Fri·Mar 3, 2023Friday·March 3, 2023

1. 01*

   Realistic evaluation of Coulomb potential in spherical nuclei and test of the traditional approach

   L. Xayavong🇰🇷 · Y. Lim🇰🇷

   A realistic evaluation of Coulomb potential has been made for some selected nuclei using the available model-independent data for the charge density and the recent development of Coulomb energy-density functional. Within the Woods-Saxon potential as a nuclear component, we are able to quantify the differences in proton single-particle energies due to the differences from the model-independent data of the uniform distribution, the two-parameter Fermi function, as well as the charge density obtained from a microscopic Hartree-Fock calculation using the effective Skyrme interaction. The obtained energy differences are generally small in magnitude, namely about 100~keV or less if the parameters of the charge density models are appropriately determined. Considerable larger differences appear when the last occupied state is highly filled and, at the same time, has a small orbital angular momentum. Sulfur isotopes ($Z=16$) are a perfect example of these nuclei. Unfortunately, despite its simplicity, the uniform distribution cannot be used for evaluating the Coulomb exchange term within a well-established method because it is not differentiable at the surface of a nucleus. Traditionally, the missing of exchange term is corrected for by simply excluding the last-proton contribution to the direct term. %% We also investigate this approach and find that its effect is simply an introduction of the factor $(Z-1)/Z$ into the Coulomb direct term. From medium to heavy nuclei (typically beyond the $sd$ shell) the resulting proton levels are 300-800~keV higher than those obtained with the exact Fock term. The result for lighter nuclei tends to be opposite because the factor $(Z-1)/Z$ decreases rapidly towards the limit of $Z\to 1$. Therefore, this traditional approach should be avoided for a precision nuclear structure calculation.

   ↳ nucl-thnucl-exPRC(2023)·4 citations
2. 02*

   Search for Two-neutrino Double-Beta Decay of ${}^{136}\mathrm{Xe}$ to the $0_1^{+}$ excited state of ${}^{136}\mathrm{Ba}$ with the Complete EXO-200 Dataset

   EXO-200 Collaboration: S. Al Kharusi🇨🇦 · G. Anton🇩🇪 · I. Badhrees🇨🇦 · P.S. Barbeau🇺🇸 · D. Beck🇺🇸 · V. Belov🇷🇺 · T. Bhatta🇺🇸 · M. Breidenbach🇺🇸 · T. Brunner🇨🇦 · G.F. Cao🇨🇳 · W.R. Cen🇨🇦 · C. Chambers🇨🇦 and 94 other authors

   A new search for two-neutrino double-beta ($2\nu \beta \beta$) decay of ${}^{136}\mathrm{Xe}$ to the $0_1^{+}$ excited state of ${}^{136}\mathrm{Ba}$ is performed with the full EXO-200 dataset. A deep learning-based convolutional neural network is used to discriminate signal from background events. Signal detection efficiency is increased relative to previous searches by EXO-200 by more than a factor of two. With the addition of the Phase II dataset taken with an upgraded detector, the median 90$\%$ confidence level half-life sensitivity of $2\nu \beta \beta$ decay to the $0_1^{+}$ state of ${}^{136}\mathrm{Ba}$ is $2.9\times 10^{24}\mathrm{yr}$ using a total ${}^{136}\mathrm{Xe}$ exposure of $234.1\mathrm{kg}\mathrm{yr}$. No statistically significant evidence for $2\nu \beta \beta$ decay to the $0_1^{+}$ state is observed, leading to a lower limit of $T_{1/2}^{2\nu }(0^{+}\to 0_1^{+})>1.4\times 10^{24}\mathrm{yr}$ at 90$\%$ confidence level, improved by 70$\%$ relative to the current world's best constraint.

