Fri·Sep 15, 2023Friday·September 15, 2023

1. 01*

   EXFOR-based simultaneous evaluation for neutron-induced fission cross section of plutonium-242

   Riko Okuyama · Naohiko Otuka · Go Chiba · Osamu Iwamoto

   The ${}^{242}$Pu neutron-induced fission cross section was evaluated from 100 keV to 200 MeV. The experimental ${}^{242}$Pu and ${}^{235}$U fission cross sections and their ratios in the EXFOR library were reviewed and analysed by the least-squares method. Additional simultaneous evaluation was performed by including the experimental database of the ${}^{233,238}$U and ${}^{239,240,241}$Pu fission cross sections and their ratios developed for JENDL-5 evaluation. The ${}^{242}$Pu fission cross sections from our evaluation and JENDL-5 evaluation are close to each other below 1 MeV while systematically differ from each other above 10 MeV. The cross section from our evaluation is systematically lower than the JENDL-4.0 cross section in the prompt fission neutron spectrum peak region ($\sim$5% lower around 1 MeV). The newly evaluated ${}^{242}$Pu fission cross section was verified against the cross section measured in the ${}^{252}$Cf spontaneous fission neutron field and criticalities of small-sized LANL fast systems, and demonstrated better performance than the JENDL-4.0 cross section on the same level with the JENDL-5 cross section.

   nucl-exJ.Nucl.Sci.Tech.(2024)·2 citations
2. 02*

   Field Theory of the Fermi Function

   Richard J. Hill🇺🇸 · Ryan Plestid🇺🇸

   The Fermi function $F(Z,E)$ accounts for QED corrections to beta decays that are enhanced at either small electron velocity $\beta$ or large nuclear charge $Z$. For precision applications, the Fermi function must be combined with other radiative corrections and with scale- and scheme-dependent hadronic matrix elements. We formulate the Fermi function as a field theory object and present a new factorization formula for QED radiative corrections to beta decays. We provide new results for the anomalous dimension of the corresponding effective operator complete through three loops, and resum perturbative logarithms and $\pi$-enhancements with renormalization group methods. Our results are important for tests of fundamental physics with precision beta decay and related processes.

   ↳ hep-phhep-thnucl-exnucl-thPRL(2024)·32 citations
3. 03*

   At the borderline of shape coexistence: Mo and Ru

   E. Maya-Barbecho · S. Baid🇪🇸 · J.M. Arias🇪🇸 · J.E. García-Ramos🇪🇸

   Background Even-even isotopes of Mo ($Z=42$) and Ru ($Z=44$) are nuclei close to the subshell closure at $Z=40$, where shape coexistence plays a significant role. As a result, their spectroscopic properties are expected to resemble those of Sr ($Z=38$) and Zr ($Z=40$). Exploring the evolution of these properties as they move away from the subshell closure is of great interest. Purpose The purpose of this study is to reproduce the spectroscopic properties of even-even ${}_{42}^{96-110}$Mo and ${}_{44}^{98-114}$Ru isotopes and to determine the influence of shape coexistence. Method We have employed the interacting boson model with configuration mixing as the framework to calculate all the observables for Mo and Ru isotopes. We have considered two types of configurations: 0-particle-0-hole and 2-particle-2-hole excitations. The model parameters have been determined using a least-squares fitting to match the excitation energies and the $B(E2)$ transition rates. Results We have obtained the excitation energies, $B(E2)$ values, two-neutron separation energies, nuclear radii, and isotope shifts for the entire chain of isotopes. Our theoretical results have shown good agreement with experimental data. Furthermore, we have conducted a detailed analysis of the wave functions and obtained the mean-field energy surfaces and the nuclear deformation parameter, $\beta$, for all considered isotopes. Conclusions Our findings reveal that shape coexistence plays a significant role in Mo isotopes, with the crossing of intruder and regular configurations occurring at neutron number $60$ ($A=102$), which induces a quantum phase transition. In contrast, in Ru isotopes, the intruder states have minimal influence, remaining at higher energies. However, at neutron number $60$, also a quantum phase transition occurs in Ru isotopes.

