Tue·Jan 16, 2018Tuesday·January 16, 2018

1. 01*

   Interaction of 160 GeV- Muon with Emulsion Nuclei

   S. M. Othman🇪🇬 · M.T. Ghoneim🇪🇬 · M.T. Hussein🇪🇬 · H.El-Smman🇪🇬 · A.Hussein🇪🇬

   In this work we present some results of the interaction of high energy muons with emulsion nuclei. The interaction results in emission of a number of fragments as a consequence of electromagnetic dissociation of the excited target nuclei. This excitation is attributed to absorption of photons by the target nuclei due to the intense electric field of the very fast incident muon particles. The interactions take place at impact parameters that allows ultra-peripheral collisions to take place, leading to giant resonances and hence multi-fragmentation of emulsion targets. Charge identification, range, energy spectra, angular distribution and topological cross-section of the produced fragments are measured and evaluated

   nucl-exhep-exhep-phphysics.ins-detIJMPE(2018)·1 citation
2. 02*

   Nuclear mass predictions based on Bayesian neural network approach with pairing and shell effects

   Z. M. Niu🇨🇳 · H. Z. Liang🇯🇵

   Bayesian neural network (BNN) approach is employed to improve the nuclear mass predictions of various models. It is found that the noise error in the likelihood function plays an important role in the predictive performance of the BNN approach. By including a distribution for the noise error, an appropriate value can be found automatically in the sampling process, which optimizes the nuclear mass predictions. Furthermore, two quantities related to nuclear pairing and shell effects are added to the input layer in addition to the proton and mass numbers. As a result, the theoretical accuracies are significantly improved not only for nuclear masses but also for single-nucleon separation energies. Due to the inclusion of the shell effect, in the unknown region, the BNN approach predicts a similar shell-correction structure to that in the known region, e.g., the predictions of underestimation of nuclear mass around the magic numbers in the relativistic mean-field model. This manifests that better predictive performance can be achieved if more physical features are included in the BNN approach.

   ↳ nucl-thastro-ph.SRnucl-exPLB(2018)·216 citations
3. 03*

   The Nuclear Contact Formalism - the Deuteron Channel

   Ronen Weiss🇮🇱 · Nir Barnea🇮🇱

   The contact formalism, devised to elucidate the important role of short-range correlations, was recently generalized for systems with coupled channels, such as the deuteron channel, where s and d waves are coupled into a $J=1$ state. The coupling of the two channels implies two independent asymptotic solutions and results a 2x2 contact matrix. For a strong coupling, with appropriate boundary conditions, such as in nuclear physics, the two solutions degenerate into a single asymptotic wave function. Here, we explore the asymptotic behavior of the correlated neutron-proton pairs in the deuteron channel using both schematic models and realistic nuclear forces.

   ↳ nucl-thcond-mat.quant-gasnucl-exphysics.atm-clus+11 citation
4. 04*

   Imprints of the nuclear symmetry energy on the tidal deformability of neutron stars

   Plamen G. Krastev🇺🇸 · Bao-An Li🇺🇸

   Applying an equation of state (EOS) with its symmetric nuclear matter (SNM) contribution and low-density symmetry energy $E_{sym}(\rho )$ constrained by heavy-ion reaction data, we calculate the dimensionless tidal deformability $\Lambda$ of neutron stars in coalescing binary systems. Corresponding to the partially constrained EOS that previously predicted a radius of 11.5 km $\le R_{1.4}\le$ 13.6 km for canonical neutron-star configurations, $\Lambda$ is found to be in the range of 292 $\le {\Lambda }_{1.4}\le$ 680, consistent with the very recent observation of the GW170817 event. We investigate the effect of the high-density behavior of $E_{sym}(\rho )$ on the tidal properties of neutron stars and find that while $\Lambda$ depends strongly on the details of the symmetry energy, different trends of $E_{sym}(\rho )$ lead to very similar values of $\Lambda$. In particular, the transition from stiff/soft to soft/stiff $E_{sym}(\rho )$ could yield the same $\Lambda$. Thus, measuring $\Lambda$ alone may not determine completely the density dependence of the symmetry energy. Coherent analyses of the dense neutron-rich nuclear matter EOS underlying both nuclear laboratory experiments and astrophysical observations are therefore necessary to break this degeneracy and determine precisely the details of the $E_{sym}(\rho )$.

