Nuclear Experiment·nucl-ex

Thu·Aug 27, 2026Thursday·August 27, 2026

8 papers—1 primary·7 cross-listed

01
Direct measurement of the in-medium $η^{'}$ mass spectrum through the $γ γ$ decay channel
Y. Matsumura🇯🇵 · N. Muramatsu🇨🇳 · T.A. Hashimoto🇯🇵 · M. Miyabe🇯🇵 · H. Shimizu🇯🇵 · A.O. Tokiyasu🇯🇵 · J.K. Ahn🇰🇷 · W.C. Chang🇹🇼 · J.Y. Chen🇹🇼 · M.L. Chu🇹🇼 · S. Daté🇯🇵 · T. Gogami🇯🇵 and 49 other authors
We measured the invariant mass of the $η^{'} (958)$ meson through the $η^{'} \to γ γ$ decay channel to search for possible character change of $η^{'}$ in a nuclear medium. The measured invariant-mass spectra were analyzed by fitting realistic spectral functions. An enhancement was observed in the lower tail of the $η^{'}$ mass peak for low-momentum ( $P_{γ γ} < 1$ ~ $GeV/c$ ) events. Three statistical methods were applied to assess the significance of the enhancement. All methods yield a statistical significance above 3.7 $σ$ . The spectral fitting indicates a mass reduction of $57. 5_{- 27.8}^{+ 5.7}$ ~ $MeV/c^{2}$ . Our result provides the first evidence for an in-medium spectral modification of the $η^{'}$ meson obtained through a direct measurement of its invariant mass.
nucl-exPRL(2026)·0 citations
02
Comparative measurements of DC electrical breakdown distributions in liquid nitrogen, liquid helium, and liquid argon
N. S. Phan🇺🇸 · S. M. Clayton🇺🇸 · R. Gautam🇮🇳 · T. M. Ito🇺🇸 · L. Kadlec · C. M. O'Shaughnessy🇺🇸 · T. J. Schaub🇺🇸
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.
↳ physics.chem-phhep-exnucl-exphysics.ins-det0 citations
03
Spectroscopy of 211,213,215Pb isotopes and seniority properties
Larry Zamick · Praveen Srivastava🇮🇳
We first consider lead isotopes with valence neutrons in the g9/2shell. We especially compare 211Pb (n=3), 213Pb (n=5) and 215Pb (n=7), 213Pb being at mid-shell. Motivated by the fact the J = 21/2+ and J =3/2+ states are pure seniority v=3 states for both n=3 and n=5, we compare the energy splitting E(J=21/2+)-E(J=3/2+) for various interactions. We then discuss the position of the lowest J=3/2+ state in both n=3 and n=5, although, this state has not been found experimentally. Calculations with configurations beyond g9/2 are also considered. We next address the fact that the J=21/2+ state is isomeric for both n=3 and n=5.
↳ nucl-thnucl-exIJMPE(2026)·0 citations
04
Resonant Induced Orbital Electron Capture: Novel method for low-energy $ν ˉ_{e}$ detection
Evgeny Akhmedov🇩🇪 · Thierry Lasserre🇩🇪 · Leonardo Maturi🇩🇪
We propose a novel approach to detecting low-energy electron antineutrinos based on the induced capture of orbital electrons by nuclei. This process is resonant, requiring the antineutrino energy to precisely match the energy difference between the final and initial atomic systems. For continuous-spectrum sources, the resonance conditions can be satisfied without fine-tuning, and the effective cross sections depend on the spectral intensity of the $ν ˉ_{e}$ flux at the resonance rather than on the neutrino energy itself. This opens the possibility of detecting neutrinos of never previously probed low energies. We identify a number of candidate nuclides that allow transitions to excited states of the daughter nuclei corresponding to resonant $ν ˉ_{e}$ energies below the inverse $β$ decay threshold of 1.8 MeV, and we consider a distinctive atomic-nuclear coincidence signature for background rejection. We discuss implications of the proposed method for detecting low-energy reactor neutrinos, geoneutrinos, and keV-scale thermal solar neutrinos. Applications to neutrino oscillation experiments and to reactor monitoring are also briefly discussed.
↳ hep-phhep-exnucl-exnucl-th0 citations
05
Feasibility demonstration of a high-momentum, high-purity muon beamline at the J-PARC Hadron Experimental Facility
Kotaro Shirotori🇯🇵 · Takaya Akaishi🇯🇵 · Kazuya Aoki🇯🇵 · Wen-Chen Chang🇹🇼 · Ryotaro Honda🇯🇵 · Yusuke Hori🇯🇵 · Takatsugu Ishikawa🇯🇵 · Nobuyuki Kobayashi🇯🇵 · Ruri Kurasaki🇯🇵 · Che-Sheng Lin🇯🇵 · Yuhei Morino🇯🇵 · Megumi Naruki🇯🇵 and 7 other authors
We have established and characterized a novel high-purity muon beam delivery scheme, designated as $μ$ 20, at the high-momentum hadron beamline (B-line) of the J-PARC Hadron Experimental Facility. This scheme delivers tertiary muons produced via the in-flight backward decays of secondary pions in the straight section of the beamline, inherently suppressing parent hadron contamination. In a systematic performance evaluation, the muon beam achieved a standalone intensity of $1.7 \times 10^{3}$ particles/spill with a spatial spread (standard deviation, $σ$ ) of approximately 15 mm at the downstream detector position. A systematic attenuation analysis utilizing an iron absorber verified a high muon purity of 98.0 $\pm$ 0.6% for the 3 GeV/ $c$ muon beam mode. Crucially, this work marks the first successful feasibility study of a high-momentum and high-purity muon beamline operation at an experimental facility in Japan.
