Nuclear Experiment·nucl-ex

Tue·Aug 25, 2026Tuesday·August 25, 2026

13 papers—2 primary·11 cross-listed

01
Isoscalar Giant Resonances in the even-A Pd Isotopes
J. Arroyo · U. Garg🇺🇸 · T. Furuno🇯🇵 · M. Itoh · H. Shimojo · S. Adachi · H. Akimune · J. Cai🇯🇵 · G. Colo🇮🇹 · M. Dozono🇯🇵 · F. Endo🇯🇵 · M. Fujiwara and 30 other authors
Studies of the isoscalar giant monopole resonance (ISGMR) across the chart of nuclides provide insight into the incompressibility of nuclear matter near saturation density, K(infinity). Such studies had revealed a discrepancy between theoretical approaches: quasiparticle random phase approximation (QRPA) derived from Skyrme interactions reproduce the strength distributions of the ISGMR in the doubly-closed-shell nuclei 90Zr and 208Pb, but their descriptions of strength distributions in open-shell medium-heavy nuclei suggest higher centroid energies should be experimentally observed. The latter nuclei required a smaller K(infinity) and were thus deemed softer. The present work serves to add to this softness discourse by extracting ISGMR strength distributions for 104,106,108,110Pd via 386-MeV inelastic alpha-scattering. The extracted giant resonance strength distributions are consistent with expectations in this isotopic range. Additional Quasiparticle Vibration Coupling (QPVC) effects are included with the QRPA approach and compared to aforementioned ISGMR strength distributions.
nucl-ex0 citations
02
Core Breaking at Low Spin in $^{68}$ Zn from Nuclear Resonance Fluorescence
S. R. Johnson · R. V. F. Janssens🇺🇸 · B. A. Brown🇺🇸 · A. D. Ayangeakaa🇺🇸 · S. S. Bhattacharjee🇨🇦 · E. Churchman · S. W. Finch · U. Friman-Gayer · S. Frye · M. Fulghieri · D. Gribble · X. H. -K. James · R. Longland🇺🇸 · C. Wegner
Low-spin excited states in $^{68}$ Zn have been studied at the High Intensity Gamma-Ray Source (HI $γ$ S) from the ground state up to the particle emission threshold using the nuclear resonance fluorescence technique (NRF) and the newly developed Clover Array. Low-spin levels were excited by linearly-polarized, $2.90 - 9.79$ MeV photon beams. Spin-parity quantum numbers as well as associated $M 1$ and $E 1$ decay strengths were determined for a large fraction of the 158 states observed. In addition, long-duration coincidence measurements at 9.46 and 9.79 MeV enabled the investigation of the level scheme near the ground state. The results have been interpreted with shell-model calculations using two different model spaces and several effective interactions often used to describe nuclei in this mass region. While the structure near the ground state can be understood in terms of excitations involving solely valence nucleons, core breaking is required to account for the evolution of the total $M 1$ strength at excitation energies above $\sim 5$ MeV.
nucl-exnucl-th0 citations
03
Development of Neutron Transmutation Doped Germanium (NTD-Ge) for Cryogenic Applications
Kangkang Zhao🇨🇳 · Mingxuan Xue🇨🇳 · Haiping Peng🇨🇳 · Deyong Duan🇨🇳 · Yunlong Zhang · Yi Li🇨🇳 · Junfeng Yang · Xintan Deng🇨🇳 · Hongjun Zhang · Huaichang Ran · Sicheng Wen🇨🇳 · Xiaolian Wang🇨🇳 · Zizong Xu🇺🇸
This paper presents the systematic fabrication and characterization of cryogenic thermometers based on neutron transmutation-doped germanium (NTD-Ge). High-purity (10N) germanium samples were irradiated by thermal neutrons with different fluences at the China Advanced Research Reactor (CARR). After irradiation and a six-month cooling-down period, positron annihilation lifetime spectroscopy and temperature-dependent Hall effect measurements were performed to characterize irradiation-induced defects and carrier concentrations in the NTD-Ge samples. Utilizing standard semiconductor fabrication techniques, point electrodes were deposited onto the processed samples to fabricate functional NTD-Ge cryogenic thermometers. The low-temperature resistance performance of the devices was characterized down to 20 mK on a millikelvin range cryogenic test platform. The measured temperature dependence of resistance follows Mott's law, showing excellent agreement across the full measured range. The extracted T0 is consistent with expectations. These results collectively verified both the applicability of the thermometers in cryogenic system and the reliability of the fabrication procedure.
