Wed·Mar 12, 2025Wednesday·March 12, 2025

1. 01*

   Fingerprints of triaxiality in the charge radii of neutron-rich Ruthenium

   Bernhard Maass🇺🇸 · Wouter Ryssens🇧🇪 · Michael Bender🇫🇷 · Daniel P. Burdette🇺🇸 · Jason Clark🇺🇸 · Adam Dockery🇺🇸 · Guilherme Grams🇧🇪 · Max Horst🇩🇪 · Phillip Imgram🇩🇪 · Kristian König🇩🇪 · Kei Minamisono🇺🇸 · Patrick Müller and 10 other authors

   We present the first measurements with a new collinear laser spectroscopy setup at the Argonne Tandem Linac Accelerator System utilizing its unique capability to deliver neutron-rich refractory metal isotopes produced by the spontaneous fission of 252Cf. We measured isotope shifts from optical spectra for nine radioactive ruthenium isotopes 106-114Ru, reaching deep into the mid-shell region. The extracted charge radii are in excellent agreement with predictions from the Brussels-Skyrme-on-a-Grid models that account for the triaxial deformation of nuclear ground states in this region. We show that triaxial deformation impacts charge radii in models that feature shell effects, in contrast to what could be concluded from a liquid drop analysis. This indicates that this exotic type of deformation should not be neglected in regions where it is known to occur, even if its presence cannot be unambiguously inferred through laser spectroscopy.

   nucl-exnucl-thPRL(2025)·6 citations
2. 02*

   Charged-hadron and identified-hadron ($K_{\mathrm{S}}^0$, $\Lambda$, ${\Xi }^{-}$) yield measurements in photo-nuclear Pb+Pb and $p$+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with ATLAS

   ATLAS Collaboration

   This paper presents the measurement of charged-hadron and identified-hadron ($K_{\mathrm{S}}^0$, $\Lambda$, ${\Xi }^{-}$) yields in photo-nuclear collisions using 1.7 $\mathrm{n}{\mathrm{b}}^{-1}$ of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV Pb+Pb data collected in 2018 with the ATLAS detector at the Large Hadron Collider. Candidate photo-nuclear events are selected using a combination of tracking and calorimeter information, including the zero-degree calorimeter. The yields as a function of transverse momentum and rapidity are measured in these photo-nuclear collisions as a function of charged-particle multiplicity. These photo-nuclear results are compared with 0.1 $\mathrm{n}{\mathrm{b}}^{-1}$ of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV $p$+Pb data collected in 2016 by ATLAS using similar charged-particle multiplicity selections. These photo-nuclear measurements shed light on potential quark-gluon plasma formation in photo-nuclear collisions via observables sensitive to radial flow, enhanced baryon-to-meson ratios, and strangeness enhancement. The results are also compared with the Monte Carlo DPMJET-III generator and hydrodynamic calculations to test whether such photo-nuclear collisions may produce small droplets of quark-gluon plasma that flow collectively.

   nucl-exhep-exPRC(2025)·12 citations
3. 03*

   Neutrino masses and mixing: Entering the era of subpercent precision

   Francesco Capozzi🇮🇹 · William Giarè🇬🇧 · Eligio Lisi🇮🇹 · Antonio Marrone🇮🇹 · Alessandro Melchiorri🇮🇹 · Antonio Palazzo🇮🇹

   We perform an updated global analysis of the known and unknown parameters of the standard $3\nu$ framework as of 2025. The known oscillation parameters include three mixing angles $({\theta }_{12},{\theta }_{23},{\theta }_{13})$ and two squared mass gaps, chosen as $\delta m^2=m_2^2-m_1^2>0$ and $\Delta m^2=m_3^2-\frac{1}{2}(m_1^2+m_2^2)$, where $\alpha =\mathrm{sign}(\Delta m^2)$ distinguishes normal ordering (NO, $\alpha =+1$) from inverted ordering (IO, $\alpha =-1$). With respect to our previous 2021 update, the combination of oscillation data leads to appreciably reduced uncertainties for ${\theta }_{23}$, ${\theta }_{13}$ and $|\Delta m^2|$. In particular, $|\Delta m^2|$ is the first $3\nu$ parameter to enter the domain of subpercent precision (0.8\% at $1\sigma$). We underline some issues about systematics, that might affect this error estimate. Concerning oscillation unknowns, we find a relatively weak preference for NO versus IO (at $2.2\sigma$), for CP violation versus conservation in NO (1.3$\sigma$) and for the first ${\theta }_{23}$ octant versus the second in NO ($1.1\sigma$). We discuss the status and qualitative prospects of the mass ordering hint in the plane $(\delta m^2,\Delta m_{ee}^2)$, where $\Delta m_{ee}^2=|\Delta m^2|+\frac{1}{2}\alpha ({\cos }^2{\theta }_{12}-{\sin }^2{\theta }_{12})\delta m^2$, to be measured by the JUNO experiment with subpercent precision. We also discuss upper bounds on nonoscillation observables. We report $m_{\beta }<0.50$~eV and $m_{\beta \beta }<0.086$~eV ($2\sigma$). Concerning the sum of neutrino masses $\Sigma$, we discuss representative combinations of data, with or without augmenting the $\Lambda$CDM model with extra parameters accounting for possible systematics or new physics. The resulting $2\sigma$ upper limits are roughly spread around the bound $\Sigma <0.2$~eV within a factor of three. [Abridged]

