Wed·Apr 3, 2019Wednesday·April 3, 2019

1. 01*

   First Observation Of Coherent Elastic Neutrino-Nucleus Scattering

   Bjorn J. Scholz🇺🇸

   Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) has the largest predicted cross-section of all low-energy neutrino couplings. However, as a neutral-current interaction, the only experimental signature of CE$\nu$NS is a low-energy nuclear recoil, which made its detection challenging. CE$\nu$NS remained unobserved for over four decades. This thesis describes the experiment that resulted in a CE$\nu$NS observation at a 6.7-sigma confidence level. A low-background, 14.6-kg CsI[Na] scintillator was exposed to the neutrino emissions from the Spallation Neutron Source at Oak Ridge National Laboratory. Characteristic CE$\nu$NS signatures in energy and time, compatible with predictions from the Standard Model, were observed in high signal-to-background conditions. CE$\nu$NS provides new opportunities to study neutrino properties, and enables the miniaturization of detectors.

   nucl-exSpringer Theses, Recognizing Outstanding …·21 citations
2. 02*

   The concept of laser-based conversion electron Mössbauer spectroscopy for a precise energy determination of ${}^{229m}$Th

   Lars C. von der Wense · Benedict Seiferle · Christian Schneider🇩🇪 · Justin Jeet · Ines Amersdorffer · Nicolas Arlt · Florian Zacherl · Raphael Haas🇺🇸 · Dennis Renisch · Patrick Mosel · Philip Mosel · Milutin Kovacev and 4 other authors

   ${}^{229}$Th is the only nucleus currently under investigation for the development of a nuclear optical clock (NOC) of ultra-high accuracy. The insufficient knowledge of the first nuclear excitation energy of ${}^{229}$Th has so far hindered direct nuclear laser spectroscopy of thorium ions and thus the development of a NOC. Here, a nuclear laser excitation scheme is detailed, which makes use of thorium atoms instead of ions. This concept, besides potentially leading to the first nuclear laser spectroscopy, would determine the isomeric energy to 40 $\mu$eV resolution, corresponding to 10 GHz, which is a $10^4$ times improvement compared to the current best energy constraint. This would determine the nuclear isomeric energy to a sufficient accuracy to allow for nuclear laser spectroscopy of individual thorium ions in a Paul trap and thus the development of a single-ion nuclear optical clock.

   nucl-exphysics.atom-phHyperfine Interact.(2019)·7 citations
3. 03*

   Dielectron production in proton-proton collisions at $\sqrt{s}=7$ TeV with ALICE

   Horst Sebastian Scheid (for the ALICE Collaboration)🇩🇪

   The ALICE Collaboration measured dielectron production as a function of the invariant mass ($m_{\mathrm{ee}}$), the pair transverse momentum ($p_{\mathrm{T},\mathrm{ee}}$) and the pair distance of closest approach ($\mathrm{DC}{\mathrm{A}}_{\mathrm{ee}}$) in pp collisions at $\sqrt{s}=7$ TeV. Prompt and non-prompt dielectron sources can be separated with the $\mathrm{DC}{\mathrm{A}}_{\mathrm{ee}}$, which will give the opportunity in heavy-ion collisions to identify thermal radiation from the medium in the intermediate-mass range dominated by contributions from open-charm and beauty hadron decays. The charm and beauty total cross sections are extracted from the data by fitting the spectra with two different MC generators, i.e. PYTHIA a leading order event generator and POWHEG a next-to-leading order event generator. Significant model dependences are observed, reflecting the sensitivity of this measurement to the heavy-flavour production mechanisms.

   nucl-exMDPI Proc.(2019)·0 citations
4. 04*

   Effect of shell structure on the fission of sub-lead nuclei

   Guillaume Scamps🇧🇪 · Cédric Simenel🇦🇺

   Fission of atomic nuclei often produces mass asymmetric fragments. However, the origin of this asymmetry was believed to be different in actinides and in the sub-lead region [A. Andreyev {\it et al.}, Phys. Rev. Lett. {\bf 105}, 252502 (2010)]. It has recently been argued that quantum shell effects stabilising pear shapes of the fission fragments could explain the observed asymmetries in fission of actinides[G. Scamps and C. Simenel, Nature {\bf 564}, 382 (2018)]. This interpretation is tested in the sub-lead region using microscopic mean-field calculations of fission based on the Hartree-Fock approach with BCS pairing correlations. The evolution of the number of protons and neutrons in asymmetric fragments of mercury isotope fissions is interpreted in terms of deformed shell gaps in the fragments. A new method is proposed to investigate the dominant shell effects in the pre-fragments at scission. We conclude that the mechanisms responsible for asymmetric fissions in the sub-lead region are the same as in the actinide region, which is a strong indication of their universality.