↳ physics.ins-detastro-ph.IMcond-mat.mtrl-scinucl-ex0 citations
04
Mitigating warp divergence in GPU optical photon Monte Carlo: an order of magnitude speedup with Shader Execution Reordering
Gabor Galgoczi🇺🇸
In high energy, nuclear, and medical physics, optical photon transport Monte Carlo is a frequent bottleneck in detector simulation. GPU ray tracing accelerates photon propagation, but one thread per photon megakernels suffer from SIMT execution divergence when photon lifetimes vary widely. Short-lived photons leave inactive lanes while a few long-lived photons delay warp completion. We evaluate NVIDIA Shader Execution Reordering (SER) in an OptiX based optical photon transport kernel and use it to regroup surviving photons during propagation. In a 14.7 kton liquid argon time projection chamber benchmark with ~61 million photons from a 2.5 GeV electromagnetic shower, SER capable execution reduces propagation kernel cycles by 16.55(23)x and end-to-end optical simulation time, including transfers and initialization, by 14.72(30)x with bit-identical hit output. We decouple the speed-up into a 3.2x contribution from the launch configuration changes introduced when SER is enabled and a further 5.1x from executing the reorder. Profiling identifies active lane recovery as the dominant mechanism, while branch efficiency and memory bandwidth change little. A volume coherent SER hint enables an analytic navigation fast path in bulk argon, adding a further 1.13x wall-time speedup. Utilizing SER resulted in a ~90% reduction in GPU energy per simulated event.
↳ physics.ins-dethep-exnucl-ex0 citations
05
Optical characterization and ionizing-radiation response of the BCF-20XL scintillating-wavelength-shifting fiber
W. Bae · L. Baker · K. Chen🇨🇳 · J. Cho🇺🇸 · K. Lang · C. Lee🇰🇷 · E. Liang🇺🇸 · C. Mathurin · C. Murthy🇺🇸 · D. Myers🇺🇸 · S. Nguyen🇺🇸 · D. Phan and 3 other authors
We report optical characterization and ionizing-radiation measurements of the scintillating-wavelength-shifting (Sci-WLS) fiber BCF-20XL from Luxium Solutions. Attenuation lengths were obtained from transmitted emission spectra using a 3.0 m fiber with a spectrophotometer and described with a two-component attenuation model, yielding a long attenuation length of 6.70 m and a short attenuation length of 0.16 m. The spectral measurements also reveal wavelength-dependent attenuation, with the long component increasing with wavelength and the short component becoming less significant at longer wavelengths. The scintillation response was also characterized under radioactive alpha, beta, and gamma irradiation using SiPM-based readout, providing a benchmark measurement of the light output from BCF-20XL.
↳ physics.ins-dethep-exnucl-ex0 citations
06
Photon production from gluon splitting and fusion induced by a magnetic field of arbitrary strength in relativistic heavy-ion collisions
Alejandro Ayala🇲🇽 · Santiago Bernal-Langarica🇲🇽 · José Jorge Medina-Serna🇲🇽 · Ana Julia Mizher🇧🇷
We compute the yield and elliptic flow coefficient for photons produced during the pre-equilibrium stage of semi-central relativistic heavy-ion collisions from the gluon fusion and splitting processes induced by the presence of a magnetic field. The calculation is performed for arbitrary values of the field strength. The pre-equilibrium gluon distribution is modeled with a glasma-inspired Bose-Einstein occupation factor, as well as with an anisotropic distribution that accounts for the rapid initial expansion along the beam axis. In both cases, we find a very good agreement between the calculation and the experimental data from PHENIX. Most notably, the shape and strength of the elliptic flow coefficient are described quite well, representing a step towards solving the outstanding photon puzzle.
