Mon·Sep 11, 2023Monday·September 11, 2023

1. 01*

   Searching for three-nucleon short-range correlations

   Nadia Fomin🇺🇸 · John Arrington🇺🇸 · Shujie Li🇺🇸

   Electron scattering measurements from high-momentum nucleons in nuclei at SLAC and Jefferson Lab (JLab) have shown that these nucleons are generally associated with two-nucleon short-range correlations (2N-SRCs). These SRCs are formed when two nucleons in the nucleus interact at short distance via the strong tensor attraction or repulsive core of the NN potential. A series of measurements at JLab have mapped out the A dependence and isospin dependence of 2N-SRCs, and have begun to map out their momentum structure. However, we do not yet know if 3N-SRCs, similar high-momentum configurations of three nucleons, play an important role in nuclei. We summarize here previous attempts to isolate 3N-SRCs, go over the limitations of these previous attempts, and discuss the present and near-term prospects for searching for 3N-SRCs, mapping out their A dependence in nuclei, and constraining their isospin and momentum structure.

   nucl-exEPJA(2023)·9 citations
2. 02*

   Fine structure of the isoscalar giant monopole resonance in ${}^{58}$Ni, ${}^{90}$Zr, ${}^{120}$Sn and ${}^{208}$Pb

   A. Bahini🇿🇦 · P. von Neumann-Cosel🇩🇪 · J. Carter🇿🇦 · I. T. Usman🇿🇦 · N. N. Arsenyev🇷🇺 · A. P. Severyukhin🇷🇺 · E. Litvinova🇺🇸 · R. W. Fearick🇿🇦 · R. Neveling🇿🇦 · P. Adsley🇿🇦 · N. Botha🇿🇦 · J. W. Brümmer🇿🇦 and 17 other authors

   Over the past two decades high energy-resolution inelastic proton scattering studies were used to gain an understanding of the origin of fine structure observed in the isoscalar giant quadrupole resonance (ISGQR) and the isovector giant dipole resonance (IVGDR). Recently, the isoscalar giant monopole resonance (ISGMR) in ${}^{58}$Ni, ${}^{90}$Zr, ${}^{120}$Sn and ${}^{208}$Pb was studied at the iThemba Laboratory for Accelerator Based Sciences (iThemba LABS) by means of inelastic $\alpha$-particle scattering at very forward scattering angles (including $0\circ$). The good energy resolution of the measurement revealed significant fine structure of the ISGMR.~To extract scales by means of wavelet analysis characterizing the observed fine structure of the ISGMR in order to investigate the role of different mechanisms contributing to its decay width. Characteristic energy scales are extracted from the fine structure using continuous wavelet transforms. The experimental energy scales are compared to different theoretical approaches performed in the framework of quasiparticle random phase approximation (QRPA) and beyond-QRPA including complex configurations using both non-relativistic and relativistic density functional theory. All models highlight the role of Landau fragmentation for the damping of the ISGMR especially in the medium-mass region. Models which include the coupling between one particle-one hole (1p-1h) and two particle-two hole (2p-2h) configurations modify the strength distributions and wavelet scales indicating the importance of the spreading width. The effect becomes more pronounced with increasing mass number. Wavelet scales remain a sensitive measure of the interplay between Landau fragmentation and the spreading width in the description of the fine structure of giant resonances.

   nucl-exnucl-thPRC(2024)·10 citations
3. 03*

   Efimov states in excited nuclear halos

   Shimpei Endo🇯🇵 · Junki Tanaka🇯🇵

   Universality -- an essential concept in physics -- implies that different systems show the same phenomenon and can be described by a unified theory. A prime example of the universal quantum phenomena is the Efimov effect, which is the appearance of multiples of low-energy three-body bound states with progressively large sizes dictated by the discrete scale invariance. The Efimov effect, originally proposed in the nuclear physics context, has been observed in cold atoms and ${}^4\mathrm{He}$ molecules. The search for the Efimov effect in nuclear physics, however, has been a long-standing challenge owing to the difficulty in identifying ideal nuclides with a large $s$-wave scattering length; such nuclides can be unambiguously considered as Efimov states. Here, we propose a systematic method to identify nuclides that exhibit Efimov states in their excited states in the vicinity of the neutron separation threshold. These nuclei are characterised by their enormous low-energy neutron capture cross-sections, hence giant $s$-wave scattering length. Using our protocol, we identified ${}^{90}$Zr and ${}^{159}$Gd as novel candidate nuclides that show the Efimov states. They are well inside the valley of stability in the nuclear chart, and are suited for experimental realisation of the Efimov states in nuclear physics.

   ↳ nucl-thcond-mat.quant-gasnucl-ex4 citations
4. 04*

   Radiation hardness study of BC408 plastic scintillator under 80 MeV proton beam irradiations

   Yue Zhang🇨🇳 · Ruirui Fan🇨🇳 · Yuhong Yu · Hantao Jing🇨🇳 · Zhixin Tan🇨🇳 · Yuhang Guo🇨🇳 · You Lv🇨🇳

   To investigate the 1.6 GeV high-energy proton beam detector utilized in the CSNS Phase-II upgrade project, a plastic scintillator detector presents a viable option due to its superior radiation hardness. This study investigates the effects of irradiation damage on a BC408 plastic scintillator induced by 80 MeV protons, including absorption and fluorescence spectroscopy, and light yield tests of BC408 pre- and post-proton irradiation, with a focus on determining the radiation resistance threshold of BC408. The results indicate that the performance of BC408 remains unimpaired at absorbed doses up to 5.14*10^3 Gy/cm3, demonstrating its ability to absorb 1.63*10^13 p/cm3 1.6 GeV protons while maintaining stability. This suggests that BC408 could potentially be used as the 1.6 GeV high-energy proton beam detector in the CSNS Phase-II upgrade project.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.B(2024)·2 citations
5. 05*

   Microscopic optical potentials for medium-mass isotopes derived at the first order of the Watson multiple scattering theory

   Matteo Vorabbi🇺🇸 · Carlo Barbieri🇮🇹 · Vittorio Somà🇫🇷 · Paolo Finelli🇮🇹 · Carlotta Giusti🇮🇹

   We perform a first-principle calculation of optical potentials for nucleon elastic scattering off medium-mass isotopes. Fully based on a saturating chiral Hamiltonian, the optical potentials are derived by folding nuclear density distributions computed with ab initio self-consistent Green's function theory with a nucleon-nucleon $t$ matrix computed with a consistent chiral interaction. The dependence on the folding interaction as well as the convergence of the target densities are investigated. Numerical results are presented and discussed for differential cross sections and analyzing powers, with focus on elastic proton scattering off Calcium and Nickel isotopes. Our optical potentials generally show a remarkable agreement with the available experimental data for laboratory energies in the range 65-200 MeV. We study the evolution of the scattering observables with increasing proton-neutron asymmetry by computing theoretical predictions of the cross section and analyzing power over the Calcium and Nickel isotopic chains.

   ↳ nucl-thnucl-exPRC(2024)·15 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.