Thu·Nov 27, 2025Thursday·November 27, 2025

1. 01*

   Constraining the Synthesis of the Lightest p Nucleus 74Se

   A. Tsantiri🇺🇸 · A. Spyrou🇺🇸 · E. C. Good🇺🇸 · K. Bosmpotinis🇺🇸 · P. Giuliani🇺🇸 · H. Arora🇺🇸 · G. Balk · L. Balliet🇺🇸 · H. C. Berg🇺🇸 · J. M. Berkman🇺🇸 · C. Dembski · P. DeYoung and 33 other authors

   We provide the first experimental cross section of the ${}^{73}\text{As}(p,\gamma {)}^{74}\text{Se}$ reaction to constrain one of the main destruction mechanisms of the p nucleus ${}^{74}\text{Se}$ in explosive stellar environments. The measurement was done using a radioactive ${}^{73}\text{As}$ beam at effective center-of-mass energies of 2.9 and 2.3 MeV/nucleon. Along with the total cross-section measurement, statistical properties of the ${}^{74}\text{Se}$ compound nucleus were extracted, constraining the reaction cross section in the upper Gamow window of the $\gamma$ process. The impact of the experimentally constrained reaction rate on ${}^{74}\text{Se}$ production in Type II supernovae was investigated through Monte Carlo one-zone network simulations. The results indicate that the overproduction of ${}^{74}$Se by Type II supernova models cannot be resolved by nuclear physics alone and point toward the need for a more detailed understanding of the astrophysical conditions of relevance for the $\gamma$ process.

   nucl-exPRL(2025)·3 citations
2. 02*

   First measurement of the energy and Mandelstam-$t$ dependence of both coherent and incoherent $J/\psi$ photonuclear production

   Vendulka Humlova (for the ALICE Collaboration)🇨🇿

   A new phenomenon, gluon saturation, is expected to emerge in quantum chromodynamics (QCD) at high energies, when gluon splitting and recombination processes reach a dynamic equilibrium. In heavy nuclei, this balance is expected to be achieved at lower energies than in protons, making lead-lead collisions at the LHC an ideal environment to probe the onset of saturation. The diffractive photoproduction of the $J/\psi$ vector meson provides an excellent tool to study this regime since it directly probes the gluon distribution in the target. ALICE offers unique kinematic coverage of the photon-nucleon centre-of-mass energy, spanning from 20 to 800 GeV, corresponding to three orders of magnitude in Bjorken-$x$ from about $10^{-2}$ down to $10^{-5}$. This contribution presents the latest ALICE results on the energy dependence of coherent $J/\psi$ production, which is sensitive to the average gluon density, and on the energy and Mandelstam-$t$ dependence of incoherent production, which probes fluctuations of the gluon field at different spatial scales. These measurements provide unprecedented constraints on models of QCD in the high-energy limit and mark a milestone in studying the gluonic structure of nuclei.

   nucl-ex0 citations
3. 03*

   High-Resolution Laser Spectroscopy on the Hyperfine Structure of ${}^{255}$Fm (Z=100)

   M. Urquiza-González🇸🇪 · M. Stemmler🇩🇪 · T. E. Albrecht🇺🇸 · B. Bally🇩🇪 · M. Bender🇫🇷 · S. Berndt🇩🇪 · M. Block🇩🇪 · A. Brizard🇩🇪 · J. S. Andrews🇩🇪 · J. Bieron🇵🇱 · P. Chhetri🇩🇪 · H. Dorrer🇩🇪 and 27 other authors

   We report on high-resolution laser spectroscopy of ${}^{255}$Fm ($T_{1/2}=20$h), one of the heaviest nuclides available from reactor breeding. The hyperfine structures in two different atomic ground-state transitions at 398.4~nm and 398.2~nm were probed by in-source laser spectroscopy at the RISIKO mass separator in Mainz, using the PI-LIST high-resolution ion source. Experimental results were combined with hyperfine fields from various atomic ab-initio calculations, in particular using MultiConfigurational Dirac-Hartree-Fock theory, as implemented in GRASP18. In this manner, the nuclear magnetic dipole and electric quadrupole moments were derived to be $\mu =-0.75(5){\mu }_{\text{N}}$ and $Q_{\text{S}}=+5.84(13)$~eb, respectively. The magnetic moment indicates occupation of the $\nu$~7/2[613] Nilsson orbital, while the large quadrupole moment confirms strong, stable prolate deformation consistent with systematics in the heavy actinides. Comparisons with available expectation values from nuclear theory show good agreement, providing a stringent benchmark for the used theoretical models. These results revise earlier data and establish ${}^{255}$Fm as a reference isotope for future high-resolution studies.

