Fri·Jun 21, 2024Friday·June 21, 2024

1. 01*

   Dihadron Azimuthal Correlations in Deep-Inelastic Scattering Off Nuclear Targets

   CLAS Collaboration

   We measured the nuclear dependence of the di-pion azimuthal correlation function in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) and a 5 GeV electron beam. As the nuclear-target size increases, transitioning from deuterium to carbon, iron, and lead, the correlation function broadens monotonically. Its shape exhibits a significant dependence on kinematics, including the transverse momentum of the pions and the difference in their rapidity. None of the various Monte-Carlo event generators we evaluated could fully replicate the observed correlation functions and nuclear effects throughout the entire phase space. As the first study of its kind in DIS experiments, this research provides an important baseline for enhancing our understanding of the interplay between the nuclear medium and the hadronization process in these reactions.

   nucl-exPRC(2025)·2 citations
2. 02*

   Revealing initial state properties through ultra-central symmetric heavy-ion collisions

   S. M. A. Tabatabaee🇮🇷 · S. F. Taghavi🇩🇪

   Heavy-ion experiments provide a new opportunity to gain a deeper understanding of the structure of nuclei. To achieve this, it is crucial to identify observables under circumstances that are minimally affected by the process that leads to the initial state of heavy-ion collisions from nuclear wavefunction. In this study, we demonstrate that when assuming scale-invariance, the effect of this stage on the initial energy or entropy density moments in ultra-central symmetric collisions is negligible for nucleon sizes of approximately 0.7 fm or larger for large nuclei. By borrowing cluster expansion method from statistical physics and using scale-invariance assumption, we calculate the average ellipticity of initial density at the presence of short-range correlation. We compare our calculations to Monte Carlo studies and assess the accuracy of various methods of short-range correlation sampling. Additionally, we find that the isobar ratio can constrain the initial state parameters, in addition to deformation. Our study indicates that the isobar ratios in ultra-central collisions are especially sensitive to the fluctuation in the weight of the nuclei constituents and the two-body correlation among nucleons. This insight is crucial for drawing conclusions about nuclear deformations based on isobar ratios.

   ↳ nucl-thnucl-exPRC(2024)·4 citations
3. 03*

   A More Precise Measurement of the Radius of PSR J0740+6620 Using Updated NICER Data

   Alexander J. Dittmann🇺🇸 · M. Coleman Miller🇺🇸 · Frederick K. Lamb🇺🇸 · Isiah Holt🇺🇸 · Cecilia Chirenti🇺🇸 · Michael T. Wolff🇺🇸 · Slavko Bogdanov🇺🇸 · Sebastien Guillot🇫🇷 · Wynn C. G. Ho🇺🇸 · Sharon M. Morsink🇨🇦 · Zaven Arzoumanian🇺🇸 · Keith C. Gendreau🇺🇸

   PSR J0740+6620 is the neutron star with the highest precisely determined mass, inferred from radio observations to be $2.08\pm 0.07{\mathrm{M}}_{\odot }$. Measurements of its radius therefore hold promise to constrain the properties of the cold, catalyzed, high-density matter in neutron star cores. Previously, Miller et al. (2021) and Riley et al. (2021) reported measurements of the radius of PSR J0740+6620 based on Neutron Star Interior Composition Explorer (NICER) observations accumulated through 17 April 2020, and an exploratory analysis utilizing NICER background estimates and a data set accumulated through 28 December 2021 was presented in Salmi et al. (2022). Here we report an updated radius measurement, derived by fitting models of X-ray emission from the neutron star surface to NICER data accumulated through 21 April 2022, totaling $\sim 1.1$ Ms additional exposure compared to the data set analyzed in Miller et al. (2021) and Riley et al. (2021), and to data from X-ray Multi-Mirror (XMM-Newton) observations. We find that the equatorial circumferential radius of PSR J0740+6620 is $12.92_{-1.13}^{+2.09}$ km (68% credibility), a fractional uncertainty $\sim 83\%$ the width of that reported in Miller et al. (2021), in line with statistical expectations given the additional data. If we were to require the radius to be less than 16 km, as was done in Salmi et al. (2024), then our 68% credible region would become $R=12.76_{-1.02}^{+1.49}$ km, which is close to the headline result of Salmi et al. (2024). Our updated measurements, along with other laboratory and astrophysical constraints, imply a slightly softer equation of state than that inferred from our previous measurements.

   ↳ astro-ph.HEgr-qcnucl-exnucl-thApJ(2024)·178 citations
4. 04*

   New ${}^{63}$Ga(p,$\gamma$)${}^{64}$Ge and ${}^{64}$Ge(p,$\gamma$)${}^{65}$As reaction rates corresponding to the temperature regime of thermonuclear X-ray bursts

   Ning Lu · Yi Hua Lam🇨🇳 · Alexander Heger🇦🇺 · Zi Xin Liu🇨🇳 · Hidetoshi Yamaguchi🇯🇵

   We compute the ${}^{63}$Ga(p,$\gamma$)${}^{64}$Ge and ${}^{64}$Ge(p,$\gamma$)${}^{65}$As thermonuclear reaction rates using the latest experimental input supplemented with theoretical nuclear spectroscopic information. The experimental input consists of the latest proton thresholds of ${}^{64}$Ge and ${}^{65}$As, and the nuclear spectroscopic information of ${}^{65}$As, whereas the theoretical nuclear spectroscopic information for ${}^{64}$Ge and ${}^{65}$As are deduced from the full pf-shell space configuration-interaction shell-model calculations with the GXPF1A Hamiltonian. Both thermonuclear reaction rates are determined with known uncertainties at the energies that correspond to the Gamow windows of the temperature regime relevant to Type I X-ray bursts, covering the typical temperature range of the thermonuclear runaway of the GS 1826$-$24 periodic bursts and SAX J1808.4$-$3658 photospheric radius expansion bursts.

   ↳ nucl-thastro-ph.HEnucl-exPRC(2024)·4 citations
5. 05*

   The neutron array of the compact spectrometer for heavy ion experiments in Fermi energy region

   Dawei Si · Sheng Xiao · Yuhao Qin · Yijie Wang · Junhuai Xu · Baiting Tian · Boyuan Zhang · Dong Guo · Qin Zhi · Xiaobao Wei · Yibo Hao · Zengxiang Wang and 13 other authors

   The emission of neutrons from heavy ion reactions is an important observable for studying the asymmetric nuclear equation of state and the reaction dynamics. A 20-unit neutron array has been developed and mounted on the compact spectrometer for heavy ion experiments (CSHINE) to measure the neutron spectra, neutron-neutron and neutron-proton correlation functions. Each unit consists of a $15\times 15\times 15\mathrm{c}{\mathrm{m}}^3$ plastic scintillator coupled to a $\varphi =52\mathrm{mm}$ photomultiplier. The Geant4 simulation with optical process is performed to investigate the time resolution and the neutron detection efficiency. The inherent time resolution of 212 ps is obtained by cosmic ray coincidence test. The n-$\gamma$ discrimination and time-of-flight performance are given by ${}^{252}\mathrm{Cf}$ radioactive source test and beam test. The neutron energy spectra have been obtained in the angle range $30^{\circ }\le {\theta }_{\mathrm{lab}}\le 51^{\circ }$ in the beam experiment of ${}^{124}$Sn+${}^{124}$Sn at 25 MeV/u with CSHINE.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2025)·5 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.