Tue·Jul 14, 2015Tuesday·July 14, 2015

1. 01*

   Elliptic flow of muons from heavy-flavour hadron decays at forward rapidity in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV

   ALICE Collaboration

   The elliptic flow, $v_2$, of muons from heavy-flavour hadron decays at forward rapidity ($2.5<y<4$) is measured in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$~=~2.76 TeV with the ALICE detector at the LHC. The scalar product, two- and four-particle $Q$ cumulants and Lee-Yang zeros methods are used. The dependence of the $v_2$ of muons from heavy-flavour hadron decays on the collision centrality, in the range 0--40\%, and on transverse momentum, $p_{\mathrm{T}}$, is studied in the interval $3<p_{\mathrm{T}}<10$~GeV/$c$. A positive $v_2$ is observed with the scalar product and two-particle $Q$ cumulants in semi-central collisions (10--20\% and 20--40\% centrality classes) for the $p_{\mathrm{T}}$ interval from 3 to about 5 GeV/$c$. The $v_2$ magnitude tends to decrease towards more central collisions and with increasing $p_{\mathrm{T}}$. It becomes compatible with zero in the interval $6<p_{\mathrm{T}}<10GeV/c$. The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions. The model calculations describe the measured $v_2$ within uncertainties.

   nucl-exhep-exPLB(2016)·57 citations
2. 02*

   Freeze-out configuration properties in the 197Au + 197Au reaction at 23 AMeV

   R.Najman🇵🇱 · R.Planeta🇵🇱 · A.Sochocka · F.Amorini🇮🇹 · L.Auditore🇮🇹 · T.Cap · G.Cardella🇮🇹 · E. De Filippo🇮🇹 · E.Geraci · A.Grzeszczuk🇵🇱 · S.Kowalski🇵🇱 · T.Kozik🇵🇱 and 16 other authors

   Data from the experiment on the 197Au + 197Au reaction at 23 AMeV are analyzed with an aim to find signatures of exotic nuclear configurations such as toroid-shaped objects. The experimental data are compared with predictions of the ETNA code dedicated to look for such configurations and with the QMD model. A novel criterion of selecting events possibly resulting from the formation of exotic freeze-out configurations, "the efficiency factor", is tested. Comparison between experimental data and model predictions may indicate for the formation of flat/toroidal nuclear systems.

   nucl-exPRC(2015)·8 citations
3. 03*

   The thermal neutron capture cross section of the radioactive isotope ${}^{60}$Fe

   T. Heftrich🇩🇪 · M. Bichler🇦🇹 · R. Dressler🇨🇭 · K. Eberhardt🇩🇪 · A. Endres🇩🇪 · J. Glorius🇩🇪 · K. Göbel🇩🇪 · G. Hampel · M. Heftrich · F. Käppeler🇩🇪 · C. Lederer🇩🇪 · M. Mikorski and 11 other authors

   50% of the heavy element abundances are produced via slow neutron capture reactions in different stellar scenarios. The underlying nucleosynthesis models need the input of neutron capture cross sections. One of the fundamental signatures for active nucleosynthesis in our galaxy is the observation of long-lived radioactive isotopes, such as ${}^{60}$Fe with a half-life of $2.60\times 10^6$ yr. To reproduce this $\gamma$-activity in the universe, the nucleosynthesis of ${}^{60}$Fe has to be understood reliably. A ${}^{60}$Fe sample produced at the Paul-Scherrer-Institut was activated with thermal and epithermal neutrons at the research reactor at the Johannes Gutenberg-Universität Mainz. The thermal neutron capture cross section has been measured for the first time to ${\sigma }_{\text{th}}=0.226{(}_{-0.049}^{+0.044})$ b. An upper limit of ${\sigma }_{\text{RI}}<0.50$ b could be determined for the resonance integral. An extrapolation towards the astrophysicaly interesting energy regime between $kT$=10 keV and 100 keV illustrates that the s-wave part of the direct capture component can be neglected.

   nucl-exastro-ph.IMPRC(2015)·3 citations
4. 04*

   Measurements of neutron-induced reactions in inverse kinematics and applications to nuclear astrophysics

   René Reifarth🇩🇪 · Yuri A. Litvinov🇩🇪 · Anne Endres🇩🇪 · Kathrin Göbel🇩🇪 · Tanja Heftrich🇩🇪 · Jan Glorius🇩🇪 · Alexander Koloczek🇩🇪 · Kerstin Sonnabend🇩🇪 · Claudia Travaglio🇮🇹 · Mario Weigand🇩🇪

