Thu·Jan 29, 2015Thursday·January 29, 2015

1. 01*

   Azimuthal Anisotropy Relative to the Participant Plane from AMPT in Central p+Au, d+Au, and ${}^3$He+Au Collisions at $\sqrt{s_{NN}}=200$ GeV

   J.D. Orjuela Koop🇺🇸 · A. Adare🇺🇸 · D. McGlinchey🇺🇸 · J.L. Nagle🇺🇸

   Recent data from p+p and p+Pb collisions at the Large Hadron Collider (LHC), and d+Au and ${}^3$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) reveal patterns that---when observed in the collision of heavy nuclei---are commonly interpreted as indicators of a locally equilibrated system in collective motion. The comparison of these data sets, including the forthcoming results from p+Au and p+Al collisions at RHIC, will help to elucidate the geometric dependence of such patterns. It has recently been shown that A-Multi-Phase-Transport-Model (AMPT) can describe some of these features in LHC data with a parton-parton scattering cross section comparable to that required to describe A+A data. In this paper, we extend these studies by incorporating a full wave function description of the ${}^3$He nucleus to calculate elliptical and triangular anisotropy moments $v_2$ and $v_3$ for p+Au, d+Au and ${}^3$He+Au collisions at the RHIC top energy of 200 GeV. We find reasonable agreement with the measured $v_2$ in d+Au and ${}^3$He+Au and $v_3$ in ${}^3$He+Au for transverse momentum ($p_T$) $\lesssim$ 1 GeV/c, but underestimate these measurements for higher values of \pt. We predict a pattern of coefficients ($v_2$, $v_3$) for \pau, dominated by differences in the number of induced local hot spots (i.e. one, two, or three) arising from intrinsic geometry. Additionally, we examine how this substantial azimuthal anisotropy accrues during each individual evolutionary phase of the collision in the AMPT model. The possibility of a simultaneous description of RHIC- and LHC-energy data, the suite of different geometries, and high multiplicity p+p data is an exciting possibility for understanding the underlying physics in these systems.

   nucl-exhep-phPRC(2015)·76 citations
2. 02*

   Bubble Chambers for Experiments in Nuclear Astrophysics

   B. DiGiovine🇺🇸 · D. Henderson🇺🇸 · R. J. Holt🇺🇸 · K. E. Rehm🇺🇸 · R. Raut🇮🇳 · A. Robinson🇺🇸 · A. Sonnenschein🇺🇸 · G. Rusev🇺🇸 · A. P. Tonchev🇺🇸 · C. Ugalde🇺🇸

   A bubble chamber has been developed to be used as an active target system for low energy nuclear astrophysics experiments. Adopting ideas from dark matter detection with superheated liquids, a detector system compatible with gamma-ray beams has been developed. This detector alleviates some of the limitations encountered in standard measurements of the minute cross sections of interest to stellar environments. While the astrophysically relevant nuclear reaction processes at hydrostatic burning temperatures are dominated by radiative captures, in this experimental scheme we measure the time-reversed processes. Such photodisintegrations allow us to compute the radiative capture cross sections when transitions to excited states of the reaction products are negligible. Due to the transformation of phase space, the photodisintegration cross sections are up to two orders of magnitude higher. The main advantage of the new target-detector system is a density several orders of magnitude higher than conventional gas targets. Also, the detector is virtually insensitive to the gamma-ray beam itself, thus allowing us to detect only the products of the nuclear reaction of interest. The development and the operation as well as the advantages and disadvantages of the bubble chamber are discussed.

   nucl-exastro-ph.IMphysics.ins-detNucl.Instrum.Meth.A(2015)·16 citations
3. 03*

   Present Status of Fission Research Based on TDDFT

   Yoritaka Iwata🇯🇵

   Fission resulting from collision of atomic nuclei is systematically investigated based on time-dependent density functional calculations. Time-dependent density functional theory (TDDFT) is a framework, which enables us to treat quantum many-body dynamics with nucleon degrees of freedom. In this article a theoretical framework called Composite-Nucleus Constrained TDDFT is introduced, and charge equilibrium hypothesis for collision fission dynamics is examined.

   ↳ nucl-thnucl-exJAEA-Conf 2015-003, INDC(JPN)-201, 93 (20…·0 citations
4. 04*

   Single and double spin asymmetries for deeply virtual Compton scattering measured with CLAS and a longitudinally polarized proton target

   S. Pisano · A. Biselli · S. Niccolai · E. Seder · M. Guidal · M. Mirazita · the CLAS Collaboration

   Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton $\vec{e}\vec{p}\to e^{\prime }{p}^{\prime }\gamma$ are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized ${}^{14}$NH${}_3$ target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. The measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the $H$ and $\tilde{H}$ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.

   ↳ hep-exnucl-exPRD(2015)·91 citations
5. 05*

   On the accuracy of using Fokker Planck equation in heavy ion collision

   Nirupam Dutta🇮🇳 · Trambak Bhattacharyya🇮🇳

   Application of Fokker-Planck equation to heavy quark transport in the evolving medium created in heavy ion collision is critically scrutinised. We realise that the approach introduces a moderate uncertainty in drag and diffusion coefficients culminating in huge ambiguity in the theoretical prediction of nuclear modification factor $R_{AA}$. Quantitative estimation of the error is presented by considering recent developments in this field.

   ↳ nucl-thhep-phnucl-ex0 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.