Fri·Sep 5, 2025Friday·September 5, 2025

1. 01*

   A high-lying isomer in ^{92}Zr with lifetime modulated by the atomic charge states: a proposed approach for a nuclear gamma-ray laser

   C. X. Jia🇨🇳 · S. Guo🇨🇳 · B. Ding🇨🇳 · X. H. Zhou🇨🇳 · C.X. Yuan🇨🇳 · W. Hua J. G. Wang🇨🇳 · S. W. Xu🇨🇳 · C. M. Petrache🇫🇷 · E. A. Lawrie🇿🇦 · Y. B. Wu🇩🇪 · Y. D. Fang🇨🇳 · Y. H. Qiang🇨🇳 and 36 other authors

   The nuclides ^{92}Zr are produced and transported by using a radioactive beam line to a lowbackground detection station. After a flight time of about 1.14 {\mu}s, the ions are implanted into a carbon foil, and four {\gamma} rays deexciting the 8+ state in ^{92}Zr are observed in coincidence with the implantation signals within a few nanoseconds. We conjecture that there exists an isomer located slightly above the 8^{+} state in ^{92}Zr. The isomeric lifetime in highly charged states is extended significantly due to the blocking of internal conversion decay channels, enabling its survival over the transportation. During the slowing-down process in the carbon foil, the ^{92}Zr ions capture electron and evolve toward neutral atoms, and consequently the lifetime is restored to a normal short value. Such a high-lying isomer depopulated by a low-energy transition may provide unique opportunity to develop nuclear {\gamma} laser.

   nucl-exphysics.atom-ph0 citations
2. 02*

   Measurement of coherent exclusive $J/\psi \to {\mu }^{+}{\mu }^{-}$ production in ultraperipheral Pb+Pb collisions at $\sqrt{s_{\text{NN}}}=5.36$ TeV with the ATLAS detector

   ATLAS Collaboration

   The ATLAS experiment has performed a measurement of coherent exclusive $J/\psi \to {\mu }^{+}{\mu }^{-}$ production in ultraperipheral Pb+Pb collisions at $\sqrt{s_{\text{NN}}}=5.36$ TeV. The data was recorded at the Large Hadron Collider (LHC) during 2023, and corresponds to an integrated luminosity of 79 $\mu$b${}^{-1}$. Exclusive $J/\psi$ candidates were selected with a dedicated track-sensitive trigger based on the ATLAS transition radiation tracker. The analysis involves reconstruction of the dimuon invariant mass based on muon tracks from the inner detector, as the muon transverse momentum range of interest precludes the use of the standard muon reconstruction and identification algorithms. Differential cross sections are measured as a function of $J/\psi$ rapidity and are compared with theoretical predictions. After extrapolation to $\sqrt{s_{\text{NN}}}=5.02$ TeV, they are also compared with previous measurements performed by other experiments using data from LHC Run 2. While the results agree reasonably well with theoretical predictions, they are in tension with previous Run-2 results for the central rapidity region.

   nucl-exhep-exJHEP(2026)·16 citations
3. 03*

   From CREX to CEvNS: The Weak Radius of 40Ar

   J. Piekarewicz🇺🇸

   Despite significant theoretical efforts, the CREX-PREX dilemma remains unresolved, preventing the reliable prediction of neutron (or weak-charge) radii that, besides their intrinsic nuclear-structure interest, often serve to quantify the impact of nuclear uncertainties in searches for new physics. Coherent elastic neutrino-nucleus scattering is a clean and attractive portal to new physics whose sensitivity may be impacted by such nuclear uncertainties. In this paper we use CREX as our main anchor, together with a strong calcium-argon correlation, to provide a robust baseline for the weak radius of ${}^{40}$Ar: $R_{\mathrm{wk}}^{40}=3.452\pm 0.028\text{(stat)}\pm 0.022\text{(syst)}\text{fm}$.The weak radius of argon is an observable highly relevant to ongoing and future liquid-argon campaigns that encodes the loss of coherence at small momentum transfers.

