Thu·Jun 23, 2016Thursday·June 23, 2016

1. 01*

   Beta-delayed gamma decay of 26P: Possible evidence of a proton halo

   D. Pérez-Loureiro (1)🇺🇸 · C. Wrede (1 and 2)🇺🇸 · M. B. Bennett (1 and 2)🇺🇸 · S.N. Liddick (3)🇺🇸 · A. Bowe (1, 2 and 4)🇺🇸 · B. A. Brown (1 and 2)🇺🇸 · A. A. Chen (5)🇨🇦 · K. A. Chipps (6, 7 and 8)🇺🇸 · N. Cooper (9)🇬🇧 · D. Irvine (9)🇨🇦 · E. McNeice (9)🇨🇦 · F. Montes (1 and 10)🇺🇸 and 14 other authors

   Background: Measurements of $\beta$ decay provide important nuclear structure information that can be used to probe isospin asymmetries and inform nuclear astrophysics studies. Purpose: To measure the $\beta$-delayed $\gamma$ decay of ${}^{26}$P and compare the results with previous experimental results and shell-model calculations. Method: A ${}^{26}$P fast beam produced using nuclear fragmentation was implanted into a planar germanium detector. Its $\beta$-delayed $\gamma$-ray emission was measured with an array of 16 high-purity germanium detectors. Positrons emitted in the decay were detected in coincidence to reduce the background. Results: The absolute intensities of ${}^{26}$P $\beta$-delayed $\gamma$-rays were determined. A total of six new $\beta$-decay branches and 15 new $\gamma$-ray lines have been observed for the first time in ${}^{26}$P $\beta$-decay. A complete $\beta$-decay scheme was built for the allowed transitions to bound excited states of ${}^{26}$Si. $ft$ values and Gamow-Teller strengths were also determined for these transitions and compared with shell model calculations and the mirror $\beta$-decay of ${}^{26}$Na, revealing significant mirror asymmetries. Conclusions: A very good agreement with theoretical predictions based on the USDB shell model is observed. The significant mirror asymmetry observed for the transition to the first excited state ($\delta =51(10)\%$) may be evidence for a proton halo in ${}^{26}$P.

   nucl-exPRC(2016)·38 citations
2. 02*

   Nuclear Modification Factor Using Tsallis Non-extensive Statistics

   Sushanta Tripathy🇮🇳 · Trambak Bhattacharyya🇿🇦 · Prakhar Garg🇮🇳 · Prateek Kumar🇮🇳 · Raghunath Sahoo🇮🇳 · Jean Cleymans🇿🇦

   The nuclear modification factor is derived using Tsallis non-extensive statistics in relaxation time approximation. The variation of nuclear modification factor with transverse momentum for different values of non-extensive parameter, $q$, is also observed. The experimental data from RHIC and LHC are analysed in the framework of Tsallis non-extensive statistics in a relaxation time approximation. It is shown that the proposed approach explains the $R_{AA}$ of all particles over a wide range of transverse momenta but doesn't seem to describe the rise in $R_{AA}$ at very high transverse momenta.

   ↳ nucl-thhep-phnucl-exEPJA(2016)·61 citations
3. 03*

   Limiting Fragmentation in a Thermal Model with Flow

   Swatantra Kumar Tiwari🇮🇳 · Raghunath Sahoo🇮🇳

   The property of limiting fragmentation of various observables such as rapidity distributions ($dN/dy$), elliptic flow ($v_2$), average transverse momentum ($⟨p_T⟩$) etc. of charged particles is observed when they are plotted as a function of rapidity ($y$) shifted by the beam rapidity ($y_{beam}$) for a wide range of energies from AGS to RHIC. Limiting fragmentation (LF) is a well studied phenomenon as observed in various collision energies and colliding systems experimentally. It is very interesting to verify this phenomenon theoretically. We study such a phenomenon for pion rapidity spectra using our hydrodynamic-like model where the collective flow is incorporated in a thermal model in the longitudinal direction. Our findings advocate the observation of extended longitudinal scaling in the rapidity spectra of pions from AGS to lower RHIC energies, while it is observed to be violated at top RHIC and LHC energies. Prediction of LF hypothesis for Pb+Pb collisions at $\sqrt{s_{NN}}$=5.02 TeV is given.

   ↳ nucl-thhep-phnucl-exEPJA(2016)·2 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.