Nuclear Experiment·nucl-ex

Tue·Jun 23, 2026Tuesday·June 23, 2026

14 papers—4 primary·10 cross-listed

01
Evidence of the Excited X(5)-like Critical-Point Symmetry Structures in 152Sm
S. Basak🇮🇳 · S. Rajbanshi🇮🇳 · T. Bhattacharjee🇮🇳 · D. Kumar🇮🇳 · A. Pal🇮🇳 · S. S. Alam🇮🇳 · A. Saha🇮🇳 · A. K. Sikdar🇮🇳 · J. Nandi🇮🇳 · Ananya Das🇮🇳 · Shabir Dar🇸🇪 · S. Samanta🇮🇳 and 14 other authors
The positive-parity structure of 152Sm has been investigated through high-statistics {\gamma}-ray spectroscopy following the (150Nd({\alpha},2n)152Sm reaction at Elab = 26 MeV. Several collective structures built on excited 0+ states have been extended through the observation of new levels and {\gamma}-ray transitions, and spin-parity assignments have been established using directional-correlation and linear-polarization measurements. Electromagnetic transition strengths (B(E2)), deduced from measured branching ratios and known level lifetimes, reveal pronounced collectivity among the excited configurations. The resulting level scheme provides evidence for a sequence of excited collective bands extending beyond the well-known ground-state and first excited 0+ structures. The excitation energies and transition strengths are examined within the framework of the X(5) critical-point description of the first-order U(5)-SU(3) shape-phase transition. In addition to the established X(5)-like features of the low-lying spectrum, the observed systematics of the higher-lying bands are found to be consistent with excited collective structures exhibiting X(5)-like characteristics. The results provide new constraints on the realization of critical-point behavior in finite nuclei and on the evolution of collectivity in the N=90 region.
nucl-exnucl-thPLB(2026)·0 citations
02
Hyper-Nuclei $_{Λ}^{4} He$ Production in $s_{NN}$ = 3 GeV Au+Au collisions at RHIC
STAR Collaboration
The STAR experiment reports the first measurement of the $_{Λ}^{4} He$ hyper-nuclei yield as a function of rapidity and transverse momentum in 0-50% central Au+Au collisions at $s_{NN} =$ 3 GeV. The $_{Λ}^{4} He$ is reconstructed through its three-body decay channel, $_{Λ}^{4} He \to^{3} He + p + π^{-}$ , with a statistical significance of about 9.5 standard deviations. We find that the yield of $_{Λ}^{4} He$ as a function of rapidity is consistent with that of $_{Λ}^{4} H$ , and the rapidity-dependent yield ratio of $_{Λ}^{4} He$ / $_{Λ}^{4} H$ is consistent with that of $^{3}$ He/t. All the measurements, as well as the transverse-momentum spectra, can be reasonably described by the JAM with a coalescence afterburner, suggesting a coalescence-based formation scenario for hyper-nuclei at this energy. The canonical thermal model reproduces the observed yield ratios but overpredicts the absolute hyper-nuclei yields.
nucl-ex0 citations
03
Development of a Neural Network-Based Background Suppression Technique for $Σ N$ Cusp Spectroscopy at J-PARC
K. Amemiya🇯🇵 · Y. Ichikawa🇯🇵 · S.H. Hayakawa🇯🇵 · K. Tanida🇯🇵 · S.H. Kim🇰🇷 · F. Oura🇯🇵 · H.I. Lee🇰🇷 · R.J. Saito🇯🇵 · K. Shimazaki🇯🇵 · R. Sasaki🇯🇵 · Y. Nakayama🇯🇵
A clear spectral enhancement, known as the `` $Σ N$ cusp'', has been observed near the $Σ N$ threshold in the $d (K^{-}, π^{-})$ reaction. To understand the dynamical origin of this enhancement, the J-PARC E90 experiment aims to investigate the missing-mass spectrum with an unprecedented resolution of 0.4 MeV ( $σ$ ). In this experiment, a Hyperon Time Projection Chamber (HypTPC) is utilized to detect charged decay products and suppress severe contamination from quasi-free (QF) background processes. While a conventional track multiplicity condition of three (Mt=3) effectively suppresses these QF events, it restricts the signal statistics to approximately 17\% and introduces a mass-dependent acceptance bias that distorts the spectrum. In contrast, events with a track multiplicity of two (Mt=2) offer roughly double the statistical power ( $\sim$ 39\%) with minimal mass dependence, but they suffer from heavy background contamination. To fully exploit the Mt=2 events, we developed an innovative background suppression technique based on a neural network. By constructing a binary classification model using the HypTPC track topology and energy loss ( $d E / d x$ ) as input features, we successfully discriminated the signal from QF backgrounds. This machine learning approach achieves a signal-to-noise ratio comparable to the strict Mt=3 condition while preserving the integrity of the spectral shape. By combining this independent ML-selected Mt=2 sample with the conventional Mt=3 sample, the total usable statistics are effectively doubled compared to traditional methods, significantly enhancing the sensitivity for determining the $Σ N$ cusp parameters.
nucl-ex0 citations
04
Single Particle Excitations, Band Structures and Octupole Correlation in $^{65}$ Zn
Anil Sharma · S. Nandi · S. S. Dutta🇮🇳 · S. Kundu · Pankaj K. Giri · A. Das · S. S. Ghugre🇮🇳 · S. S. Nayak · S. Basu · S. Pal🇨🇦 · S. Das🇮🇳 · S. Dar🇸🇪 and 6 other authors
The excitation scheme of the $^{65}$ Zn ( $Z = 30, N = 35$ ) nucleus has been probed following its population in the $^{63}$ Cu( $α$ ,pn) reaction at E $_{b e am}$ = 30 MeV and using an array of Compton suppressed HPGe clovers as the detection system. This work has identified several new transitions of the nucleus and have modified the placements of some of the previously known ones. The multipolarities and the electric/ magnetic nature of the observed $γ$ -ray rays have been measured, using the conventional methodologies. The spin-parity assignments for the levels have consequently been made; some of the spin-parities are new while others are either validation of the existing values or are modified results based on the present analysis. The experimental level scheme exhibits collective as well as single particle structures. The measured level energies have been compared with those calculated in the framework of the large basis shell model using a model space of $p_{3/2}, f_{5/2}, p_{1/2}, g_{9/2}$ orbitals and two different interactions. The collective excitations of the nucleus were probed through the properties of its band structures and through the calculations of the Total Routhian Surface (TRS) for the associated deformations/ shapes. The results of this study brings out the essential features of evolving structural characteristics and developing collectivity with increasing number of nucleons outside a doubly-magic core and with their occupancy of deformation driving high- $j$ orbitals.
nucl-ex0 citations
05
Ab Initio Nuclear Theory for Heavy Nuclei and Its Application to Dark Matter-Nucleus Scattering
Bai-Shan Hu🇺🇸
The era of precision ab initio nuclear theory has arrived, enabling uncertainty-quantified predictions for nuclear structure and for interactions with external probes directly from the underlying nuclear force and electroweak currents. This review highlights recent breakthroughs that extend ab initio calculations to the heavy nucleus $^{208}$ Pb, to medium-mass systems with complex deformation, and to weakly-bound nuclei near the driplines. We also summarize ab initio calculations of nuclear responses for dark matter direct detection. Together, these advances demonstrate how ab initio methods can substantially reduce nuclear-physics uncertainties in searches for physics beyond the Standard Model, providing a more robust interpretation of current and forthcoming precision experiments.