   ↳ hep-exnucl-exCPC(2023)·13 citations
3. 03*

   Single-particle spectroscopic strength from nucleon transfer reactions with a three-nucleon force contribution

   N. K. Timofeyuk🇬🇧 · L. Moschini · M. Gómez-Ramos🇪🇸

   The direct reaction theory widely used to study single-particle spectroscopic strength in nucleon transfer experiments is based on a Hamiltonian with two-nucleon interactions only. We point out that in reactions with a loosely-bound projectile, where clustering and breakup effects are important, an additional three-body force arises due to three-nucleon ($3N$) interaction between two nucleons belonging to different clusters in the projectile and a target nucleon. We study the effects of this force on nucleon transfer in $(d,p)$ and $(d,n)$ reactions on ${}^{56}$Ni, ${}^{48}$Ca, ${}^{26m}$Al and ${}^{24}$O targets at deuteron incident energies between 4 and 40 MeV/nucleon. Deuteron breakup is treated exactly within a continuum discretized coupled-channel approach. It was found that an additional three-body force can noticeably alter the angular distributions at forward angles, with consequences for spectroscopic factors' studies. Additional study of transfer to $2p$ continuum in the ${}^{25}$F$(p,2p{)}^{24}$O reaction, involving the same overlap function as in the ${}^{24}$O($d,n{)}^{25}$F case, revealed that $3N$ force affects the $(d,n)$ and $(p,2p)$ reactions in a similar way, increasing the cross sections and decreasing spectroscopic factors, although its influence at the main peak of $(p,2p)$ is weaker. The angle-integrated cross sections are found to be less sensitive to the 3N force contribution, they increase by less than 20$\%$. Including 3N interactions in nucleon removal reactions makes an essential step towards bringing together nuclear structure theory, where 3N force is routinely used, and nuclear direct reaction theory, based on two-nucleon interactions only.

   ↳ nucl-thnucl-exPLB(2023)·1 citation
4. 04*

   A Compact Dication Source for Ba${}^{2+}$ Tagging and Heavy Metal Ion Sensor Development

   K.E. Navarro · B.J.P. Jones · J. Baeza-Rubio · M. Boyd · A.A. Denisenko · F.W. Foss · S.Giri · R. Miller · D.R. Nygren · M.R. Tiscareno · F. J. Samaniego · K. Stogsdill and 98 other authors

   We present a tunable metal ion beam that delivers controllable ion currents in the picoamp range for testing of dry-phase ion sensors. Ion beams are formed by sequential atomic evaporation and single or multiple electron impact ionization, followed by acceleration into a sensing region. Controllability of the ionic charge state is achieved through tuning of electrode potentials that influence the retention time in the ionization region. Barium, lead, and cobalt samples have been used to test the system, with ion currents identified and quantified using a quadrupole mass analyzer. Realization of a clean $\mathrm{B}{\mathrm{a}}^{2+}$ ion beam within a bench-top system represents an important technical advance toward the development and characterization of barium tagging systems for neutrinoless double beta decay searches in xenon gas. This system also provides a testbed for investigation of novel ion sensing methodologies for environmental assay applications, with dication beams of Pb${}^{2+}$ and Cd${}^{2+}$ also demonstrated for this purpose.

   ↳ physics.ins-dethep-exnucl-exJINST(2023)·2 citations
5. 05*

   Towards the Precision Nucleon Energy-Energy Correlator in Lepton-Ion Collisions

   Haotian Cao🇨🇳 · Xiaohui Liu🇨🇳 · Hua Xing Zhu🇨🇳

   The nucleon energy-energy correlator (NEEC) was proposed in 2209.02080 as a new way of studying nucleon intrinsic dynamics. In this work, we present a detailed derivation of the factorization theorem that enables the measurement of the unpolarized NEEC in lepton-ion collisions. As a first step towards a precise measurement of this quantity, we obtained the next-to-leading-logarithmic (NLL, $\sim \mathcal{O}({\alpha }_s^n{L}^{n-1})$) resummation in a concise analytic form, and predicted the analytic $\theta$-angle distribution at $\mathcal{O}({\alpha }_s^2)$. Extending our analytic resummation formula to higher logarithmic accuracy and the factorization theorem to hadron-hadron collisions is straightforward.

   ↳ hep-phhep-exnucl-exPRD(2023)·60 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.