Tue·Jan 11, 2022Tuesday·January 11, 2022

1. 01*

   Experimental study of the ${}^{30}$Si(${}^3$He,$d$)${}^{31}$P reaction and thermonuclear reaction rate of ${}^{30}$Si($p$,$\gamma$)${}^{31}$P

   D. S. Harrouz🇫🇷 · N. de Séréville🇫🇷 · P. Adsley🇿🇦 · F. Hammache🇫🇷 · R. Longland🇺🇸 · B. Bastin🇫🇷 · T. Faestermann🇩🇪 · R. Hertenberger🇩🇪 · M. La Cognata🇮🇹 · L. Lamia🇮🇹 · A. Meyer🇩🇪 · S. Palmerini🇮🇹 and 4 other authors

   [Background] Abundance anomalies in some globular clusters, such as the enhancement of potassium and the depletion of magnesium, can be explained in terms of an earlier generation of stars polluting the presently observed ones. It was shown that the potential range of temperatures and densities of the polluting sites depends on the strength of a few number of critical reaction rates. The reaction has been identified as one of these important reactions. [Purpose] The key ingredient for evaluating the thermonuclear reaction rate is the strength of the resonances which, at low energy, are proportional to their proton width. Therefore the goal of this work is to determine the proton widths of unbound 31P states. [Method] States in 31P were studied at the Maier-Leibnitz-Laboratorium using the one-proton transfer reaction. Deuterons were detected with the Q3D magnetic spectrometer. Angular distribution and spectroscopic factors were extracted for 27 states, and proton widths and resonance strengths were calculated for the unbound states. [Results] Several unbound states have been observed for the first time in a one-proton transfer reaction. Above 20 MK, the reaction rate is now entirely estimated from the observed properties of states. The reaction rate uncertainty from all resonances other than the resonance has been reduced down to less than a factor of two above that temperature. The unknown spin and parity of the resonance dominates the uncertainty in the rate in the relevant temperature range. [Conclusion] The remaining source of uncertainty on the reaction rate comes from the unknown spin and parity of the resonance which can change the reaction rate by a factor of ten in the temperature range of interest.

   nucl-exastro-ph.GAPRC(2022)·6 citations
2. 02*

   Observation of the B${}_{\mathrm{c}}^{+}$ meson in PbPb and pp collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV and measurement of its nuclear modification factor

   CMS Collaboration

   The B${}_{\mathrm{c}}^{+}$ meson is observed for the first time in heavy ion collisions. Data from the CMS detector are used to study the production of the B${}_{\mathrm{c}}^{+}$ meson in lead-lead (PbPb) and proton-proton (pp) collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV, via the B${}_{\mathrm{c}}^{+}$ $\to$ (J/$\psi$ $\to$ ${\mu }^{+}{\mu }^{-}$)${\mu }^{+}{\nu }_{\mu }$ decay. The B${}_{\mathrm{c}}^{+}$ nuclear modification factor, derived from the PbPb-to-pp ratio of production cross sections, is measured in two bins of the trimuon transverse momentum and of the PbPb collision centrality. The B${}_{\mathrm{c}}^{+}$ meson is shown to be less suppressed than quarkonia and most of the open heavy-flavor mesons, suggesting that effects of the hot and dense nuclear matter created in heavy ion collisions contribute to its production. This measurement sets forth a promising new probe of the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma.

   ↳ hep-exnucl-exPRL(2022)·46 citations
3. 03*

   Extracting the jet transport coefficient from hadron suppressions by confronting current NLO parton fragmentation functions

   Qing-Fei Han🇨🇳 · Man Xie🇨🇳 · Han-Zhong Zhang🇨🇳

   Nuclear modification factors of single hadrons and dihadrons at large transverse momentum ($p_{\mathrm{T}}$) in high-energy heavy-ion collisions are studied in a next-to-leading-order (NLO) perturbative QCD parton model. Parton fragmentation functions (FFs) in $A+A$ collisions are modified due to jet energy loss which is proportional to the jet transport coefficient $\hat{q}$ characterizing the interaction between the parton jet and the produced medium. By confronting 6 current sets of NLO parton FFs for large $p_{\mathrm{T}}$ hadron productions, we extract $\hat{q}$ quantitatively via a global fit to data for both single hadron and dihadron suppressions, and obtain $\hat{q}/T^3=4.74-6.72$ at $T=370$ MeV in central $Au+Au$ collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV, and $\hat{q}/T^3=3.07-3.98$ at $T=480$ MeV in central $Pb+Pb$ collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV. The numerical results show that the uncertainties for $\hat{q}$ extraction are brought by the different contributions of gluon-to-hadron in the 6 sets of FFs due to gluon energy loss being $9/4$ times of quark energy loss.