↳ hep-phnucl-exnucl-th0 citations
07
How Architecture and Training Affect TPC Representations Across Experiments
Tyler Wheeler · Michelle P. Kuchera · Raghuram Ramanujan · William Sieland · Ryan Krupp · Yassid Ayyad🇪🇸 · Daniel Bazin🇺🇸 · Connor L. Cross · Hoi Yan Ian Heung · Andrew J. Jones · Ruchi Mahajan · Saiprasad Ravishankar🇺🇸 and 3 other authors
Deep-learning efforts have increasingly shifted toward foundation model approaches. In experimental physics, this allows models and learned representations to be reused beyond the experiments in which they were developed. This work evaluates the reusability of representations across experiments and detector systems using probes on frozen encoders. These probes reveal task-relevant structure before downstream adaptation, complementing fine-tuning. Together with random-weight controls, they distinguish contributions from architecture and encoder training that downstream performance alone cannot resolve. Time projection chamber (TPC) data provide a useful testbed because events from TPC systems can be represented as variable-length sparse tensors, while detector geometries, event topologies, and scientific tasks can differ substantially. We investigate whether fixed-dimensional TPC event representations can be reused across classification tasks, experiments, and detector systems. Sparse ResNet and PointNet-style encoders produce 512-dimensional embeddings for four datasets from the GADGET II TPC and AT-TPC. Randomly initialized encoders isolate the contribution from architecture before supervised training. We then train each encoder on a classification task, freeze its parameters, and train a linear or nonlinear probe for each downstream task. We find that this architecture-induced structure remains useful across experiments and detector systems. The randomly initialized PointNet-style representation is highly informative on several tasks. The two architectures organize their embedding spaces differently, but neither exhibits a large, systematic loss of utility cross-detector. These results show that architecture is a major source of task-relevant structure in TPC embeddings and should be treated explicitly when assessing representation learning and developing reusable detector models.
↳ cs.LGcs.CVnucl-exphysics.ins-det0 citations
08
Bound and Resonant Spectra of Few-Lepton Coulomb Systems
Liang-Zhen Wen🇨🇳 · Yao Ma🇨🇳 · Zhi-He Shen · Shi-Lin Zhu🇨🇳
We present a unified calculation of bound and resonant states in purely leptonic Coulomb systems: $e^{-} e^{-} e^{+}$ ( $Ps^{-}$ ), $μ^{+} e^{-} e^{-}$ ( $Mu^{-}$ ), $μ^{+} μ^{+} e^{-}$ ( $Mu_{2}^{+}$ ), $e^{+} e^{+} e^{-} e^{-}$ ( $Ps_{2}$ ), and $μ^{+} μ^{+} e^{-} e^{-}$ ( $Mu_{2}$ ). Using an extended stochastic variational method combined with the complex scaling method, we resolve the natural-parity $S$ - and $P$ -wave spectra. Near their respective $n = 2$ thresholds, all three trilepton systems exhibit Gailitis--Damburg sequences generated by $2 S$ and $2 P$ Stark mixing and the resulting inverse-square attraction. Although microscopically distinct from the Efimov effect, this mechanism produces the same inverse-square asymptotics and geometric scaling. The $Ps^{-}$ and $Mu^{-}$ systems exhibit resonance sequences of comparable density, whereas the $Mu_{2}^{+}$ produces a much denser spectrum, with 20 resolved members in the $^{3} P^{o}$ channel. In $Mu_{2}^{+}$ , the deeper states follow molecular Born--Oppenheimer configurations, while the near-threshold spectrum is governed by the atomic $Mu (2) + μ^{+}$ structure. In $Ps_{2}$ , coupling between threshold-degenerate configurations is essential for a near-threshold bound state. In $Mu_{2}$ , the Born--Oppenheimer organization of the resonance spectrum is channel dependent.