   Neutron capture cross sections of unstable isotopes are important for neutron-induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes. The idea is to measure neutron-induced reactions on radioactive ions in inverse kinematics. This means, the radioactive ions will pass through a neutron target. In order to efficiently use the rare nuclides as well as to enhance the luminosity, the exotic nuclides can be stored in an ion storage ring. The neutron target can be the core of a research reactor, where one of the central fuel elements is replaced by the evacuated beam pipe of the storage ring. Using particle detectors and Schottky spectroscopy, most of the important neutron-induced reactions, such as (n,$\gamma$), (n,p), (n,$\alpha$), (n,2n), or (n,f), could be investigated.

   nucl-exastro-ph.IMEPJ Web Conf.(2015)·0 citations
5. 05*

   Reference material for natural radionuclides in glass designed for underground experiments

   P. P. Povinec (1)🇸🇰 · M. K. Pham (2)🇲🇨 · J. Busto (3)🇫🇷 · C. Cerna (3,4)🇫🇷 · D. Degering (5)🇩🇪 · Y. Hamajima (6)🇯🇵 · K. Holy (1)🇸🇰 · M. Hult (7)🇧🇪 · M. Jeskovsky (1)🇸🇰 · M. Koehler (5)🇩🇪 · A. Kovacik (1)🇸🇰 · M. Laubenstein (8)🇮🇹 and 14 other authors

   A reference material designed for the determination of natural radionuclides in solid samples (glass pellets) is described and the results of certification are presented. The material has been certified for 7 natural radionuclides (40K, 226Ra, 228Ra, 228Th, 232Th, 235U and 238U). An information value is given for 210Pb. Radon (222Rn) emanation experiments showed results comparable within participating laboratories, however, the number of data and precision was too low to carry out a certification process. The reference material may be used for quality management of analytical laboratories engaged in the high-sensitive analysis of radionuclides in the construction materials of detectors placed in ultra low background underground laboratories.

   ↳ physics.ins-detnucl-exJ.Radioanal.Nucl.Chem.(2016)·2 citations
6. 06*

   Symmetry potential of $\Delta (1232)$ resonance and its effects on the ${\pi }^{-}/{\pi }^{+}$ ratio in heavy-ion collisions near the pion production threshold

   Bao-An Li🇺🇸

   Effects of the completely unknown symmetry (isovector) potential of the \D on the total and differential \rpi in heavy-ion collisions at beam energies from 100 to 1000 MeV/A are explored within an isospin-dependent transport model IBUU. The effects are found to be negligible at beam energies above the pion production threshold due to the very short lifetimes of less than 2 fm/c for $\Delta$ resonances with masses around $m_{\Delta }=1232$ MeV, leaving the ${\pi }^{-}/{\pi }^{+}$ ratios of especially the energetic pions still a reliable probe of the high-density behavior of nuclear symmetry energy $E_{sym}(\rho )$. However, as the beam energy becomes deeply sub-threshold for pion production, effects of the $\Delta$ symmetry potential becomes appreciable especially on the \rpi of low-energy pions from the decays of low-mass $\Delta$ resonances which have lived long enough to be affected by their mean-field potentials, providing a useful tool to study the symmetry potential and spectroscopy of $\Delta$ resonances in neutron-rich nuclear matter. Interestingly though, even at the deeply sub-threshold beam energies, the differential \rpi of energetic pions remains sensitive to the \esym at supra saturation densities with little influence from the uncertain symmetry potential of the $\Delta$ resonance.

   ↳ nucl-thastro-ph.SRnucl-exPRC(2015)·40 citations
7. 07*

   Beyond relativistic mean-field approach for nuclear octupole excitations

   J. M. Yao🇯🇵 · E. F. Zhou🇨🇳 · Z. P. Li🇨🇳

   We report the first beyond-mean-field study of low-lying parity-doublet states in 224Ra by extending the multireference relativistic energy density functional method to include dynamical correlations related to symmetry restoration and quadrupole-octupole shape fluctuation with a generator coordinate method combined with parity, particle-number, and angular-momentum projections. We clarify full microscopically that the origin of spin-dependent parity splitting in low-spin states is related to the octupole shape stabilization of positive-parity states, the dominated shapes of which drift gradually to that of negative-parity ones.

   ↳ nucl-thcond-mat.str-elhep-phnucl-exPRC(2015)·65 citations
8. 08*

   GIOVE - A New Detector Setup for High Sensitivity Germanium Spectroscopy At Shallow Depth

   Gerd Heusser🇩🇪 · Marc Weber🇩🇪 · Janina Hakenmüller🇩🇪 · Matthias Laubenstein🇮🇹 · Manfred Lindner🇩🇪 · Werner Maneschg🇩🇪 · Hardy Simgen🇩🇪 · Dominik Stolzenburg🇩🇪 · Herbert Strecker🇩🇪

   We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer Veto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut für Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of <100 {\mu}Bq/kg for primordial radionuclides from U and Th in typical {\gamma} ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites.

   ↳ astro-ph.IMnucl-exphysics.ins-detEPJC(2015)·61 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.