↳ physics.acc-phhep-exnucl-ex0 citations
06
Development and Commissioning of the Cryogenic Target Detectors for the Technical Run of the NUCLEUS Experiment
N. Schermer🇩🇪 · H. Abele🇦🇹 · G. Angloher🇩🇪 · B. Arnold🇦🇹 · M. Atzori Corona🇮🇹 · A. Bento🇵🇹 · E. Bossio🇫🇷 · F. Buchsteiner🇦🇹 · J. Burkhart🇦🇹 · F. Cappella🇮🇹 · M. Cappelli🇮🇹 · N. Casali🇮🇹 and 48 other authors
The NUCLEUS experiment aims to study coherent elastic neutrino-nucleus scattering (CE $ν$ NS) of reactor electron antineutrinos at the Chooz nuclear power plant in France. In this work, the cryogenic target-detector module for the NUCLEUS Technical Run was developed and commissioned at the Technical University of Munich. The module comprises four gram-scale CaWO $_{4}$ detectors, each equipped with two Transition Edge Sensors (TES), providing a total target mass of 6.96 g. We present the design, integration, detector characterization, and X-ray-based energy calibration of these detectors. Across six characterized detectors, a mean baseline resolution of $σ_{BL} = (2.79 \pm 0.60) eV$ was achieved. The best-performing detector reached $σ_{BL} = (2.16 \pm 0.0 2_{stat}) eV$ , surpassing the design goal by a factor of two and representing a state-of-the-art result for a cryogenic CaWO $_{4}$ detector. The target detector module was successfully operated simultaneously with the surrounding Cryogenic Outer Veto, which consists of six kg-scale Ge detectors for background discrimination, showing no measurable cross-talk. These results demonstrate the readiness of the target-detector system for the NUCLEUS Technical Run at Chooz and mark a key milestone in the development of cryogenic detectors for reactor-CE $ν$ NS measurements.
↳ physics.ins-dethep-exnucl-ex0 citations
07
Directional correlations in nuclear charge-radius model residuals enable extrapolation with calibrated uncertainties
Debodyuti Kar🇿🇦 · Soumya Bagchi · Timo Dickel🇩🇪 · Rituparna Kanungo🇨🇦
We identify a pronounced directional anisotropy in the residuals between measured nuclear charge radii and two structurally distinct global models: the phenomenological Weizsäcker--Skyrme formula (WS*) and the microscopic Hartree--Fock--Bogoliubov model (HFB-25). In both cases, the residuals remain correlated over several neutron steps along isotopic chains but decorrelate almost completely after a single proton step along isotonic chains. This common pattern, reinforced by a strong correlation between the two residual fields ( $r ≃ 0.73$ ), points to a shared deficiency of both global descriptions rather than a model-specific artefact. Motivated by this geometry, we introduce ARCUS (Anisotropic Residual Calibration with Uncertainty Scaling), which applies an anisotropic kernel-regression correction with empirically calibrated prediction intervals. In out-of-fold cross-validation, ARCUS reduces the root-mean-square errors of both WS* and HFB-25 by approximately a factor of two. On an independent, temporally blind test set of 129 nuclei, its prediction intervals retain coverage close to nominal under extrapolation. An isotropic kernel matched to the same cross-validation coverage instead substantially overestimates uncertainties on the blind set, showing that reliable calibration transfer depends on encoding the directional residual structure. In regions with anomalous structure, such as around $^{52}$ Ca, ARCUS keeps its prediction intervals wide enough to cover the increased errors, rather than yielding overconfident point predictions. We also extend these calibrated predictions to 1008 unmeasured nuclei near known isotopic chains, ranked by uncertainty to support the future charge-radius measurements.
↳ nucl-thnucl-ex0 citations
08
Evidence for Quartet Binding of Valence Neutrons in $^{8}$ He
Young-Ho Song · Yuan-Zhuo Ma🇺🇸 · Dean Lee🇺🇸
Multimodal neutron superfluidity predicts quartets formed as bound states of two spin-singlet $s$ -wave neutron pairs. We present evidence that the four valence neutrons of $^{8}$ He realize the finite-system analogue. Quartet binding depends not only on the strength of neutron-neutron attraction but also on the number and symmetry of sufficiently strong attractive pair modes. Pauli blocking limits reuse of the same pair structure, while additional modes can provide extra binding. A partial-wave analysis of the neutron-neutron interaction in Daejeon16 no-core shell-model calculations identifies cooperative $^{1} S_{0}$ pairing and additional $^{3} P_{2}$ attraction as the dominant neutron-neutron contributions to this nonadditive binding, while density cumulants reveal connected four-neutron correlations.
↳ nucl-thnucl-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE