Mon·Dec 21, 2020Monday·December 21, 2020

1. 01*

   The reactor antineutrino spectrum calculation

   S. V. Silaeva🇷🇺 · V. V. Sinev🇷🇺

   New fissile isotopes antineutrino spectra (${}^{235}$U, ${}^{238}$U, ${}^{239}$Pu and ${}^{241}$Pu) calculation is presented. On base of summation method the toy model was developed. It was shown that total antineutrino number is conserved in framework of given database on individual fragments yields. The analysis of antineutrino spectrum shape says that any presented antineutrino spectrum should satisfy to the total antineutrino number conservation.

   nucl-exhep-phnucl-th6 citations
2. 02*

   Particlization of an interacting hadron resonance gas with global conservation laws for event-by-event fluctuations in heavy-ion collisions

   Volodymyr Vovchenko🇺🇸 · Volker Koch🇺🇸

   We revisit the problem of particlization of a QCD fluid into hadrons and resonances at the end of the fluid dynamical stage in relativistic heavy-ion collisions in a context of fluctuation measurements. The existing methods sample an ideal hadron resonance gas, therefore, they do not capture the non-Poissonian nature of the grand-canonical fluctuations, expected due to QCD dynamics such as the chiral transition or QCD critical point. We address the issue by partitioning the particlization hypersurface into locally grand-canonical fireballs populating the space-time rapidity axis that are constrained by global conservation laws. The procedure allows to quantify the effect of global conservation laws, volume fluctuations, thermal smearing and resonance decays on fluctuation measurements in various rapidity acceptances, and can be used in fluid dynamical simulations of heavy-ion collisions. As a first application, we study event-by-event fluctuations in heavy-ion collisions at the LHC using an excluded volume hadron resonance gas model matched to lattice QCD susceptibilities, with a focus on (pseudo)rapidity acceptance dependence of net baryon, net proton, and net charge cumulants. We point out large differences between net proton and net baryon cumulant ratios that make direct comparisons between the two unjustified. We observe that the existing experimental data on net-charge fluctuations at the LHC shows a strong suppression relative to a hadronic description.

   ↳ hep-phnucl-exnucl-thPRC(2021)·51 citations
3. 03*

   Enhanced production of strange baryons in high energy nuclear collisions from a multiphase transport model

   Tianhao Shao🇨🇳 · Jinhui Chen🇨🇳 · Che Ming Ko🇺🇸 · Zi-Wei Lin🇺🇸

   We introduce additional coalescence factors for the production of strange baryons in a multiphase transport (AMPT) model in order to describe the enhanced production of multistrange hadrons observed in Pb-Pb collisions at $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}$ = 2.76 TeV at the Large hadron Collider (LHC) and Au+Au collisions at $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}$ = 200 GeV at Relativistic Heavy-Ion Collider (RHIC).This extended AMPT model is found to also give a reasonable description of the multiplicity dependence of the strangeness enhancement observed in high multiplicity events in $pp$ collisions at $\sqrt{\mathrm{s}}$ = 7 TeV and $p$-Pb collisions at $\sqrt{{\mathrm{s}}_{\mathrm{NN}}}$ = 5.02 TeV. We find that the coalescence factors depend on the system size but not much on whether the system is produced from A+A or p+A collisions. The extended AMPT model thus provides a convenient way to model the mechanism underlying the observed strangeness enhancement in collisions of both small and large systems at RHIC and LHC energies.

   ↳ nucl-thnucl-exPRC(2020)·25 citations
4. 04*

   Dependence of related parameters on centrality and mass in a new treatment for transverse momentum spectra in high energy collisions

