Tue·Apr 14, 2015Tuesday·April 14, 2015

1. 01*

   Highlights from BNL and RHIC 2014

   M. J. Tannenbaum🇺🇸

   Highlights of news from Brookhaven National Laboratory (BNL) and results from the Relativistic Heavy Ion Collider (RHIC) in the period July 2013-June 2014 are presented. It was a busy year for news, most notably a U. S. Government shutdown for 16 days beginning October 1, 2013 due to the lack of an approved budget for FY2014. Even with this unusual government activity, the $\sqrt{s_{NN}}=200$ GeV Au+Au Run14 at RHIC was the best ever with integrated luminosity exceeding the sum of all previous runs. Additionally there was a brief He${}^3$+Au run to continue the study of collective flow in small systems which was reinforced by new results presented on identified particle flow in d+Au. The other scientific highlights are also mostly concerned with ``soft (low $p_T$)'' physics complemented by the first preliminary results of reconstructed jets from hard-scattered partons in Au+Au collisions at RHIC . The measurements of transverse energy ($E_T$) spectra in p-p, d+Au and Au+Au collisions, which demonstrated last year that constituent quarks are the fundamental elements of particle production in all 3 systems, led to the conclusion that the two-component ansatz which has been used to represent $E_T$ distributions as a function of centrality is simply a proxy for the number of constituent quark participants as well as to an explanation of the surprising elliptical flow results from U+U collisions. An extensive discussion of the latest measurements in Au+Au of net-charge and net-proton distributions represented by Cumulants of the distributions and plans for a Beam Energy Scan at RHIC to look for a QCD critical point is presented and compared to the claim implied by a press release during the 2011 ISSP.

   nucl-exSubnucl.Ser.(2017)·3 citations
2. 02*

   Reduced quasifission competition in fusion reactions forming neutron-rich heavy elements

   K. Hammerton · Z. Kohley🇺🇸 · D. J. Hinde🇦🇺 · M. Dasgupta🇦🇺 · A. Wakhle🇦🇺 · E. Williams🇦🇺 · V. E. Oberacker🇺🇸 · A. S. Umar🇺🇸 · I. P. Carter · K. J. Cook🇦🇺 · J. Greene · D. Y. Jeung🇦🇺 and 6 other authors

   Measurements of mass-angle distributions (MADs) for Cr + W reactions, providing a wide range in the neutron-to-proton ratio of the compound system, (N/Z)CN, have allowed for the dependence of quasifission on the (N/Z)CN to be determined in a model-independent way. Previous experimental and theoretical studies had produced conflicting conclusions. The experimental MADs reveal an increase in contact time and mass evolution of the quasifission fragments with increasing (N/Z)CN, which is indicative of an increase in the fusion probability. The experimental results are in agreement with microscopic time-dependent Hartree-Fock calculations of the quasifission process. The experimental and theoretical results favor the use of the most neutron-rich projectiles and targets for the production of heavy and superheavy nuclei.

   nucl-exnucl-thPRC(2015)·61 citations
3. 03*

   R-Matrix description of particle energy spectra produced by low-energy T+T reactions

   C.R. Brune🇺🇸 · J.A. Caggiano · D.B. Sayre · A.D. Bacher · G.M. Hale🇺🇸 · M.W. Paris🇺🇸

   An R-matrix model for three-body final states is presented and applied to a recent measurement of the neutron energy spectrum from the T+T->2n+alpha reaction. The calculation includes the n-alpha and n-n interactions in the final state, angular momentum conservation, antisymmetrization, and the interference between different channels. A good fit to the measured spectrum is obtained, where clear evidence for the 5He ground state is observed. The model is also used to predict the alpha-particle spectrum from T+T as well as particle spectra from 3He+3He. The R-matrix approach presented here is very general, and can be adapted to a wide variety of problems with three-body final states.

   ↳ nucl-thnucl-exPRC(2015)·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.