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Physics Physics Instrumentation and Detectors

physics.ins-det Watch Instrumentation and Detectors

Thursday 8 October

Instrumentation and Detectors

Cavity Characterization for the Princeton Axion Search

Nate Otto, Jianyang Fu, Joelle-Marie Begin et al. (+4 more)

The Princeton Axion Search (PXS) targets the mass window $0.8\text{--}2.1~\mu\text{eV}$ (corresponding to frequencies $200\text{--}500~\text{MHz}$) at DFSZ sensitivity. The experiment, a haloscope, will use a cylindrical copper-plated aluminum cavity of $700~\text{mm}$ diameter and $1022~\text{mm}$ height, immersed in a $5~\text{T}$ solenoidal magnetic field. A $152~\text{mm}$ diameter tuning rod spanning the height of the cavity rotates to tune the primary mode resonance from $390\text{--}480~\text{MHz}$, the frequency range for initial operations. We deduce the electric and magnetic field mode patterns using a combination of dielectric and metallic bead perturbations on the empty cavity. The measured mode frequencies and the $\text{TM}_{010}$ field profile, as a function of tuning rod position, are in excellent agreement with simulations. We describe the effect of fabrication and assembly imperfections, including the bowing of end plates and tilt of the tuning rod. The welded seams and end-cap joints are demonstrated to not significantly degrade $Q$. We combine measurement and simulation to assess an uncertainty on form factor across the full tuning range. Our results validate PXS's cavity architecture and inform future searches for sub-$\mu\text{eV}$ axions, in which large-volume high-$Q$ structures are required to reach QCD sensitivity.
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All authors Nate Otto, Jianyang Fu, Joelle-Marie Begin, Saptarshi Chaudhuri, Roman Kolevatov, Lyman Page, Joe Wiedemann

Instrumentation and Detectors

First demonstration of $50\,\mathrm{ps}$ four-dimensional vertex reconstruction with the Timepix4 beam telescope

David Bacher, Kazu Akiba, Martin van Beuzekom et al. (+10 more)

The first demonstration of 4D vertex reconstruction at the $50\,\mathrm{ps}$ scale using a silicon pixel detector is reported. Hadronic interactions are produced by directing a $180\,\mathrm{GeV}/c$ mixed-hadron beam onto a fixed target upstream of the Timepix4 beam telescope at the CERN SPS. The resulting particles are reconstructed using 4D track and vertex fits that include time directly alongside the spatial parameters. The vertex time resolution follows the expected statistical scaling with the number of timing measurements, reaching $54\pm5\,\mathrm{ps}$ for vertices reconstructed from 16 timing-plane clusters. An irreducible component of $29.2\pm0.6\,\mathrm{ps}$ remains in the fitted resolution model, including sizeable contributions from the clock distribution and the time reference system rather than from the combination of the timing measurements. The observed scaling down to $54\,\mathrm{ps}$ without an unforeseen resolution floor above represents a significant experimental step towards precision-timing in future high-pile-up detectors.
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All authors David Bacher, Kazu Akiba, Martin van Beuzekom, Victor Coco, Raphael Dumps, Tim Evans, Kevin Heijhoff, Malcolm John, Edgar Lemos Cid, Loris Martinazzoli, Tommaso Pajero, Yutaro Takahashi, Espen de Wit

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

Femtosecond Three-Dimensional Imaging of Single-Protein with Hard X-ray Laser

Paul Lourdu Xavier, Andrew J. Morgan, Johan Bielecki et al. (+66 more)

The extremely intense pulses of X-ray free-electron lasers (XFELs) have enabled imaging of radiation-sensitive samples, such as macromolecular microcrystals, beyond radiation damage limits. These sources have the potential to deliver biomolecular single-particle imaging, similar to cryo-electron microscopy but without the need for cryo-fixation and with temporal resolution from femtoseconds to milliseconds. While this possibility was recognized before XFELs were built, the biological single-particle imaging work-flow has previously only been demonstrated on large virus particles. Based on decades of improvements in X-ray beam focusing, particle delivery, diffraction detection, and advanced analysis, here we demonstrate imaging of a single molecular complex, the giant-hemoglobin erythrocruorin (Ery) with X-ray laser pulses. Two-dimensional classes of diffraction patterns could be reconstructed to 15 Angstrom resolution, and 3D images to approximately 20 Angstrom, while the 3D merged intensity in reciprocal space extended beyond 20 Angstrom. The resolution discrepancy is likely due to heterogeneity caused by gas-phase compaction of the complexes. With increased throughput, this approach could be used to reveal in-situ structural details during mass spectrometry studies of biomolecules, while improvements in sample delivery may provide ultrafast snapshot imaging of biological single-particles in their native-state beyond the limitations of radiation damage.
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All authors Paul Lourdu Xavier, Andrew J. Morgan, Johan Bielecki, Amit K. Samanta, Simon Dold, Chufeng Li, Xinyue Gao, Spencer K. Passmore, Ruslan P. Kurta, Tim B. Berberich, Emiliano De Santis, Wenhui Zhang, Juncheng E, Faisal H. M. Koua, Romain Letrun, Luca Gelisio, Oleksii Turkot, Egor Sobolev, Lukas V. Haas, Jannik Lübke, Jingxuan He, Madeline B. F. Memovich, Kevin Janson, Stefanie Lenzen, Safi Rafie-Zinedine, Mansi Butola, Oleksandr Yefanov, Fabian Trost, Chan Kim, Tomas Popelar, Tokushi Sato, Yevheniy Ovcharenko, Rebecca Boll, Sergey Usenko, Thomas M. Baumann, Alberto De Fanis, Björn Senftleben, Matteo Porro, Andrea Castoldi, Ibrahym Dourki, Cyril Danilevski, Ekaterina Round, Christina Schmidt, Huijong Han, Roberto Alvarez, Ervin Chia, Cornelia Cazey, Carolin Seuring, Ruojie Sha, Maia Azubel, David A. Bushnell, Sébastien Boutet, Sergey Ovchinnikov, Adrian P. Mancuso, Michael Meyer, Richard Bean, Anton Barty, Filipe R. N. C. Maia, Richard A. Kirian, Thomas D. Grant, N. Duane Loh, Carl Caleman, Erik G. Marklund, Nadia Zatsepin, Andrew V. Martin, Saša Bajt, Roger D. Kornberg, Jochen Küpper, Henry N. Chapman

Instrumentation and Detectors

Thomson Scattering Measurement of 1 keV Electron Temperature on Lawson Machine 26

P. Carle, S. Edwards, X. Feng et al. (+11 more)

LM26 is a magnetized target fusion experiment built to demonstrate compressional heating of a plasma with a collapsing solid lithium liner. We report the design of a Thomson scattering diagnostic for LM26 and measurements from the LMC-12 compression shot where an electron temperature of $1090 \pm 40 \rm{eV}$ was measured with high confidence. The LM26 Thomson scattering diagnostic can measure temperature during compression at 8 times and 2 spatial points. Access limitations restricted the design to narrow f/30 views, and a forward scattering configuration with scattering angles < 20deg. The small solid angle of the scattered light view is largely compensated for by the 10 times increase in the density during compression to $> 10^{20}\rm{m}^{-3}$. Measuring at a small scattering angle significantly narrows the Thomson spectral broadening of the laser line. The narrow spectrum (1030-1063 nm) is advantageous for the design of optical components and to minimize noise from plasma background light. UKAEA polychromators specialized for small broadening measurements were used to analyze the scattered light. Results are also presented for an uncompressed plasma preceding LMC-12. Stray light was not a significant source of error. This design provides a strong design basis for Thomson scattering systems on future LM26 configurations.
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All authors P. Carle, S. Edwards, X. Feng, A. Froese, M. Greenwood, A. Lee, M. Reynolds, A. Rudy, J. Sanchez Rojo, M. Schellenberg-Beaver, R. Svihra, R. Tingley, R. Zindler, M. Maslov

