Mon·Feb 24, 2025Monday·February 24, 2025

1. 01*

   Measuring dark currents in multiple cryogenic SiPMs with sub-pA sensitivity using an automated IV multiplexer

   Lucas Darroch🇨🇦 · Eamon Egan · Marc-Antoine Leclerc · Thomas McElroy · Thomas Brunner🇨🇦

   We present the design of an automated current-voltage (IV) multiplexer (MUX) that enables accurate measurement of the dark current in cryogenic silicon photomultipliers (SiPMs), achieving a sensitivity equivalent to detecting less than one avalanche per second. Dynamic pulse-counting measurements were used as a benchmark for reconstructing the dark current in static IV measurements. The IV-MUX features 15 channels on a single board and up to seven boards can be connected in parallel under the control of one Arduino microcontroller. To minimize leakage and enhance performance, the layout includes guard rings and high-isolation relays, enabling resolution of currents as small as 49 fA. The IV-MUX can be integrated into systems designed for IV or pulse-counting measurements, enabling seamless switching between IV and pulse-counting modes. Moreover, the IV-MUX is vacuum-compatible, validated by testing an SiPM array in a cryostat. This feature reduces the need for multiple feedthroughs when testing sensor arrays in vacuum. The design is open source and can be used to facilitate rapid and automated testing of SiPMs or similar low-current devices in one measurement cycle.

   ↳ physics.ins-detnucl-exMeasurement(2025)·0 citations
2. 02*

   Examination of the multiple-scattering expansion in the four-nucleon system

   A. Deltuva🇱🇹

   The elastic neutron-${}^3\mathrm{H}$ scattering at intermediate energies is studied using rigorous integral equations solved in the momentum-space partial-wave basis. The four-particle transition operators are expanded into multiple-scattering series in terms of subsystem transition operators. Various approximations resulting from truncation of the series in different ways are evaluated and their validity is investigated. They fail at lower energies but at higher energies provide a rough reproduction of exact results at small scattering angles. In the large-angle region all approximations fail heavily, indicating that the scattering amplitude results from a delicate interplay of many multiple-scattering terms. The partial-wave analysis reveals that the developed approximations are reliable in higher partial waves, and for practical calculations an efficient ``hybrid'' approach is proposed, combining exact amplitudes in lower partial waves with approximations in higher partial waves. The implications for often used approximation of the first order in two-body transition matrix and development of microscopic optical potentials are discussed.

   ↳ nucl-thnucl-exPRC(2025)·0 citations
3. 03*

   Projective Imaging of High-Energy Nuclei via Coherent Exclusive Vector Meson Production in Electron-Nucleus Collisions

   Maci Kesler🇺🇸 · Ashik Ikbal Sheikh🇺🇸 · Rongrong Ma🇺🇸 · Zhoudunming Tu🇺🇸 · Thomas Ullrich🇺🇸 · Zhangbu Xu🇺🇸

   One of the major goals of modern nuclear experiments is to study the distributions of gluons inside nuclei at high energy. A key measurement is the coherent exclusive vector meson (VM) production in diffractive electron-nucleus collisions, where the gluon spatial distribution inside the nucleus can be obtained through a Fourier transform of the squared nuclear momentum transfer ($|t|$) distribution. This research aims to overcome the two main obstacles of the $|t|$ measurement: limited precision in measuring $|t|$ arising from the momentum resolution of the outgoing electron and the overwhelming incoherent background. We demonstrate that by measuring the projected $|t|$ distribution along the direction perpendicular to the electron scattering plane, the effect of the outgoing electron's momentum resolution can be effectively mitigated, and the diffractive pattern is largely restored. Furthermore, we propose to measure the angular distribution of the VM's decay daughters to statistically remove the incoherent background.

   ↳ nucl-thhep-phnucl-exPLB(2026)·5 citations
4. 04*

   Improving Optics Control and Measurement at RHIC

   W. Fung🇺🇸 · Y. Hao🇺🇸 · X. Gu🇨🇳 · G. Robert-Demolaize🇺🇸

   Maximizing luminosity requires precise control of the optics function at the interaction point (IP), implying that the location ($s^{\ast }$) of the beta function's minimum value (${\beta }^{\ast }$) must be moved to the collision location ($s_{IP}$) as much as possible. Accurate optics measurements and reliable control of $s^{\ast }$ in both planes are therefore essential for optimal collider performance. During Relativistic Heavy Ion Collider (RHIC) operations in 2024, measurements indicate an average horizontal beta beat of approximately $20\%$ at IP8, accompanied by measurement variation in measured $s^{\ast }$ in both planes. In this paper, a sensitivity-matrix-based optics correction scheme is demonstrated to effectively steer the optics toward desired targets using power supply currents of IR quadrupoles in the 8 o'clock interaction region (IR8). In addition, a method for measuring linear optics based on the one-turn map within the interaction regions is developed and systematically compared with established optics measurement methods used in RHIC operations. A comprehensive error analysis is performed for all measurement methods considered. Through these methods, a consistent reduction of $10\%$ beta beat is achieved by moving $s_x^{\ast }$ as well as a significant improvement in the reproducibility of $s^{\ast }$ measurements in both planes. The techniques demonstrated here will be further developed to support linear optics analysis and control of the future Electron-Ion Collider project.

   ↳ physics.acc-phnucl-exNucl.Instrum.Meth.A(2026)·1 citation
5. 05*

   New constraints on coherent elastic neutrino-nucleus scattering by the nuGeN experiment

   V. Belov🇷🇺 · A. Bystryakov🇷🇺 · M. Danilov🇷🇺 · S. Evseev🇷🇺 · M. Fomina🇷🇺 · G. Ignatov🇷🇺 · S. Kazartsev🇷🇺 · J. Khushvaktov🇷🇺 · T. Khussainov🇷🇺 · A. Konovalov🇷🇺 · A. Kuznetsov🇷🇺 · A. Lubashevskiy🇷🇺 and 12 other authors

   The nuGeN experiment searches for coherent elastic neutrino-nucleus scattering (CEvNS) at the Kalinin Nuclear Power Plant. A 1.41-kg high-purity low-threshold germanium detector surrounded by active and passive shielding is deployed at the minimal distance of 11.1 m allowed by the lifting mechanism from the center of reactor core, utilizing one of the highest antineutrino fluxes among the competing experiments. The direct comparison of the count rates obtained during reactor-ON and reactor-OFF periods with the energy threshold of 0.29~keV${}_{ee}$ shows no statistically significant difference. New upper limits on the number of CEvNS events are evaluated on the basis of the residual ON$-$OFF count rate spectrum.

   ↳ hep-exnucl-exCPC(2025)·20 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.