Tue·Apr 20, 2021Tuesday·April 20, 2021

1. 01*

   Novel method for producing very-neutron-rich hypernuclei via charge-exchange reactions with heavy ion projectiles

   Takehiko Saito🇯🇵 · Hiroyuki Ekawa🇯🇵 · Manami Nakagawa🇯🇵

   We propose a novel method for producing very-neutron-rich hypernuclei and corresponding resonance states by employing charge-exchange reactions via pp(${}^{12}$C, ${}^{12}$N $K^{+}$)n$\Lambda$ with single-charge-exchange and ppp(${}^9$Be, ${}^9$C $K^{+}$)nn$\Lambda$ with double-charge-exchange, both of which produce $\Lambda K^{+}$ in a target nucleus. The feasibility of producing very-neutron-rich hypernuclei using the proposed method was analysed by applying an ultra-relativistic quantum molecular dynamics model to a ${}^6$Li+${}^{12}$C reaction at 2 $A$ GeV. The yields of very-neutron-rich hypernuclei, signal-to-background ratios, and background contributions were investigated. The proposed method is a powerful tool for studying very-neutron-rich hypernuclei and resonance states with a hyperon for experiments employing the Super-FRS facility at FAIR and HFRS facility at HIAF.

   nucl-exnucl-thEPJA(2021)·18 citations
2. 02*

   Deeply virtual Compton scattering on the neutron with positron beam

   Silvia Niccolai🇫🇷 · Pierre Chatagnon🇫🇷 · Mostafa Hoballah🇫🇷 · Dominique Marchand🇫🇷 · Carlos Munoz Camacho🇫🇷 · Eric Voutier🇫🇷

   Measuring DVCS on a neutron target is a necessary step to deepen our understanding of the structure of the nucleon in terms of Generalized Parton Distributions (GPDs). The combination of neutron and proton targets allows to perform a flavor decomposition of the GPDs. Moreover, neutron-DVCS plays a complementary role to DVCS on a transversely polarized proton target in the determination of the GPD $E$, the least known and constrained GPD that enters Ji's angular momentum sum rule. A measurement of the beam-charge asymmetry (BCA) in the $e^{\pm }d\to e^{\pm }n\gamma (p)$ reaction can significantly impact the experimental determination of the real parts of the $E$ and, to a lesser extent, $\tilde{H}$ GPDs.

   nucl-exEPJA(2021)·3 citations
3. 03*

   Equation of state of asymmetric nuclear matter and the tidal deformability of neutron star

   Ngo Hai Tan🇻🇳 · Dao T. Khoa🇻🇳 · Doan Thi Loan🇻🇳

   Neutron star (NS) is a unique astronomical compact object where the four fundamental interactions have been revealed from the observation and studied in different ways. While the macroscopic properties of NS like mass and radius can be determined within the General Relativity using a realistic equation of state (EOS) of NS matter, such an EOS is usually generated by a nuclear structure model like, e.g., the nuclear mean-field approach to asymmetric nuclear matter. Given the radius of NS extended to above 10 km and its mass up to twice the solar mass, NS is expected to be tidally deformed when it is embedded in a strong tidal field. Such a tidal effect was confirmed unambiguously in the gravitation wave signals detected recently by the LIGO and Virgo laser interferometers from GW170817, the first ever direct observation of a binary NS merger. A nonrelativistic mean-field study is carried out in the present work within the Hartree-Fock formalism to construct the EOS of NS matter, which is then used to determine the tidal deformability, gravitational mass, and radius of NS. The mean-field results are compared with the constraints imposed for these quantities by the global analysis of the observed GW170817 data, and a strong impact by the incompressibility of nuclear matter on the hydrostatic configuration of NS is shown.

   ↳ nucl-thnucl-exEPJA(2021)·7 citations
4. 04*

   UCGretina GEANT4 Simulation of the GRETINA Gamma-Ray Energy Tracking Array

   L. A. Riley🇺🇸 · D. Weisshaar🇺🇸 · H. L. Crawford🇺🇸 · M. L. Agiorgousis🇺🇸 · C. M. Campbell🇺🇸 · M. Cromaz🇺🇸 · P. Fallon🇺🇸 · A. Gade🇺🇸 · S. D. Gregory🇺🇸 · E. B. Haldeman🇺🇸 · L. R. Jarvis🇺🇸 · E. D. Lawson-John🇺🇸 and 3 other authors

   UCGretina, a GEANT4 simulation of the GRETINA gamma-ray tracking array of highly-segmented high-purity germanium detectors is described. We have developed a model of the array, in particular of the Quad Module and the capsules, that gives good agreement between simulated and measured photopeak efficiencies over a broad range of gamma-ray energies and reproduces the shape of the measured Compton continuum. Both of these features are needed in order to accurately extract gamma-ray yields from spectra collected in in-beam gamma-ray spectroscopy measurements with beams traveling at $v/c\gtrsim 0.3$ at the National Superconducting Cyclotron Laboratory and the Facility for Rare Isotope Beams. In the process of developing the model, we determined that millimeter-scale layers of passive germanium surrounding the active volumes of the simulated crystals must be included in order to reproduce measured photopeak efficiencies. We adopted a simple model of effective passive layers and developed heuristic methods of determining passive-layer thicknesses by comparison of simulations and measurements for a single crystal and for the full array. Prospects for future development of the model are discussed.

   ↳ physics.ins-detastro-ph.IMnucl-exNucl.Instrum.Meth.A(2021)·18 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.