Thu·Aug 15, 2019Thursday·August 15, 2019

1. 01*

   Exploring the mass surface near the rare-earth abundance peak via precision mass measurements at JYFLTRAP

   M. Vilen🇫🇮 · J.M. Kelly🇫🇮 · A. Kankainen🇫🇮 · M. Brodeur🇺🇸 · A. Aprahamian🇺🇸 · L. Canete🇫🇮 · R. de Groote🇫🇮 · A. de Roubin🇫🇮 · T. Eronen🇫🇮 · A. Jokinen🇫🇮 · I.D. Moore🇫🇮 · M.R. Mumpower🇺🇸 and 7 other authors

   The JYFLTRAP double Penning trap at the Ion Guide Isotope Separator On-Line (IGISOL) facility has been used to measure the atomic masses of 13 neutron-rich rare-earth isotopes. Eight of the nuclides, ${}^{161}$Pm, ${}^{163}$Sm, ${}^{164,165}$Eu, ${}^{167}$Gd, and ${}^{165,167,168}$Tb, were measured for the first time. The systematics of the mass surface has been studied via one- and two-neutron separation energies as well as neutron pairing-gap and shell-gap energies. The proton-neutron pairing strength has also been investigated. The impact of the new mass values on the astrophysical rapid neutron capture process has been studied. The calculated abundance distribution results in a better agreement with the solar abundance pattern near the top of the rare-earth abundance peak at around $A\approx 165$.

   nucl-exPRC(2020)·28 citations
2. 02*

   Measurement of angular and momentum distributions of charged particles within and around jets in Pb+Pb and $pp$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector

   ATLAS Collaboration

   Studies of the fragmentation of jets into charged particles in heavy-ion collisions can provide information about the mechanism of jet-quenching by the hot and dense QCD matter created in such collisions, the quark-gluon plasma. This paper presents a measurement of the angular distribution of charged particles around the jet axis in $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV Pb+Pb and $pp$ collisions, using the ATLAS detector at the LHC. The Pb+Pb and $pp$ data sets have integrated luminosities of 0.49 nb${}^{-1}$ and 25 pb${}^{-1}$, respectively. The measurement is performed for jets reconstructed with the anti-$k_t$ algorithm with radius parameter $R=0.4$ and is extended to an angular distance of $r=0.8$ from the jet axis. Results are presented as a function of Pb+Pb collision centrality and distance from the jet axis for charged particles with transverse momenta in the 1$-$63 GeV range, matched to jets with transverse momenta in the 126$-$316 GeV range and an absolute value of jet rapidity of less than 1.7. Modifications to the measured distributions are quantified by taking a ratio to the measurements in $pp$ collisions. Yields of charged particles with transverse momenta below 4 GeV are observed to be increasingly enhanced as a function of angular distance from the jet axis, reaching a maximum at $r=0.6$. Charged particles with transverse momenta above 4 GeV have an enhanced yield in Pb+Pb collisions in the jet core for angular distances up to $r=0.05$ from the jet axis, with a suppression at larger distances.

   nucl-exhep-exPRC(2019)·54 citations
3. 03*

   Hyperon electromagnetic timelike elastic form factors at large $q^2$

   G. Ramalho🇧🇷 · M.T. Peña🇵🇹 · K. Tsushima🇧🇷

   We present estimates of the hyperon elastic form factors for the baryon octet and the ${\Omega }^{-}$ baryon for large four-momentum transfer squared, $q^2$, in the timelike region ($q^2>0$). Experimentally, those form factors can be extracted from the $e^{+}{e}^{-}\to B\bar{B}$ and $p\bar{p}\to B\bar{B}$ processes, where $B$ stands for a general baryon. Our results are based on calculations of the elastic electromagnetic form factors in the spacelike region ($Q^2=-q^2>0$) within a covariant quark model. To connect the results in the spacelike region to those in the timelike region, we use asymptotic relations between the two regions which are constraints derived from analyticity and unitarity. We calculate the effective form factors $|G(q^2)|$ and compare them with the integrated cross section data ${\sigma }_{\mathrm{Born}}(q^2)$ from BaBar, BES III, and CLEO. The available data are at the moment restricted to $\Lambda$, ${\Sigma }^0$, ${\Sigma }^{-}$, ${\Xi }^{-}$, ${\Xi }^0$, and ${\Omega }^{-}$ as well as to $e^{+}{e}^{-}\to \Lambda {\bar{\Sigma }}^0$ and $e^{+}{e}^{-}\to {\Sigma }^0\bar{\Lambda }$ reactions. Our results provide useful reference for future experiments and seem to indicate that the present data are still in the non-perturbative QCD region, while the onset for the asymptotic constraints from analyticity and unitarity happens much before the region of the perturbative QCD falloff of the form factors.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2020)·39 citations
4. 04*