   ↳ nucl-thnucl-exPRC(2023)·10 citations
4. 04*

   Normalized factorial moments of spatial distributions of particles in high multiplicity events: A Toy model study

   Sheetal Sharma🇮🇳 · Salman Khurshid Malik🇮🇳 · Zarina Banoo🇮🇳 · Ramni Gupta🇮🇳

   In ultra-relativistic heavy-ion collisions a strongly interacting complex system of quarks and gluons is formed. The nature of the system so created and the mechanism of multi-particle production in these collisions may be revealed by studying the normalized factorial moments ($F_{\mathrm{q}}$) as function of various parameters. The resilience of $F_{\mathrm{q}}$ moments studied using Toy model events shows that these are sensitive to the presence of dynamical fluctuations in the system and are robust against the uniform efficiencies in the data measurements. Results of this study serve as a suitable reference baseline for the experimental and simulation studies.

   ↳ hep-phhep-exnlin.AOnucl-exNPA(2025)·2 citations
5. 05*

   Particle identification with machine learning in ALICE Run 3

   Maja Karwowska🇨🇭 · Monika Jakubowska🇵🇱 · Łukasz Graczykowski🇵🇱 · Kamil Deja🇵🇱 · Miłosz Kasak (for the ALICE Collaboration)🇵🇱

   The main focus of the ALICE experiment, quark--gluon plasma measurements, requires accurate particle identification (PID). The ALICE subdetectors allow identifying particles over a broad momentum interval ranging from about 100 MeV/c up to 20 GeV/c. However, a machine learning (ML) model can explore more detector information. During LHC Run 2, preliminary studies with Random Forests obtained much higher efficiencies and purities for selected particles than standard techniques. For Run 3, we investigate Domain Adaptation Neural Networks that account for the discrepancies between the Monte Carlo simulations and the experimental data. Preliminary studies show that domain adaptation improves particle classification. Moreover, the solution is extended with Feature Set Embedding and attention to give the network more flexibility to train on data with various sets of detector signals. PID ML is already integrated with the ALICE Run 3 Analysis Framework. Preliminary results for the PID of selected particle species, including real-world analyzes, are discussed as well as the possible optimizations.

   ↳ hep-exnucl-exphysics.ins-detEPJ Web Conf.(2024)·6 citations
6. 06*

   Recent Progress in Low Energy Neutrino Scattering Physics and Its Implications for the Standard and Beyond the Standard Model Physics

   V. Pandey🇺🇸

   Neutrinos continue to provide a testing ground for the structure of the standard model of particle physics as well as hints towards the physics beyond the standard model. Neutrinos of energies spanning over several orders of magnitude, originating in many terrestrial and astrophysical processes, have been detected via various decay and interaction mechanisms. At MeV scales, there has been one elusive process, until a few years ago, known as coherent elastic neutrino-nucleus scattering (CEvNS) that was theoretically predicted over five decades ago but was never observed experimentally. The recent experimental observation of the CEvNS process by the COHERENT collaboration at a stopped pion neutrino source has inspired physicists across many subfields. This has vital implications for nuclear physics, high-energy physics, astrophysics, and beyond. CEvNS, being a low-energy process, provides a natural window to study light, weakly-coupled, new physics in the neutrino sector. In this review, we intend to provide the current status of low energy neutrino scattering physics and its implications for the standard and beyond the standard model physics. We discuss the general formalism of calculating the tree-level CEvNS cross section and present estimated theoretical uncertainties on the CEvNS cross section stemming from different sources. We also discuss the inelastic scattering of tens of MeV neutrinos that have implications for supernova detection in future neutrino experiments. We discuss how the CEvNS experiments can be used as a testing ground for the Standard Model (SM) weak physics as well as in searching for the Beyond the Standard Model (BSM) physics signals. Any deviation from the SM predicted event rate either with a change in the total event rate or with a change in the shape of the recoil spectrum, could indicate new contributions to the interaction cross-section.