   ↳ hep-phnucl-exnucl-thEur.Phys.J.Plus(2022)·9 citations
4. 04*

   Beta-delayed fission in the coupled Quasi-particle Random Phase Approximation plus Hauser-Feshbach approach

   M. R. Mumpower🇺🇸 · T. Kawano🇺🇸 · T. M. Sprouse🇺🇸

   Beta-delayed neutron emission and $\beta$-delayed fission ($\beta$df) probabilities were calculated for heavy, neutron-rich nuclei using the Los Alamos coupled Quasi-Particle Random Phase Approximation plus Hauser-Feshbach (QRPA+HF) approach. In this model, the compound nucleus is initially populated by $\beta$-decay and is followed through subsequent statistical decays taking into account competition between neutrons, $\gamma$-rays and fission. The primary output of these calculations includes branching ratios along with neutron and $\gamma$-ray spectra. We find a relatively large region of heavy nuclides where the probability of $\beta$df is near 100%. For a subset of nuclei near the neutron dripline, delayed neutron emission and the probability to fission are both large which leads to the possibility of multi-chance $\beta$df (mc-$\beta$df). We comment on prospective neutron-rich nuclei that could be probed by future experimental campaigns and provide a full table of branching ratios in ASCII format in the supplemental material for use in various applications.

   ↳ nucl-thnucl-exPRC(2022)·15 citations
5. 05*

   Moments and Radii of exotic Na and Mg isotopes

   Takaharu Otsuka🇯🇵 · Noritaka Shimizu🇯🇵 · Yusuke Tsunoda🇯🇵

   The ground-state properties of neutron-rich exotic Na and Mg isotopes with even numbers of neutrons, N, are studied up to driplines. The shell-model calculations with an ab initio effective nucleon-nucleon interaction reported in [Tsunoda, Otsuka, Takayanagi et al., Nature 587, 66 (2020)] are extended to observables such as magnetic dipole and electric quadrupole moments, and charge and matter radii. Good agreements with experimental data are found, and predictions are shown up to driplines. A prescription to extract the deformation parameters for the eigenstates of Monte Carlo Shell Model is presented, and the obtained values are used to calculate charge and matter radii. The increase of these radii from the Droplet model is described as the consequences of the varying deformation of the surface and the growing neutron excitations or occupations in the pf shell, consistently with the dripline mechanism presented in the above reference. The neutron skin thickness is shown to be about 0.1 fm for N=20, which can be compared to the value for 208Pb in an A1/3 scaling. The relation of the neutron skin thickness to the electromagnetic moments is discussed for an exotic nucleus, 31Na.

   ↳ nucl-thnucl-exPRC(2022)·16 citations
6. 06*

   Nuclear mass table in deformed relativistic Hartree-Bogoliubov theory in continuum: I. even-even nuclei

   DRHBc Mass Table Collaboration: Kaiyuan Zhang🇨🇳 · Myung-Ki Cheoun🇰🇷 · Yong-Beom Choi🇰🇷 · Pooi Seong Chong🇨🇳 · Jianmin Dong🇨🇳 · Zihao Dong🇨🇳 · Xiaokai Du🇨🇳 · Lisheng Geng🇨🇳 · Eunja Ha🇰🇷 · Xiao-Tao He🇨🇳 · Chan Heo🇨🇳 · Meng Chit Ho🇨🇳 and 34 other authors

