Thu·Jun 4, 2020Thursday·June 4, 2020

1. 01*

   Measurements of ${\Xi }^{-}$ and ${\overline{\Xi }}^{+}$ production in proton-proton interactions at $\sqrt{s_{NN}}$ = 17.3 GeV in the NA61/SHINE experiment

   NA61/SHINE Collaboration: A. Aduszkiewicz🇵🇱 · E.V. Andronov🇷🇺 · T. Antićić🇭🇷 · V. Babkin🇷🇺 · M. Baszczyk🇵🇱 · S. Bhosale🇵🇱 · A. Blondel🇫🇷 · M. Bogomilov🇧🇬 · A. Brandin🇷🇺 · A. Bravar🇨🇭 · W. Bryliński🇵🇱 · J. Brzychczyk🇵🇱 and 125 other authors

   The production of $\Xi (1321{)}^{-}$ and $\overline{\Xi }(1321{)}^{+}$ hyperons in inelastic p+p interactions is studied in a fixed target experiment at a beam momentum of 158 GeV/textit{c}. Double differential distributions in rapidity y and transverse momentum $p_T$ are obtained from a sample of 33M inelastic events. They allow to extrapolate the spectra to full phase space and to determine the mean multiplicity of both ${\Xi }^{-}$ and ${\overline{\Xi }}^{+}$. The rapidity and transverse momentum spectra are compared to transport model predictions. The ${\Xi }^{-}$ mean multiplicity in inelastic p+p interactions at 158~\GeVc is used to quantify the strangeness enhancement in A+A collisions at the same centre-of-mass energy per nucleon pair.

   nucl-exhep-exEPJC(2020)·16 citations
2. 02*

   Two-particle correlations in azimuthal angle and pseudorapidity in central ${}^7$Be+${}^9$Be collisions at the CERN Super Proton Synchrotron

   NA61/SHINE Collaboration: A. Aduszkiewicz🇵🇱 · E.V. Andronov🇷🇺 · T. Antićić🇭🇷 · V. Babkin🇷🇺 · M. Baszczyk🇵🇱 · S. Bhosale🇵🇱 · A. Blondel🇫🇷 · M. Bogomilov🇧🇬 · A. Brandin🇷🇺 · A. Bravar🇨🇭 · W. Bryliński🇵🇱 · J. Brzychczyk🇵🇱 and 125 other authors

   A measurement of charged hadron pair correlations in two-dimensional $\Delta \eta \Delta \varphi$ space is presented. The analysis is based on total 30 million central Be+Be collisions observed in the NA61/SHINE detector at the CERN SPS for incident beam momenta of 19$A$, 30$A$, 40$A$, 75$A$, and 150$A$ GeV/$c$. Measurements were carried out for unlike-sign and like-sign charge hadron pairs independently. The $C(\Delta \eta ,\Delta \varphi )$ correlation functions were compared with results from a similar analysis on p+p interactions at similar beam momenta per nucleon. General trends of the back-to-back correlations are similar in central Be+Be collisions and p+p interactions, but are suppressed in magnitude due to the increased combinatorial background. Predictions from the EPOS and UrQMD models are compared to the measurements. Evolution of an enhancement around $(\Delta \eta ,\Delta \varphi )=(0,0)$ with incident energy is observed in central Be+Be collisions. It is not predicted by both models and almost non-existing in proton-proton collisions at the same momentum per nucleon.

   nucl-exhep-exEPJC(2020)·5 citations
3. 03*

   Decay studies of the long-lived states in ${}^{186}$Tl

   M. Stryjczyk🇧🇪 · B. Andel🇧🇪 · A. N. Andreyev🇬🇧 · J. Cubiss🇨🇭 · J. Pakarinen🇫🇮 · K. Rezynkina🇧🇪 · P. Van Duppen🇧🇪 · S. Antalic🇸🇰 · T. Berry🇬🇧 · M. J. G. Borge🇨🇭 · C. Clisu🇷🇴 · D. M. Cox🇸🇪 and 36 other authors

   Decay spectroscopy of the long-lived states in ${}^{186}$Tl has been performed at the ISOLDE Decay Station at ISOLDE, CERN. The $\alpha$ decay from the low-spin $(2^{-})$ state in ${}^{186}$Tl was observed for the first time and a half-life of $3.4_{-0.4}^{+0.5}$ s was determined. Based on the $\alpha$-decay energy, the relative positions of the long-lived states were fixed, with the $(2^{-})$ state as the ground state, the $7^{(+)}$ state at 77(56)~keV and the $10^{(-)}$ state at 451(56) keV. The level scheme of the internal decay of the ${}^{186}$Tl($10^{(-)}$) state ($T_{1/2}=3.40(9)$ s), which was known to decay solely through emission of 374 keV $\gamma$-ray transition, was extended and a lower-limit for the $\beta$-decay branching $b_{\beta }>5.9(3)\%$ was determined. The extracted retardation factors for the $\gamma$ decay of the $10^{(-)}$ state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the $\pi d_{3/2}$ shell in the isomeric decay and significant structure differences between ${}^{184}$Tl and ${}^{186}$Tl.