↳ physics.atom-phhep-exhep-phnucl-ex0 citations
09
Impact of Environmental Stress on Low Gain Avalanche Diode Sensors Response
Mohamed Hijas Mohamed Farook🇺🇸 · Gaetano Barone🇺🇸 · Diallo Boye · Gabriele D'Amen🇺🇸 · Gabriele Giacomini🇺🇸 · Timo Peltola · Jennifer Roloff🇺🇸 · Enrico Rossi🇺🇸 · Trevor Russell · Sally Seidel🇺🇸 · Alessandro Tricoli🇺🇸 · Lixing Wang🇨🇳
Low Gain Avalanche Diodes or LGADs are silicon sensors capable of achieving excellent timing resolution due to their characteristic internal gain. Detectors based on LGAD technology play a crucial role in High Energy and Nuclear Physics experiments, among other applications. However, their performance is affected by environmental factors such as temperature, humidity, and storage conditions. A systematic evaluation of the response of LGAD sensors as a function of these environmental parameters is therefore of essential importance for any application. LGAD sensors fabricated at the Brookhaven National Laboratory are characterized and stress-tested against various operating conditions, such as rapid temperature and humidity changes. Dedicated and detailed simulations are used to interpret the experimental results.
↳ physics.ins-dethep-exnucl-ex0 citations
10
Ab initio anatomy of quadrupole correlations in $^{16}$ O and $^{20}$ Ne
Chenrong Ding🇨🇳 · Benjamin Bally🇩🇪 · Stavros Bofos🇫🇷 · Thomas Duguet🇫🇷 · Yi Li🇨🇳 · Jiangming Yao🇨🇳
Azimuthal hadronic flow measured in ultra-relativistic ion--ion collisions provides a new means of imaging multipole correlations in the ground state of atomic nuclei. Early interpretations largely relied on a classical-rotor picture, in which the measured mean-square elliptic flow is directly related to an intrinsic quadrupole deformation. Atomic nuclei, however, contain additional many-body correlations generated by the Pauli exclusion principle, collective shape fluctuations and non-collective dynamical processes, whose impact on this correspondence has not yet been elucidated. Here, we resolve this issue through an ab initio analysis of $^{16}$ O and $^{20}$ Ne based on chiral nuclear interactions, combining the in-medium similarity renormalization group with the quantum-number-projected generator coordinate method. By successively isolating antisymmetrization, collective rotational and vibrational, and non-collective dynamical correlations, we determine, for the first time, how each component contributes to the mean-square quadrupole eccentricity. We uncover an unexpected compensation among these distinct correlation mechanisms: despite sizable individual contributions, the squared effective quadrupole deformation inferred from the elliptic flow remains close to the square intrinsic deformation of the nucleus. This result provides a microscopic explanation for the surprising success of the classical-rotor approximation and establishes a quantitative foundation for interpreting $^{16}$ O+ $^{16}$ O and $^{20}$ Ne+ $^{20}$ Ne collision data recently collected at the Large Hadron Collider.
↳ nucl-thnucl-ex0 citations
11
$Δ$ resonance contributions to QED radiative corrections in neutron and inverse beta decay
Oleksandr Tomalak🇨🇳 · Yi-Bo Yang🇨🇳
We incorporate the $Δ (1232)$ resonance into pion-induced QED radiative corrections to neutron decay and inverse beta decay (IBD). Within the framework of heavy-baryon chiral perturbation theory with explicit $Δ$ degrees of freedom, we compute additional contributions and study their impact on IBD cross sections and on the renormalization of the nucleon isovector vector and axial-vector charges. $Δ$ resonance does not renormalize the vector charge. For the axial-vector charge, including the $Δ$ resonance restores power counting and significantly reduces the QED radiative correction to the experiment-over-lattice-QCD ratio $g_{A} / (g_{A}^{QCD} g_{V})$ , bringing it to zero within radiative-correction uncertainties. $Δ$ resonance increases the pion-induced QED radiative corrections to IBD by a factor $1.2$ - $1.3$ .
