Fri·May 20, 2022Friday·May 20, 2022

1. 01*

   Emergence of an island of extreme nuclear isomerism at high excitation near ${}^{208}$Pb

   S.G. Wahid🇮🇳 · S.K. Tandel · Saket Suman · P.C. Srivastava🇮🇳 · Anil Kumar🇮🇳 · P. Chowdhury🇺🇸 · F.G. Kondev🇺🇸 · R.V.F. Janssens🇺🇸 · M.P. Carpenter🇺🇸 · T. Lauritsen🇺🇸 · D. Seweryniak🇺🇸 · S. Zhu

   Metastable states with T${}_{1/2}$ = 8(2) ms in ${}^{205}$Bi and T${}_{1/2}$ = 0.22(2) ms in ${}^{204}$Pb, with $\approx$ 8 MeV excitation energy and angular momentum $\ge$ 22 $\hslash$, have been established. These represent, by up to two orders of magnitude, the longest-lived nuclear states above an excitation energy of 7 MeV, ever identified in the nuclear chart. Additionally, the half-life of the 10.17 MeV state in ${}^{206}$Bi has been determined to be 0.027(2) ms, the next highest value in this highly excited regime. These observations indicate the emergence of an island of extreme nuclear isomerism arising from core-excited configurations at high excitation in the vicinity of the doubly closed-shell nucleus ${}^{208}$Pb. These results are expected to provide discriminating tests of the effective interactions used in current large-scale shell-model calculations.

   nucl-exPLB(2022)·15 citations
2. 02*

   Feasibility of studying astrophysically important charged-particle emission with the variable energy $\gamma$-ray system at the Extreme Light Infrastructure -- Nuclear Physics facility

   H.Y. Lan🇨🇳 · W. Luo🇺🇸 · Y. Xu · D.L. Balabanski🇷🇴 · G.L. Guardo · M. La Cognata🇮🇹 · D. Lattuada🇮🇹 · C. Matei🇷🇴 · R.G. Pizzone🇮🇹 · T. Rauscher🇨🇭 · J.L. Zhou🇨🇳

   In the environment of a hot plasma, as achieved in stellar explosions, capture and photodisintegration reactions proceeding on excited states in the nucleus can considerably contribute to the astrophysical reaction rate. Such reaction rates including the excited-state contribution are obtained from theoretical calculations as the direct experimental determination of these astrophysical rates is currently unfeasible. In the present study, ($\gamma$,p) and ($\gamma$,$\alpha$) reactions in the mass and energy range relevant to the astrophysical $p$ process are considered and the feasibility of measuring them with the ELISSA detector system at the future Variable Energy $\gamma$-ray (VEGA) facility at ELI-NP is investigated. The simulation results reveal that, for the ($\gamma$,p) reaction on twelve targets of ${}^{29}$Si, ${}^{56}$Fe, ${}^{74}$Se, ${}^{84}$Sr, ${}^{91}$Zr, ${}^{96,98}$Ru, ${}^{102}$Pd, ${}^{106}$Cd, and ${}^{115,117,119}$Sn, and the ($\gamma$,$\alpha$) reaction on five targets of ${}^{50}$V, ${}^{87}$Sr, ${}^{123,125}$Te, and ${}^{149}$Sm, the yields of the reaction channels with the transitions to the excited states in the residual nucleus are relevant and even dominant. It is further found that for each considered reaction, the total yields of the charged-particle $X$ may be dominantly contributed from one, two or three ($\gamma$,$X_i$) channels within a specific, narrow energy range of the incident $\gamma$-beam. Furthermore, the energy spectra of the ($\gamma$,$X_i$) channels with $0\le i\le 10$ are simulated for each considered reaction, with the incident $\gamma$-beam energies in the respective energy range as derived before. It becomes evident that measurements of the photon-induced reactions with charged-particle emissions considered in this work are feasible with the VEGA+ELISSA system and will provide knowledge useful for nuclear astrophysics.

   nucl-exastro-ph.IMnucl-thPRC(2022)·6 citations
3. 03*

   AI-assisted Optimization of the ECCE Tracking System at the Electron Ion Collider

   C. Fanelli · Z. Papandreou · K. Suresh · J. K. Adkins · Y. Akiba · A. Albataineh · M. Amaryan · I. C. Arsene · C. Ayerbe Gayoso · J. Bae · X. Bai · M.D. Baker and 271 other authors

   The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to leverage Artificial Intelligence (AI) already starting from the design and R&D phases. The EIC Comprehensive Chromodynamics Experiment (ECCE) is a consortium that proposed a detector design based on a 1.5T solenoid. The EIC detector proposal review concluded that the ECCE design will serve as the reference design for an EIC detector. Herein we describe a comprehensive optimization of the ECCE tracker using AI. The work required a complex parametrization of the simulated detector system. Our approach dealt with an optimization problem in a multidimensional design space driven by multiple objectives that encode the detector performance, while satisfying several mechanical constraints. We describe our strategy and show results obtained for the ECCE tracking system. The AI-assisted design is agnostic to the simulation framework and can be extended to other sub-detectors or to a system of sub-detectors to further optimize the performance of the EIC detector.

   ↳ physics.ins-detcs.LGhep-exnucl-ex+1Nucl.Instrum.Meth.A(2023)·12 citations
4. 04*

   Impact of the Dresden-II and COHERENT neutrino scattering data on neutrino electromagnetic properties and electroweak physics

   M. Atzori Corona🇮🇹 · M. Cadeddu🇮🇹 · N. Cargioli🇮🇹 · F. Dordei🇮🇹 · C. Giunti🇮🇹 · Y.F. Li🇨🇳 · C. A. Ternes🇮🇹 · Y.Y. Zhang🇨🇳

   Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) represents a powerful tool to investigate key electroweak physics parameters and neutrino properties since its first observation in 2017 by the COHERENT experiment exploiting the spallation neutron source at Oak Ridge National Laboratory. In light of the recent detection of such a process with antineutrinos produced by the Dresden-II reactor scattering off a germanium detector, we revisit the limits so far set on the neutrino magnetic moments, charge radii and millicharges as well as on the weak mixing angle. In order to do so, we also include the contribution of elastic neutrino-electron scattering, whose effect becomes non negligible in some beyond the Standard Model theories. By using different hypotheses for the germanium quenching factor and the reactor antineutrino flux, we provide a measurement of the weak mixing angle at the low-energy scale of the Dresden-II reactor experiment and, thanks to a combined analysis with the latest cesium iodide and argon data set released by the COHERENT Collaboration, we deliver updated limits for the neutrino electromagnetic properties. Interestingly, we are able to set a new best upper limit on the electron neutrino charge radius and significantly improve the other CE$\nu$NS-related limits on the neutrino electric charge and magnetic moment.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2022)·81 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.