Mon·Jun 4, 2018Monday·June 4, 2018

1. 01*

   Phase transition dynamics for hot nuclei

   B. Borderie🇫🇷 · N. Le Neindre🇫🇷 · M.F. Rivet🇫🇷 · P. Désesquelles🇫🇷 · E. Bonnet🇫🇷 · R. Bougault🇫🇷 · A. Chbihi🇫🇷 · D. Dell'Aquila🇫🇷 · Q. Fable🇫🇷 · J.D. Frankland🇫🇷 · E. Galichet🇫🇷 · D. Gruyer🇫🇷 and 14 other authors

   An abnormal production of events with almost equal-sized fragments was theoretically proposed as a signature of spinodal instabilities responsible for nuclear multifragmentation in the Fermi energy domain. On the other hand finite size effects are predicted to strongly reduce this abnormal production. High statistics quasifusion hot nuclei produced in central collisions between Xe and Sn isotopes at 32 and 45 AMeV incident energies have been used to definitively establish, through the experimental measurement of charge correlations, the presence of spinodal instabilities. N/Z influence was also studied.

   nucl-exnucl-thPLB(2018)·28 citations
2. 02*

   Comment on "Sensitivity of ($d,p$) Reactions to High $n$-$p$ Momenta and the Consequences for Nuclear Spectroscopy Studies"

   A. Deltuva🇱🇹

   Using adiabatic distorted-wave approximation (ADWA) with nonlocal optical potentials (NLOP) for $(d,p)$ transfer reactions [G.W. Bailey, N.K. Timofeyuk, and J.A. Tostevin, Phys. Rev. Lett. 117, 162502 (2016)] reported strong sensitivity to the $n$-$p$ force model. This sensitivity disappears in rigorous three-body Faddeev-type results. Some shortcomings of ADWA with NLOP are pointed out.

   ↳ nucl-thnucl-ex4 citations
3. 03*

   Momentum dependence of pion-induced $\varphi$ meson production on nuclei near threshold

   E. Ya. Paryev🇷🇺

   We study the near-threshold pion-induced production of $\varphi$ mesons off nuclei in the kinematical conditions of the HADES experiment, recently performed at GSI. The calculations have been performed within a collision model based on the nuclear spectral function. The model accounts for both the primary ${\pi }^{-}$ meson--proton ${\pi }^{-}p\to \varphi n$ and the secondary pion--nucleon $\pi N\to \varphi N$ $\varphi$ production processes as well as the effects of the nuclear $\varphi$ and nucleon mean-field potentials. We find that the primary reaction channel ${\pi }^{-}p\to \varphi n$ dominates in the $\varphi$ production off ${}^{12}$C and ${}^{184}$W target nuclei in the HADES acceptance window at incident pion momentum of 1.7 GeV/c. We calculate the momentum dependence of the absolute and relative (transparency ratio) $\varphi$ meson yields from the above direct channel. The calculations have been performed for this initial pion momentum allowing for different options for the $\varphi N$ absorption cross section ${\sigma }_{\varphi N}$ and different scenarios for the in-medium mass shifts of the $\varphi$ meson and secondary neutron, produced together with $\varphi$ in this channel. We demonstrate that the transparency ratio for the $\varphi$ mesons has, contrary to the absolute cross sections, an insignificant sensitivity to the $\varphi$ meson and secondary neutron in-medium mass shifts at $\varphi$ momenta studied in the HADES experiment. On the other hand, we show that there are measurable changes in the transparency ratio due to the $\varphi N$ absorption cross section, which means that such relative observable can be useful to help determine this cross section from the data taken in the HADES experiment.

   ↳ nucl-thnucl-exCPC(2018)·12 citations
4. 04*

   Polarized EMC Effect in the QMC Model

   Stephen Tronchin🇦🇺 · Hrayr H. Matevosyan🇦🇺 · Anthony W. Thomas🇦🇺

   The ratios of the in-medium to free nucleon structure functions for the unpolarized and polarized cases are obtained using the MIT bag model for the free case, along with the QMC model to incorporate the in-medium modifications of the structure functions. As discussed in earlier work, the observed nuclear EMC effect is reasonably well described. This gives us confidence to investigate the predictions of the model for the polarized EMC effect, the ratio $g_1^{\ast }(x)/g_1(x)$ for a bound proton to that of a free proton. This ratio is found to be substantially different from unity and very similar in shape and size to that found in the unpolarized case. This prediction of such a fundamental change in the valence structure of a bound nucleon needs to be tested experimentally at the earliest opportunity.

   ↳ nucl-thhep-phnucl-exPLB(2018)·12 citations
5. 05*

   Characterization and performance of the DTAS detector

   V. Guadilla🇪🇸 · J.L. Tain🇪🇸 · A. Algora🇪🇸 · J. Agramunt🇪🇸 · J. Äystö🇫🇮 · J.A. Briz🇫🇷 · A. Cucoanes🇫🇷 · T. Eronen🇫🇮 · M. Estienne🇫🇷 · M. Fallot🇫🇷 · L.M. Fraile🇪🇸 · E. Ganioğlu🇹🇷 and 33 other authors

   DTAS is a segmented total absorption {\gamma}-ray spectrometer developed for the DESPEC experiment at FAIR. It is composed of up to eighteen NaI(Tl) crystals. In this work we study the performance of this detector with laboratory sources and also under real experimental conditions. We present a procedure to reconstruct offline the sum of the energy deposited in all the crystals of the spectrometer, which is complicated by the effect of NaI(Tl) light-yield non-proportionality. The use of a system to correct for time variations of the gain in individual detector modules, based on a light pulse generator, is demonstrated. We describe also an event-based method to evaluate the summing-pileup electronic distortion in segmented spectrometers. All of this allows a careful characterization of the detector with Monte Carlo simulations that is needed to calculate the response function for the analysis of total absorption {\gamma}-ray spectroscopy data. Special attention was paid to the interaction of neutrons with the spectrometer, since they are a source of contamination in studies of \b{eta}-delayed neutron emitting nuclei.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2018)·18 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.