   ↳ nucl-thastro-ph.HEnucl-exJ.Phys.G(2019)·76 citations
5. 05*

   Separation of gamma-ray and neutron events with CsI(Tl) pulse shape analysis

   Y. Ashida · H. Nagata · Y. Koshio🇯🇵 · T. Nakaya🇯🇵 · R. Wendell🇯🇵

   Fast neutrons are a large background to measurements of gamma-rays emitted from excited nuclei, such that detectors which can efficiently distinguish between the two are essential. In this paper we describe the separation of gamma-rays from neutrons with the pulse shape information of the CsI(Tl) scintillator, using a fast neutron beam and several gamma-ray sources. We find that a figure of merit optimized for this separation takes on large and stable values (nearly 4) between 5 and 10 MeV of electron equivalent deposited energy, the region of most interest to the study of nuclear de-excitation gamma-rays. Accordingly this work demonstrates the ability of CsI(Tl) scintillators to reject neutron backgrounds to gamma-ray measurements at these energies.

   ↳ physics.ins-detnucl-exPTEP(2018)·6 citations
6. 06*

   $Abinitio$ calculations for Gamow-Teller strengths in $sd$ shell

   Archana Saxena · Praveen C. Srivastava🇮🇳 · Toshio Suzuki🇯🇵

   In the present work we perform a systematic shell model study of Gamow-Teller transition strength distributions in $sd$ shell nuclei using $abinitio$ effective interactions. The $abinitio$ effective interactions are based on in-medium similarity renormalization group (IM-SRG) and coupled-cluster effective interaction (CCEI) approaches. The aim of the present work is to test the predictive power of $abinitio$ effective interactions by using the available experimental data of Gamow-Teller strength distributions in $sd$ shell nuclei. We perform calculations for ${}^{20}$Ne $\to$ ${}^{20}$F, ${}^{23}$Na $\to$ ${}^{23}$Mg, ${}^{23}$Na $\to$ ${}^{23}$Ne, ${}^{24}$Mg $\to$ ${}^{24}$Na, ${}^{24}$Mg $\to$ ${}^{24}$Al, ${}^{25}$Mg $\to$ ${}^{25}$Al, ${}^{26}$Mg $\to$ ${}^{26}$Na, ${}^{26}$Mg $\to$ ${}^{26}$Al, ${}^{26}$Si $\to$ ${}^{26}$Al, ${}^{27}$Al $\to$ ${}^{27}$Si, ${}^{28}$Si $\to$ ${}^{28}$P, ${}^{31}$P $\to$ ${}^{31}$Si, and ${}^{32}$S $\to$ ${}^{32}$P transitions. For comparison we also show the results obtained by using the phenomenological USDB Hamiltonian. The phenomenological USDB results of the Gamow-Teller (GT${}_{+}$/GT${}_{-}$) strength distributions show reasonable agreements with the experimental data in comparison to the $abinitio$ interactions. We also calculate the electron capture reaction rates for ${}^{23}$Na(e${}^{-}$, $\nu$)${}^{23}$Ne and ${}^{25}$Mg(e${}^{-}$, $\nu$)${}^{25}$Na using $abinitio$ and USDB interactions.

   ↳ nucl-thnucl-exPRC(2018)·24 citations
7. 07*

   Observation of medium induced modifications of jet fragmentation in PbPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV using isolated-photon-tagged jets

   CMS Collaboration

   Measurements of fragmentation functions for jets associated with an isolated photon are presented for the first time in pp and PbPb collisions. The analysis uses data collected with the CMS detector at the CERN LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Fragmentation functions are obtained for jets with p${}_{\mathrm{T}}^{\text{jet}}>$ 30 GeV in events containing an isolated photon with p${}_{\mathrm{T}}^{\gamma }>$ 60 GeV, using charged tracks with transverse momentum p${}_{\mathrm{T}}^{\text{trk}}>$ 1 GeV in a cone around the jet axis. The association with an isolated photon constrains the initial p${}_{\mathrm{T}}$ and azimuthal angle of the parton whose shower produced the jet. For central PbPb collisions, modifications of the jet fragmentation functions are observed when compared to those measured in pp collisions, while no significant differences are found in the 50% most peripheral collisions. Jets in central PbPb events show an excess (depletion) of low (high) p${}_{\mathrm{T}}$ particles, with a transition around 3 GeV. This measurement shows for the first time the in-medium shower modifications of partons (quark dominated) with well defined initial kinematics. It constitutes a new well-controlled reference for testing theoretical models of the parton passage through the QGP.

   ↳ hep-exnucl-exPRL(2018)·117 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.