Fri·Feb 14, 2020Friday·February 14, 2020

1. 01*

   Jet splitting measurements in Pb--Pb and pp collisions at ${\sqrt{s}}_{\mathrm{NN}}=$ 5.02 TeV with ALICE

   Laura Havener (on behalf of the ALICE Collaboration)🇺🇸

   Recent ALICE measurements of jet splittings in Pb--Pb and pp collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are reported. These measurements scan the phase space of jet emissions in search of medium-induced signals which are expected to emerge at different scales. These include effects such as multiple soft-radiation, single hard emissions, and color coherence. The Lund plane diagram is shown, including projections onto distributions of the splitting scale $k_{\mathrm{T}}$ in intervals of the splitting angle $R_{\mathrm{g}}$. Soft Drop grooming is applied to access hard splittings within the jet, enabling measurements of groomed substructure variables. These include the shared momentum fraction $z_{\mathrm{g}}$ between the two hardest subjets and the number of Soft Drop splittings $n_{\mathrm{SD}}$. The results in Pb--Pb collisions are compared to PYTHIA events embedded into a Pb--Pb background to separate out background from in-medium effects. Measurements of $z_{\mathrm{g}}$ and the normalized splitting angle ${\theta }_{\mathrm{g}}$ will also be shown in pp collisions at $\sqrt{s}$ = 5.02 TeV for different grooming settings.

   nucl-exhep-exNPA(2021)·6 citations
2. 02*

   Simultaneous determination of neutron-induced fission and radiative-capture cross sections from decay probabilities obtained with a surrogate reaction

   R. Perez Sanchez🇫🇷 · B. Jurado🇫🇷 · V. Meot🇫🇷 · O. Roig🇫🇷 · M. Dupuis🇫🇷 · O. Bouland🇫🇷 · D. Denis-Petit🇫🇷 · P. Marini🇫🇷 · L. Mathieu🇫🇷 · I. Tsekhanovich🇫🇷 · M. Aiche🇫🇷 · L. Audouin🇫🇷 and 11 other authors

   Reliable neutron-induced reaction cross sections of unstable nuclei are essential for nuclear astrophysics and applications but their direct measurement is often impossible. The surrogate-reaction method is one of the most promising alternatives to access these cross sections. In this work, we successfully applied the surrogate-reaction method to infer for the first time both the neutron-induced fission and radiative-capture cross sections of 239Pu in a consistent manner from a single measurement. This was achieved by combining simultaneously-measured fission and gamma-emission probabilities for the 240Pu(4He,4He') surrogate reaction with a calculation of the angular-momentum and parity distributions populated in this reaction. While other experiments measure the probabilities for some selected gamma-ray transitions, we measure the gamma-emission probability. This enlarges the applicability of the surrogate-reaction method.

   nucl-exPRL(2020)·33 citations
3. 03*

   Early thermalization and shear viscosity to entropy ratio in heavy-ion collisions at energies of BES, FAIR and NICA

   E. Zabrodin🇳🇴 · L. Bravina🇳🇴 · M. Teslyk🇳🇴 · O. Vitiuk🇺🇦

   Equilibration of highly excited baryon-rich matter is studied within the microscopic model calculations in A+A collisions at energies of BES, FAIR and NICA. It is shown that the system evolution from the very beginning of the collision can be approximated by relativistic hydrodynamics, although the hot and dense nuclear matter is not in local equilibrium yet. During the evolution of the fireball the extracted values of energy density, net baryon and net strangeness densities are used as an input to Statistical Model (SM) in order to calculate temperature $T$, chemical potentials ${\mu }_B$ and ${\mu }_S$, and entropy density $s$ of the system. Also, they are used as an input for the box with periodic boundary conditions to investigate the momentum correlators in the infinite nuclear matter. Shear viscosity $\eta$ is calculated according to the Green-Kubo formalism. At all energies, shear viscosity to entropy density ratio shows minimum at time corresponding to maximum baryon density. The ratio dependence on $T,{\mu }_B,{\mu }_S$ is investigated for both in- and out of equilibrium cases.

   ↳ nucl-thhep-phnucl-exNPA(2021)·5 citations
4. 04*

   Probing Early-Time Dynamics and Quark-Gluon Plasma Transport Properties with Photons and Hadrons

   Charles Gale🇨🇦 · Jean-François Paquet🇺🇸 · Björn Schenke🇺🇸 · Chun Shen🇺🇸

   We use a hybrid model which relies on QCD effective kinetic theory -- K\oMP\oST -- to dynamically bridge the gap between IP-Glasma initial states and viscous hydrodynamics, for the theoretical interpretation of heavy-ion collision results. The hydrodynamic phase is then followed by dynamical freeze-out handled by UrQMD. It is observed that the new pre-equilibrium/pre-hydro phase does influence the extraction of transport coefficients. We also show how the early dynamics is reflected in photon observables.

   ↳ hep-phnucl-exnucl-thNPA(2021)·32 citations
5. 05*

   Development of readout electronics a novel beam monitoring system for ion research facility accelerator

   Honglin Zhang🇨🇳 · Haibo Yang · Xianqin Li🇨🇳 · Yuezhao Zhang🇨🇳 · Xiangming Sun🇨🇳 · Dong Wang · Ran Huang🇺🇸 · Yao Wang · Wei Zhou🇨🇳 · Chengxin Zhao

   This article presents the readout electronics of a novel beam monitoring system for ion research facility accelerator. The readout electronics are divided into Front-end Card (FEC) and Readout Control Unit (RCU). FEC uses Topmetal II minus to processes the energy of the hitting particles and convert it into a voltage signal. The main function of RCU is to digitize the analog output signal of FEC and format the raw data. On the other hand, the RCU also processes the control commands from the host and distributes the commands according to the mapping. The readout electronic has been characterized and calibrated in the laboratory, and have been installed with the detector. Implementation and testing of readout electronics have been discussed.

   ↳ physics.ins-detnucl-ex0 citations
6. 06*

   Study of a data analysis method for the angle resolving silicon telescope

   P. Žugec🇭🇷 · M. Barbagallo🇮🇹 · J. Andrzejewski🇵🇱 · J. Perkowski🇵🇱 · N. Colonna🇮🇹 · D. Bosnar🇭🇷 · A. Gawlik🇵🇱 · M. Sabate-Gilarte🇨🇭 · M. Bacak🇨🇭 · F. Mingrone🇨🇭 · E. Chiaveri🇨🇭 · M. Šako🇯🇵

   A new data analysis method is developed for the angle resolving silicon telescope introduced at the neutron time of flight facility n_TOF at CERN. The telescope has already been used in measurements of several neutron induced reactions with charged particles in the exit channel. The development of a highly detailed method is necessitated by the latest joint measurement of the ${}^{12}$C($n,p$) and ${}^{12}$C($n,d$) reactions from n_TOF. The reliable analysis of these data must account for the challenging nature of the involved reactions, as they are affected by the multiple excited states in the daughter nuclei and characterized by the anisotropic angular distributions of the reaction products. The unabridged analysis procedure aims at the separate reconstruction of all relevant reaction parameters - the absolute cross section, the branching ratios and the angular distributions - from the integral number of the coincidental counts detected by the separate pairs of silicon strips. This procedure is tested under the specific conditions relevant for the ${}^{12}$C($n,p$) and ${}^{12}$C($n,d$) measurements from n_TOF, in order to assess its direct applicability to these experimental data. Based on the reached conclusions, the original method is adapted to a particular level of uncertainties in the input data.

   ↳ physics.data-annucl-exJINST(2020)·3 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.