   ↳ nucl-thnucl-exPRC(2019)·91 citations
5. 05*

   Characterization of the Si(Li) detector for Monte Carlo calculations of beta spectra

   Pavel Novotny · Pavel Dryak · Jaroslav Solc · Petr Kovar · Zdenek Vykydal🇨🇿

   A precise model of a Si(Li) detector ORTEC model SLP-06165P-OPT-0.5 was created for beta spectra calculations using the Monte Carlo (MC) code MCNPX. Detector parameters were determined from X-ray radiograms obtained with a film and a Timepix detector. The MC model of the detector was validated by comparison of calculated and experimental full-energy peak efficiencies in the energy range from 5 to 136 keV using a range of point-like photon emitting radionuclide standards. A comparison of measured and calculated beta spectrum of a radionuclide Pm-147 is presented.

   ↳ physics.ins-detnucl-exJINST(2018)·0 citations
6. 06*

   Off-diagonal cumulants of net-charge, net-proton and net-kaon multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7-200 GeV from STAR

   Arghya Chatterjee🇮🇳

   Fluctuations of conserved quantities such as net-baryon, net-charge, and net-strangeness numbers have generated considerable interest in the study of the thermodynamic properties of the hot and dense QCD matter. Theoretical calculations suggest that the off-diagonal cumulants of conserved charges along with the diagonal cumulants can help better constrain the freeze-out parameters and, therefore, help to map the QCD phase diagram. In this proceeding, we briefly outline the recent STAR measurements on the second-order off-diagonal cumulants of net-charge, net-proton, and net-kaon multiplicity distributions in Au+Au collisions from the RHIC BES-I program in the energy range of $\sqrt{s_{NN}}$ = 7.7-200 GeV. The measured cumulant ratios are compared to the predictions from both thermal (HRG) and non-thermal (UrQMD) models.

   ↳ hep-exhep-phnucl-exPoS(2019)·2 citations
7. 07*

   Equation-of-state Constraints and the QCD Phase Transition in the Era of Gravitational-Wave Astronomy

   Andreas Bauswein🇩🇪 · Niels-Uwe Friedrich Bastian🇵🇱 · David Blaschke🇵🇱 · Katerina Chatziioannou🇺🇸 · James Alexander Clark🇺🇸 · Tobias Fischer🇵🇱 · Hans-Thomas Janka🇩🇪 · Oliver Just🇯🇵 · Micaela Oertel🇫🇷 · Nikolaos Stergioulas🇬🇷

   We describe a multi-messenger interpretation of GW170817, which yields a robust lower limit on NS radii. This excludes NSs with radii smaller than about 10.7 km and thus rules out very soft nuclear matter. We stress the potential of this type of constraints when future detections become available. A very similar argumentation may yield an upper bound on the maximum mass of nonrotating NSs. We also discuss simulations of NS mergers, which undergo a first-order phase transition to quark matter. We point out a different dynamical behavior. Considering the gravitational-wave signal, we identify an unambiguous signature of the QCD phase transition in NS mergers. The occurrence of quark matter through a strong first-order phase transition during merging leads to a characteristic shift of the dominant postmerger frequency. The frequency shift is indicative for a phase transition if it is compared to the postmerger frequency which is expected for purely hadronic EoS models. A very strong deviation of several 100 Hz is observed for hybrid EoSs in an otherwise tight relation between the tidal deformability and the postmerger frequency. We address the potential impact of a first-order phase transition on the electromagnetic counterpart of NS mergers. Our simulations suggest that there would be no significant qualitative differences between a system undergoing a phase transition to quark matter and purely hadronic mergers. The quantitative differences are within the spread which is found between different hadronic EoS models. This implies on the one hand that GW170817 is compatible with a possible transition to quark matter. On the other hand these considerations show that it may not be easy to identify quantitative differences between purely hadronic mergers and events in which quark matter occurs considering solely their electromagnetic counterpart or their nucleosynthesis products. (abridged)

   ↳ astro-ph.HEnucl-exnucl-thAIP Conf.Proc.(2019)·78 citations
8. 08*

   Wounded nucleon, quark and quark-diquark emission functions versus experimental results from RHIC

   Michał Barej🇵🇱 · Adam Bzdak🇵🇱 · Paweł Gutowski🇵🇱

   Using the wounded nucleon, quark, and quark-diquark models, we extract the wounded source emission functions from the PHOBOS data for d+Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV. We apply these models to compute charged particle multiplicity distributions as functions of pseudorapidity for p+p, p+Al, p+Au, d+Au, ${}^3$He+Au, Cu+Cu, Cu+Au, Au+Au, and U+U collisions at the same energy and compare them with experimental data from the PHOBOS and PHENIX collaborations. In symmetric collisions of heavy nuclei, the obtained distributions differ among the tested models. On the other hand, in asymmetric collisions, all three models give essentially the same distributions. The wounded quark-diquark and quark models are in reasonable agreement with data for all the investigated systems.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2019)·9 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.