   nucl-exPRC(2020)·3 citations
4. 04*

   A comprehensive study of analyzing powers in the proton-deuteron break-up channel at 135 MeV

   M. T. Bayat · H. Tavakoli-Zaniani🇳🇱 · H. R. Amir-Ahmadi🇳🇱 · A. Deltuva🇱🇹 · M. Eslami-Kalantari🇮🇷 · J. Golak🇵🇱 · N. Kalantar-Nayestanaki🇳🇱 · St. Kistryn🇵🇱 · A. Kozela🇵🇱 · H. Mardanpour🇳🇱 · J. G. Messchendorp🇳🇱 · M. Mohammadi-Dadkan🇳🇱 and 5 other authors

   A measurement of the analyzing powers for the ${}^2$H$(\vec{p},pp)n$ break-up reaction was carried out at KVI exploiting a polarized-proton beam at an energy of 135 MeV. The scattering angles and energies of the final-state protons were measured using the Big Instrument for Nuclear-polarization Analysis (BINA) with a nearly $4\pi$ geometrical acceptance. In this work, we analyzed a large number of kinematical geometries including forward-forward configurations in which both the final-state particles scatter to small polar angles and backward-forward configurations in which one of the final-state particles scatters to large polar angles. The results are compared with Faddeev calculations based on modern nucleon-nucleon (NN) and three-nucleon (3N) potentials. Discrepancies between polarization data and theoretical predictions are observed for configurations corresponding to small relative azimuthal angles between the two final-state protons. These configurations show a large sensitivity to 3N force effects.

   nucl-exEPJA(2020)·4 citations
5. 05*

   Pre-hydrodynamic evolution and its signatures in final-state heavy-ion observables

   Tiago Nunes da Silva🇧🇷 · David Chinellato🇧🇷 · Mauricio Hippert🇧🇷 · Willian Serenone🇧🇷 · Jun Takahashi🇧🇷 · Gabriel S. Denicol🇧🇷 · Matthew Luzum🇧🇷 · Jorge Noronha🇺🇸

   We investigate the effects of pre-hydrodynamic evolution on final-state observables in heavy-ion collisions using state-of-the art event simulations coupled to different pre-hydrodynamic scenarios, which include the recently-developed effective kinetic transport theory evolution model KoMPoST. Flow observables are found to be insensitive to the details of pre-hydrodynamic evolution. The main effect we observe is in the $p_T$ spectra, particularly the mean transverse momentum. However, at least part of this effect is a consequence of the underlying conformal invariance assumption currently present in such approaches, which is known to be violated in the temperature regime probed in heavy-ion collisions. This assumption of early time conformal invariance leads to an artificially large out-of-equilibrium bulk pressure when switching from (conformal) pre-hydrodynamic evolution to hydrodynamics (using the non-conformal QCD equation of state), which in turn increases the transverse momentum. Our study indicates that a consistent treatment of pre-hydrodynamic evolution in heavy-ion collisions requires the use of non-conformal models of early time dynamics.

   ↳ nucl-thhep-phnucl-exPRC(2021)·45 citations
6. 06*

   Nanodiamond photocathodes for MPGD-based single photon detectors at future EIC

   F. M. Brunbauer🇨🇭 · C. Chatterjee🇮🇹 · G. Cicala🇮🇹 · A. Cicuttin🇮🇹 · P. Ciliberti🇮🇹 · M. L. Crespo🇮🇹 · D. D`Ago🇮🇹 · S. Dalla Torre🇮🇹 · S. Dasgupta🇮🇹 · M. Gregori🇮🇹 · T. Ligonzo🇮🇹 · S. Levorato🇮🇹 and 8 other authors

   We are developing gaseous photon detectors for Cherenkov imaging applications in the experiments at the future Electron Ion Collider. CsI, converting photons in the far ultraviolet range, is, so far, the only photoconverter compatible with the operation of gaseous detectors. It is very delicate to handle due to its hygroscopic nature: the absorbed water vapour decomposes the CsI molecule. In addition, its quantum efficiency degrades under ion bombardment. These are the key reasons to quest for novel, less delicate materials for photocathodes adequate for gaseous photon detectors. Layers of hydrogenated nanodiamond particles have recently been proposed as an alternative material and have shown promising characteristics. The performance of nanodiamond photocathodes coupled to thick GEM-based detectors is the object of our ongoing R\&D. The first phase of these studies includes the characterization of thick GEM coated with nanodiamond layers and the robustness of its photoconverting properties with respect to the bombardment by ions from the multiplication process in the gaseous detector. The approach is described in detail as well as all the results obtained so far within these exploratory studies.

   ↳ physics.ins-dethep-exnucl-exJINST(2020)·5 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.