Tue·Dec 5, 2023Tuesday·December 5, 2023

1. 01*

   Proposal to PAC 51: Color Transparency in Maximal Rescattering Kinematics

   Shujie Li🇺🇸 · Carlos Yero🇺🇸 · Jennifer Rittenhouse West🇺🇸 · Holly Szumila-Vance🇺🇸 · Douglas W. Higinbotham🇺🇸

   With the current highest beam energy at Jefferson Lab and traditional methods, we have exhausted our sensitivity for observing the onset of proton color transparency in a nucleus in A(e,e'p) parallel scattering kinematics for up to $Q^2$ = 14 GeV${}^2$ . One of the disadvantages in A(e,e'p) experiments is that even if a point-like color singlet is produced at such $Q^2$, its expansion is unconstrained over the full radius of the nuclei, with the potential to significantly reduce the size of the color transparency effect. Therefore, in order to be sensitive to the effects of color transparency, we enhance the sensitivity of the measurement to the production of a point-like color neutral object prior to the onset of wave-function expansion. In this experiment, we propose a color transparency measurement in maximal rescattering ("dirty") kinematics in deuterium where final-state interactions (FSIs) are known to be huge effects, thereby enhancing our sensitivity to a reduction in FSIs indicative of color transparency. The kinematics in exclusive processes in deuterium can be precisely chosen such that the inter-nucleon distances of the struck and spectator nucleon lead to well-controlled FSIs.

   nucl-ex1 citation
2. 02*

   Isospin diffusion from ${}^{40,48}$Ca${+}^{40,48}$Ca experimental data at Fermi energies: Direct comparisons with transport model calculations

   Q. Fable (L2IT)🇫🇷 · L. Baldesi (INFN, Sezione di Firenze)🇮🇹 · S. Barlini (INFN, Sezione di Firenze)🇮🇹 · Eric Bonnet (SUBATECH)🇫🇷 · Bernard Borderie (IJCLab)🇫🇷 · Remi Bougault (LPCC)🇫🇷 · A. Camaiani (INFN, Sezione di Firenze)🇮🇹 · G. Casini (INFN, Sezione di Firenze)🇮🇹 · A. Chbihi (GANIL)🇫🇷 · Caterina Ciampi (GANIL)🇫🇷 · J. A. Dueñas🇪🇸 · J.D. Frankland (GANIL)🇫🇷 and 21 other authors

   This article presents an investigation of isospin equilibration in cross-bombarding ${}^{40,48}$Ca${+}^{40,48}$Ca reactions at 35 MeV/nucleon, by comparing experimental data with filtered transport model calculations. Isospin diffusion is studied using the evolution of the isospin transport ratio with centrality. The asymmetry parameter $\delta =(N-Z)/A$ of the quasiprojectile (QP) residue is used as isospin-sensitive observable, while a recent method for impact parameter reconstruction is used for centrality sorting. A benchmark of global observables is proposed to assess the relevance of the antisymmetrized molecular dynamics (AMD) model, coupled to GEMINI++, in the study of dissipative collisions. Our results demonstrate the importance of considering cluster formation to reproduce observables used for isospin transport and centrality studies. Within the AMD model, we prove the applicability of the impact parameter reconstruction method, enabling a direct comparison to the experimental data for the investigation of isospin diffusion. For both, we evidence a tendency to isospin equilibration with an impact parameter decreasing from 9 to 3 fm, while the full equilibration is not reached. A weak sensitivity to the stiffness of the equation of state employed in the model is also observed, with a better reproduction of the experimental trend for the neutron-rich reactions.

   nucl-exnucl-thPRC(2024)·9 citations
3. 03*

   Impacts of hexadecapole deformations on the collective energy spectra of axially deformed nuclei

   L. Lotina🇭🇷 · K. Nomura🇯🇵

   The hexadecapole deformation, as well as the quadrupole one, influences the low-lying states of finite nuclei. The hexadecapole correlations are often overshadowed by the large quadrupole effects, and hence have not been much investigated. Here we address the relevance of hexadecapole deformations in the calculations of low-energy collective states of heavy nuclei, by using the theoretical framework of the self-consistent mean-field method and the interacting-boson approximation. The interacting-boson Hamiltonian that explicitly includes the quadrupole and hexadecapole collective degrees of freedom is specified by a choice of the energy density functional and pairing interaction. In an illustrative application to axially deformed Gd isotopes, it is shown that the inclusion of the hexadecapole degree of freedom does not affect most of the low-spin and low-lying states qualitatively, but that has notable effects in that it significantly improves the description of high-spin states of the ground-state bands of nearly spherical vibrational nuclei and gives rise to $K^{\pi }=4^{+}$ bands exhibiting strong $E4$ transitions in strongly deformed nuclei.

   ↳ nucl-thnucl-exPRC(2024)·14 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.