   ↳ hep-phhep-exnucl-exnucl-thPPNP(2024)·23 citations
7. 07*

   Method for measuring the charge radii of charged hyperons from the time-like region

   Yong-Hui Lin🇩🇪 · Feng-Kun Guo🇨🇳 · Ulf-G. Meißner🇩🇪

   We propose a novel method for measuring the charge radii of charged stable hadrons, with which the first measurement of the charge radii of the ${\Sigma }^{+}$ and the ${\Xi }^{-}$ is foreseen. The method explores the facts that the Dalitz decay $\psi (2S)\to Y\bar{Y}{e}^{+}{e}^{-}$ contains the hyperon form factors and the lowest measurable four-momentum transfer squared can be as low as $\sim 4m_e^2=1.05\times 10^{-6}\mathrm{Ge}{\mathrm{V}}^2$ in the time-like region. We identify a kinematic region where the hyperon form factors are essential and propose a method for subtracting the background from the data. It is estimated that the hyperon charge radii can be measured to a precision of about {0.2~fm} with the BES\Rom{3} experiment and one order of magnitude better at the future Super $\tau$-Charm Facility. Moreover, the same method can be used to measure the charge radius of the proton, which provides an independent cross-check on the extraction of proton radius from elastic $ep$ scattering or leptonic hydrogen spectroscopy.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2024)·3 citations
8. 08*

   Nuclear Recoil Identification in a Scientific Charge-Coupled Device

   K.J. McGuire🇺🇸 · A.E. Chavarria🇺🇸 · N. Castello-Mor🇪🇸 · S. Lee🇨🇭 · B. Kilminster🇨🇭 · R. Vilar🇪🇸 · A. Alvarez🇺🇸 · J. Jung🇺🇸 · J. Cuevas-Zepeda🇺🇸 · C. De Dominicis🇫🇷 · R. Gaïor🇫🇷 · L. Iddir🇫🇷 and 10 other authors

   Charge-coupled devices (CCDs) are a leading technology in direct dark matter searches because of their eV-scale energy threshold and high spatial resolution. The sensitivity of future CCD experiments could be enhanced by distinguishing nuclear recoil signals from electronic recoil backgrounds in the CCD silicon target. We present a technique for event-by-event identification of nuclear recoils based on the spatial correlation between the primary ionization event and the lattice defect left behind by the recoiling atom, later identified as a localized excess of leakage current under thermal stimulation. By irradiating a CCD with an ${}^{241}$Am${}^9$Be neutron source, we demonstrate $>93\%$ identification efficiency for nuclear recoils with energies $>150$ keV, where the ionization events were confirmed to be nuclear recoils from topology. The technique remains fully efficient down to 90 keV, decreasing to 50$\%$ at 8 keV, and reaching ($6\pm 2$)$\%$ at 1.5--3.5 keV. Irradiation with a ${}^{24}$Na $\gamma$-ray source shows no evidence of defect generation by electronic recoils, with the fraction of electronic recoils with energies $<85$ keV that are spatially correlated with defects $<0.1$$\%$.

   ↳ physics.ins-detastro-ph.COhep-exnucl-exPRD(2024)·3 citations
9. 09*

   Shell-model study for allowed and forbidden ${\beta }^{-}$ decay properties in the mass region "south" of ${}^{208}$Pb

   Shweta Sharma🇮🇳 · Praveen C. Srivastava🇮🇳 · Anil Kumar🇮🇳 · Toshio Suzuki🇯🇵 · Cenxi Yuan🇨🇳 · Noritaka Shimizu🇯🇵

   The large-scale shell-model calculations have been performed for the neutron-rich nuclei in the south region of ${}^{208}$Pb in the nuclear chart. The $\beta$-decay properties, such as the $\log ft$, average shape factor values, half-lives, and partial decay rates are calculated for these neutron-rich nuclei using recent effective interaction for the ${}^{208}$Pb region. These calculations have been performed without truncation in a particular model space for nuclei $N\le 126$; additionally, particle-hole excitations are included in the case of core-breaking nuclei ($Z\le 82,N>126$). An extensive comparison with the experimental data has been made, and spin parities of several states have been proposed.

   ↳ nucl-thnucl-exPRC(2024)·6 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.