   ↳ nucl-thhep-exhep-thnucl-exPRC(2025)·4 citations
4. 04*

   Light nuclei under magnetic field and the lithium problem

   Nodoka Yamanaka🇯🇵

   We analyze the effect of the magnetic field on the proton and neutron density distributions of the nuclei 2H, 3H, 3He, which are calculated ab initio, and the 6Li nucleus in the alpha-cluster model. It is found that the asymptotic exponential damp of the probability density at long distance is modified, and that the linear component of the exponent with respect to the magnetic field yields the leading contribution, while those of the second derivative and the confining magnetic force are subleading. Due to the linear dependence of the exponent, fluctuating magnetic fields always enhance the tunneling rate, i.e. the cross section of low energy nuclear reactions which occur at large separation across the Coulomb barrier. While this mechanism cannot suppress the production of 7Be in the early Universe, it has the potential to resolve the lithium problem either by increasing the reaction rate of 7Be + p -> 8B at the bigbang nucleosynthesis era if the magnetic field at this time was sufficiently strong, or by correcting the systematically enlarged 4He + 3He -> 7Be cross section by the unwanted magnetic field generated in the nuclear experimental setup, which was so far used as the input of the simulation of bigbang nucleosynthesis.

   ↳ nucl-thastro-ph.COhep-phnucl-ex2 citations
5. 05*

   Exploring the fluid behavior in p+p collisions at $\sqrt{s}=13\mathrm{TeV}$ with viscous anisotropic hydrodynamics

   Shujun Zhao🇨🇳 · Yiyang Peng🇨🇳 · Ulrich W. Heinz🇺🇸 · Huichao Song🇨🇳

   The applicability of hydrodynamics in small collision systems remains controversial due to the small size and short lifetime of the system. In this letter, we employ viscous anisotropic hydrodynamics (VAH), which incorporates large pressure anisotropies, to study the collectivity in p+p collisions at $\sqrt{s}=13\mathrm{TeV}$.VAH provides a good description for $v_2\{2\}$ and $v_3\{2\}$ over a wide range of multiplicities and correctly reproduces the experimentally observed negative $c_2\{4\}$. Traditional second-order viscous hydrodynamics (VH), on the other hand, can describe the measurements, in particular the negative $c_2\{4\}$, only with model parameters for which the bulk of the evolution is characterized by large values of the shear Knudsen number. It also can not capture the large longitudinal/transverse pressure anisotropy during the early evolution. These demonstrate the failure of traditional viscous hydrodynamics in small collision systems and establish viscous anisotropic hydrodynamics as a more reliable framework to describe the bulk evolution and the observed anisotropic flow in p-p collisions at the LHC.

   ↳ nucl-thhep-phnucl-exPRL(2026)·2 citations
6. 06*

   Three models for charged hadron nuclear modification from light to heavy ions

   Wilke van der Schee🇨🇭 · Isobel Kolbé🇿🇦 · Govert Nijs🇨🇭 · Kumail Ruhani🇵🇰 · Ishtiaq Ahmed🇵🇰 · Shahin Iqbal🇵🇰

   In July 2025 the Large Hadron Collider (LHC) collided ${}^{16}$O${}^{16}$O and ${}^{20}$Ne${}^{20}$Ne isotopes in a quest to understand the physics of ultrarelativistic light ion collisions. One of the key motivations for this run is to discover partonic energy loss in systems with a small quark-gluon plasma (QGP). In this letter we combine a BDMPS-Z based model, a path-length based energy loss prescription, and JEWEL together with two realistic geometries of the ${}^{16}$O and ${}^{20}$Ne isotopes. The different sizes of the ions affect the energy loss in characteristically different ways depending on the model.

   ↳ nucl-thhep-phnucl-ex15 citations
7. 07*

   Detection of ultracold neutrons with powdered scintillator screens

   M. Krivos · N. C. Floyd🇺🇸 · C. L. Morris🇺🇸 · Z. Tang🇺🇸 · M. Blatnik🇺🇸 · S. M. Clayton🇺🇸 · C. B. Cude-Woods🇺🇸 · A.Fratangelo🇨🇭 · A. T. Holley🇺🇸 · D. E. Hooks · T. M. Ito🇺🇸 · C.-Y. Liu and 15 other authors

   Zinc sulfide (ZnS:Ag) scintillators coated with a thin 10B layer are widely used for ultracold neutron (UCN) detection, but their application is limited by long decay times and significant phosphorescence. We investigated two possible replacement scintillators: yttrium aluminum perovskite (YAP:Ce) and lutetium ttrium orthosilicate (LYSO:Ce). Both exhibit decay times on the order of 30-40 ns, which can help reduce dead time in high-count-rate experiments. YAP:Ce showed approximately 60% lower phosphorescence than ZnS:Ag after 2 days and detected about 20% more UCN. In contrast, LYSO:Ce exhibited higher phosphorescence and produced fewer UCN counts compared to both ZnS:Ag and YAP:Ce. While both tested scintillators are capable UCN detectors, YAP:Ce consistently outperformed LYSO:Ce across all measured performance metrics.

   ↳ physics.ins-detnucl-ex0 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.