↳ nucl-thhep-exhep-thnucl-exFront.in Phys.(2026)·0 citations
06
Characterization of GaN:Si and ZnO:Ga for position-resolved fast timing applications
Julius Meyer🇩🇪 · Joshua W. Cates · Woon-Seng Choong · Juan Cristhian Luque Gutierrez · Federico Moretti🇩🇪 · Ryan Pavlovsky · Mauricio Ayllon Unzueta · Weronika W. Wolszczak · Markus Roth🇩🇪 · Arun Persaud
We present the characterization of two fast, crystalline inorganic scintillators, silicon-doped gallium nitride (GaN:Si) and gallium-doped zinc oxide (ZnO:Ga), and compare their performance with cerium-doped yttrium aluminium perovskite (YAP:Ce) for in-vacuum alpha-detection applications that require high-performance timing, position, and energy resolution, such as 3D elemental mapping, medical imaging, and homeland security applications. In this paper, we propose ZnO:Ga and GaN:Si as high-performance drop-in replacements for the alpha detector in Associated Particle Imaging (API) systems. However, the results reported here also have wide applicability. Prior work has reported on polycrystalline forms of ZnO:Ga, which suffer from self-absorption. To our knowledge, GaN:Si has not been proposed to be used in API systems. We present room-temperature scintillation time constants obtained via X-ray-induced time-correlated single-photon counting for both proposed materials. They both exhibit exceedingly fast rise times of <15ps, and high brightness >1000ph/MeV with resolved alpha-peaks. Single-crystal ZnO:Ga and single-crystal GaN:Si yield single-component decays of 805ps and 32ps, respectively. Using a plastic scintillator reference setup, coincidence timing resolution (CTR) and detector timing resolution (DTR) measurements demonstrate a >3x improvement in timing resolution compared to traditional YAP:Ce. GaN:Si and ZnO:Ga exhibit (35(9))ps and (49(5))ps DTR, respectively, compared to(144(2))ps for conventional, single-crystal YAP:Ce. Finally, we evaluate their position resolution in an experimental setup designed for API and measure better than 0.2mm for YAP:Ce and approximately 1mm for GaN:Si. We obtain a position resolution of 0.3mm for ZnO:Ga from simulations. We also present alpha-induced ionoluminescence emission spectra that reveal direct, red-shifted near-bandgap emission.
↳ physics.ins-detnucl-ex0 citations
07
A New Scaling of Neutron Star Tidal Deformability for Directly Probing the Core Equation of State
Jian-Hao Shi🇨🇳 · Bao-Jun Cai🇨🇳 · Bao-An Li🇺🇸 · Yu-Gang Ma🇨🇳
The dimensionless tidal deformability, $Λ$ , of neutron stars (NSs), inferred from gravitational-wave (GW) observations, has thus far been used primarily to constrain the pressure of dense matter near twice nuclear saturation density, leaving the core equation of state (EOS) largely inaccessible to inspiral-phase GW observations. We show that the core EOS can be probed directly through $Λ$ using a perturbative analysis of the dimensionless stellar-structure and tidal-response equations formulated in terms of scaled intrinsic variables, without invoking any specific EOS model. We uncover a remarkable EOS-insensitive scaling relation between $Λ$ and the central EOS parameter $X \equiv P_{c} / ε_{c}$ , where $P_{c}$ and $ε_{c}$ denote the central pressure and energy density, respectively. The relation is validated against a broad ensemble of physically viable EOSs. Applying it to tidal deformabilities inferred from events such as GW170817 enables a direct determination of $X$ . We further derive a tight lower bound, $Λ_{TOV} ≳ 9. 2_{- 1.2}^{+ 1.2}$ , for maximum-mass NSs along stable mass-radius sequences, quantitatively demonstrating that even the most compact stable NSs remain distinctly separated from black holes, for which $Λ_{BH} = 0$ . These findings reveal a previously unrecognized connection between inspiral-phase tidal deformability and the core EOS, establishing a direct link between GW observables and the microphysics of ultradense matter in the strong-gravity regime. The resulting scaling establishes inspiral-phase tidal deformability as a direct and largely model-insensitive probe of the EOS of NS cores.