↳ hep-phhep-exhep-latnucl-ex+10 citations
12
Radiative decays of the isoscalar $S$ -wave $D D ˉ$ molecule
Yuan-Jun Gao🇨🇳 · Gang Li🇨🇳 · Shi-Dong Liu🇨🇳 · Pan-Pan Shi🇪🇸
In the hadronic molecular picture, an isoscalar $S$ -wave $D D ˉ$ molecule is naturally expected as the spin-0 partner of $X (3872)$ . Assuming this state, denoted by $X_{0}$ , to be a pure $D D ˉ$ molecule with quantum numbers $J^{P C} = 0^{++}$ , we investigate its radiative decays $X_{0} \to γ V (V = ρ^{0}, ω)$ within an effective Lagrangian framework. The decay amplitudes are generated by intermediate charmed-meson loops, with electromagnetic gauge invariance consistently maintained throughout the calculation. We evaluate the partial decay widths and examine their dependence on the $X_{0}$ mass and the cutoff. Although the individual decay widths exhibit a sizable dependence on the cutoff, their ratio is remarkably stable. In particular, we obtain that the ratio for the decays $X_{0} \to γ ρ^{0}$ and $X_{0} \to γ ω$ is approximately 2.26, which is insensitive to the variation of the cutoff. This robust ratio provides a useful model-insensitive signature of the molecular structure of $X_{0}$ .
↳ hep-phhep-exnucl-exnucl-th0 citations
13
Performance Evaluation of a High-Granularity LYSO-SiPM-Based Position-Sensitive Detector for a One-Shot Gamma-Scanning System with Sub-Millimeter Spatial Resolution
Katyayni Tiwari · Arzoo Sharma · Jürgen Gerl🇩🇪 · Ivan Kojouharov🇩🇪 · P. Herrmann · H. Schaffner🇩🇪 · G. Aggez · Pushpendra P. Singh🇮🇳
A compact position-sensitive {\gamma}-detector based on a thin monolithic LYSO crystal and a 96-channel SiPM array is developed for the spatial characterization and calibration of segmented {\gamma}-ray detector systems used in nuclear-physics experiments. The detector is designed to provide localized irradiation and rapid two-dimensional response mapping. A 7 cm diameter and 3 mm thick LYSO crystal is optically coupled to the SiPM array, and the position of the incident {\gamma}-ray interaction is reconstructed from the relative scintillation-light signals collected by neighboring SiPM channels. An asymmetry-based charge-sharing method is employed to determine the interaction position from the spatial distribution of the detected scintillation light. Detailed GEANT4 simulations, including optical photon transport, were performed to investigate the detector response and estimate its intrinsic spatial resolution. The simulations predict a spatial resolution of approximately 0.5 mm for 60 keV and 511 keV {\gamma}-rays under idealized conditions. A prototype detector was developed and experimentally characterized using coincidence measurements with the {\gamma}-scanning facility at GSI, Germany. The experimental measurements demonstrate a spatial resolution better than 1 mm in the central detector region, while the position-dependent response and degradation near the detector boundaries are investigated. The experimental results are compared with GEANT4 predictions to identify the contributions of optical photon transport, charge sharing, and detector geometry to the measured spatial resolution. The developed detector provides a compact solution for the three-dimensional characterization of highly segmented {\gamma}-ray detector arrays in nuclear physics experiments.
↳ physics.ins-detnucl-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE