order to use its online processing server farm also for offline processing in an efficient way while the LHC is not operating, ALICE has been running the offline TPC tracking on GPUs since 2023. Since then, ALICE has been conducting an ongoing effort to offload more offline reconstruction steps to GPUs, and to use the GPUs at other GRID sites beyond the ALICE online computing farm for offline reconstruction. In particular, porting the track model decoding and ITS tracking to GPU has improved the throughput by 29%. In 2026, ALICE ran the first GPU reconstruction jobs on the NVIDIA GPUs of the NERSC Perlmutter cluster, marking the first use of GPUs for LHC offline reconstruction on the GRID. Users can submit GPU reconstruction jobs by specifying only the required GPU count and type, while the underlying infrastructure handles all remaining configurations transparently.
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Instrumentation and Detectors

Development and Initial Performance of an Upgraded NaI(Tl) Crystal Encapsulation for COSINE-100U

Doohyeok Lee, Jae Young Cho, Chang Hyon Ha et al. (+23 more)

The COSINE-100 experiment was designed to test the DAMA/LIBRA annual-modulation claim using low-background NaI(Tl) detectors. For the COSINE-100U upgrade, we developed a new crystal-encapsulation system to increase light-collection efficiency while preserving long-term detector stability, thereby improving sensitivity to low-mass dark matter. The upgraded design eliminates the quartz optical windows used in COSINE-100 and directly couples the photomultiplier tubes (PMTs) to the crystal end faces through 2-mm-thick silicone optical pads, thereby reducing the number of optical interfaces. For the larger crystals, the crystal edges were beveled to guide scintillation light more efficiently onto 3-inch high-quantum-efficiency PMTs. The performance study uses 2462~h (102.6~days) of room-temperature COSINE-100U data and, for direct background comparisons, reference COSINE-100 data acquired near the end of operation. 698~h (29.1~days) of COSINE-100 data acquired near the end of operation in March 2023. All eight crystals showed higher light yields than in COSINE-100, with values ranging from 15.8 to 27.7~p.e./keV; six crystals exceeded 20~p.e./keV. The measured bulk-$\alpha$ rates were lower than the COSINE-100 values and consistent with the expected time evolution of internal $^{210}$Pb, while the 1–2-MeV surface-$\alpha$ rates were substantially reduced. The upgrade also restored two crystals that had previously been excluded from the COSINE-100 physics analysis because of poor optical performance. Independent validation tests demonstrated that the encapsulation remains mechanically robust and optically stable during long-term immersion in liquid scintillator at low temperature. This paper presents the encapsulation design, the room-temperature detector performance, and the reduction in surface-related backgrounds achieved at the Yemilab facility.
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All authors Doohyeok Lee, Jae Young Cho, Chang Hyon Ha, Eunju Jeon, Hongjoo Kim, Jinyoung Kim, Kyungwon Kim, SungHyun Kim, Sun Kee Kim, Won Kyung Kim, Yeongduk Kim, Young Ju Ko, Hyunseok Lee, Hyun Su Lee, In Soo Lee, Jaison Lee, Seo Hyun Lee, Seung Mok Lee, Reina H. Maruyama, Jong-Chul Park, Kangsoon Park, Kihong Park, Se Dong Park, Kyungmin Seo, Min Ki Son, Gyun Ho Yu

Tuesday 11 August

Instrumentation and Detectors

Cusp-singularity-enhanced Coriolis effect for ultrasensitive chip-scale gyroscopes

Sen Zhang, Dingbang Xiao, Fei Wang et al. (+8 more)

Gyroscopes, as fundamental inertial sensors, are crucial for rotation measurements in consumer electronics, automotive, and aerospace industries, with the most widely used kind relying on the Coriolis effect. The chip-scale Coriolis vibratory gyroscopes (CVGs) show reduced size, weight, and cost, but remain far lower performance than traditional macroscale CVGs, as the weak intrinsic Coriolis factor sets a fundamental limit on scaling the sensitivity against the inherently louder Brownian noise in microchips compared to the macroscale ones. Here, to overcome this physical limit, for the first time, we propose and experimentally demonstrate the use of third-order singularities lying within cusp catastrophes in the phase-tracked oscillations of an on-chip CVG to facilitate a cubic-root scaling of the Coriolis-effect-induced frequency modulation. Employing this effect, we achieve a three-order-of-magnitude enhancement in the Coriolis factor, yielding a 253-fold improvement in signal-to-noise ratio and a 297-fold increase in precision. Moreover, the cusp singularity enables a previously unattainable ultrasensitive phase-modulated sublinear measurement, achieving a world-record signal-to-noise ratio performance for silicon-chip gyroscopes. These findings not only provide revolutionary advancements in gyroscope technologies, by filling the gap in observing and controlling the singularity-enhanced Coriolis effect, but also shed new light on other ultrasensitive sensing applications.
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All authors Sen Zhang, Dingbang Xiao, Fei Wang, Ran Huang, Lei Yu, Ning Zhou, Kaixuan He, Xuezhong Wu, Franco Nori, Hui Jing, Xin Zhou

Instrumentation and Detectors

Compact nondestructive generator for microsecond-class ultrafast pulsed magnetic fields