↳ astro-ph.HEgr-qcnucl-exnucl-th2 citations
08
Microscopic mechanism of the Fayans pairing for the enhancement of charge radii
Tomoya Naito🇯🇵 · Gianluca Colò🇮🇹 · Xavier Roca-Maza🇪🇸 · Hiroyuki Sagawa🇯🇵 · Enrico Vigezzi🇮🇹
The Fayans energy density functional (EDF), and in particular its pairing sector, have been claimed to be able to reproduce the experimental data of charge radii in many instances. A particularly intriguing case is that of the $Ca$ isotopes between $A = 40$ and $48$ , where charge radii exhibit a "bell shape". In our work, we examine the microscopic origin of this behaviour. We prepare in total $25$ paramerizations of the Fayans-like pairing interaction, that are equivalent in fulfilling the same criteria for the reproduction of empirical pairing gaps. We find that both the density and the density-gradient dependence of the pairing interaction are important to reproduce the well-known enhancement of charge radii in the open-shell nuclei, leading to the "bell shape" behaviour of $Ca$ isotopes. In particular, this originates from the repulsive nature of the rearrangement potential, and cannot simply be mocked up by a refit of the pairing strength. At the same time, we notice some drawbacks of the Fayans standard EDFs, that may call for investigating a more general form of it.
↳ nucl-thnucl-ex0 citations
09
Quantum noninvasive three-component beam-spin polarimetry in the Hadron Storage Ring of the Electron-Ion Collider
Frank Rathmann🇺🇸
We propose a noninvasive SQUID-based polarimeter for the polarized proton beam in the Electron-Ion Collider (EIC) Hadron Storage Ring (HSR), exploiting the collective magnetic dipole moment of the bunches rather than scattering. The six-snake HSR lattice has synchronous-particle spin tune $ν_{s} = 1/2$ , placing the in-plane spin-precession signal at half the revolution frequency ( $\sim$ 39 kHz), in the DC SQUID band. Three pickup channels (cosine- $θ$ and sine- $θ$ saddle loops for the transverse components, a coaxial axial gradiometer for the longitudinal one) reconstruct the full polarization vector $(P_{x}, P_{y}, P_{z})$ in two complementary modes. Static mode, the default for continuous noninvasive monitoring, reads all three components: $P_{y}$ at the revolution frequency and the residual in-plane components at $ν_{s} f_{rev}$ , bunch by bunch over an hours-long fill, including $P_{z}$ , inaccessible to single-spin scattering polarimetry by parity conservation. Dynamic mode gives a precise polarization-magnitude measurement: a longitudinal kicker tips a small fraction of the polarization into the horizontal (ring) plane to produce a free-induction-decay (FID) signal, and many phase-locked tip- $π$ -echo-restore cycles are summed coherently via a matched filter across all bunches, with $O (α^{2} / π^{2}) \sim 1 0^{- 4}$ loss per cycle, negligible over a full $δ P / P = 1%$ measurement. For tipping angle $α = 30$ mrad, polarization $P = 0.7$ , and effective rms spin-tune spread $σ_{ν_{s}}^{eff} = 1 0^{- 3}$ (coherence time $\sim$ 2 ms), the integration time to reach $δ P / P = 1%$ is about 18 s at injection and 5 min at flattop. The architecture extends to deuteron and $^{3}$ He beams via species-specific spin-magnetic factors, with applications to storage-ring EDM searches.
↳ physics.acc-phhep-exnucl-exphysics.ins-det0 citations
10
Multistage dynamical modeling of heavy-ion collisions
Lipei Du🇺🇸
Relativistic heavy-ion collisions create deconfined QCD matter whose properties must be inferred from final-state observables through dynamical modeling. This contribution discusses recent progress and open issues in multistage simulations, with emphasis on the connection between bulk evolution, conserved charges, strangeness, and heavy flavor. At RHIC Beam Energy Scan energies, the breaking of longitudinal boost invariance makes charge stopping and rapidity-dependent observables essential for constraining the finite-density medium. Strange hadrons are sensitive to the local chemical environment and conserved-charge correlations, while heavy flavor probes microscopic transport and hadronization. Combining these observables within multi-sector inference frameworks provides a path toward more robust constraints on the equation of state and transport properties of QCD matter.
