Tue·Mar 21, 2017Tuesday·March 21, 2017

1. 01*

   Dilepton radiation and bulk viscosity in heavy-ion collisions

   Gojko Vujanovic🇺🇸 · Jean-François Paquet🇺🇸 · Chun Shen🇺🇸 · Gabriel S. Denicol🇧🇷 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦 · Ulrich Heinz🇺🇸

   Starting from IP-Glasma initial conditions, we investigate the effects of bulk pressure on thermal dilepton production at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) energies. Though results of the thermal dilepton $v_2$ under the influence of both bulk and shear viscosity is presented for top RHIC energy, more emphasis is put on LHC energy where such a calculation is computed for the first time. The effects of the bulk pressure on thermal dilepton $v_2$ at the LHC are explored through bulk-induced modifications on the dilepton yield.

   ↳ nucl-thhep-phnucl-exNucl.Part.Phys.Proc.(2017)·5 citations
2. 02*

   Neutron Production by Cosmic-Ray Muons in Various Materials

   K.V. Manukovsky · O.G. Ryazhskaya🇷🇺 · N.M. Sobolevsky · A.V. Yudin🇷🇺

   The results obtained by studying the background of neutrons produced by cosmic-ray muons in underground experimental facilities intended for rare-event searches and in surrounding rock are presented. The types of this rock may include granite, sedimentary rock, gypsum, and rock salt. Neutron production and transfer were simulated using the Geant4 and SHIELD transport codes. These codes were tuned via a comparison of the results of calculations with experimental data: in particular, with data of the Artemovsk research station of the Institute for Nuclear Research (INR, Moscow, Russia), as well as via an intercomparison of results of calculations with the Geant4 and SHIELD codes. It turns out that the atomic-number dependence of the production and yield of neutrons has an irregular character and does not allow a description in terms of a universal function of the atomic number. The parameters of this dependence are different for two groups of nuclei-nuclei consisting of alpha particles and all of the remaining nuclei. Moreover, there are manifest exceptions from a power-law dependence, for example, argon. This may entail important consequences both for the existing underground experimental facilities and for those under construction. Investigation of cosmic-ray-induced neutron production in various materials is of paramount importance for the interpretation of experiments conducted at large depths under the Earth's surface.

   ↳ physics.ins-dethep-exnucl-exPhys.Atom.Nucl.(2016)·9 citations
3. 03*

   Comparison of the pp -> pi+ pn and pp -> pi+ d production rates

   G.Faeldt🇸🇪 · C.Wilkin🇬🇧

   Fully constrained bubble chamber data on the pp -> pi+ pn and pp -> pi+ d reactions are used to investigate the ratio of the counting rates for the two processes at low pn excitation energies. Whereas the ratio is in tolerable agreement with that found in a high resolution spectrometer experiment, the angular distribution in the final pn rest frame shows that the deviation from the predictions of final state interaction theory must originate primarily from higher partial waves in the pn system. These considerations might also be significant for the determination of the S-wave Lambda:p scattering length from data on the pp -> K+ Lambda p reaction.

   ↳ nucl-thnucl-exPLB(2017)·1 citation
4. 04*

   Quenching Measurements and Modeling of a Boron-Loaded Organic Liquid Scintillator

   Shawn Westerdale🇺🇸 · Jingke Xu🇺🇸 · Emily Shields🇺🇸 · Francis Froborg🇺🇸 · Frank Calaprice🇺🇸 · Thomas Alexander🇬🇧 · Ani Aprahamian🇺🇸 · Henning O. Back🇺🇸 · Clark Casarella🇺🇸 · Xiao Fang🇺🇸 · Yogesh K. Gupta🇺🇸 · Edward Lamere🇺🇸 and 4 other authors

   Organic liquid scintillators are used in a wide variety of applications in experimental nuclear and particle physics. Boron-loaded scintillators are particularly useful for detecting neutron captures, due to the high thermal neutron capture cross section of ${}^{10}$B. These scintillators are commonly used in neutron detectors, including the DarkSide-50 neutron veto, where the neutron may produce a signal when it scatters off protons in the scintillator or when it captures on ${}^{10}$B. Reconstructing the energy of these recoils is complicated by scintillation quenching. Understanding how nuclear recoils are quenched in these scintillators is an important and difficult problem. In this article, we present a set of measurements of neutron-induced proton recoils in a boron-loaded organic liquid scintillator at recoil energies ranging from 57--467 keV, and we compare these measurements to predictions from different quenching models. We find that a modified Birks' model whose denominator is quadratic in $dE/dx$ best describes the measurements, with ${\chi }^2$/NDF$=1.6$. This result will help model nuclear recoil scintillation in similar detectors and can be used to improve their neutron tagging efficiency.

   ↳ physics.ins-dethep-exnucl-exJINST(2017)·10 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.