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

Three-dimensional imaging of isolated membrane-protein complexes in vacuo with an X-ray laser

Kartik Ayyer, Tej Varma Yenupuri, Johan Bielecki et al. (+51 more)

The prospect of imaging single biomolecules, viruses and cells with intense, ultrashort X-ray pulses has driven the development of X-ray free-electron lasers (XFELs). However, the weak scattering from small particles is easily swamped by background from residual gas, which has so far limited applications to strongly scattering targets such as viruses, cell organelles and cells. Here we report a three-dimensional (3D) reconstruction of an isolated 1-MDa membrane-protein complex, photosystem I (PS I), from single-particle diffraction data. PS I trimers were aerosolised by charge-reduction electrospray ionisation and injected into the European XFEL beam, with partial helium gas exchange reducing background scattering by 80%. From 32 788 diffraction patterns of single trimers in random orientations, we reconstructed the 3D electron density to a resolution of 3.8 nm, limited by the detector geometry. The disc-shaped density, about 22 nm across and 10 nm thick, matches the size of a PS I trimer in a detergent micelle and is consistent with the compaction predicted by molecular dynamics simulations of the complex in vacuo and observed in native mass spectrometry. These results show that membrane-protein complexes can be imaged in vacuo with X-ray lasers, an important step towards ultrafast diffractive imaging of single macromolecules.
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All authors Kartik Ayyer, Tej Varma Yenupuri, Johan Bielecki, Lutz A. Eichacker, J. Domingo Meza-Aguilar, Louise J. Persson, Lena Worbs, Patrick Adams, Roberto Alvarez, Adil Ansari, Alfredo Bellisario, Rebecca Boll, Carl Caleman, Sebastian Cardoch, Andrea Castoldi, Joe P. J. Chen, Cyril Danilevski, Merle Dechering, Simon Dold, Armando D. Estillore, Alberto De Fanis, Lukas V. Haas, Patrick Konold, David Lomitze, Abhishek Mall, Dimitra Manatou, Iñaki de Diego Martinez, Parichita Mazumder, Andrew J. Morgan, Anna Munke, Yevheniy Ovcharenko, Matteo Porro, Safi Rafie-Zinedine, Amit K. Samanta, Christina Schmidt, Arezu Sehati, Jonas A. Sellberg, Björn Senfftleben, Carolin Seuring, Zhou Shen, Nicusor Timneanu, Sergey Usenko, Daniel Westphal, August Wollter, Tamme Wollweber, Paul Lourdu Xavier, Henry N. Chapman, Janos Hajdu, Richard A. Kirian, Jochen Küpper, Erik G. Marklund, Petra Fromme, Michael Meyer, Filipe R. N. C. Maia

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

Generation, Accumulation, and Utilization of Data in the Automatically Controlled End-Station of a Soft X-ray Beamline

Yasunobu Ando, Masashige Miyamamoto, Keita Hiromori et al. (+4 more)

AI is rapidly transforming materials exploration, yet reliable AI-assisted research depends on experimental data that retains their context, provenance, and machine-readable structure. High-throughput synchrotron measurements therefore require more than automated data acquisition: data generation, accumulation, and utilization must be connected within a continuous workflow. Here, we present a data-centric research framework that integrates the PIONEER system, the OMNES, and ML analysis. The PIONEER system automates sample handling, vacuum transfer, and scanning XAS at the BL08U soft X-ray beamline of NanoTerasu, systematically generating large volumes of spatially resolved spectral data. Measurement and analysis files are stored in the cloud-based ARIM-mdx data system, while OMNES manages metadata describing samples, preparation procedures, measurement conditions, instrument settings, data locations, and analysis histories. Tabular and JavaScript Object Notation formats are used according to the metadata structure, with numerical values stored separately from units to facilitate machine processing. OMNES organizes these records based on causal relationships among experimental and analytical processes, linking samples, measurements, raw data, processed data, and analysis results through a relational data model and visualizing their relationships as a graph. This causality-based organization preserves experimental and analytical provenance and clarifies how each result was derived from the preceding processes and data. The accumulated spectra can subsequently be processed using ML methods, including dimensionality reduction and materials classification, and the resulting data can be registered back into OMNES. Previously reported ML analysis of BN XAS spectra is presented as an example of the analytical workflow that can be applied to data acquired at the beamline.
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All authors Yasunobu Ando, Masashige Miyamamoto, Keita Hiromori, Takeru Nakashima, Masafumi Horio, Masato Kotsugi, Iwao Matsuda

Instrumentation and Detectors

Autocorrelation-based beam shape optimization in scanning electron microscopy

Rebecca Guan, Andreas Werbrouck, Matthew M. Maschmann et al. (+1 more)

Many automatically focusing algorithms for scanning electron microscopes exist. Typically, these optimize a single derived metric (such as image sharpness) without considering the intrinsic beam shape. We describe an algorithm to automatically focus and stigmate scanning electron microscopes based on the autocorrelation of captured images. In the first part of this work, we develop the theoretical basis of using the autocorrelation to approximate the current beam shape. In the second part, we use this to condition the beam shape on various surfaces, using Bayesian optimization to tune both working distance and, in particular, stigmation. Through a comparison of the full width at half maximum of the autocorrelation arrays before and after optimization and a visual comparison of images taken of the sample surface before and after optimization, we show that the algorithm is able to successfully optimize the scanning parameters. Overall, our algorithm can effectively focus on a variety of topographies at different magnifications.
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All authors Rebecca Guan, Andreas Werbrouck, Matthew M. Maschmann, Matthias J Young

Instrumentation and Detectors

From Tunnel Overburden Reconstruction to Tidal Measurements via atmospheric muon

Jiwon Seo, Jongseok Chung, Chang Hyon Ha et al. (+8 more)

Muography with scintillator-based detectors enables the investigation of density distributions within large structures. The Hankuk Atmospheric-muon Wide Landscaping (HAWL) project is the first real-time portable muon tomography. It successfully charted the mountainous region of eastern Korea by measuring cosmic-ray muons with a detector operated in a moving vehicle. HAWL achieved a tunnel length accuracy of 6.0 % and an overburden measurement range of 8-400 meter-water-equivalent (m.w.e.). The HAWL upgrade (HAWLU) features a more compact design and enables trajectory reconstruction. Using this upgraded system, we measured tidal water-level variations with meter-scale precision over 31.6 days in the Boryeong Undersea Tunnel. The measured muon rate decreased by $1.72 \pm 0.04$ % per meter of increasing tidal level, while the reconstruction of undersea tunnel scan independently validated the detector performance. These results demonstrate the capabilities of dynamic muography in two approaches, one with a portable detector in motion and the other with a detector measuring a target that changes over time.
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All authors Jiwon Seo, Jongseok Chung, Chang Hyon Ha, TongZhou Huang, Jinyoung Kim, Sooa Kim, Hani Kimku, Byoung-cheol Koh, Minsu Kwak, Sihyun Lee, Yujin Lee

