Tue·Sep 2, 2014Tuesday·September 2, 2014

1. 01*

   Latest CMS Heavy-Ion Results on Jets

   Marguerite B. Tonjes (CMS Collaboration)🇺🇸

   Jet studies provide an experimental method to explore the features of energy loss in the strongly interacting quark-gluon plasma. Recent jet results from 2.76 TeV PbPb and pp collisions measured with the CMS detector are presented. Jets in the most head-on (central) PbPb collisions are quenched in comparison to pp, and the jets fragment in different ways in the two systems. Measurements from pPb collisions at 5.02 TeV show that the jet and charged particle suppression seen in central PbPb measurements are not due to initial state nuclear effects.

   nucl-exhep-ex0 citations
2. 02*

   Hadron Production Model Developments and Benchmarking in the 0.7 - 12 GeV Energy Region

   N.V. Mokhov🇺🇸 · K.K. Gudima🇲🇩 · S.I. Striganov🇺🇸

   Driven by the needs of the intensity frontier projects with their Megawatt beams, e.g., ESS, FAIR and Project X, and their experiments, the event generators of the MARS15 code have been recently improved. After thorough analysis and benchmarking against data, including the newest ones by the HARP collaboration, both the exclusive and inclusive particle production models were further developed in the crucial for the above projects - but difficult from a theoretical standpoint - projectile energy region of 0.7 to 12 GeV. At these energies, modelling of prompt particle production in nucleon-nucleon and pion-nucleon inelastic reactions is now based on a combination of phase-space and isobar models. Other reactions are still modeled in the framework of the Quark-Gluon String Model. Pion, kaon and strange particle production and propagation in nuclear media are improved. For the alternative inclusive mode, experimental data on large-angle (> 20 degrees) pion production in hadron-nucleus interactions are parameterized in a broad energy range using a two-source model. It is mixed-and-matched with the native MARS model that successfully describes low-angle pion production data. Predictions of both new models are - in most cases - in a good agreement with experimental data obtained at CERN, JINR, LANL, BNL and KEK.

   nucl-exnucl-th4 citations
3. 03*

   Particle spectra and HBT radii for simulated central nuclear collisions of C+C, Al+Al, Cu+Cu, Au+Au, and Pb+Pb from Sqrt(s)=62.4-2760 GeV

   M. Habich🇺🇸 · J. L. Nagle🇺🇸 · P. Romatschke🇺🇸

   We study the temperature profile, pion spectra and HBT radii in central symmetric and boost-invariant nuclear collisions using a super hybrid model for heavy-ion collisions (SONIC) combining pre-equilibrium flow with viscous hydrodynamics and late-stage hadronic rescatterings. In particular, we simulate Pb+Pb collisions at Sqrt(s)=2.76 TeV, Au+Au, Cu+Cu, Al+Al, and C+C collisions at Sqrt(s)=200 GeV and Au+Au, Cu+Cu collisions at Sqrt(s)=62.4 GeV. We find that SONIC provides a good match to the pion spectra and HBT radii for all collision systems and energies, confirming earlier work that a combination of pre-equilibrium flow, viscosity and QCD equation of state can resolve the so-called HBT puzzle. For reference, we also show p+p collisions at Sqrt(s)=7 TeV. We make tabulated data for the 2+1 dimensional temperature evolution of all systems publicly available for the use in future jet energy loss or similar studies.

   ↳ nucl-thhep-phnucl-exEPJC(2015)·86 citations
4. 04*

   First Calorimetric Measurement of OI-line in the Electron Capture Spectrum of ${}^{163}$Ho

   P. C.-O. Ranitzsch🇩🇪 · C. Hassel🇩🇪 · M. Wegner🇩🇪 · S. Kempf🇩🇪 · A. Fleischmann🇩🇪 · C. Enss🇩🇪 · L. Gastaldo🇩🇪 · A. Herlert🇨🇭 · K. Johnston🇨🇭

   The isotope ${}^{163}$Ho undergoes an electron capture process with a recommended value for the energy available to the decay, $Q_{\mathrm{EC}}$, of about 2.5 keV. According to the present knowledge, this is the lowest $Q_{\mathrm{EC}}$ value for electron capture processes. Because of that, ${}^{163}$Ho is the best candidate to perform experiments to investigate the value of the electron neutrino mass based on the analysis of the calorimetrically measured spectrum. We present for the first time the calorimetric measurement of the atomic de-excitation of the ${}^{163}$Dy daughter atom upon the capture of an electron from the 5s shell in ${}^{163}$Ho, OI-line. The measured peak energy is 48 eV. This measurement was performed using low temperature metallic magnetic calorimeters with the ${}^{163}$Ho ion implanted in the absorber. We demonstrate that the calorimetric spectrum of ${}^{163}$Ho can be measured with high precision and that the parameters describing the spectrum can be learned from the analysis of the data. Finally, we discuss the implications of this result for the Electron Capture ${}^{163}$Ho experiment, ECHo, aiming to reach sub-eV sensitivity on the electron neutrino mass by a high precision and high statistics calorimetric measurement of the ${}^{163}$Ho spectrum.