   ↳ hep-phastro-ph.COhep-exnucl-exPRD(2025)·93 citations
4. 04*

   Gain characterization of LGAD sensors with beta particles and 28-MeV protons

   Mohamed Hijas Mohamed Farook🇺🇸 · Gabriele Giacomini🇺🇸 · Gabriele DAmen🇺🇸 · Giovanni Pinaroli🇺🇸 · Enrico Rossi🇺🇸 · Sally Seidel🇺🇸 · Alessandro Tricoli🇺🇸

   Low Gain Avalanche Diodes, also known as LGADs, are widely considered for fast-timing applications in high energy physics, nuclear physics, space science, medical imaging, and precision measurements of rare processes. Such devices are silicon-based and feature an intrinsic gain due to a $p{}^{+}$-doped layer that allows the production of a controlled avalanche of carriers, with multiplication on the order of 10-100. This technology can provide time resolution on the order of 20-30 ps, and variants of this technology can provide precision tracking too. The characterization of LGAD performance has so far primarily been focused on the interaction of minimum ionizing particles for high energy and nuclear physics applications. This article expands the study of LGAD performance to highly-ionizing particles, such as 28-MeV protons, which are relevant for several future scientific applications, e.g. in biology and medical physics, among others. These studies were performed with a beam of 28-MeV protons from a tandem Van de Graaff accelerator at Brookhaven National Laboratory and beta particles from a ${}^{90}\mathrm{Sr}$ source; these were used to characterize the response and the gain of an LGAD as a function of bias voltage and collected charge. The experimental results are also compared to TCAD simulations.

   ↳ physics.ins-dethep-exnucl-exphysics.app-phJINST·0 citations
5. 05*

   Study of 14.1 MeV Neutron Moderation in Beryllium

   Serena Fattori · Rino Persiani · Ugo Abundo

   This study investigates the moderation of 14.1 MeV neutrons in a natural beryllium moderator arranged in a spherical geometry. The neutron interactions and moderation efficiency were analyzed using Monte Carlo simulations with the GEANT4 toolkit. Various sphere radii were tested to determine the optimal moderator thickness for neutron thermalization.

   ↳ physics.ins-detnucl-exnucl-thphysics.comp-ph1 citation
6. 06*

   Investigating the broadening phenomenon in two-particle correlations induced by gluon saturation

   Kiera Cassar🇺🇸 · Zhen Wang🇨🇳 · Xiaoxuan Chu🇺🇸 · Elke-Caroline Aschenauer🇺🇸

   It has been found that the gluon density inside the proton grows rapidly at small momentum fractions. Quantum Chromodynamics (QCD) predicts that this growth can be regulated by nonlinear effects, ultimately leading to gluon saturation. Within the color glass condensate framework, nonlinear QCD effects are predicted to suppress and broaden back-to-back angular correlations in collisions involving heavy nuclei. While suppression has been observed in various experiments in $d/p$$+$A collisions compared to $p$$+$$p$ collisions, the predicted broadening remains unobserved. This study investigates the contributions of intrinsic transverse momentum ($k_T$), which is associated with saturation physics, as well as parton showers and transverse motion from fragmentation ($p_T^{\mathrm{frag}}$), which are not saturation dependent, to the width of the correlation function. Our findings show that the non-saturation dependent effects, especially the initial-state parton shower and $p_T^{\mathrm{frag}}$, which occur independently of the collision system, smear the back-to-back correlation more than gluon saturation does, making the broadening phenomenon difficult to observe.

   ↳ hep-phnucl-exnucl-thPRD(2025)·6 citations
7. 07*

   Most stringent bound on electron neutrino mass obtained with a scalable low temperature microcalorimeter array

   B.K. Alpert🇺🇸 · M. Balata🇮🇹 · D.T. Becker🇺🇸 · D.A. Bennett🇺🇸 · M. Borghesi🇮🇹 · P. Campana🇮🇹 · R. Carobene🇮🇹 · M. De Gerone🇮🇹 · W.B. Doriese🇺🇸 · M. Faverzani🇮🇹 · L. Ferrari Barusso🇮🇹 · E. Ferri🇮🇹 and 27 other authors

   The determination of the absolute neutrino mass scale remains a fundamental open question in particle physics, with profound implications for both the Standard Model and cosmology. Direct kinematic measurements, independent of model-dependent assumptions, provide the most robust approach to address this challenge. In this Letter, we present the most stringent upper bound on the effective electron neutrino mass ever obtained with a calorimetric measurement of the electron capture decay of ${}^{163}$Ho. The HOLMES experiment employs an array of ion-implanted transition-edge sensor (TES) microcalorimeters, achieving an average energy resolution of 6 eV FWHM with a scalable, multiplexed readout technique. With a total of $7\times 10^7$ decay events recorded over two months and a Bayesian statistical analysis, we derive an upper limit of $m_{\beta }<27$ eV/c${}^2$ at 90% credibility. These results validate the feasibility of ${}^{163}$Ho calorimetry for next-generation neutrino mass experiments and demonstrate the potential of a scalable TES-based microcalorimetric technique to push the sensitivity of direct neutrino mass measurements beyond the current state of the art.

   ↳ hep-exnucl-exphysics.ins-detPRL(2025)·19 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.