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

Data-Driven Variable-Exponent Analysis for Photoemission Yield Spectroscopy: An Autonomous Self-Diagnosing Framework Based on Integrated Residual Metrics

Shinjiro Yagyu, Takahiro Nagata and Yoshiyuki Nakajima

Photoemission yield spectroscopy (PYS) is widely used for evaluating the electronic states of materials. As automated materials discovery advances, unsupervised extraction of physical information from ambient-air PYS data becomes important. Conventional fixed-exponent analyses and logarithmic transformations suffer from heteroscedasticity, which destabilizes estimation in low-signal regions. To address this, we propose a data-driven analysis framework based on the 1/n-Scan method, which operates directly in the original signal space, removing the geometric bias inherent in log-transform approaches. We further integrate a self-diagnostic quality-evaluation system that quantifies estimation uncertainty with Akaike weights, together with independent residual metrics–the normalized mean absolute error (NMAE), the RMSE-to-MAE ratio (RMR), the Durbin-Watson (DW) statistic, and a macroscopic metric ($\Delta R^2$)–that distinguish hardware-related data degradation from a physical-model mismatch. Applying the framework to differently doped Si and a polycrystalline Au reference in air, we demonstrate autonomous detection, without assumptions on the emission mechanism, of the breakdown of the single-component approximation in heavily doped p-type Si, arising from the overlap of two emission components with different thresholds, as a statistical anomaly–a decrease in DW below its critical value with an auxiliary increase in $\Delta R^2$, despite sound NMAE and RMR–independently confirmed by a two-component fit ($\Delta$AIC $\approx$ 57, DW recovering from 0.8 to 2.0). For heavily doped n-type Si, the gradual surface evolution was classified as a change within the single-component description. This framework provides a robust, self-diagnosing analysis engine for closed-loop autonomous materials exploration.
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Instrumentation and Detectors

Enhanced micrometre spatial resolution and usable photon flux for hybrid pixel detectors via deep-learning-based X-ray localization

Xiangyu Xie, Anna Bergamaschi, Martin Brückner et al. (+30 more)

Micrometre spatial resolution is achieved for X-rays with the MÖNCH detector, a charge-integrating hybrid pixel detector with a 25 {\mu}m pixel pitch, by exploiting charge sharing between neighbouring pixels. The conventional analytical interpolation method, however, relies on a global mapping derived from the charge-sharing statistics and is applicable only to isolated single-photon clusters, which limits both the achievable resolution and the usable photon flux. To overcome these limitations, we trained deep learning models to localize single-photon and pile-up events based on high-fidelity simulation data. For knife-edge measurements at 12 keV and a low occupancy of 0.74% (photons per pixel and frame), where single-photon events dominate, the proposed method reaches a of the edge spread function of 1.36 {\mu}m, compared with 1.54 {\mu}m for the conventional eta interpolation. We demonstrate experimentally that resolving up to three photons per cluster raises the reconstruction efficiency from 59% to 93% at a 2.4{\times} higher occupancy of 1.81%, while preserving a of 1.39 {\mu}m.
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All authors Xiangyu Xie, Anna Bergamaschi, Martin Brückner, Maria Carulla, Tomáš Celko, Roberto Dinapoli, Simon Ebner, Simone Emiliani, Khalil Daniel Ferjaoui, Erik Lars Fröjdh, Viveka Gautam, Dominic Greiffenberg, Shqipe Hasanaj, Viktoria Hinger, Marius Hürst, Vadym Kedych, Thomas King, Shuqi Li, Carlos Lopez-Cuenca, Leonid Lunin, Federica Marone, Alice Francesca Mazzoleni, Davide Mezza, Scharon Moses, Konstantinos Moustakas, Aldo Mozzanica, Jonathan Franklin Mulvey, Martin Müller, Christian Ruder, Bernd Schmitt, Saverio Silletta, Dhanya Thattil, Jiaguo Zhang

Wednesday 7 October

Instrumentation and Detectors · Cross-listed from hep-ex

Short-Baseline Near Detector (SBND): Design and Initial Performance

SBND Collaboration: P. Abratenko, R. Acciarri, C. Adams et al. (+351 more)

