Tue·May 25, 2021Tuesday·May 25, 2021

1. 01*

   Isotope Shifts of Radium Monofluoride Molecules

   S.M. Udrescu🇺🇸 · A.J. Brinson🇺🇸 · R.F. Garcia Ruiz🇺🇸 · K. Gaul🇩🇪 · R. Berger🇩🇪 · J. Billowes🇬🇧 · C.L. Binnersley🇬🇧 · M.L. Bissell🇬🇧 · A.A. Breier🇩🇪 · K. Chrysalidis🇨🇭 · T.E. Cocolios🇧🇪 · B.S. Cooper🇬🇧 and 16 other authors

   Isotope shifts of ${}^{223-226,228}$Ra${}^{19}$F were measured for different vibrational levels in the electronic transition $A^2{\Pi }_{1/2}\leftarrow X^2{\Sigma }^{+}$. The observed isotope shifts demonstrate the particularly high sensitivity of radium monofluoride to nuclear size effects, offering a stringent test of models describing the electronic density within the radium nucleus. Ab initio quantum chemical calculations are in excellent agreement with experimental observations. These results highlight some of the unique opportunities that short-lived molecules could offer in nuclear structure and in fundamental symmetry studies.

   nucl-exnucl-thphysics.atom-phPRL(2021)·44 citations
2. 02*

   Resonance-like structure near the $\eta d$ threshold in the $\gamma d${$\to$}${\pi }^0\eta d$ reaction

   T. Ishikawa🇯🇵 · H. Fujimura🇯🇵 · H. Fukasawa🇯🇵 · R. Hashimoto🇯🇵 · Q. He🇯🇵 · Y. Honda🇯🇵 · T. Iwata🇯🇵 · S. Kaida🇯🇵 · J. Kasagi🇯🇵 · A. Kawano🇯🇵 · S. Kuwasaki🇯🇵 · K. Maeda🇯🇵 and 25 other authors

   To investigate the interaction between the nucleon $N$ and nucleon resonance $N(1535)1/2^{-}$, the $\eta d$ threshold structure connected to the isoscalar $S$-wave $N$-$N(1535)1/2^{-}$ system has been experimentally studied in the $\gamma d${$\to$}${\pi }^0\eta d$ reaction at incident photon energies ranging from the reaction threshold to 1.15 GeV. A strong enhancement is observed near the $\eta d$ threshold over the three-body phase-space contribution in the $\eta d$ invariant-mass distribution. An analysis incorporating the known isovector resonance ${\mathcal{D}}_{12}$ with a spin-parity of $2^{+}$ in the ${\pi }^{0}d$ channel reveals the existence of a narrow isoscalar resonance-like structure with $1^{-}$ in the $\eta d$ system. Using a Flatté parametrization, the mass is found to be $2.427_{-0.006}^{+0.013}$ GeV, close to the $\eta d$ threshold, and the width is $\left(0.029_{-0.029}^{+0.006}\mathrm{GeV}\right)+\left(0.00_{-0.00}^{+0.41}\right)p_{\eta }c$, where $p_{\eta }$ denotes the $\eta$ momentum in the rest frame of the $\eta d$ system. The observed structure would be attributed to a predicted isoscalar $1^{-}$ $\eta NN$ bound state from $\eta NN$ and $\pi NN$ coupled-channel calculation, or an $\eta d$ virtual state owing to strong $\eta d$ attraction.

   nucl-exPRC(2021)·15 citations
3. 03*

   GETaLM: A Generator for Electron Tagger and Luminosity Monitor for electron - proton and ion collisions

   Jaroslav Adam🇺🇸

   The study of elastic bremsstrahlung and electron tagging in electron-proton or ion collisions is gaining importance with the planned construction of several experimental facilities focused on deep-inelastic scattering (DIS) measurements. This paper describes a program which generates bremsstrahlung photons in electron-proton and electron-ion interactions as well as scattered electrons in bremsstrahlung processes and in a quasi-real photon approximation to the general DIS process. The effects of electron beam divergence and the spread of the interaction vertex are implemented. The program can be used as an input to simulations of instrumentation for bremsstrahlung photon detection, luminosity measurements, electron tagging, and the determination of the cross sections of corresponding processes.

   ↳ hep-phnucl-exComput.Phys.Commun.(2022)·3 citations
4. 04*

   Nuclear masses in extended kernel ridge regression with odd-even effects

   X. H. Wu🇨🇳 · L. H. Guo · P. W. Zhao🇨🇳

   The kernel ridge regression (KRR) approach is extended to include the odd-even effects in nuclear mass predictions by remodulating the kernel function without introducing new weight parameters and inputs in the training network. By taking the WS4 mass model as an example, the mass for each nucleus in the nuclear chart is predicted with the extended KRR network, which is trained with the mass model residuals, i.e., deviations between experimental and calculated masses, of other nuclei with known masses. The resultant root-mean-square mass deviation from the available experimental data for the 2353 nuclei with $Z\ge 8$ and $N\ge 8$ can be reduced to 128 keV, which provides the most precise mass model from machine learning approaches so far. Moreover, the extended KRR approach can avoid the risk of worsening the mass predictions for nuclei at large extrapolation distances, and meanwhile, it provides a smooth extrapolation behavior with respect to the odd and even extrapolation distances.