   Hadronization using the Wigner function approach for a multiphase transport model

   Feng-Tao Wang🇨🇳 · Jun Xu🇨🇳

   In the string melting version of a multiphase transport model, the hadronization algorithm has been improved by favoring parton combinations close in not only coordinate space but also momentum space. Formation probabilities of mesons, baryons, and antibaryons during hadronization are determined by their corresponding Wigner functions for the valence parton combinations with no free parameters, and the net baryon, electric, and strangeness charges are conserved during quark coalescence. Effects of the hadronization on anisotropic flows, collision energy dependence of the proton directed flow, relative particle yield ratios, as well as di-hadron correlations in relativistic heavy-ion collisions at the energies ranging from RHIC beam energy scan to LHC have been extensively discussed.

   ↳ nucl-thhep-exnucl-exPRC(2019)·9 citations
5. 05*

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

   C. Chatterjee🇮🇹 · G. Cicala🇮🇹 · A. Cicuttin🇮🇹 · P. Ciliberti🇮🇹 · M.L. Crespo🇮🇹 · S. Dalla Torre🇮🇹 · S. Dasgupta🇮🇹 · M. Gregori🇮🇹 · S. Levorato🇮🇹 · G. Menon🇮🇹 · F. Tessarotto🇮🇹 · Triloki🇮🇹 and 3 other authors

   The design of a Ring Imaging CHerenkov (RICH) detector for the identification of high momentum particles at the future Electron Ion Collider (EIC) is extremely challenging by using current technology. Compact collider setups impose to construct RICH with short radiator length, hence limiting the number of generated photons. The number of detected photons can be increased by selecting the far UV region. As standard fused-silica windows is opaque below 165 nm, a windowless RICH can be a possible approach. CsI is widely used photocathode (PC) for photon detection in the far UV range. Due to its hygroscopic nature it is very delicate to handle. In addition, its Quantum Efficiency (QE) degrades in high intensity ion fluxes. These are the key reasons to quest for novel PC with sensitivity in the far UV region. Recent development of layers of hydrogenated nanodiamond powders as an alternative PC material and their performance, when coupled to the THick Gaseous Electron Multipliers (THGEM)-based detectors, are the objects of an ongoing R\&D. We report here some preliminary results on the initial phase of these studies.

   ↳ physics.ins-dethep-exnucl-exJ.Phys.Conf.Ser.(2020)·4 citations
6. 06*

   Radiation shielding composites using thermoplastic polymers mouldable at low temperature

   John McMillan

   The formulation of a low temperature thermoplastic mouldable radiation shielding composite is given. The material is based on a low temperature melting polymer filled with lead shot. It can be easily moulded to shape after immersing in hot water, or by using a hot air gun. When cooled it is a rigid self supporting mass. Alternative formulations to provide low background or low toxicity gamma shielding or neutron shielding are also considered.

   ↳ physics.ins-detnucl-exphysics.med-ph0 citations
7. 07*

   Nucleon-to-Resonance Form Factors at Large Photon Virtualities

   J. Segovia🇪🇸 · C. Chen🇩🇪 · Z.-F. Cui🇨🇳 · Y. Lu🇨🇳 · C.D. Roberts🇺🇸

   We present a unified description of elastic and transition form factors involving the nucleon and its resonances; in particular, the $N(1440)$, $\Delta (1232)$ and $\Delta (1600)$. We compare predictions made using a framework built upon a Faddeev equation kernel and interaction vertices that possess QCD-kindred momentum dependence with results obtained using a confining, symmetry-preserving treatment of a vector$\otimes$vector contact-interaction in a widely-used leading-order (rainbow-ladder) truncation of QCD's Dyson-Schwinger equations. This comparison explains that the contact-interaction framework produces hard form factors, curtails some quark orbital angular momentum correlations within a baryon, and suppresses two-loop diagrams in the elastic and transition electromagnetic currents. Such defects are rectified in our QCD-kindred framework and, by contrasting the results obtained for the same observables in both theoretical schemes, shows those objects which are most sensitive to the momentum dependence of elementary quantities in QCD.

   ↳ nucl-thhep-exhep-lathep-ph+1AIP Conf.Proc.(2020)·6 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.