The Short-Baseline Near Detector (SBND) is a 112 tonne active mass liquid argon time projection chamber (LArTPC) situated in the Booster Neutrino Beam at Fermilab, forming part of the Short-Baseline Neutrino (SBN) Program. SBND began operation in 2024 and has since accumulated the world's largest sample of neutrino-argon interactions. This paper describes the as-built detector and presents performance results from the first year of beam operation. All detector systems performed at or above design requirements. The liquid argon purity achieved an electron lifetime exceeding 30ms, ten times the design requirement, for more than 95% of Run 1. The TPC wire plane readout achieved noise levels at the theoretical minimum for the given wire geometry (an average of 388e$^-$ for the 4m long collection plane wires) with 99.3% of readout channels live. Together, the liquid argon purity and TPC performance are enabling extremely clean event reconstruction in the SBND TPC. The photon detection system, consisting of passive reflectors and multiple active components (PMTs and X-ARAPUCAs), has achieved a light yield exceeding 10 photoelectrons per MeV throughout the detector volume and a timing resolution of a few nanoseconds, sufficient to resolve the 19ns bunch structure of the Booster Neutrino Beam. A nearly 4$\pi$ cosmic ray tagger system surrounds the TPC to mitigate cosmic backgrounds in neutrino and BSM physics analyses. The data acquisition system has demonstrated stable performance up to an event rate of 8Hz, and a data collection efficiency of 98.6% was achieved throughout SBND's first neutrino run in 2025. These results demonstrate that SBND represents the state of the art in multi-tonne-scale LArTPC detector performance.
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All authors SBND Collaboration: P. Abratenko, R. Acciarri, C. Adams, T. Alafaro, L. Aliaga-Soplin, R. Alvarez-Garrote, J. Ameel, D. Andrade Aldana, C. Andreopoulos, A. Antonakis, L. Arellano, J. Asaadi, W. Badgett, L. Bagby, S. Balasubramanian, D. Barker, A. Barnard, C. Barnes, N. Barros, A. Basharina-Freshville, V. Basque, J.R. Bateman, M.C. Bazetto, A. Beever, B. Behera, E. Belchior, O. Beltramello, M. Betancourt, A. Bhat, K. Biery, M. Bishai, A. Bitadze, A. Blake, B. Bogart, J. Boissevain, C. Bonifazi, J. Book Motzkin, G. Botogoske, D. Brailsford, A. Brandt, J. Bremer, S. Brickner, T. Brooks, M.B. Brunetti, G. Buccino, A. Bullock, G.A.N. Buzzard, L. Camilleri, D. Caratelli, D. Carber, B. Carlson, M.F. Carneiro, M. Cascella, R. Castillo Fernandez, F. Cavanna, M. Chalifour, P. Chambouvet, A. Chan, A. Chappell, H. Chen, S. Chung, D. Cianci, M.F. Cicala, R. Coackley, L. Cooper-Troendle, J.I. Crespo-Anadon, E. Cristaldo, C. Cuesta, Y. Dabburi, O. Dalager, M. Dall'Olio, R. Darby, I. de Icaza Astiz, M. Del Tutto, S. Dennis, V. Di Benedetto, S. Dixon, M. Donnachie, Z. Djurcic, V. do Lago Pimentel, S. Dominguez-Vidales, R. Doubnik, M. Dubnowski, K. Duffy, S. Dytman, A. Elvin, A. Ereditato, E. Espinoza, J. Estrada, J.J. Evans, A.C. Ezeribe, C. Fan, J. Farrell, A. Filkins, B. Fleming, W. Foreman, D. Franco, H. Frandini, J. Freestone, G. Fricano, J. Fried, D. Friend, I. Furic, A.P. Furmanski, T. Gamble, S. Gao, D. Garcia-Gamez, S. Gardiner, G. Ge, M. Geynisman, I. Gil-Botella, S. Gollapinni, M. Goodman, O. Goodwin, P. Green, H. Greenlee, W.C. Griffith, R. Guenette, P. Guzowski, L. Hagaman, T. Ham, A. Hamer, P. Hamilton, R. Hanni, K. Hardin, B. Harris, S. Hentschel, A. Hergenhan, M. Hernandez-Morquecho, C. Hilgenberg, C. Hill, A. Hoffman, P. Holanda, A. Holin, B. Howard, B. Howe, J. Howell, J. Hrivnak, C. James, C. James, T. Johnson, R.S. Jones, M. Jung, T. Junk, Y.-J. Jwa, D. Kalra, G. Karagiorgi, L. Kashur, K.J. Kelly, W. Ketchum, M.J. Kim, M. King, J. Klein, L. Kotsiopoulou, S. Kr Das, I. Kreslo, T. Kroupova, S. Kubecki, V.A. Kudryavtsev, F. Kumar, M. Langstaff, J. Larkin, K. Laureto, H. Lay, R. LaZur, G. Leigh, I. Lepetic, J.-Y. Li, K. Lin, B.R. Littlejohn, F. Liu, L. Liu, S. Lockwitz, D. Lorca, W.C. Louis, G. Lukhanin, X. Luo, A.A. Machado, P. Machado, G. Mahler, S. Manohari Kancharla, S. Marcocci, C. Mariani, F. Marinho, J. Marshall, L. Martinez, C. Martin-Morales, A. Mastbaum, K. Mavrokoridis, N. McConkey, B. McCusker, J. Mclaughlin, V. Meddage, D. Mendez, I. Mercer, T. Mettler, T. Miao, M. Micheli, G. Miller, D. Mishins, K. Mistry, D. Mladenov, A. Mogan, J. Molina, D. Montanari, M. Mooney, A.F. Moor, G. Moreno-Granados, F. Morgadinho-Inacio, C.A. Moura, J. Mousseau, J. Mueller, S. Mulleriababu, J. Najdzion, R. Natieli de Oliveira, A. Navrer-Agasson, M. Nebot-Guinot, M. Nessi, V.C.L. Nguyen, S. Ni, T. Nichols, F. Nicolas-Arnaldos, B. Norris, R. Northrop, J. Nowak, S.B. Oh, O. Olorife, N. Oza, L. Pagliuso, O. Palamara, N. Pallat, V. Pandey, A. Papadopoulou, H.B. Parkinson, J. Pater, J. Paton, L. Paulucci, Z. Pavlovic, D. Payne, L. Pelegrina-Gutierrez, O.L.G. Peres, R. Pfaff, F. Pietropaolo, J. Plows, J. Poirot, I.D. Ponce Pinto, A. Popov, F. Psihas, D. Pushka, G. Putnam, X. Qian, Y. Qie, V. Radeka, E. Raguzin, R. Rajagopalan, P. Ratoff, H. Ray, B. Rebel, R. Rechenmacher, M. Reggiani-Guzzo, F. Resnati, D. Rivera, A. Roberts, M. Roda, O. Rodrigues, J. Romeo-Araujo, M. Ross-Lonergan, N. Rowe, P. Roy, M. Rumore, A. Sanchez-Castillo, P. Sanchez-Lucas, G. Savage, G. Scanavini, A. Scarff, A. Scherf, D.W. Schmitz, A. Schneider, A. Schukraft, F. Schwartz, W. Scofield, H. Scott, E. Segreto, Z. Semovski, J. Sensenig, M. Shaevitz, R. Sharankova, S. Shetty, K. Shiba, P. Singh, B. Slater, J. Smith, M. Soares-Nunes, M. Soderberg, S. Soldner-Rembold, F. Spagliardi, M. Spanu, J. Spitz, N. Spooner, M. Stancari, A. Stefanik, G.V. Stenico, T. Strauss, P. Sutcliffe, K. Sutton, A.M. Szelc, W. Tang, C. Thorn, C. Thorpe, J. Tillman, A. Timilsina, D. Torretta, D. Totani, M. Toups, C. Touramanis, M. Tripathi, S. Tufanli, L. Tung, E. Tyley, S. Unnikrishnan G.A. Valdiviesso, R. Van de Water, A. Vazquez-Ramos, A. Verdugo de Osa, B. Villa Ferre, L. Wan, M. Weber, H. Wei, Z. West, T. Wester, A.J. White, A. Wilkinson, P. Wilson, T. Wongjirad, E. Worcester, M. Worcester, M. Wright, W. Wu, S. Yadav, E. Yandel, T. Yang, G. Yarbrough, L. Yates, S. Yebes, J. Yu, B. Yu, H. Yu, V. Zamazal, B. Zamorano, A. Zeglam, J. Zennamo, J. Zhang, C. Zhang, M. Zhao, M. Zuckerbrot

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

Microwave Loss in Low-Temperature ICPCVD Silicon Nitride: Dependence on Precursor Ratio and RF Substrate Bias

H. Athreya, J. Cornelison, M. Mikhailov et al. (+5 more)

Low-loss dielectric films are an important component of superconducting circuits with applications ranging from quantum information to superconducting detectors for astrophysics. In millimeter-wave detector circuits, dielectric loss can be the limiting factor on efficiency and resonator performance. Some advantageous detector fabrication architectures require dielectric deposition at temperatures substantially lower than those conventionally used to achieve low dielectric loss. In this work, we characterize silicon nitride (SiN$_x$) films deposited by inductively coupled plasma chemical vapor deposition (ICPCVD) at $150\,^{\circ}\mathrm{C}$ for use in temperature-constrained superconducting detector fabrication. We measure the dielectric loss tangent of these films at $\sim 4-7$ GHz using superconducting niobium microstrip resonators and extract the loss by fitting the temperature-dependent resonant frequency to a two-level-system model. We vary the N$_2$/SiH$_4$ precursor-flow ratio between dielectric depositions and find a clear trend of decreasing loss with decreasing N$_2$/SiH$_4$. We additionally find that applying an RF substrate bias during deposition reduces the loss compared to films deposited without bias. These results identify precursor ratio and substrate bias as practical process parameters for improving low-temperature SiN$_x$ for superconducting detector circuits.
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All authors H. Athreya, J. Cornelison, M. Mikhailov, R.J.H. van der Kolk, C. Chang, T. Cecil, M. N. Ali, J. A. Zebrowski

Instrumentation and Detectors

Neural network-based timewalk correction for the Timepix4 ASIC

David Bacher, Kazu Akiba, Martin van Beuzekom et al. (+7 more)