Y. Ishii, A. Ikeda, H. Sun et al. (+2 more)

The sweep rate of pulsed magnetic fields is a key factor in exploring of nonequilibrium phenomena in matter. However, the nondestructive generation of ultrafast pulsed magnetic fields is challenging because of the large time constants associated with the large inductance and capacitance of conventional pulsed magnetic field generators, as well as the residual inductance of the power devices and the system itself. We have developed a new compact pulsed magnetic field generator using commercially available state-of-the-art ultrafast power devices, enabling the generation of ultrafast pulsed magnetic fields up to approximately 1 T with a pulse duration of 3.8 $\mu$s. We present the performance of the newly developed system and compare the experimentally obtained magnetic field waveforms with the results of a simple circuit simulation. In addition, we demonstrate magnetization measurements on cobalt powder and Faraday rotation measurements on CdS single crystal using the developed system.
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All authors Y. Ishii, A. Ikeda, H. Sun, H. Oike, Y. H. Matsuda

Instrumentation and Detectors

Temperature-Dependent Performance of NaI(Tl) Crystal with Dual-Channel SiPM Readout for Low-Mass Dark Matter Searches

W. K. Kim, H. Y. Lee, K. W. Kim et al. (+1 more)

We report the first temperature-dependent characterization of a NaI(Tl) crystal readout by two silicon photomultipliers (SiPMs) directly coupled to opposite ends of the crystal for rare-event searches. A $6 \text{ mm} \times 6 \text{ mm} \times 13 \text{ mm}$ NaI(Tl) crystal was directly coupled to two SiPMs and characterized in a liquid nitrogen-cooled cryostat over a temperature range of 94$-$293 K. The light yield, energy resolution, and scintillation decay time were measured using $\gamma$-ray peak from a $^{241}$Am source. After correcting for optical crosstalk contributions, the light yield increased, reaching $17.7 \pm 1.1$ photoelectrons/keV at 238 K, corresponding to a 34.5% enhancement relative to room temperature (293 K). Furthermore, dual-channel configuration effectively suppresses random thermal noise via coincidence triggers, which together with the observed increase in light yield, provides a critical pathway toward lowering the energy threshold for dark matter and coherent elastic neutrino$-$nucleus scattering searches.
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All authors W. K. Kim, H. Y. Lee, K. W. Kim, H. S. Lee

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

Real-Time Requirements and Transferability in Compton Imaging: From the Detector Chain to the Application

F. Albiol, Elena Larrea Estrelles, Salvador Tortajada et al. (+4 more)

Compton cameras are proposed for tasks whose value decays with delay: verifying a range during irradiation, guiding an intervention, characterising an inaccessible volume, surveying a band no telescope covers. Whether a device can serve such a task is settled by the composition of its whole chain, while the literature that would answer the question is organised by stage – so claims made at application level routinely rest on evidence obtained at component level. This review walks that chain, asking at each stage what binds first and what a reader can determine from the published text, and then asks what governs whether a capability transfers between groups and between application domains. The evidence is of two kinds: 83 full texts scored in context against defined markers, and, for five application domains measured alike, the size of the receiving literature, of the need it states, of the incumbent and of deployment commitment. Performance is reported at one operating point in 65 of 83 full texts, with count rate swept in none: the field reports values where transfer requires gradients. An accelerator is used in 39 works and a learned model in 31, while separability is discussed in 28, a memory footprint given in 9, and the cost of a precomputation or the inference time of a model in none. Across domains, neither the size of the receiving literature, nor of the incumbent, nor of the stated need orders the domains as deployment commitment does, while whether the incumbent can serve the task at all, and how many domain boundaries the output must cross, do so consistently. The distribution of publication is close to the inverse of the distribution of deployment commitment. We give the quantities a report must contain for a third party to judge whether a method fits an application it was not built for.
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All authors F. Albiol, Elena Larrea Estrelles, Salvador Tortajada, Luis Caballero, Jose Escalante, Alberto Albiol, Jose Luis Leganes-Nieto

Monday 10 August

Instrumentation and Detectors

Anemometer-free indoor calibration of Doppler lidar using fiber optics and Monte Carlo simulation

Andrew Black, Klaus Franke, Davide Trabucci et al. (+3 more)

Existing methods for calibrating and classifying Doppler lidars for wind energy applications are time-consuming and overestimate lidar measurement uncertainty. These shortcomings are due to the reference instruments: anemometers on meteorological masts. The input signals in field calibrations are real wind conditions, and include uncertainties associated with the met mast and the terrain. This research presents validation of a new method for lidar calibration. The new approach has two steps. First, the uncertainty of the lidar line of sight velocities (LOS) are measured. Second, those intermediate uncertainties are used to derive the uncertainty of the horizontal wind speed using a simulated wind field. LOS uncertainties are assessed using a fiber optic bench as a synthetic wind tunnel called Simulation of the Atmosphere with Fiber Optics Multi-Velocity (SAFO-MV). Using SAFO-MV, the lidar LOS is shifted using an acousto-optic modulator (AOM) and backscattered from a fiber spool, mimicking backscatter from a uniform, low turbulence wind field. The reference signals are SI-traceable via calibration of the AOM's RF-driver. Sources of uncertainty in the bench and the laboratory process are examined and found to be small. Wind speed uncertainties are derived via Monte Carlo uncertainty propagation. Wind fields are simulated using PyConTurb, an implementation of the KSEC turbulence model. A virtual lidar in the simulation replicates lidar sensitivities derived by IEC 61400-50-2 classification campaigns. Replication of device sensitivities and the traceability of the approach comprise a validation of the measurement model, enabling its use for lidar calibration. The proposed method yields uncertainties comparable to IEC lidar calibration, while greatly reducing calibration time. This new technology can streamline lidar deployment and reduce uncertainty in wind resource assessment.
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All authors Andrew Black, Klaus Franke, Davide Trabucci, Pierre E. Allain, Lisa Lopez, Axel Albers