   Pei-Pin Yang🇨🇳 · Mai-Ying Duan🇨🇳 · Fu-Hu Liu🇨🇳

   We collected the experimental data of transverse momentum spectra of identified particles produced in proton-proton ($p$-$p$), deuteron-gold ($d$-Au or $d$-$A$), gold-gold (Au-Au or $A$-$A$), proton-lead ($p$-Pb or $p$-$A$), and lead-lead (Pb-Pb or $A$-$A$) collisions measured by the ALICE, CMS, LHCb, NA49, NA61/SHINE, PHENIX, and STAR collaborations at different center-of mass energies. The multisource thermal model at the quark level or the participant quark model is used to describe the experimental data. The free parameters, the effective temperature $T$, entropy index-related $n$, and revised index $a_0$, in the revised Tsallis--Pareto-type function are extracted at the quark level. In most cases, $T$ and $n$ in central collisions are larger than those in peripheral collisions, and $a_0$ does not change in different centrality classes. With the increase in the mass of produced particle or participant quark, $T$ and $a_0$ increase, and $n$ does not change significantly. The behaviors of related parameters from $p$-$p$, $p(d)$-$A$, and $A$-$A$ collisions are similar.

   ↳ hep-phhep-exnucl-exnucl-thEPJA(2021)·11 citations
5. 05*

   A benchmark of initial state models for heavy-ion collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=$ 27 and 62 GeV

   Jakub Cimerman🇨🇿 · Iurii Karpenko🇨🇿 · Boris Tomášik🇸🇰 · Barbara Antonina Trzeciak🇨🇿

   Description of relativistic heavy-ion collisions at the energies of RHIC Beam Energy Scan program with fluid dynamic approach poses several challenges, one of which being a complex geometry and a longer duration of the pre-hydrodynamic stage. Therefore, existing fluid dynamic models for heavy-ion collisions at the RHIC Beam Energy Scan energies rely on rather complex initial states, such as UrQMD cascade or multi-fluid dynamics. In this study, we show that functionally simpler, non-dynamical initial states can be employed for the fluid dynamical simulations of Au-Au collisions at \mbox{\sqrt{s_{_{\rm NN}}}}=27 and 62.4~GeV. We adapt the initial states based on Monte Carlo Glauber model (GLISSANDO 2) and $\sqrt{T_A{T}_B}$ ansatz based on reduced thickness (T${}_{\mathrm{R}}$ENTo $p=0$), extended into the longitudinal direction and finite baryon density. We find that both initial states, when coupled to a 3D event-by-event viscous fluid dynamic + cascade model, result in an overall fair reproduction of basic experimental data: pseudorapidity distributions, transverse momentum spectra and elliptic flow, at both collision energies. This is a rather surprising, given that the $\sqrt{T_A{T}_B}$ ansatz is functionally similar to the EKRT and IP-Glasma models, which are successful at much larger energies and rely on a partonic picture of the initial state.

   ↳ nucl-thnucl-exPRC(2021)·12 citations
6. 06*

   Imaging neutron capture cross sections: i-TED proof-of-concept and future prospects based on Machine-Learning techniques

   V. Babiano-Suárez🇪🇸 · J. Lerendegui-Marco · J. Balibrea-Correa🇪🇸 · L. Caballero🇪🇸 · D. Calvo🇪🇸 · I. Ladarescu🇪🇸 · C. Domingo-Pardo🇪🇸 · F. Calviño🇪🇸 · A. Casanovas🇪🇸 · A. Tarifeño-Saldivia🇪🇸 · V. Alcayne🇪🇸 · C. Guerrero🇪🇸 and 123 other authors

   i-TED is an innovative detection system which exploits Compton imaging techniques to achieve a superior signal-to-background ratio in ($n,\gamma$) cross-section measurements using time-of-flight technique. This work presents the first experimental validation of the i-TED apparatus for high-resolution time-of-flight experiments and demonstrates for the first time the concept proposed for background rejection. To this aim both ${}^{197}$Au($n,\gamma$) and ${}^{56}$Fe($n,\gamma$) reactions were measured at CERN n\_TOF using an i-TED demonstrator based on only three position-sensitive detectors. Two \cds detectors were also used to benchmark the performance of i-TED. The i-TED prototype built for this study shows a factor of $\sim$3 higher detection sensitivity than state-of-the-art \cds detectors in the $\sim$10~keV neutron energy range of astrophysical interest. This paper explores also the perspectives of further enhancement in performance attainable with the final i-TED array consisting of twenty position-sensitive detectors and new analysis methodologies based on Machine-Learning techniques.

   ↳ physics.ins-detastro-ph.IMnucl-exEPJA(2021)·24 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.