Thu·May 16, 2019Thursday·May 16, 2019

1. 01*

   Electromagnetic Backgrounds and Potassium-42 Activity in the DEAP-3600 Dark Matter Detector

   (DEAP Collaboration) · R. Ajaj · G. R. Araujo · M. Batygov · B. Beltran · C. E. Bina · M. G. Boulay · B. Broerman · J. F. Bueno · P. M. Burghardt · A. Butcher · M. Cárdenas-Montes and 80 other authors

   The DEAP-3600 experiment is searching for WIMP dark matter with a 3.3 tonne single phase liquid argon (LAr) target, located 2.1 km underground at SNOLAB. The experimental signature of dark matter interactions is keV-scale ${}^{40}$Ar nuclear recoils (NR) producing 128 nm LAr scintillation photons observed by PMTs. The largest backgrounds in DEAP-3600 are electronic recoils (ER) induced by $\beta$ and $\gamma$-rays originating from internal and external radioactivity in the detector material. A background model of the ER interactions in DEAP-3600 was developed and is described in this work. The model is based on several components which are expected from radioisotopes in the LAr, from ex-situ material assay measurements, and from dedicated independent in-situ analyses. This prior information is used in a Bayesian fit of the ER components to a 247.2 d dataset to model the radioactivity in the surrounding detector materials. While excellent discrimination between ERs and NRs is reached with pulse shape discrimination, utilizing the large difference between fast and slow components of LAr scintillation light, detailed knowledge of the ER background and activity of detector components, sets valuable constraints on other key types of backgrounds in the detector: neutrons and alphas. In addition, the activity of ${}^{42}$Ar in LAr in DEAP-3600 is determined by measuring the daughter decay of ${}^{42}$K. This cosmogenically activated trace isotope is a relevant background at higher energies for other rare event searches using atmospheric argon e.g. DarkSide-20k, GERDA or LEGEND. The specific activity of ${}^{42}$Ar in the atmosphere is found to be $40.4\pm 5.9$ $\mu$Bq/kg of argon.

   nucl-exastro-ph.IMPRD(2019)·52 citations
2. 02*

   Modelling the Nonlinear Response of Silicon Photomultipliers

   Jaime Rosado🇸🇾

   A statistical model of the nonlinear response of silicon photomultipliers is presented. It includes losses of both the photodetection efficiency and the gain during pixel recovery periods as well as the effect of correlated and uncorrelated noise. The model provides either the mean output charge of a SiPM for incident light pulses of arbitrary shape or the output current for continuous light. The dependence of the SiPM response on both the overvoltage and the pulse shape is also properly described. The model has been validated for two different silicon photomultipliers using scintillation light pulses from a LYSO crystal as well as continuous light from a LED. Good agreement is found with experimental data at moderate nonlinearity.

   ↳ physics.ins-dethep-exnucl-exphysics.med-phIEEE Sensors J.(2019)·7 citations
3. 03*

   Measurements of the transverse-momentum-dependent cross sections of $J/\psi$ production at mid-rapidity in proton+proton collisions at $\sqrt{s}=$ 510 and 500 GeV with the STAR detector

   STAR Collaboration: J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · R. Aoyama🇯🇵 · A. Aparin🇷🇺 · D. Arkhipkin🇺🇸 and 340 other authors

   We present measurements of the differential cross sections of inclusive $J/\psi$ meson production as a function of transverse momentum ($p_T^{J/\psi }$) using the ${\mu }^{+}{\mu }^{-}$ and $e^{+}{e}^{-}$ decay channels in proton+proton collisions at center-of-mass energies of 510 and 500 GeV, respectively, recorded by the STAR detector at the Relativistic Heavy Ion Collider. The measurement from the ${\mu }^{+}{\mu }^{-}$ channel is for 0 $<p_T^{J/\psi }<$ 9 GeV/$c$ and rapidity range $|y^{J/\psi }|<$ 0.4, and that from the $e^{+}{e}^{-}$ channel is for 4 $<p_T^{J/\psi }<$ 20 GeV/$c$ and $|y^{J/\psi }|<$ 1.0. The $\psi (2S)$ to $J/\psi$ ratio is also measured for 4 $<p_T^{\mathrm{meson}}<$ 12 GeV/$c$ through the $e^{+}{e}^{-}$ decay channel. Model calculations, which incorporate different approaches toward the $J/\psi$ production mechanism, are compared with experimental results and show reasonable agreement within uncertainties.

   ↳ hep-exnucl-exPRD(2019)·29 citations
4. 04*

   Capitalizing on Nuclear Data Libraries' Comprehensiveness to Obtain Solar System r-process Abundances

   Boris Pritychenko🇺🇸

   The recent observation of neutron stars merger by the Laser Interferometer Gravitational-Wave Observatory (LIGO) collaboration and the measurements of the event's electromagnetic spectrum as a function of time for different wavelengths have altered profoundly our understanding of the r-process site as well as considerably energized nuclear astrophysics research efforts. R-process abundances are a key element in r-process simulations, as a successful calculation must account for these abundances in the final debris of a stellar cataclysmic event. In this article, mankind's complete knowledge of neutron cross sections obtained over the last 80 years, as encapsulated in the latest release of the Evaluated Nuclear Data File (ENDF/B) library, is used to obtain solar system r-process abundances in a comprehensive data approach. ENDF/B cross sections have been successfully used for decades in nuclear power and defense applications and are now used to obtain r-process abundances in a fully traceable and documented way. This article r-process abundances provide complementary insights on the astrophysical events, overall quality of neutron capture data in the astrophysical region of temperatures, and demonstrate issues with the s-process contribution subtraction procedure.

   ↳ astro-ph.SRnucl-exJ.Phys.G(2021)·7 citations
5. 05*

   Valence parton distribution function of pion from fine lattice

   Taku Izubuchi🇺🇸 · Luchang Jin🇺🇸 · Christos Kallidonis🇺🇸 · Nikhil Karthik🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Charles Shugert🇺🇸 · Sergey Syritsyn🇺🇸

   We present a lattice QCD study of valence parton distribution inside the pion within the framework of Large Momentum Effective Theory. We use a mixed action approach with 1-HYP smeared valence Wilson clover quarks on 2+1 flavor HISQ sea with the valence quark mass tuned to 300 MeV pion mass. We use $48^3\times 64$ lattice at a fine lattice spacing $a=0.06$ fm for this computation. We renormalize the quasi-PDF matrix element in the non-perturbative RI-MOM scheme. As a byproduct, we test the validity of 1-loop matching procedure by comparing the RI-MOM renormalized quasi-PDF matrix element with off-shell quark external states as computed in the continuum 1-loop perturbation theory with the lattice results at $a=0.04$ and 0.06 fm. By applying the RI-MOM to $\overline{\mathrm{MS}}$ one-loop matching, implemented through a fit to phenomenologically motivated PDFs, we obtain the valence PDF of pion.

   ↳ hep-lathep-exhep-phnucl-ex+1PRD(2019)·139 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.