Wed·Feb 27, 2019Wednesday·February 27, 2019

1. 01*

   Comparison of fragmentation functions for light-quark- and gluon-dominated jets from $pp$ and Pb+Pb collisions in ATLAS

   ATLAS Collaboration

   Charged-particle fragmentation functions for jets azimuthally balanced by a high-transverse-momentum, prompt, isolated photon are measured in $25$ pb${}^{-1}$ of $pp$ and $0.49$ nb${}^{-1}$ of Pb+Pb collision data at $5.02$ TeV per nucleon pair recorded with the ATLAS detector at the Large Hadron Collider. The measurements are compared to predictions of Monte Carlo generators and to measurements of inclusively selected jets. In $pp$ collisions, a different jet fragmentation function in photon-tagged events from that in inclusive jet events arises from the difference in fragmentation between light quarks and gluons. The ratios of the fragmentation functions in Pb+Pb events to that in $pp$ events are used to explore the parton color-charge dependence of jet quenching in the hot medium. In relatively peripheral collisions, fragmentation functions exhibit a similar modification pattern for photon-tagged and inclusive jets. However, photon-tagged jets are observed to have larger modifications than inclusive jets in central Pb+Pb events.

   nucl-exhep-exPRL(2019)·93 citations
2. 02*

   Evidence of Neutrino Flux effect on Alpha Emission Radioactive Half-Life

   Jonathan Walg · Anatoly Rodnianski · Itzhak Orion

   Radioactive sources presented annual periodical half-life changes in several accurate measurements, although customary practice claims that radioactive decay should be a physical constant for each radionuclide. Besides that, the Purdue measurements of Mn-54 decay-rates indicated response to solar X-ray flare events in 2006. The Mn-54 source emits neutrino from the nucleus and therefore allows interpreting those solar neutrinos can interact with this radiation source. In order to track more radiation count-rate responses to solar flare events, we built an experimental detector system for gamma radiation count-rates measurements, facing an Am-241 source. The system was placed at an underground laboratory, permanently locked to avoid any influence by unexpected radiation perturbations, and environmentally controlled in means of temperature and clean-air flow, in order to maintain detector stabilization. The detector consist of NaI(Tl) scintillators for gamma radiation and total-counting reader devices for remote counting. Each radiation counting system was shielded by a 5 cm lead. One month prior to flare events from the Sun, all three detectors showed reasonably stable count-rates, which were tallied every 15 minutes. Five solar-flares occurred and reported by the SpaceWeatherLive website on 12th to 13th of October 2018. The Am-241 system response to solar flares found to be with a delay of around 20 days. We conclude that also for alpha emitter radioactive sources, the half-life altered due to changes of neutrino flux from the Sun. Our measurements indicated that an alpha emitter was affected by the neutrino flux change from the Sun.

   nucl-ex0 citations
3. 03*

   Charge correlations using balance functions of identified particles in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV with ALICE

   Sk Noor Alam (for the ALICE Collaboration)🇮🇳

   By studying the balance functions of several hadronic species, one can gain insight into the chem-ical evolution of the Quark \textendash Gluon Plasma and radial flow. In a picture of early hadronisation,pairs of particles and anti-particles (created at the same space \textendash time point) are separated furtherin rapidity due to the higher initial temperature and diffusive interactions with other particles.Therefore delayed hadronisation will lead to strong correlations in rapidity in the final state. In this work, balance functions for identified charged-pion pairs measured by the ALICE detector atthe Large Hadron Collider (LHC) in Pb \textendash Pb collisions at \sqrt{s_{NN}} = 2.76 TeV are presented. These balance functions are presented in relative rapidity (\Delta y) and relative azimuthal angle (\Delta \varphi). It isobserved that the charged-pion balance function widths in \Delta y and \Delta \varphi get narrower in central Pb \textendash Pb collisions compared to peripheral collisions. The findings in this analysis are consistent withthe effects of delayed hadronisation and radial flow.

   ↳ hep-exnucl-exPoS(2017)·3 citations
4. 04*

   Neutron-induced cross sections -- from raw data to astrophysical rates

   René Reifarth🇩🇪 · Philipp Erbacher🇩🇪 · Stefan Fiebiger · Kathrin Göbel🇩🇪 · Tanja Heftrich🇩🇪 · Michael Heil · Franz Käppeler🇩🇪 · Nadine Klapper🇩🇪 · Deniz Kurtulgil🇩🇪 · Christoph Langer🇩🇪 · Claudia Lederer-Woods🇬🇧 · Alberto Mengoni🇮🇹 and 4 other authors

   Neutron capture cross sections are one of the most important nuclear inputs to models of stellar nucleosynthesis of the elements heavier than iron. The activation technique and the time-of-flight method are mostly used to determine the required data experimentally. Recent developments of experimental techniques allow for new experiments on radioactive isotopes. Monte-Carlo based analysis methods give new insights into the systematic uncertainties of previous measurements. We present an overview over the state-of-the-art experimental techniques, a detailed new evaluation of the ${}^{197}$Au(n,$\gamma$) cross section in the keV-regime and the corresponding re-evaluation of 63 more isotopes, which have been measured in the past relative to the gold cross section.

   ↳ astro-ph.IMnucl-exEur.Phys.J.Plus(2018)·35 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.