Fri·Nov 21, 2014Friday·November 21, 2014

1. 01*

   Peripheral nucleon-nucleon scattering at fifth order of chiral perturbation theory

   D.R. Entem🇪🇸 · N. Kaiser🇩🇪 · R. Machleidt🇺🇸 · Y. Nosyk🇺🇸

   We present the two- and three-pion exchange contributions to the nucleon-nucleon interaction which occur at next-to-next-to-next-to-next-to-leading order (N4LO, fifth order) of chiral effective field theory, and calculate nucleon-nucleon scattering in peripheral partial waves with L>=3 using low-energy constants that were extracted from pi-N analysis at fourth order. While the net three-pion exchange contribution is moderate, the two-pion exchanges turn out to be sizeable and prevailingly repulsive, thus, compensating the excessive attraction characteristic for NNLO and N3LO. As a result, the N4LO predictions for the phase shifts of peripheral partial waves are in very good agreement with the data (with the only exception of the 1F3 wave). We also discuss the issue of the order-by-order convergence of the chiral expansion for the NN interaction.

   ↳ nucl-thhep-phnucl-exPRC(2015)·189 citations
2. 02*

   Neutron Time-Of-Flight Spectrometer Based on HIRFL for Studies of Spallation Reactions Related to ADS Project

   Suyalatu Zhang🇨🇳 · Zhiqiang Chen · Rui Han🇨🇳 · Roy Wada · Xingquan Liu · Weiping Lin🇹🇼 · Jianli Liu · Fudong Shi · Peipei Ren🇨🇳 · Guoyu Tian · Fei Luo

   A Neutron Time-Of-Flight (NTOF) spectrometer based on Heavy Ion Research Facility in Lanzhou (HIRFL) is developed for studies of neutron production of proton induced spallation reactions related to the ADS project. After the presentation of comparisons between calculated spallation neutron production double-differential cross sections and the available experimental one, a detailed description of NTOF spectrometer is given. Test beam results show that the spectrometer works well and data analysis procedures are established. The comparisons of the test beam neutron spectra with those of GEANT4 simulations are presented.

   ↳ physics.ins-detnucl-exNucl.Sci.Tech.(2015)·1 citation
3. 03*

   Quarkonia Disintegration due to time dependence of the $q\bar{q}$ potential in Relativistic Heavy Ion Collisions

   Partha Bagchi🇮🇳 · Ajit M. Srivastava🇮🇳

   Rapid thermalization in ultra-relativistic heavy-ion collisions leads to fast changing potential between a heavy quark and antiquark from zero temperature potential to the finite temperature one. Time dependent perturbation theory can then be used to calculate the survival probability of the initial quarkonium state. In view of very short time scales of thermalization at RHIC and LHC energies, we calculate the survival probability of $J/\psi$ and ${\rm Y}$ using sudden approximation. Our results show that quarkonium decay may be significant even when temperature of QGP remains low enough so that the conventional quarkonium melting due to Debye screening is ineffective.

   ↳ hep-phnucl-exnucl-thMod.Phys.Lett.A(2015)·13 citations
4. 04*

   Pion-pion cross section from proton-proton collisions at the LHC

   B.Z. Kopeliovich🇨🇱 · H.-J. Pirner🇩🇪 · I.K. Potashnikova🇨🇱 · K. Reygers🇩🇪 · Ivan Schmidt🇨🇱

   The zero-degree calorimeters (ZDC) installed in the ALICE, ATLAS and CMS experiments at the LHC, make possible simultaneous detection of forward-backward leading neutrons, pp=>nXn. Such data with sufficiently high statistics could be a source of information about the pion-pion total cross section at high energies, provided that the absorption corrections, which are expected to be strong, are well understood. Otherwise, making a plausible assumption about the magnitude of the pion-pion cross section, one can consider such measurements as a way to study the absorption effects, which is the main focus of the present paper. These effects introduced at the amplitude level, are found to be different for the pion fluxes, which either conserve or flip the nucleon helicity. The pion fluxes from both colliding protons are essentially reduced by absorption, moreover, there is a common absorption suppression factor, which breaks down the factorized form of the cross section. We also evaluate the feed-down corrections related to the initial/final state inelastic processes possessing a rapidity gap, and found them to be small in the kinematic range under consideration. The contribution of other iso-vector Reggeons, spin-flip natural parity rho and a2, and spin non-flip unnatural parity a1 are also evaluated and found to be rather small.

   ↳ hep-phhep-exnucl-exPRD(2015)·14 citations
5. 05*

   Measurement of Leakage Neutron Spectra for Tungsten with D-T Neutrons and Validation of Evaluated Nuclear Data

   S. Zhanga · Z. Chen · Y. Nie🇨🇳 · R. Wada · X. Ruan🇿🇦 · R. Han · X. Liu · W. Lin🇨🇳 · J. Liu · F. Shi🇨🇳 · P. Ren · G. Tian🇨🇳 and 3 other authors

   Integral neutronics experiments have been investigated at Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS) in order to validate evaluated nuclear data related to the design of Chinese Initiative Accelerator Driven Systems (CIADS). In present paper, the accuracy of evaluated nuclear data for Tungsten has been examined by comparing measured leakage neutron spectra with calculated ones. Leakage neutron spectra from the irradiation of D-T neutrons on Tungsten slab sample were experimentally measured at 60${}^{\circ }$ and 120${}^{\circ }$ by using a time-of-flight method. Theoretical calculations are carried out by Monte Carlo neutron transport code MCNP-4C with evaluated nuclear data of the ADS-2.0, ENDF/B-VII.0, ENDF/B-VII.1, JENDL-4.0 and CENDL-3.1 libraries. From the comparisons, it is found that the calculations with ADS-2.0 and ENDF/B-VII.1 give good agreements with the experiments in the whole energy regions at 60${}^{\circ }$, while a large discrepancy is observed at 120${}^{\circ }$ in the elastic scattering peak, caused by a slight difference in the oscillation pattern of the elastic angular distribution at angles larger than 20${}^{\circ }$. However, the calculated spectra using data from ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries showed larger discrepancies with the measured ones, especially around 8.5-13.5 MeV. Further studies are presented for these disagreements.

   ↳ physics.ins-detnucl-exAppl.Radiat.Isot.(2016)·1 citation

* 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.