Fri·Mar 25, 2016Friday·March 25, 2016

1. 01*

   Glauber modeling of high-energy nuclear collisions at sub-nucleon level

   Constantin Loizides🇺🇸

   Glauber models based on nucleon--nucleon interactions are commonly used to characterize the initial state in high-energy nuclear collisions, and the dependence of its properties on impact parameter or number of participating nucleons. In this paper, an extension to the Glauber model is presented, which accounts for an arbitrary number of effective sub-nucleon degrees of freedom, or active constituents, in the nucleons. Properties of the initial state, such as the number of constituent participants and collisions, as well as eccentricity and triangularity, are calculated and systematically compared for different assumptions of how to distribute the sub-nuclear degrees of freedom and for various collision systems. It is demonstrated that at high collision energy the number of produced particles scales with an average number of sub-nucleon degrees of freedom of between $3$ and $5$. The source codes for the constituent Monte Carlo Glauber extension, as well as for the calculation of the overlap area and participant density in a standard Glauber model, are made publicly available.

   nucl-exnucl-thPRC(2016)·153 citations
2. 02*

   Time-of-flight mass measurements of neutron-rich chromium isotopes up to N = 40 and implications for the accreted neutron star crust

   Z. Meisel🇺🇸 · S. George🇩🇪 · S. Ahn🇺🇸 · D. Bazin🇺🇸 · B.A. Brown🇺🇸 · J. Browne🇺🇸 · J.F. Carpino🇺🇸 · H. Chung🇺🇸 · R.H. Cyburt🇺🇸 · A. Estradé🇬🇧 · M. Famiano🇺🇸 · A. Gade🇺🇸 and 20 other authors

   We present the mass excesses of 59-64Cr, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The mass of 64Cr is determined for the first time, with an atomic mass excess of -33.48(44) MeV. We find a significantly different two-neutron separation energy S2n trend for neutron-rich isotopes of chromium, removing the previously observed enhancement in binding at N=38. Additionally, we extend the S2n trend for chromium to N=40, revealing behavior consistent with the previously identified island of inversion in this region. We compare our results to state-of-the-art shell-model calculations performed with a modified Lenzi-Nowacki-Poves-Sieja interaction in the fp shell, including the g9/2 and d5/2 orbits for the neutron valence space. We employ our result for the mass of 64Cr in accreted neutron star crust network calculations and find a reduction in the strength and depth of electron-capture heating from the A=64 isobaric chain, resulting in a cooler than expected accreted neutron star crust. This reduced heating is found to be due to the >1-MeV reduction in binding for 64Cr with respect to values from commonly used global mass models.

   nucl-exPRC(2016)·31 citations
3. 03*

   Strange Quark Stars as Probe of Dark Matter

   Hao Zheng🇨🇳 · Lie-Wen Chen🇨🇳

   We demonstrate that the observation of old strange quark stars (SQSs) can set important limits on the scattering cross sections ${\sigma }_q$ between the light quarks and the non-interacting scalar dark matter (DM). By analyzing a set of 1403 of solitary pulsarlike compact stars in the Milky Way, we find the old solitary pulsar PSR J1801-0857D can set the most stringent upper limits on ${\sigma }_q$ or the DM-proton scattering cross sections ${\sigma }_p$. By converting ${\sigma }_q$ into ${\sigma }_p$ based on effective operator analyses, we show the resulting ${\sigma }_p$ limit by assuming PSR J1801-0857D to be a SQS could be comparable with that of the current direct detection experiments but much weaker (by several orders of magnitude) than that obtained by assuming PSR J1801-0857D to be a neutron star (NS), which requires an extremely small ${\sigma }_p$ far beyond the limits of direct detection experiments. Our findings imply that the old pulsars are favored to be SQSs rather than NSs if the scalar DM were observed by future terrestrial experiments.

   ↳ nucl-thastro-ph.COastro-ph.SRhep-ph+1ApJ(2016)·20 citations
4. 04*

   Three-cluster breakup in deuteron-deuteron collisions: single-scattering approximation

   A. Deltuva🇱🇹 · A.C. Fonseca🇵🇹

   We present results for the three-cluster breakup in deuteron-deuteron collisions at 130 and 270 MeV deuteron beam energy. The breakup amplitude is calculated using the first term in the Neumann series expansion of the corresponding exact four-nucleon equations. In analogy with nucleon-deuteron breakup where an equivalent approximation is compared with exact calculations, we expect this single-scattering approximation to provide a rough estimation of three-body breakup observables in quasifree configurations. We predict the nucleon-deuteron and deuteron-deuteron three-cluster breakup cross sections to be of a comparable size and thereby question the reliability of the recent experimental data [A. Ramazani-Moghaddam-Arani, Ph.D. thesis, University of Groningen, 2009; A. Ramazani-Moghaddam-Arani et al., EPJ Web of Conferences 3, 04012 (2010)] that is smaller by about three orders of magnitude. We also show that an equivalent single-scattering approximation provides a reasonable description of deuteron-deuteron elastic scattering at forward scattering angles.

   ↳ nucl-thnucl-exPRC(2016)·17 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.