Thu·Jan 11, 2018Thursday·January 11, 2018

1. 01*

   Improved search for two-neutrino double electron capture on ${}^{124}$Xe and ${}^{126}$Xe using particle identification in XMASS-I

   XMASS Collaboration: K. Abe🇯🇵 · K. Hiraide🇯🇵 · K. Ichimura🇯🇵 · Y. Kishimoto🇯🇵 · K. Kobayashi🇯🇵 · M. Kobayashi🇯🇵 · S. Moriyama🇯🇵 · M. Nakahata🇯🇵 · T. Norita🇯🇵 · H. Ogawa🇯🇵 · K. Sato🇯🇵 · H. Sekiya🇯🇵 and 29 other authors

   We conducted an improved search for the simultaneous capture of two $K$-shell electrons on the ${}^{124}$Xe and ${}^{126}$Xe nuclei with emission of two neutrinos using 800.0 days of data from the XMASS-I detector. A novel method to discriminate $\gamma$-ray/$X$-ray or double electron capture signals from $\beta$-ray background using scintillation time profiles was developed for this search. No significant signal was found when fitting the observed energy spectra with the expected signal and background. Therefore, we set the most stringent lower limits on the half-lives at $2.1\times 10^{22}$ and $1.9\times 10^{22}$ years for ${}^{124}$Xe and ${}^{126}$Xe, respectively, with 90% confidence level. These limits improve upon previously reported values by a factor of 4.5.

   nucl-exhep-exphysics.ins-detPTEP(2018)·34 citations
2. 02*

   Cadmium Resonance Parameters from Neutron Capture and Transmission Measurements at the RPI LINAC

   G. Leinweber · D. P. Barry · R. C. Block · J. A. Burke · K. E. Remley · M. J. Rapp · Y. Danon🇺🇸

   Cadmium has been used historically as an important component of integral experiments because of its high thermal neutron absorption cross section. Correct interpretation of such experiments depends on accurate differential neutron cross section measurements. The 60 MeV electron accelerator at the Gaerttner LINAC Center was used to generate neutrons for neutron capture and total cross section measurements of natural Cd. Measurements were performed in the thermal and epithermal resonance range with sample thicknesses ranging from 1 x 10-4 to 4 x 10-2 atoms per barn. A full resonance region analysis was performed in order to determine the thermal cross sections and resonance integrals of the cadmium isotopes. The Bayesian R-Matrix code SAMMY 8.0 was used to shape fit the data and extract the resonance parameters. Resonance parameter and cross section uncertainties were determined from their primary components: transmission background, capture normalization, experimental resolution function, burst width, sample thickness, and counting statistics. The experiments were analyzed for consistency within the measured capture and transmission using multiple sample thicknesses. Results are compared to previously published measurements and evaluated nuclear libraries. No major changes to the thermal cross section or the first resonance in Cd113 were identified from the consensus achieved from measurements and evaluations over the past decade.

   nucl-exProc. 13th International Topical Meeting …·1 citation
3. 03*

   Small System Collectivity in Relativistic Hadron and Nuclear Collisions

   J.L. Nagle🇺🇸 · W.A. Zajc🇺🇸

   The bulk motion of nuclear matter at the ultra-high temperatures created in heavy-ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider is well described in terms of nearly inviscid hydrodynamics, thereby establishing this system of quarks and gluons as the most perfect fluid in nature. A revolution in the field is underway, spearheaded by the discovery of similar collective, fluid-like phenomena in much smaller systems including p+p, p+A, d+Au, and ${}^3$He$+$Au collisions. We review these exciting new observations and their implications.

   nucl-exhep-phnucl-thAnn.Rev.Nucl.Part.Sci.(2018)·471 citations
4. 04*

   Generalized Lomb-Scargle analysis of ${}^{90}\mathrm{Sr}{/}^{90}\mathrm{Y}$ decay rate measurements from the Physikalisch-Technische Bundesanstalt

   P Tejas · Shantanu Desai🇮🇳

   We apply the generalized Lomb-Scargle (LS) periodogram to independently confirm the claim by Sturrock et al (arXiv:1605.03088) of oscillation at a frequency of 11/year in the decay rates of ${}^{90}\mathrm{Sr}{/}^{90}\mathrm{Y}$ from measurements at the Physikalisch Technische Bundesanstalt (PTB), which however has been disputed by Kossert and Nahle (arXiv:1407.2493). For this analysis, we made two different {\it ansatze} for the errors. For each peak in the LS periodogram, we evaluate the statistical significance using non-parametric bootstrap resampling. We find using both of these error models evidence for ~11/year periodicity in the ${}^{90}\mathrm{Sr}{/}^{90}\mathrm{Y}$ data for two of the three samples, but at a lower significance than that claimed by Sturrock et al.

   ↳ astro-ph.HEnucl-exEPJC(2018)·5 citations
5. 05*

   New results on the multiplicity and centre-of-mass energy dependence of identified particle production in pp collisions with ALICE

   Gyula Bencedi (for the ALICE Collaboration)🇭🇺

   The study of identified particle production in proton-proton (pp) collisions as a function of center-of-mass energy ($\sqrt{s}$) and event charged-particle multiplicity is a key tool for understanding similarities and differences between small and large collision systems. We report on new measurements of the production of identified particles and their dependence on multiplicity and $\sqrt{s}$. Latest results for light flavor hadrons, comprising ${\pi }^{\pm }$, ${\mathrm{K}}^{\pm }$, $\mathrm{p}(\bar{\mathrm{p}})$, single-strange (${\mathrm{K}}_{\mathrm{S}}^0$, $\bar{\Lambda }$, and $\Lambda$), multi-strange (${\Xi }^{-}$, ${\overline{\Xi }}^{+}$, ${\Omega }^{-}$, and ${\overline{\Omega }}^{+}$) particles as well as resonances (${\mathrm{K}}^{\ast 0}$, ${\overline{\mathrm{K}}}^{\ast 0}$, $\varphi$), are presented for $\sqrt{s}=5.02,7$, and 13 TeV. The measured minimum bias $p_{\mathrm{T}}$ spectra and yields were complemented with multiplicity-dependent measurements for single- and multi-strange hadrons at $\sqrt{s}=7$ and $\sqrt{s}=13$ TeV. Results are compared to measurements at lower $\sqrt{s}$ as well as to those in proton-lead and lead-lead (Pb-Pb) collisions, respectively at ${\sqrt{s}}_{\mathrm{NN}}=5.02$ TeV and ${\sqrt{s}}_{\mathrm{NN}}=2.76$ TeV. The results unveil intriguing similarities among collision systems at different $\sqrt{s}$. The production rates of strange hadrons are found to increase more than those of non-strange particles, showing an enhancement pattern with multiplicity which does not depend on the collision energy. These yield ratios take values which are alike for small systems at comparable multiplicities and show smooth evolution with multiplicity across all collision systems. Although the multiplicity dependence of spectral shapes can be qualitatively described by general-purpose Monte Carlo (MC) event generators, the evolution of yield ratios is barely (or not) captured by MC model predictions.

   ↳ hep-exnucl-exPoS(2018)·4 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.