Wed·Aug 14, 2024Wednesday·August 14, 2024

1. 01*

   An assay-based background projection for the MAJORANA DEMONSTRATOR using Monte Carlo Uncertainty Propagation

   I.J. Arnquist🇺🇸 · F.T. Avignone III🇺🇸 · A.S. Barabash🇷🇺 · C.J. Barton🇺🇸 · K.H. Bhimani🇺🇸 · E. Blalock🇺🇸 · B. Bos🇺🇸 · M. Busch🇺🇸 · T.S. Caldwell🇺🇸 · Y.-D. Chan🇺🇸 · C.D. Christofferson🇺🇸 · P.-H. Chu🇺🇸 and 44 other authors

   The background index is an important quantity which is used in projecting and calculating the half-life sensitivity of neutrinoless double-beta decay ($0\nu \beta \beta$) experiments. A novel analysis framework is presented to calculate the background index using the specific activities, masses and simulated efficiencies of an experiment's components as distributions. This Bayesian framework includes a unified approach to combine specific activities from assay. Monte Carlo uncertainty propagation is used to build a background index distribution from the specific activity, mass and efficiency distributions. This analysis method is applied to the MAJORANA DEMONSTRATOR, which deployed arrays of high-purity Ge detectors enriched in ${}^{76}$Ge to search for $0\nu \beta \beta$. The framework projects a mean background index of $\left[8.95\pm 0.36\right]\times 10^{-4}$cts/(keV kg yr) from ${}^{232}$Th and ${}^{238}$U in the DEMONSTRATOR's components.

   nucl-exphysics.ins-detPRC(2024)·1 citation
2. 02*

   Shape Coexistence in ${}^{94}$Zr from a Model-Independent Analysis

   N. Marchini (1 and 2)🇮🇹 · M. Rocchini (1)🇮🇹 · M. Zielinska (3)🇫🇷 · A. Nannini (1)🇮🇹 · D.T. Doherty (4)🇬🇧 · N. Gavrielov (5)🇫🇷 · P.E. Garrett (6)🇨🇦 · K. Hadynska-Klek (7)🇵🇱 · A. Goasduff (8 and 9)🇮🇹 · D. Testov (8)🇮🇹 · S.D. Bakes (4 and 9 and 10)🇬🇧 · D. Bazzacco (8 and 9)🇮🇹 and 24 other authors

   Low-lying states of ${}^{94}$Zr were investigated via low-energy multi-step Coulomb excitation. From the measured $\gamma$-ray yields, \textcolor{black}{16} reduced \textcolor{black}{E2} transition probabilities between low-spin states were determined, together with the spectroscopic quadrupole moments of the $2_{1,2}^{+}$ states. Based on this information, for the first time in the Zr isotopic chain, the shapes of the $0_{1,2}^{+}$ states including their deformation softness were inferred in a model-independent way using the quadrupole sum rules approach. The ground state of ${}^{94}$Zr possesses a rather diffuse shape associated with a spherical configuration, while the $0_2^{+}$ state is \textcolor{black}{triaxial tending towards} oblate and more strongly deformed. {\color{black}The observed features of shape coexistence in ${}^{94}$Zr are consistent with both Monte-Carlo shell-model predictions and IBM-CM calculations, and provide model-independent constraints on the shape character assigned in the IBM-CM to the intruder configuration in ${}^{92\text{–}96}$Zr.}

   nucl-exnucl-thPLB(2026)·3 citations
3. 03*

   The triton lifetime from nuclear lattice effective field theory

   Serdar Elhatisari🇹🇷 · Fabian Hildenbrand🇩🇪 · Ulf-G. Meißner🇩🇪

   In this work, we present a calculation of the triton $\beta$-decay lifetime using Nuclear Lattice Effective Field Theory (NLEFT) at next-to-next-to-next-to-leading order in the chiral expansion. By incorporating a non-perturbative treatment of the higher-order corrections, we achieve consistent predictions for the Fermi and Gamow-Teller matrix elements, which are crucial for determining the triton lifetime. Our results are consistent with earlier theoretical calculations, confirming the robustness of our approach. This study marks a significant advancement in the systematic application of NLEFT to nuclear $\beta$-decay processes, paving the way for future high-precision calculations in more complex nuclear systems. Additionally, we discuss potential improvements to our approach, including the explicit inclusion of two-pion exchange mechanisms and the refinement of three-nucleon forces. These developments are essential for extending the applicability of NLEFT to a broader range of nuclear phenomena, including neutrinoless double-$\beta$ decay.

   ↳ nucl-thhep-lathep-phnucl-exPLB(2024)·10 citations
4. 04*

   Nuclear Excitation by Near-Resonant Electron Transition in ${}^{229}$Th${}^{39+}$ Ions

   Karol Kozioł · Jacek Rzadkiewicz

   Theoretical considerations are made for the nuclear excitation from the ground state to the 8 eV ${}^{229m}$Th isomer via near-resonant electron transitions in Sb-like ($q=39+$) thorium ions. The energy of the first excited atomic state ($J=7/2$) in the ${}^{229}$Th${}^{39+}$ ion is estimated to be 8.308$\pm$0.069 eV, which is very close to the new reference value for the ${}^{229m}$Th nuclear isomer energy, 8.356 eV [Zhang et al., Nature 633, 63 (2024)]. Therefore, the ${}^{229}$Th${}^{39+}$ ion provides a unique opportunity to study the nuclear excitation by electron transition process under well-defined atomic conditions in the regime of extremely low nuclear excitation energy. Our results indicate that the upper theoretical limit for the ${}^{229m}$Th isomer excitation rate reaches an enormous value of $1.27\times 10^{16}$ s${}^{-1}$ at resonance ($\Delta =0$ meV), but drops many orders of magnitude for the value of electronic transition energy within its uncertainty interval. Additionally, it was shown that using an electron beam ion trap, the production of the ${}^{229}$Th isomer can reach rates ranging from a few to approximately $7\times 10^{19}$ ${}^{-1}$.

   ↳ physics.atom-phnucl-exnucl-thquant-phPRC(2025)·4 citations
5. 05*

   Search for baryon junctions in e+A collisions at the Electron Ion Collider

   Niseem Magdy🇺🇸 · Abhay Deshpande🇺🇸 · Roy Lacey🇺🇸 · Wenliang Li🇺🇸 · Prithwish Tribedy🇺🇸 · Zhangbu Xu🇺🇸

   Constituent quarks in a nucleon are the essential elements in the standard ``quark model" associated with the electric charge, spin, mass, and baryon number of a nucleon. Quantum Chromodynamics (QCD) describes nucleon as a composite object containing current quarks (valence quarks and sea (anti-)quarks) and gluons. These subatomic elements and their interactions are known to contribute in complex ways to the overall nucleon spin and mass. In the early development of QCD theory in the 1970s, an alternative hypothesis postulated that the baryon number might manifest itself through a non-perturbative configuration of gluon fields forming a Y-shaped topology known as the gluon junction. In this work, we propose to test such hypothesis by measuring (i) the Regge intercept of the net-baryon distributions for $e$+($p$)Au collisions, (ii) baryon and charge transport in the isobaric ratio between $e$+Ru and $e$+Zr collisions, and (iii) target flavor dependence of proton and antiproton yields at large rapidity, transported from the hydrogen and deuterium targets in $e+p$(d) collisions. Our study indicates that these measurements at the EIC can help determine what carries the baryon number.

   ↳ hep-phhep-exnucl-exnucl-thEPJC(2024)·3 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.