↳ nucl-thhep-phnucl-ex1 citation
11
Full Configuration Interaction Quantum Monte Carlo for Accurate $Ab Initio$ Nuclear Structure Calculations
Rongzhe Hu🇨🇳 · Furong Xu🇨🇳 · Baishan Hu🇺🇸 · Ali Alavi🇮🇷
We introduce novel full configuration interaction quantum Monte Carlo (FCIQMC) as an accurate many-body solver for $ab initio$ nuclear structure calculations. This stochastic approach directly samples the exact wave function in the full configuration space, enabling high-fidelity treatment of high-order many-body correlations in strongly interacting nuclear systems. Using interactions from chiral effective field theory, we have computed ground-state energies and charge radii of $^{4}$ He, $^{8}$ Be, $^{12}$ C and $^{16}$ O with sub-percent-level many-body uncertainties. These results establish FCIQMC as a stochastic full-configuration-space solver capable of treating systems beyond the reach of the conventional no-core shell model, and as an accurate benchmark for truncated many-body expansion methods.
↳ nucl-thnucl-ex1 citation
12
Exploring Pion-Induced High-Momentum Components in Nuclei via $(p, p^{'} π)$ Reactions
Junki Tanaka🇯🇵 · Junichi Kato · Hiroshi Toki🇯🇵
Pion exchange plays a fundamental role in nuclear structure and is responsible for tensor correlations and high-momentum components in nuclei. The $(p, p^{'} π)$ reaction provides a unique opportunity to investigate pion dynamics under large-momentum-transfer conditions. Its three-body kinematics allows large momentum transfer to be achieved while keeping the excitation energy of the residual nucleus low. We investigate the kinematical properties of the $^{12} C (p, p^{'} π^{+})^{12} B$ reaction using Lorentz-invariant three-body phase-space calculations. The calculations were performed for a 392-MeV proton beam assuming a constant transition amplitude. The resulting momentum-transfer map and phase-space distribution identify experimentally accessible regions of large momentum transfer and provide guidance for optimizing a double-arm spectrometer experiment at RCNP. The present study establishes a model-independent kinematical foundation for future investigations of pion-induced correlations, high-momentum components, and pion dynamics in nuclei.
↳ nucl-thnucl-ex0 citations
13
Ultra-Peripheral Collisions as a Nuclear-Structure Interferometer with Interpretable Multitask Deep Learning
Jing-Zong Zhang🇨🇳 · Wang-Mei Zha🇨🇳 · Lingxiao Wang🇯🇵 · Guo-Liang Ma🇨🇳
Precise knowledge of nuclear structure is essential across fundamental physics, yet probing these structures is notoriously difficult. To address this challenge, ultra-peripheral collisions (UPCs) provide a femtoscopic tomography for imaging the atomic nucleus. UPCs offer a pristine electromagnetic pathway: coherent vector-meson photoproduction generates patterns of diffraction and two-source interference that directly encode the nuclear spatial density. Turning these patterns into quantitative constraints is, however, a challenging inverse problem, complicated by correlated sensitivities to deformation and neutron skin, phase smearing, and experimental backgrounds. Here we introduce an interpretable Multitask deep-learning framework that maps transverse momentum distributions to multiple nuclear-structure indicators simultaneously and identifies the kinematic regions driving each inference. We demonstrate the approach with coherent $J / ψ$ photoproduction in $_{40}^{96} Zr +_{40}^{96} Zr$ collisions, showing that the learned features separate diffraction-dominated and interference-dominated information and provide analysis-ready observables for future high-luminosity data.
↳ nucl-thcs.LGnucl-exphysics.optics+10 citations
14
Quantification of the Flavor Diagonal Hadronic CP Violation
Nodoka Yamanaka🇯🇵
The flavor diagonal CP violation of elementary particle physics contributes to the atomic, nuclear, and nucleon electric dipole moments (EDMs), T-violating neutron optics, and to the angular correlations of beta decay. In this contribution, we review the basics and the importance of CP violation in the search for new physics beyond the standard model, the recent progress in the quantification of the hadron level CP violation contributing to the aforementioned observables, and finally the current attempt to solve the strong CP problem without additional interactions and fields.
↳ hep-phhep-exhep-thnucl-ex+10 citations

Affiliations

first authorsco-authorsvia INSPIRE