   ↳ nucl-thnucl-exPLB(2021)·57 citations
5. 05*

   Impact of NICER's Radius Measurement of PSR J0740+6620 on Nuclear Symmetry Energy at Suprasaturation Densities

   Nai-Bo Zhang🇨🇳 · Bao-An Li🇺🇸

   By directly inverting several neutron star observables in the three-dimensional parameter space for the Equation of State of super-dense neutron-rich nuclear matter, we show that the lower radius limit for PSR J0740+6620 of mass $2.08\pm 0.07M_{\odot }$ from Neutron Star Interior Composition Explorer (NICER)'s very recent observation sets a much tighter lower boundary than previously known for nuclear symmetry energy in the density range of $(1.0\sim 3.0)$ times the saturation density ${\rho }_0$ of nuclear matter. The super-soft symmetry energy leading to the formation of proton polarons in this density region of neutron stars is clearly disfavoured by the first radius measurement for the most massive neutron star observed reliably so far.

   ↳ nucl-thastro-ph.HEnucl-exApJ(2021)·53 citations
6. 06*

   Numerical investigation of spallation neutrons generated from petawatt-scale laser-driven proton beams

   B. Martinez🇫🇷 · S. N. Chen🇷🇴 · S. Bolaños · N. Blanchot · G. Boutoux · W. Cayzac · C. Courtois · X. Davoine🇫🇷 · A. Duval · V. Horny🇫🇷 · I. Lantuejoul · L. Le Deroff and 6 other authors

   Due to their high cost of acquisition and operation, there are still a limited number of high-yield, high-flux neutron source facilities worldwide. In this context, laser-driven neutron sources offer a promising, cheaper alternative to those based on large-scale accelerators, with, in addition, the potential of generating compact neutron beams of high brightness and ultra-short duration. In particular, the predicted capability of next-generation petawatt (PW)-class lasers to accelerate protons beyond the 100 MeV range should unlock efficient neutron generation through spallation reactions. In this paper, this scenario is investigated numerically through particle-in-cell and Monte Carlo simulations, modeling, respectively, the laser acceleration of protons from thin-foil targets and their subsequent conversion into neutrons in secondary heavy-ion targets. Laser parameters relevant to the 1 PW LMJ-PETAL and 1-10 PW Apollon systems are considered. Under such conditions, neutron fluxes exceeding $10^{23}\mathrm{n}\mathrm{c}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}$ are predicted, opening up attractive fundamental and applicative prospects.

   ↳ physics.acc-phastro-ph.HEnucl-exphysics.plasm-phMatter Radiat.Extremes(2022)·7 citations
7. 07*

   Systematic shell-model study of Rn isotopes with $A=$ 207 to 216 and isomeric states

   Bharti Bhoy🇮🇳 · Praveen C. Srivastava🇮🇳

   We present systematic large-scale shell-model calculations for Rn isotopes with $A=$ 207 to 216. For the ${}^{207-212}$Rn isotopes, we perform calculations with KHH7B interaction, while for ${}^{213-216}$Rn isotopes with KHPE and KHH7B interactions. The calculated energies and electromagnetic properties are compared with the available experimental data and predicted where experimental data are not available. We also suggest spins and parities of several unconfirmed states available from the recent experimental data. Comprehensive study of several isomeric states from the calculated shell-model configurations and half-lives is also reported.

   ↳ nucl-thnucl-exJ.Phys.G(2021)·11 citations
8. 08*

   Effect of non-uniform efficiency on higher-order cumulants in heavy-ion collisions

   Fan Si🇨🇳 · Yifei Zhang🇨🇳 · Xiaofeng Luo🇨🇳

   We perform a systematic study on the effect of non-uniform track efficiency correction in higher-order cumulant analysis in heavy-ion collisions. Through analytical derivation, we find that the true values of cumulants can be successfully reproduced by the efficiency correction with an average of the realistic detector efficiency for particles with the same charges within each single phase space. The theoretical conclusions are supported by a toy model simulation by tuning the non-uniformity of the efficiency employed in the track-by-track efficiency correction method. The valid averaged efficiency is found to suppress the statistical uncertainties of the reproduced cumulants dramatically. Thus, usage of the averaged efficiency requires a careful study of phase space dependence. This study is important for carrying out precision measurements of higher-order cumulants in heavy-ion collision experiments at present and in future.

   ↳ physics.data-annucl-exnucl-thCPC(2021)·1 citation

* 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.