Tue·Feb 21, 2023Tuesday·February 21, 2023

1. 01*

   New measurement of the elemental fragmentation cross sections of 218 MeV/nucleon 28 Si on a carbon target

   Guang-Shuai Li🇨🇳 · Jun Su🇨🇳 · Bao-Hua Sun🇨🇳 · Satoru Terashima🇨🇳 · Jian-Wei Zhao🇩🇪 · Xiao- Dong Xu🇨🇳 · Ji-Chao Zhang · Ge Guo🇨🇳 · Liu-Chun He · Wei-Ping Lin · Wen-Jian Lin · Chuan-Ye Liu and 15 other authors

   Elemental fragmentation cross sections (EFCSs) of stable and unstable nuclides have been investigated with various projectile-target combinations at a wide range of incident energies. These data are critical to constrain and develop the theoretical reaction models and to study the propagation of galactic cosmic rays (GCR). In this work, we present a new EFCS measurement for ${}^{28}$Si on carbon at 218~MeV/nucleon performed at the Heavy Ion Research Facility (HIRFL-CSR) complex in Lanzhou. The impact of the target thickness has been well corrected to derive an accurate EFCS. Our present results with charge changes $\Delta Z$ = 1-6 are compared to the previous measurements and to the predictions from the models modified EPAX2, EPAX3, FRACS, ABRABLA07, NUCFRG2, and IQMD coupled with GEMINI (IQMD+GEMINI). All the models fail to describe the odd-even staggering strength in the elemental distribution, with the exception of the IQMD+GEMINI model, which can reproduce the EFCSs with an accuracy of better than 3.5\% for $\Delta Z\le 5$. The IQMD+GEMINI analysis shows that the odd-even staggering in EFCSs occurs in the sequential statistical decay stage rather than in the initial dynamical collision stage. This offers a reasonable approach to understand the underlying mechanism of fragmentation reactions.

   nucl-exPRC(2023)·13 citations
2. 02*

   Study of the threshold anomaly in the elastic scattering of d+${}^{197}$Au

   T. Giudice · D. Abriola🇦🇷 · A. Arazi · E. de Barbará🇦🇷 · M.A. Cardona🇺🇸 · J. Gómez · D. Hojman · R.M. Id Betan🇦🇷 · M.S. Kohen · N. Llaneza · G.V. Martí · B. Paes and 3 other authors

   Measurements of the elastic scattering angular distribution for the d+${}^{197}$Au system were carried out covering deuteron incident energies in the range from 5 to 16 MeV, i.e. approximately 50% below and above the Coulomb barrier. A critical interaction distance of $d_I$= 2.49 fm was determined from these distributions, which is comparable to that of the radioactive halo nucleus ${}^6$He. The experimental angular distributions were systematically analyzed using two alternative models: the semi-microscopic Sao Paulo and the effective Woods-Saxon optical potentials, for which the best-fitting parameters were determined. These potentials, integrated in the vicinity of the sensitivity radius, were calculated for each energy. For both models, the energy dependence of these integrals presented the breakup threshold anomaly around the coulomb barrier, a typical signature of weakly bound nuclei.

   nucl-exnucl-thJ.Phys.G(2023)·3 citations
3. 03*

   Bayesian quantification of strongly-interacting matter with color glass condensate initial conditions

   Matthew R. Heffernan🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Jean-François Paquet🇺🇸

   A global Bayesian analysis of relativistic Pb + Pb collisions at ${\sqrt{s}}_{\mathrm{NN}}$ = 2.76 TeV is performed, using a multistage model consisting of an IP-Glasma initial state, a viscous fluid dynamical evolution, and a hadronic transport final state. The observables considered are from the soft sector hadronic final state. Posterior and Maximum a Posteriori parameter distributions that pertain to the IP-Glasma and hydrodynamic phases are obtained, including the shear and bulk specific viscosity of strong interacting matter. The first use of inference with transfer learning in heavy-ion analyses is presented, together with Bayes Model Averaging.