   ↳ physics.ins-dethep-exnucl-ex16 citations
5. 05*

   Effect of the spin-orbit interaction on flows in heavy-ion collisions at intermediate energies

   Chenchen Guo🇨🇳 · Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳 · Feng-Shou Zhang🇨🇳

   The effect of the spin-orbit coupling in heavy ion collisions is investigated based on an updated version of the ultra-relativistic quantum molecular dynamics (UrQMD) model, in which the Skyrme potential energy density functional is employed. And in special, the spin-orbit coupling effects on the directed and elliptic flows of free nucleons emitted from ${}^{197}$Au+${}^{197}$Au collisions as functions of both the beam energy and the impact parameter are studied. Our results show that the net contribution of the spin-orbit term to flows of nucleons is negligible, whereas a directed flow splitting between spin-up and spin-down nucleons is visible especially at large impact parameters and a peak of the splitting is found at the beam energy around 150 MeV$/$nucleon. We also found that the directed flow splitting between spin-up and spin-down neutrons is comparable with the neutron directed flow difference calculated by a soft and a stiff symmetry energy, indicating that the directed flow of neutrons cannot be used to pin down the stiffness of symmetry energy any more without considering the spin degree of freedom in models in case of spin polarization.

   ↳ nucl-thnucl-exPRC(2014)·5 citations
6. 06*

   The Role of Flavor Physics in the LHC Era

   Stephen Lars Olsen🇰🇷

   Although searches for new physics at the CERN Large Hadron Collider will probably dominate the the agenda of the experimental high energy physics community during the next decade or more, high-intensity experiments at the tau-charm and beauty thresholds will continue to play important complementary roles. These include the establishment of stringent constraints on proposed theories for beyond-the-Standard-Model physics and unique opportunities to address some new physics scenarios that are inaccessible at the LHC. In addition, in the event that the LHC does discover some new phenomena, high sensitivity flavor physics measurements could provide diagnostic clues as to the physics processes responsible for the observed effects. In this talk I present a few examples that illustrate the close inter-relation of new physics searches at the high-energy frontier and high-sensitivity measurements at the intensity frontier.

   ↳ hep-exhep-phnucl-ex4 citations
7. 07*

   Isotopic 32S/33S ratio as a diagnostic of presolar grains from novae

   A. Parikh🇪🇸 · K. Wimmer🇺🇸 · T. Faestermann🇩🇪 · R. Hertenberger🇩🇪 · J. Jose🇪🇸 · H.-F. Wirth🇩🇪 · C. Hinke · R. Krucken🇩🇪 · D. Seiler · K. Steiger🇩🇪 · K. Straub🇩🇪

   Measurements of sulphur isotopes in presolar grains can help to identify the astrophysical sites in which these grains were formed. A more precise thermonuclear rate of the 33S(p,gamma)34Cl reaction is required, however, to assess the diagnostic ability of sulphur isotopic ratios. We have studied the 33S(3He,d)34Cl proton-transfer reaction at 25 MeV using a high-resolution quadrupole-dipole-dipole-dipole magnetic spectrograph. Deuteron spectra were measured at ten scattering angles between 10 and 55 degrees. Twenty-four levels in 34Cl over Ex = 4.6 - 5.9 MeV were observed, including three levels for the first time. Proton spectroscopic factors were extracted for the first time for levels above the 33S+p threshold, spanning the energy range required for calculations of the thermonuclear 33S(p,gamma)34Cl rate in classical nova explosions. We have determined a new 33S(p,gamma)34Cl rate using a Monte Carlo method and have performed new hydrodynamic nova simulations to determine the impact on nova nucleosynthesis of remaining nuclear physics uncertainties in the reaction rate. We find that these uncertainties lead to a factor of less than 5 variation in the 33S(p,gamma)34Cl rate over typical nova peak temperatures, and variation in the ejected nova yields of S--Ca isotopes by less than 20%. In particular, the predicted 32S/33S ratio is 110 - 130 for the nova model considered, compared to 110 - 440 with previous rate uncertainties. As recent type II supernova models predict ratios of 130 - 200, the 32S/33S ratio may be used to distinguish between grains of nova and supernova origin.

   ↳ astro-ph.SRnucl-exPLB(2014)·13 citations
8. 08*

   Calculation of multichannel reactions in the four-nucleon system above breakup threshold

   A. Deltuva🇵🇹 · A. C. Fonseca🇵🇹

   Exact four-body equations of Alt, Grassberger and Sandhas are solved for neutron-${}^3\mathrm{He}$ and proton-${}^3\mathrm{H}$ scattering in the energy regime above the four-nucleon breakup threshold. Cross sections and spin observables for elastic, transfer, charge-exchange, and breakup reactions are calculated using realistic nucleon-nucleon interaction models, including the one with effective many-nucleon forces due to explicit $\Delta$-isobar excitation. The experimental data are described reasonably well with only few exceptions such as vector analyzing powers.

   ↳ nucl-thcond-mat.quant-gasnucl-exphysics.atom-phPRL(2014)·34 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.