Mon·Sep 12, 2011Monday·September 12, 2011

1. 01*

   Dimuon results in PbPb and pp collisions in CMS

   Manuel Calderón de la Barca Sánchez (for the CMS Collaboration)🇺🇸

   The LHC offers unique opportunities for studying the properties of hot QCD matter created in Pb+Pb collisions at extreme temperatures and very low parton momentum fractions. With its high precision, large acceptance for tracking and calorimetry, and a trigger scheme that allows analysis of each minimum bias Pb+Pb event, CMS is fully equipped to measure dimuons in the high multiplicity environment of Pb+Pb collisions. Such probes are especially relevant since they are produced at early times and propagate through the medium, mapping its evolution. The capabilities of the CMS experiment to study dimuon production in pp and Pb+Pb collisions based on the 2010 LHC runs will be reviewed. CMS is able to measure primary and secondary J/psi, as well as the three Upsilon states. Quarkonia results at sqrt(s)=2.76 TeV in pp and Pb+Pb will be presented, including a tantalizing observation of suppression of the Upsilon excited states. The Z0 boson inclusive and differential measurement as a probe of the initial state will be described.

   nucl-exAIP Conf.Proc.(2012)·2 citations
2. 02*

   Resonance Contribution to Radiative Neutron Capture on Lithium-7

   Lakma Fernando (Mississippi State U.)🇺🇸 · Renato Higa (KVI Groningen and U. of Sao Paulo)🇳🇱 · Gautam Rupak (Mississippi State U.)🇺🇸

   Using halo effective field theory, we provide a model-independent calculation of the radiative neutron capture on lithium-7 over an energy range where the contribution from the 3+ resonance becomes important. One finds that a satisfactory description of the capture reaction, in the present single-particle approximation, suggests the use of a resonance width about three times larger than the experimental value. We also present power counting arguments that establish a hierarchy for electromagnetic one- and two-body currents.

   ↳ nucl-thastro-ph.SRnucl-exEPJA(2012)·41 citations
3. 03*

   Kinematics of a cascade decay for the precision measurement of ${}^{29}\mathrm{Si}$ binding energy

   Yongkyu Ko🇰🇷 · K. S. Kim🇰🇷

   Comparison of a Penning trap and a flat-crystal spectrometer experiments gives a direct test of $E=m{c}^2$. The result is $1-\Delta m{c}^2/E=(-1.4\pm 4.4)\times 10^{-7}$ for ${}^{29}\mathrm{Si}$ and ${}^{33}\mathrm{S}$. The dominant uncertainty is on the $\gamma$-ray measurement in neutron capture reactions, and the secondary $\gamma$-ray has the uncertainty 4.0 eV for ${}^{29}\mathrm{Si}$. We calculated the Doppler effect of the secondary $\gamma$-ray as $-646.9\cos \theta$ eV from the relativistic energy momentum relation of the ${}^{28}\mathrm{Si}(n,\gamma {)}^{29}\mathrm{Si}$ reaction. This corresponds to the full wave of half maximum of 431.3 eV. The error 4.0 eV comes mainly from the Bragg angle measurement between the centroids of the linewidths which means that only the most probable part of the whole data has been considered. It is necessary to confirm the assumption of the isotropy for the object to measure. We discussed a coincidence measurement as one of the methods to overcome the assumption.

   ↳ nucl-thnucl-ex0 citations
4. 04*

   Imaging Pion Showers with the CALICE Analogue Hadron Calorimeter

   Nils Feege (for the CALICE collaboration)🇩🇪

   The CALICE collaboration investigates different technology options for highly granular calorimeters for detectors at a future electron-positron collider. One of the devices constructed and tested by the collaboration is a 1m^3 prototype for an imaging scintillator-steel sampling calorimeter for hadrons with analogue readout (AHCAL). The light from 7608 small scintillator cells is detected with silicon photomultipliers. The AHCAL has been successfully operated during electron and hadron test-beam measurements at DESY, CERN, and Fermilab since 2005. The collected data allow for evaluating the novel technologies employed. In addition, these data provide a valuable basis for validating pion cascade simulations. This paper presents the current status of comparisons between the AHCAL data and predictions from different Monte Carlo models implemented in GEANT4. The comparisons cover the total visible energy, longitudinal and radial shower profiles, and the shower substructure. Furthermore, this paper discusses a software compensation algorithm for improving the energy resolution of the AHCAL for single pions.

   ↳ physics.ins-dethep-exnucl-ex2 citations
5. 05*

   Shape fluctuations in the ground and excited 0+ states of 30Mg and 32Mg

   Nobuo Hinohara🇯🇵 · Koichi Sato🇯🇵 · Kenichi Yoshida🇯🇵 · Takashi Nakatsukasa🇯🇵 · Masayuki Matsuo🇯🇵 · Kenichi Matsuyanagi🇯🇵

   Large-amplitude collective dynamics of shape phase transition in the low-lying states of 30-36Mg is investigated by solving the five-dimensional (5D) quadrupole collective Schroedinger equation. The collective masses and potentials of the 5D collective Hamiltonian are microscopically derived with use of the constrained Hartree-Fock-Bogoliubov plus local quasiparticle RPA method. Good agreement with the recent experimental data is obtained for the excited 0+ states as well as the ground bands. For 30Mg, the shape coexistence picture that the deformed excited 0+ state coexists with the spherical ground state approximately holds. On the other hand, large-amplitude quadrupole-shape fluctuations dominate in both the ground and the excited 0+ states in 32Mg, so that the interpretation of 'coexisting spherical excited 0+ state' based on the naive inversion picture of the spherical and deformed configurations does not hold.

   ↳ nucl-thnucl-exPRC(2011)·50 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.