arXiv subjects

M. Luxnat

Publications and source records attributed to M. Luxnat.

7 recordsLinked to original sources

arXiv2026

Development of a Modular Current-Mode NaI(Tl) Detector Array for Parity Odd (n,{\gamma}) Cross Section Measurements

The Neutron Optics Parity and Time-Reversal Violation Experiment (NOPTREX) Collaboration has developed a modular array of 24 NaI(Tl) detectors to measure parity and time-reversal symmetry violation in neutron-nucleus interactions. These detectors feature custom electronics that allow for operation in pulse or current mode. This paper describes the design, construction, characterization, and testing of the detectors in this array. We demonstrate the ability of the array to detect parity-odd asymmetries in neutron resonances by observing the known 0.7 eV parity-violating resonance in 139La in measurements at LANSCE.

physics.ins-det↗

arXiv2026

Measurement of coherent elastic neutrino nucleus scattering on germanium by COHERENT

The COHERENT collaboration reports the most precise measurement of the coherent elastic neutrino-nucleus scattering cross section to date. This measurement was performed with COHERENT's germanium detector array, Ge-Mini, at the Spallation Neutron Source at Oak Ridge National Laboratory. A cumulative exposure of $4.68\times10^{22}$ protons on target yielded a total number of observed counts of $124^{+14}_{-12}$ and a flux-averaged cross section of $1.00 \pm 0.10 \mathrm{(statistical)} \pm 0.10 \mathrm{(systematic)}$ relative to the standard-model expectation of $5.9\times10^{-39} \mathrm{cm}^2$. The well-understood energy and timing distributions of the neutrino source allow for independent measurements of muon- and electron-neutrino scattering rates. This information is used to improve constraints on non-standard neutrino interactions mediated by heavy particles.

hep-ex↗

arXiv2026

The COHERENT Experiment: 2026 Update

The COHERENT experiment measures neutrino-induced recoils from coherent elastic neutrino-nucleus scattering (CEvNS) with multiple nuclear targets at the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL), USA. Several successful CEvNS measurements have been achieved in recent years with tens-of-kg detector masses, with a CsI scintillating crystal, a liquid argon single-phase detector, and high-purity germanium spectrometers. For the next phase, COHERENT aims at high-statistics detection of CEvNS events for precision tests of the standard model of particle physics, and to probe new physics beyond-the-standard model. Percent-level precision can be achieved by lowering thresholds, reducing backgrounds, and by scaling up the detector masses. It goes hand in hand with benchmarking the neutrino flux from the SNS. Further detectors will measure CEvNS in additional nuclei, including lighter target nuclei such as sodium and neon, to continue to test the expected neutron-number-squared dependence of the cross section. COHERENT can furthermore study charged-current and neutral-current inelastic neutrino-nucleus cross sections on various nuclei at neutrino energies below $\sim$50 MeV. Many of these cross sections have never been measured before, but are critical input for the interpretation of core-collapse supernova detection in large-scale neutrino experiments such as DUNE, Super-K, Hyper-K, and HALO.

hep-ex↗

arXiv2025

New Upper Bounds on Exotic Neutron Spin-Electron Spin Interactions via Neutron Spin Rotation Measurements in a Compensated Ferrimagnet

We report a search for exotic spin-spin interactions between neutrons and electrons which could signal new physics beyond the Standard Model using slow neutron polarimetric imaging through a dense medium of polarized electrons. Our dense polarized electron target is a ferrimagnet held at its magnetic compensation temperature, which realizes a polarized electron ensemble with zero net magnetization. We sought the spin rotation of transversely polarized neutrons from a neutron spin-electron spin interaction of the form $V_2=-g_A^eg_A^n\frac{\hbar c}{4\pi}\vec\sigma_e\cdot\vec\sigma_n\frac{e^{-r/\lambda_c}}{r}$, where $g_{A}^{e}$ and $g_{A}^{n}$ are the electron and neutron axial couplings, $\vec{\sigma_e}$ and $\vec{\sigma_n}$ are the electron and neutron spin, and $\lambda_c$ is the interaction range for an exotic axial vector interaction from massive spin-1 boson exchange of mass $\hbar c/\lambda_c$. The resulting average neutron spin rotation angle per unit length, $\frac{d\bar{\phi}_{F5}}{dz}=[0.41\pm6.30\ (stat.)\pm4.4\ (sys.)]\times10^{-3}$ rad/m, is consistent with zero. Our novel approach improves the previous upper limits on the coupling constant product $g_A^eg_A^n$ by several orders of magnitude in the poorly explored $10^{-8}\leq\lambda_c\leq10^{-2}$ range.

nucl-ex↗

arXiv2024

Polarized Neutron Measurements of the Internal Magnetization of a Ferrimagnet Across its Compensation Temperature

We present the first polarized neutron transmission image of a model Neel ferrimagnetic material, polycrystalline terbium iron garnet (Tb3Fe5O12, TbIG for short), as it is taken through its compensation temperature Tcomp where the macroscopic magnetization vanishes. Our polarized neutron imaging data and the additional supporting measurements using neutron spin echo spectroscopy and SQUID magnetometry are all consistent with a vanishing internal magnetization at Tcomp.

cond-mat.mtrl-sci↗

arXiv2024

Evidence of Coherent Elastic Neutrino-Nucleus Scattering with COHERENT's Germanium Array

We report the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) on natural germanium, measured at the Spallation Neutron Source at Oak Ridge National Laboratory. The Ge-Mini detector of the COHERENT collaboration employs large-mass, low-noise, high-purity germanium spectrometers, enabling excellent energy resolution, and an analysis threshold of 1.5 keV electron-equivalent ionization energy. We observe a on-beam excess of 20.6 +7.1 -6.3 counts with a total exposure of 10.22 GWhkg and we reject the no-CEvNS hypothesis with 3.9 sigma significance. The result agrees with the predicted standard model of particle physics signal rate within 2 sigma.

hep-ex↗

arXiv2022

Angular distribution of $\gamma$-rays from a neutron-induced $p$-wave resonance of $^{132}$Xe

A neutron-energy dependent angular distribution was measured for individual $\gamma$-rays from the 3.2 eV $p$-wave resonance of $^{131}$Xe+$n$, that shows enhanced parity violation owing to a mixing between $s$- and $p$-wave amplitudes. The $\gamma$-ray transitions from the $p$-wave resonance were identified, and the angular distribution with respect to the neutron momentum was evaluated as a function of the neutron energy for 7132 keV $\gamma$-rays, which correspond to a transition to the 1807 keV excited state of $^{132}$Xe. The angular distribution is considered to originate from the interference between $s$- and $p$-wave amplitudes, and will provide a basis for a quantitative understanding of the enhancement mechanism of the fundamental parity violation in compound nuclei.

nucl-ex↗