Timewalk corrections of hybrid pixel detectors conventionally employ heuristic fits performed independently in bins of the relevant input variables. This requires both an explicit functional ansatz and binning scheme, as well as densely populated calibration data whose required size grows rapidly as further input variables are added. This paper presents a timewalk correction for the Timepix4 readout chip based on a compact feed-forward neural network (NN), which learns the dependence directly from the input variables without requiring an explicit functional ansatz or binning. The NN is compared against the fit-based baseline using data from the Timepix4 beam telescope at the CERN SPS in 2025, with $100\,\mathrm{\mu m}$ and $300\,\mathrm{\mu m}$ thick planar sensors. Both methods parameterise the timewalk correction as a function of the measured charge and reconstructed intrapixel impact position. With only 20 % of the calibration data, the NN already achieves the same asymptotic time resolutions as the fit-based baseline: $180\,\mathrm{ps}$ and $300\,\mathrm{ps}$ for the two thicknesses, respectively.
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All authors David Bacher, Kazu Akiba, Martin van Beuzekom, Victor Coco, Raphael Dumps, Tim Evans, Kevin Heijhoff, Malcolm John, Edgar Lemos Cid, Tommaso Pajero

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

Prediction of the thermal neutron response of grain-boundary impedance in Gd-doped ceria based on the radiation-ionic effect

Zhongming Zhang

The radiation-ionic effect was recently reported in 3 mol% Gd-doped CeO$_2$ (3GDC): under $^{60}$Co gamma irradiation at 35 Gy/min, the grain-boundary (GB) ionic resistance of a bulk pellet decreased 680-fold at room temperature, because electrons trapped at the GB core lower the space-charge potential. The effect has been demonstrated only with photons. Gd has the largest thermal-neutron capture cross section of any stable element and is also the dopant that creates the GB barrier in GDC, so the same mechanism could link GB impedance to thermal-neutron sensing; whether it does, and under what conditions, has not been examined. Here the thermal-neutron response of 3GDC is modelled with the gamma-calibrated Mott-Schottky/Seager framework, with unmeasured parameters carried as intervals and propagated jointly. Each capture deposits about 50 keV by conversion and Auger electrons within 1 $\mu$m, the remaining 8 MeV leaving as prompt photons; Gd segregation to the GBs adds a factor of only 1-2 because the electron range exceeds the grain size. A thermal flux of $8\times10^{9}$ cm$^{-2}$s$^{-1}$ (6-12$\times10^{9}$) matches the GB-effective generation rate of the 35 Gy/min calibration, and the predicted room-temperature GB resistance ratio is 110 (70-170) at $10^{9}$ and 970 (600-1500) at $10^{10}$ cm$^{-2}$s$^{-1}$, falling to 2 at 61 (55-68) and 81 (73-92) $^\circ$C. The neutron case differs from gamma irradiation in three respects: capture events are discrete, so the continuous-source approximation depends on the unmeasured trapped-charge lifetime; self-shielding (mean free path 0.27 mm) makes the response thickness dependent; and capture photons absorbed in the pellet add a gamma term comparable to the local term for pellets of 0.3 mm or more. The intervals are conditional on the model and exclude its structural error. The conditions under which the prediction can be tested are given.
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Instrumentation and Detectors

Wavelength-Resolved Timing of Near-Infrared Scintillation in Gaseous Xenon

Robert Hammann, Steffen Form, Humaira Nazneen et al. (+3 more)

The near-infrared (NIR) scintillation signal of xenon has the potential to enhance the performance of xenon-based detectors, but a robust understanding of its properties is a prerequisite for its application. In this work, we measure the NIR time response for $\alpha$-particle interactions in gaseous xenon in 12 wavelength bands spanning approximately $(950-1620)\,$nm. The time response is decomposed into a fast (ns-scale) component and a dominant slow ($\mu$s-scale) component. The fast-component spectrum coincides with strong atomic emission lines, predominantly 6p$\,\to\,$6s, whereas the slow-component spectrum follows the broad continuum centred around $1.3\,\mu$m. The pressure dependence of the continuum can be described by a two-step kinetic model in which the emitting state is formed by a three-body process and depopulated by a two-body collisional process, with density-independent terms in both rates. Interpreting the slower of these as radiative decay yields an intrinsic lifetime of $\sim3\,\mu$s. Theoretical calculations identify a neutral-excimer transition $0_u^- \rightarrow 0_g^-$ and an ionic-dimer transition $1/2_{u} \rightarrow 1/2_g$ as plausible candidates for the continuum emission, with the ionic-dimer transition showing better overall agreement with the measurements.
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All authors Robert Hammann, Steffen Form, Humaira Nazneen, Gabriel Schöpfer, Milan Ončák, Teresa Marrodán Undagoitia

Instrumentation and Detectors

Timing Challenges in Transmission Silicon Detectors for Light Ions

Diego Tarrio, Friedrich Karl Moraht, Lucas de Arruda et al. (+3 more)

Transmission silicon detectors are widely used in $\Delta E$–$E$ telescope configurations for particle identification and timing in nuclear physics experiments. Variations in signal rise time can introduce time-walk effects that degrade time-of-flight measurements, as recently observed in light-ion production experiments at the Neutrons For Science (NFS) facility at GANIL using the Medley setup. This work investigates the influence of particle energy and detector non-uniformity on signal rise time.
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All authors Diego Tarrio, Friedrich Karl Moraht, Lucas de Arruda, Stephan Pomp, Xavier Ledoux, Diego Ramos

Instrumentation and Detectors · Cross-listed from cond-mat.str-el

Polarized neutron diffraction with ex-situ $^3$He neutron spin filter and two-dimensional detector for noncollinear incommensurate magnetic order

Shingo Takahashi, Yuta Osawa, Ryuju Kobayashi et al. (+11 more)

Polarized neutron scattering has been widely used for studying magnetic orders in condensed matter. A typical setup for this technique is a triple-axis spectrometer with a ferromagnetic single-crystal monochromator and analyzer, which is suited for point-by-point measurements within the horizontal scattering plane. However, this setup cannot fully meet the demands of recent studies on complex magnetic orders with emergent cross-correlated phenomena. For instance, multiferroics, magnetic skyrmions, and other topologically nontrivial magnetic orders tend to have incommensurate magnetic modulation vectors running along various directions in reciprocal space, which cannot be captured by measurements restricted to the horizontal scattering plane. To overcome these limitations, we have developed an experimental setup combining a $^3$He neutron spin filter ($^3$He-NSF) and a two-dimensional (2D) detector, which enables us to analyze the polarization of neutrons scattered away from the horizontal plane. We also establish a data reduction procedure to convert the 2D intensity maps into three-dimensional intensity distributions in reciprocal space, correcting for the effect of imperfect $^3$He polarization. This method is applied to single-crystal diffraction measurements on the multiferroic material Mn$_3$WO$_6$, which exhibits complex incommensurate magnetic orders. We have successfully observed polarization-dependent intensities of out-of-plane incommensurate magnetic reflections, demonstrating the effectiveness of the present method for analyzing complex magnetic structures.
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All authors Shingo Takahashi, Yuta Osawa, Ryuju Kobayashi, Takashi Ino, Hiraku Saito, Takuro Kawasaki, Takayuki Oku, Tatsuya Nakamura, Yoichi Ikeda, Masaki Fujita, Daisuke Koto, Yusuke Tokunaga, Taka-hisa Arima, Taro Nakajima