   ↳ nucl-thhep-phnucl-exPRC(2024)·55 citations
4. 04*

   Measurement of ${}^{19}$F($p$,$\gamma$)${}^{20}$Ne reaction suggests CNO break-out in first stars

   Liyong Zhang🇨🇳 · Jianjun He🇨🇳 · Richard J. deBoer🇺🇸 · Michael Wiescher🇺🇸 · Alexander Heger🇦🇺 · Daid Kahl🇷🇴 · Jun Su · Daniel Odell🇺🇸 · Yinji Chen🇨🇳 · Xinyue Li🇨🇳 · Jianguo Wang🇨🇳 · Long Zhang🇨🇳 and 24 other authors

   The origin of calcium production in the first stars (Pop III stars), which formed out of the primordial matter of the Big Bang, and their fates, remain most fascinating mysteries in astrophysics. Advanced nuclear burning and supernovae were thought to be the dominant source of the Ca production seen in all stars. Here we report on a qualitatively different path to Ca production through break-out from the "warm" carbon-nitrogen-oxygen (CNO) cycle. We extend direct measurement of the ${}^{19}$F($p$, $\gamma$)${}^{20}$Ne break-out reaction down to an unprecedentedly low energy point of 186 keV and discover a key resonance at 225 keV. In the domain of astrophysical interest, at around 0.1 giga kelvin, this thermonuclear ${}^{19}$F($p$,$\gamma$)${}^{20}$Ne rate is up to a factor of 7.4 larger than the previous recommended rate. Our stellar models show a stronger break-out during stellar hydrogen burning than thought before, and may reveal the nature of Ca production in Pop III stars imprinted on the oldest known ultra-iron poor star, SMSS0313-6708. This result from the China Jinping Underground Laboratory, the deepest laboratory in the world, offering an environment with extremely low cosmic-ray induced background, has far-reaching implications on our understanding of how the first stars evolve and die. Our rate showcases the impact that faint Pop III star supernovae can have on the nucleosynthesis observed in the oldest known stars and first galaxies, key mission targets of the James Webb Space Telescope.

   ↳ astro-ph.SRastro-ph.HEnucl-exNature(2022)·37 citations
5. 05*

   Optical potential for incident and emitted low-energy $\alpha$ particles. III. Non-statistical processes induced by neutrons on Zr, Nb, and Mo nuclei

   Marilena Avrigeanu · Vlad Avrigeanu

   The reliability of a previous $\alpha$-particle optical-model potential (OMP) on nuclei with mass number 45$\le$$A$$\le$209 was proved for emitted $\alpha$ particles as well, for proton--induced reactions on Zn isotopes [Phys. Rev. C {\bf 91}, 064611 (2015), Paper I]. However, the same was not the case of neutrons on Zr stable isotopes [Phys. Rev. C {\bf 96}, 044610 (2017), Paper II]. A recent assessment of this potential also for nucleon--induced $\alpha$-emission on $A$$\sim$60 nuclei, including pickup direct reaction and eventual Giant Quadrupole Resonance (GQR) $\alpha$-emission, is completed for neutrons incident on Zr, Nb, and Mo stable isotopes. Consistent sets of input parameters, determined through analysis of independent data, is involved while no further empirical rescaling factors of the $\gamma$ and nucleon widths have been involved. A suitable account of all competitive reaction channels is confirmed by careful uncertainty analysis, to avoid parameter ambiguities and/or error compensation. Additional validation of this potential is also supported by recently measured $(\alpha ,\gamma )$ and $(\alpha ,n)$ cross--sections of Zr and Mo nuclei. An increase of the $\alpha$-emission beyond the statistical predictions, through consideration of additional reaction channels of the pickup direct interaction and {\it like}--GQR decay, makes possible the description of both absorption and emission of $\alpha$ particles by the same optical potential.

   ↳ nucl-thnucl-exPRC(2023)·7 citations
6. 06*

   Revisiting the Gamow Factor of Reactions on Light Nuclei

   Eunseok Hwang🇰🇷 · Heamin Ko🇰🇷 · Kyoungsu Heo · Myung-Ki Cheoun🇰🇷 · Dukjae Jang🇰🇷

   This study provides an improved understanding of the penetration probabilities (PPs) in nuclear reactions of light nuclei by correcting the assumptions used in the conventional Gamow factor. The Gamow factor effectively describes the PP in nuclear reactions based on two assumptions: low particle energy than the Coulomb barrier and neglecting the dependence of nuclear interaction potential. However, we find that the assumptions are not valid for light nuclei. As a result of a calculation that excludes the assumptions, we obtain the PP that depends on the nuclear interaction potential depth for the light nuclei. For the potential depth fitted by the experimental fusion cross-section, we present that PPs of light nuclei (D+D, D+T, D+${}^3$He, p+D, p+${}^6$Li, and p+${}^7$Li) become higher than the conventional one near the Coulomb barrier. We also discuss the implications of the modified PP, such as changes in the Gamow peak energy, which determine the measurement of the energy range of the nuclear cross-section in experiments, and the electron screening effect.

   ↳ nucl-thastro-ph.SRnucl-exApJ(2023)·3 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.