   Ground-state properties of even-even nuclei with $8\le Z\le 120$ from the proton drip line to the neutron drip line have been investigated using the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the density functional PC-PK1. With the effects of deformation and continuum included simultaneously, 2583 even-even nuclei are predicted to be bound. The calculated binding energies, two-nucleon separation energies, root-mean-square (rms) radii of neutron, proton, matter, and charge distributions, quadrupole deformations, and neutron and proton Fermi surfaces are tabulated and compared with available experimental data. The rms deviation from the 637 mass data is 1.518 MeV, providing one of the best microscopic descriptions for nuclear masses. The drip lines obtained from DRHBc calculations are compared with other calculations, including the spherical relativistic continuum Hartree-Bogoliubov (RCHB) and triaxial relativistic Hartree-Bogoliubov (TRHB) calculations with PC-PK1. The deformation and continuum effects on the limits of the nuclear landscape are discussed. Possible peninsulas consisting of bound nuclei beyond the two-neutron drip line are predicted. The systematics of the two-nucleon separation energies, two-nucleon gaps, rms radii, quadrupole deformations, potential energy curves, neutron densities, neutron mean-field potentials, and pairing energies in the DRHBc calculations are also discussed. In addition, the $\alpha$ decay energies extracted are in good agreement with available data.

   ↳ nucl-thastro-ph.SRnucl-exAtom.Data Nucl.Data Tabl.(2022)·177 citations
7. 07*

   Evidence of Two-Source King Plot Nonlinearity in Spectroscopic Search for New Boson

   Joonseok Hur🇺🇸 · Diana P. L. Aude Craik🇺🇸 · Ian Counts🇺🇸 · Eugene Knyazev🇺🇸 · Luke Caldwell🇺🇸 · Calvin Leung🇺🇸 · Swadha Pandey🇺🇸 · Julian C. Berengut🇦🇺 · Amy Geddes🇦🇺 · Witold Nazarewicz🇺🇸 · Paul-Gerhard Reinhard🇩🇪 · Akio Kawasaki🇯🇵 and 3 other authors

   Optical precision spectroscopy of isotope shifts can be used to test for new forces beyond the Standard Model, and to determine basic properties of atomic nuclei. We measure isotope shifts on the highly forbidden ${}^2{S}_{1/2}\to {}^2{F}_{7/2}$ octupole transition of trapped ${}^{168,170,172,174,176}$Yb ions. When combined with previous measurements in Yb${}^{+}$ and very recent measurements in Yb, the data reveal a King plot nonlinearity of up to 240$\sigma$. The trends exhibited by experimental data are explained by nuclear density functional theory calculations with the Fayans functional. We also find, with 4.3$\sigma$ confidence, that there is a second distinct source of nonlinearity, and discuss its possible origin.

   ↳ physics.atom-phhep-exnucl-exnucl-thPRL(2022)·75 citations
8. 08*

   Expected yields of ${}^{181}$Ta (e,e') ${}^{181}$Ta${}^{\ast }$ in the multi-keV range with a plasma-cathode electron beam

   F.Gobet🇫🇷 · A.Ya.Dzyublik🇺🇦 · G.Gosselin🇫🇷 · V.Méot🇫🇷 · M.Versteegen🇫🇷

   Calculations of the cross sections of inelastic electron scattering $(e,e^{\prime })$ on a nucleus in the multi-keV energy range strongly depend on the description of the screening of the nuclear Coulomb potential as well as on the deformation of the wave functions of the incoming and outgoing electron in the vicinity of the nucleus. These cross sections are evaluated at values lower than $10^{-30}$ cm${}^2$ which vary by several orders of magnitude according to the models. Experimental measurements would be required to constrain the models but it is a real challenge to measure such low cross sections. In this study, we demonstrate that inelastic electron scattering is the main nuclear excitation mechanism in a ${}^{181}$Ta target irradiated with a new intense 10 - 30 keV electron beam produced with a biased laser-plasma. Calculations show that through the detection of conversion electrons, it should be possible to measure the nuclear excitation yields. The effect of electron beam heating and of plasma deposition on the tantalum target are quantified, thus allowing the dimensioning of a possible experimental configuration to study $(e,e^{\prime })$ processes in this range of energy for the first time.

   ↳ nucl-thnucl-exphysics.atom-phphysics.plasm-phPRC(2022)·2 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.