Tuesday 6 October

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

Low-Cost Spectrophotometers: A Comparative Evaluation of Open-Source Architectures

Alex M. Rivera-Rivera, Daniela Martinez-Ortiz, François Quitin et al. (+4 more)

The rapid growth of low-cost and open-source spectrophotometers has created a need for systematic methodologies to evaluate and compare alternative instrument architectures. This study presents a comparative assessment of three representative open-source spectrophotometric platforms, encompassing discrete multispectral sensing and continuous-spectrum imaging approaches. Their performance was evaluated against a commercial Thermo Scientific Genesys 30 spectrophotometer in terms of spectral agreement, portability, implementation complexity, and cost. The results demonstrate that no single architecture is universally optimal; instead, each presents distinct trade-offs that determine its suitability for specific applications. Multispectral sensor-based systems offer compact, low-power solutions for field deployment, whereas imaging-based platforms provide spectral performance closer to laboratory-grade instrumentation. All hardware designs, firmware, and software developed in this work are released as open-source resources to support reproducibility and further development. The study highlights the importance of matching instrument architecture to application requirements and proposes a practical framework for the evaluation and selection of low-cost spectrophotometers, facilitating the adoption of open-source analytical tools for water quality monitoring and related applications.
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All authors Alex M. Rivera-Rivera, Daniela Martinez-Ortiz, François Quitin, Denis Terwagne, Stamatios C. Nicolis, Ernesto Altshuler, Alexandre Campo

Instrumentation and Detectors

A Differentiable Surrogate for Loss-Dominated Ion Beam Transport

Jose M. Munoz-Arias, Laura Ruiz-Arango, Derick Gonzalez-Acevedo et al. (+3 more)

Radioactive nuclei with extreme proton-to-neutron ratios provide unique probes of nuclear structure, fundamental symmetries, astrophysical processes, and applications such as medicine. However, their short half-lives and low production rates mean that experiments must work with few desired ions, often amid contaminant backgrounds exceeding the signal by six orders of magnitude. Efficiently isolating, transporting, and delivering these ions through multi-stage apparatus is therefore a central challenge. We introduce a differentiable probabilistic surrogate for ion-beam transport in regimes dominated by particle loss. The model jointly captures the survival probability of ions along the beamline and the evolving phase-space distribution of the surviving particles by combining discrete-time survival analysis with conditional normalizing flows. Applied to a high-dimensional electrostatic beamline, the resulting likelihood enables gradient-based optimization of operating voltages and inference of beam properties from sparse detector observations. Once trained, the surrogate provides millisecond-scale differentiable predictions, transforming particle-tracking simulations with hard losses into an inference-ready model for experimental design, beamline optimization, and future digital twins of experiments with rare nuclei.
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All authors Jose M. Munoz-Arias, Laura Ruiz-Arango, Derick Gonzalez-Acevedo, Fabian C. Pastrana-Cruz, Jackson Hacias, Ronald F. Garcia Ruiz

Instrumentation and Detectors

Omnidirectional Radiation Detector with Perpendicular Dual Silicon Photomultiplier Readout - Directional Sensitivity and Machine Learning Source Positioning

Ana Marija Kožuljević, Gabriela Jazvac, Luka Lotina et al. (+1 more)

Directional information of incident gamma rays in radiation detection is essential to many applications, from medical imaging to mapping radioactive contamination after nuclear accidents, characterization of nuclear waste during decommissioning, and nuclear security. In this work, we present a radiation detector capable of detecting gamma-ray photons in 4$\pi$, utilizing Gadolinium Aluminum Gallium Garnet (GAGG) scintillating crystals and silicon photomultipliers (SiPMs). The GAGG crystals are assembled in a cubical 4$\times$4$\times$4 matrix, and their light output is read out by SiPMs from two neighboring sides. The size of each crystal is 3$\times$3$\times$3 mm$^3$, while the matrix pitch is 3.2 mm, matching the size and the pitch of the 4$\times$4 SiPMs for one-to-one coupling. The layers perpendicular to the SiPMs are separated by optical reflectors, providing efficient light collection while lowering the probability of inter-crystal leakage. The design of the radiation detector offers high detection efficiency and full-view imaging of gamma-ray sources through Compton scattering. Monte Carlo simulations were performed in Geant4 to evaluate the detection efficiency of the proposed design due to its geometrical non-uniformity. Machine learning models developed with the XGBoost algorithm were trained and tested on the simulated data to assess the capability of the detector to localize point sources of 511, 662, and 1275 keV energies. We find that the proposed design does not influence the collection efficiency of the high-energy gamma-ray photons and offers sensitivity to the direction of the incoming gamma rays. The trained models are capable of determining the source-to-detector distance of the Na-22 and Cs-137 point sources from measurements, thus providing initial conditions for faster image reconstruction.
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All authors Ana Marija Kožuljević, Gabriela Jazvac, Luka Lotina, Luka Pavelić

Instrumentation and Detectors

GEANT4-Based Comparative Study of Detector Response in Reduced and Fully Instrumented Silicon-Tungsten Sampling Calorimeter

A. Laha, S. Choudhury, S. Muhuri et al. (+1 more)

{A GEANT4-based simulation study of a silicon–tungsten (Si–W) sampling calorimeter is presented to investigate electromagnetic shower development and detector response in the energy range of 1–120 GeV. Two detector configurations are considered: a reduced sequential-sampling prototype (Configuration-I), where a single silicon detector layer is placed downstream of progressively increasing tungsten absorber depths to sample the longitudinal shower evolution, and a fully instrumented sampling calorimeter (Configuration-II) consisting of twenty silicon layers interleaved with tungsten absorbers. The detector response is studied in terms of longitudinal shower development, shower maximum position, energy deposition, detector linearity, and calorimetric performance. Configuration-II provides simultaneous longitudinal sampling and allows event-by-event reconstruction of the deposited energy, yielding the expected linear response and energy resolution. Configuration-I reproduces the average longitudinal shower profiles and exhibits a strong linear correlation with the integrated shower response of Configuration-II. Although the absence of event-by-event multi-layer sampling prevents a direct determination of calorimetric energy resolution in Configuration-I, the observed correlation between two configurations is used to relate the response of the reduced prototype to that of the fully instrumented calorimeter and to estimate the corresponding calorimetric performance. The results demonstrate that the reduced prototype successfully reproduces the main characteristics of electromagnetic shower development observed in the fully instrumented detector, establishing its usefulness for detector characterization and test-beam studies when the construction of a complete prototype is limited by available resources.
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All authors A. Laha, S. Choudhury, S. Muhuri, M. Mondal

Monday 5 October

Instrumentation and Detectors

The CosmicWatch Desktop Muon Detector (v3X): Prototype Design and Adaptation for Spaceflight

Anvay Ajmera and Spencer N. G. Axani

The CosmicWatch Desktop Muon Detector (v3X) is a compact and low-cost scintillator-based instrument designed to detect ionizing radiation, including cosmic-ray muons. Built around a plastic scintillator, a silicon photomultiplier (SiPM), and a dual-core Raspberry Pi Pico microcontroller, the v3X achieves a 400 microsecond dead time per event, sustained event logging at 700 Hz, and two-detector coincidence triggering for more accurate counts. This paper first summarizes the design, firmware, and demonstrated performance of the v3X prototype. It then outlines the design changes needed to prepare the detector for operation aboard a satellite, including a passive copper thermal strap that conducts heat from the microcontroller to the spacecraft chassis, a dedicated flight enclosure, material changes to meet outgassing standards, and a Controller Area Network (CAN) bus interface to connect the detector to the host spacecraft. The flight unit is targeted for launch via Oligo Space.
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Instrumentation and Detectors