   ↳ physics.atom-phnucl-exPRL(2026)·1 citation
4. 04*

   Isotope Production in Muon-Catalyzed-Fusion Systems

   J. F. Parisi · A. Rutkowski

   Producing valuable isotopes with high-flux high-energy neutrons generated by muon-catalyzed fusion ($\mu$CF) reactions could substantially improve the economic prospects for muon-catalyzed fusion. Because no external heating is required for $\mu$CF, heat flux constraints are significantly relaxed compared with fusion systems requiring external heating. This could allow $\mu$CF to attain much higher neutron flux without breaching material heat flux limits. If muon production rates can be increased, $\mu$CF systems employing transmutation could be viable well before energy breakeven is possible. For $\mu$CF systems transmuting valuable isotopes, the required number of catalyzed fusion events per muon and muon energy generation cost can be relaxed by several orders of magnitude relative to electricity-generating systems, making $\mu$CF an attractive high-flux neutron source. We show an example $\mu$CF system with a 10 gram ${}^{226}\mathrm{Ra}$ feedstock and a steady-state muon rate of $10^{12}$ muons / second - roughly half a kilowatt of fusion power - could produce 20 mg of ${}^{225}\mathrm{Ac}$ per year - comparable to 400 times global supply in 2024. As higher muon rate sources become available, many other radioisotope transmutation pathways become viable. These findings motivate the accelerated development of $\mu$CF systems for neutron-driven isotope production far before net energy generation is possible.

   ↳ physics.plasm-phnucl-exphysics.acc-ph2 citations
5. 05*

   Updated bounds on the (1,2) neutrino oscillation parameters after first JUNO results

   Francesco Capozzi🇮🇹 · Eligio Lisi🇮🇹 · Francesco Marcone🇮🇹 · Antonio Marrone🇮🇹 · Antonio Palazzo🇮🇹

   Within the standard $3\nu$ framework, we discuss updated bounds on the leading oscillation parameters related to the $({\nu }_1,{\nu }_2)$ states, namely, the squared mass difference $\delta m^2=m_2^2-m_1^2$ and the mixing parameter ${\sin }^2{\theta }_{12}$. A previous global analysis of 2024 oscillation data estimated $\delta m^2$ and ${\sin }^2{\theta }_{12}$ with fractional $1\sigma$ errors of about $2.3\%$ and $4.5\%$, respectively. First we update the analysis by applying the latest SNO+ constraints, that slightly shift the $(\delta m^2,{\sin }^2{\theta }_{12})$ best fits. Then we apply the constraints placed by the first JUNO results, that significantly reduce the uncertainties of both parameters. Our updated global bounds (as of 2025) can be summarized as: $\delta m^2/10^{-5}{\mathrm{eV}}^2=7.48\pm 0.10$ and ${\sin }^2{\theta }_{12}=0.3085\pm 0.0073$ (with correlation $\rho =-0.20$), corresponding to $1\sigma$ uncertainties as small as $1.3\%$ and $2.4\%$, respectively. We also comment on minor physical and statistical effects that, in the future, may contribute to lift the current mass-ordering degeneracy of $(\delta m^2,{\theta }_{12})$ estimates.

   ↳ hep-phhep-exnucl-exPRD(2026)·24 citations
6. 06*

   Coincidence Algebra Bundle for Decay Quivers: An Algebraic Approach to Gamma-ray Spectroscopy

   Liam Schmidt

   Motivated by the need for a more comprehensive algebraic structure to calculate coincidence probabilities of a general decay scheme for gamma ray spectroscopy, we model the decay scheme, rather naturally, as a quiver through which we define a decay quiver. The path algebra of quivers is the underlying, more general, algebra for transition matrices that is typically used in modeling decay schemes. The path algebra allows for concatenation of transitions which affords the calculation of cascade probabilities. We extend the path algebra to allow for the multiplication of non-composable paths, i.e., transition that don't directly share a level connecting them. We define the coincidence algebra as the algebra that allows for such an extension and realize it as the fibres for a coincidence algebra bundle, the base space of which is the path algebra where decay schemes live. A given decay schemes coincidence probabilities are calculated on its fibre. \textit{Detection maps} are defined as maps on the base space that map transition probabilities to detected probabilities.

   ↳ physics.data-annucl-exphysics.ins-det0 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.