Polyurethane Scintillators for High-Energy Physics Detectors: Optimization, Scale-up, and Radiation Response

Rafael Angel Narcio Laveaga, Ildefonso León Monzón, Juan Carlos Cabanillas Noris et al. (+8 more)

Plastic scintillators remain attractive for large-area particle detectors because of their fast response, mechanical flexibility, and relatively simple fabrication. Motivated by future applications including the ALICE~3 Muon Identifier (MID) and the upgrade of the ALICE Fast Interaction Trigger (FIT), this work investigates polyurethane (PU)-based plastic scintillators doped with 2,5-diphenyloxazole (PPO) and 1,4-bis(5-phenyloxazol-2-yl)benzene (POPOP). Systematic information on the optimization and radiation response of this material system remains limited. A series of compositions was therefore fabricated and characterized using minimum-ionizing particles (MIP), optical spectroscopy, and time-correlated single-photon counting. The measurements show that the scintillation response is governed primarily by the PPO concentration, while POPOP mainly modifies the spectral response, and fast effective decay times of approximately 1.6–1.75~ns are maintained across the doped samples. The best-performing formulation was subsequently scaled to 20-$cm$ and 1-m scintillator bars and successfully operated with a single embedded wavelength-shifting fiber and SiPM readout, demonstrating its suitability for meter-scale light collection. Proton-irradiation measurements at the CERN IRRAD facility further revealed systematic degradation of the optical and scintillation responses with increasing exposure, together with substantial recovery after approximately two months. These results demonstrate that optimized PU–PPO–POPOP scintillators can combine fast timing, high light output, scalable detector geometry, and recoverable radiation response, supporting their further development for future large-area particle-detector systems.
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All authors Rafael Angel Narcio Laveaga, Ildefonso León Monzón, Juan Carlos Cabanillas Noris, Thanh Luan Nguyen, Jan Král, Vítezslav Jarýd, Gerardo Herrera Corral, Vojtech Zabloudil, Etiennette Auffray, Carlos Duarte Galván, Solangel Rojas Torres

Instrumentation and Detectors · Cross-listed from hep-ex

FPGA-based muon shower identification and graph neural network tracking algorithms for HL-LHC triggers

Daniel Estrada, Elena Aller, Andrea Cardini et al. (+3 more)

This work presents two hardware-accelerated strategies for the upgrade of the CMS Level-1 Trigger (L1T) to target efficiency losses due to highly energetic radiating muons and unconventional physics signatures, such as Long-Lived Particles (LLPs). Operating directly on low-level detector hits, the first strategy implements a dedicated muon shower identification algorithm in the CMS barrel region that monitors hit multiplicities in the Drift Tube chambers to generate Shower Primitives. Executing with sub-bunch-crossing latency and ultra-low resource consumption, this algorithm successfully tags showered muons and provides essential context for downstream track finders. The second approach targets the barrel-endcap transition (overlap) region by evaluating Graph Neural Networks to reconstruct displaced muon tracks. Following a divided methodology that first isolates hardware feasibility from evolving physics refinements, an initial proxy model based on a GraphSAGE architecture is evaluated to validate its viability on FPGAs within strict latency limits. This implementation utilizes an INT8-PO2 quantization technique coupled with a data-driven bit-width optimization. By replacing DSP-heavy fixed-point multiplications with fast compile-time arithmetic bit-shifts and allocating the minimum required bits per signal, this hardware-software co-design reduces DSP utilization to $20\%$ and achieves a deterministic inference latency of just $19$ clock cycles. Together, these developments pave the way for triggering on non-standard muon signatures, such as those from LLP decays, at L1T.
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All authors Daniel Estrada, Elena Aller, Andrea Cardini, Santiago Folgueras, Pelayo Leguina, Javier Prado

Instrumentation and Detectors

Expanding Neutron Capacity at the ESS through Symbiotic Instruments: SLEIPNIR & Remora

Nicolai Lindaa Amin, Mohamed Aouane, Peter Kjær Willendrup et al. (+6 more)

The long pulse of the European Spallation Source (ESS) offers unique opportunities to host more than one neutron instrument on a single beam-port. Here, we present two symbiotic instrument concepts designed for previously unexploited neutrons, without imposing significant perturbation on existing or planned beamlines. The first concept employs a doubly focusing dual-monochromator system to vertically translate the neutron beam, enabling compact instruments to be stacked within spatially constrained beam ports inaccessible to conventional instruments. The second extracts excess spectral bandwidth from an existing guide via Bragg reflection upstream of the flagship instrument's chopper system, feeding a second instrument. Both concepts are optimized using gradient-descent Monte Carlo ray-tracing simulations in McStas and benchmarked against existing productive instruments at other sources. Despite operating under significant geometric and flux constraints, the resulting instruments demonstrate performance comparable to well-established reference instruments at the ILL. The two concepts together illustrate a modular and cost-effective route to expanding ESS scientific capacity, using the facility's resources that would otherwise go unused.
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All authors Nicolai Lindaa Amin, Mohamed Aouane, Peter Kjær Willendrup, Jörg Voigt, Gregory S. Tucker, Robert Georgii, Ellen Fogh, Niels Bech Christensen, Rasmus Toft-Petersen

Instrumentation and Detectors

Investigating Optical Coupling Material Candidates in NaI(Tl) Detectors for the SABRE-North Dark Matter Experiment

Chemseddine Ananna, Gabriella Cataldi, Davide D'Angelo et al. (+21 more)

Direct dark matter detection with NaI(Tl) scintillators requires ultra-low-background materials. Silicone optical pads can couple NaI(Tl) crystals to photomultiplier tubes (PMTs) if they provide adequate optical transmission and radiopurity. We characterize four candidate materials for the SABRE-North experiment: commercial EJ-560, used as a reference, and three materials produced at the University of Salento (SYLGARD 184, EGel 3002 A/B, and a hybrid formulation) using different catalyst ratios and curing conditions, yielding ten samples in total. Optical transmittance was measured from 310 to 850 nm by UV/Vis/NIR spectrophotometry. Radiopurity was assessed at the STELLA facility at LNGS using high-purity germanium (HPGe) $\gamma$-ray spectrometry and, for EJ-560, high-resolution ICP-MS. At the 410 nm NaI(Tl) emission peak, EJ-560 shows an absorbance coefficient of $0.064\pm0.017$ mm$^{-1}$. The best locally produced samples reach $0.097\pm0.015$ and $0.093\pm0.014$ mm$^{-1}$ for SYLGARD 184 with a 10:2 base-to-catalyst ratio cured at room temperature and at $40^\circ$C, respectively, $0.125\pm0.015$ mm$^{-1}$ for EGel 3002 with a 2B:A ratio cured at $40^\circ$C, and $0.106\pm0.014$ mm$^{-1}$ for the hybrid 10:1 EGel A:CataSYL formulation cured at room temperature. EJ-560 exhibits detectable $^{232}$Th-chain activity at about 1.8 mBq/kg and the highest $^{40}$K activity, $(120\pm20)$ mBq/kg. The locally produced materials show no detectable Th-chain contamination but exhibit $^{226}$Ra activities of about 2.3 mBq/kg and lower $^{40}$K levels. No single material is optimal across all criteria. Additional ICP-MS screening, HPGe measurements of cured pads, and direct NaI(Tl)-PMT light-yield tests are required for a conclusive SABRE-North material selection.
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All authors Chemseddine Ananna, Gabriella Cataldi, Davide D'Angelo, Giulia D'Imperio, Maria Luisa De Giorgi, Giuseppe Di Carlo, Attilio Di Giacinto, Marcella Diemoz, Aldo Ianni, Sana Gul Khattak, Edoardo Martinenghi, Alessandro Miccoli, Marcin Misiaszek, Daniele Montanino, Valerio Pettinacci, Lidio Pietrofaccia, Shahram Rahatlou, Krzysztof Szczepaniec, Claudia Tomei, Valerio Toso, Chiara Vignoli, Samina Zuhra, Francesco Ferella, Stefano Nisi

Sunday 4 October

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

MRI-Free CT-to-Ultrasound Skull Registration in Transcranial Focused Ultrasound using CMUT based Integrated Therapeutic and Imaging Arrays

Reza Pakdaman Zangabad, Sai Vikas Satyanarayana, Costas D. Arvanitis et al. (+1 more)

Accurate skull-to-array registration is essential for transcranial focused ultrasound (tFUS) because CT-derived skull models must be aligned with the physical-array coordinate system to support patient-specific aberration correction. Current workflows typically use MRI and/or external tracking to establish this spatial relationship, adding imaging infrastructure and coordinate transformations to the treatment workflow. Here, we describe an MRI-free CT-to-ultrasound registration framework using a hybrid hemispherical CMUT tFUS array that combines a sparse therapeutic array with an integrated CMUT US-Cross imaging array. The therapeutic array provides pulse-echo measurements of skull location, while the US-Cross array provides local high-resolution images of the skull surface. The approach was evaluated using a CT-derived outer cortical skull surface across a 25-pose matrix with 10-mm lateral offsets between the skull and array centers and +/-5 degree angular perturbations. Five randomized radial-noise seeds were applied to therapeutic pulse-echo measurements to model measurement or element-placement errors, yielding 125 pose-seed realizations per noise and active-element setting. US-Cross imaging features were generated using Field II and delay-multiply-and-sum plane-wave compounding. Four registration modes were evaluated: Therapeutic only, US-imaging only, Sequential, and Fused registration. Fused registration yielded the best overall performance, with a median total displacement error of 0.271 mm [0.169-0.420] and a median rotation error of 0.904 degrees [0.432-1.639]. These results support an all-ultrasound-based approach using a hybrid CMUT tFUS array for MRI-free CT-US skull registration.
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All authors Reza Pakdaman Zangabad, Sai Vikas Satyanarayana, Costas D. Arvanitis, F. Levent Degertekin

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

A cryogenic apparatus with a rotatable substrate for matrix isolation spectroscopy of BaF in neon crystals down to 3.2 K

Alessandro Lippi, Diego Bisero, Caterina Braggio et al. (+7 more)

We present a new experimental apparatus for matrix isolation spectroscopy capable of growing cryogenic crystal matrices doped with barium monofluoride (BaF), a candidate for measurements of the electron electric dipole moment (eEDM). \\ In this work, BaF molecules are produced in a cryogenic buffer-gas source and used to dope a neon matrix grown on a substrate, cooled by a cryocooler, reaching temperatures as low as 3.2 K. A rotatable flange allows for multiple substrate orientations, optimizing spectroscopic investigations and matrix crystal growth. \\ Fluorescence emission analysis of BaF in neon crystal show emission when exciting the $A\,^2\Pi_{1/2}$, $A\,^2\Pi_{3/2}$ and $B\,^2\Sigma^+$ states, along with the presence of fluorescence from barium atoms in the crystal. A first estimation of the column density of BaF in the crystal is given on the order of $5 \times 10^{-13} \, \text{cm}^{-2}$. \\ We also demonstrated the production of BaF using parahydrogen as the buffer gas of the cryogenic source, a first step toward BaF molecules embedded in a para-hydrogen matrix. \\ Finally, we also observed fast fluorescence decay, attributed to optical bleaching effects, whose amplitude arise at lower temperatures or higher laser intensities, introducing a systematic effect to be studied in future experiments.
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All authors Alessandro Lippi, Diego Bisero, Caterina Braggio, Giovanni Carugno, Roberto Calabrese, Federico Chiossi, Marco Guarise, Madiha M. Makhdoom, Giuseppe Messineo, Jacopo Pazzini

Instrumentation and Detectors

A Cryogenic Geophone with stable response from Room Temperature to millikelvin

Stefano Pirro, Marco Ricci and Simone Cioccolini

With the development of pulse-tube cryocoolers, the availability and use of low-temperature environments have increased exponentially in recent years. However, replacing liquid helium with a mechanical cooling device has, since its introduction, highlighted the need to attenuate the mechanical vibrations generated by the cryocooler itself. In the case of dilution refrigerators, which are capable of reaching temperatures on the order of few mK, the issue of mechanical vibrations reaching the experimental setup is, in many situations, extremely critical. This has led to the development of several customized experimental approaches aimed at attenuating vibrations. However, the inertial measurement of vibrations at cryogenic and, in particular, ultracryogenic temperatures has relied on customized sensors, since no commercially available, calibrated instruments exist for measurements at these temperatures. Nevertheless, many research groups employ commercial geophones that are recalibrated at low temperatures. This approach, however, is not free from systematic errors and presents significant challenges in quantitatively assessing the absolute response. In this work, we describe the development of cryogenic geophones exhibiting an almost temperature-independent response, from room temperature down to approximately 10 mK.
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Saturday 3 October

Instrumentation and Detectors · Cross-listed from gr-qc

Covariance scaling and a dual-mode torque diagnostic in measurements of the gravitational constant

Vineet Kumar

Laboratory determinations of the Newtonian gravitational constant $G$ disagree by more than their quoted uncertainties allow. We examine the sixteen determinations comprising the CODATA-2018 archive using a proportional covariance-scale model that retains the full reported covariance matrix. Because the 2026 NIST torsion-balance redetermination shares apparatus lineage with the BIPM Mark II balance, our primary historical fit excludes the BIPM-14 determination, giving $\hat{\lambda} = 2.967$ for the remaining fifteen measurements. Evaluated against this historical model under the declared uniform covariance-scaling convention, the correlated four-configuration NIST result is highly unlikely under the archive's reported, unscaled covariance but is statistically unremarkable once the historically inferred extra dispersion is applied ($Q_\lambda = 4.840$; finite-sample $F$ tail $p = 0.382$); a mean-only scaling sensitivity leaves the vector discrepant. Retaining the complete archive also gives a comparable result. We further examine four matched free-minus-servo torque differences reported by NIST. They are consistent with a single common absolute torque offset across the four tested configurations, $\widehat{\Delta N} = 1.918 \pm 0.215$ pN m, and poorly described by an equally simple fractional-scale alternative under the stated independent-Type-A treatment, with a chi-square contrast of $\Delta\chi^{2} = 11.041$ between the two torque models. The paper provides a covariance audit of the historical archive, a lineage-qualified consistency check, and an experimentally testable diagnostic for dual-mode torsion balances, without proposing a revised value of $G$.
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