Wed·Dec 3, 2014Wednesday·December 3, 2014

1. 01*

   Search for Neutrinoless Double-Beta Decay

   Werner Tornow🇺🇸

   After the pioneering work of the Heidelberg-Moscow (HDM) and International Germanium Experiment (IGEX) groups, the second round of neutrinoless double-$\beta$ decay searches currently underway has or will improve the life-time limits of double-$\beta$ decay candidates by a factor of two to three, reaching in the near future the $T_{1/2}=3\times 10^{25}$ yr level. This talk will focus on the large-scale experiments GERDA, EXO-200, and KamLAND-Zen, which have reported already lower half-life time limits in excess of $10^{25}$ yr. Special emphasis is given to KamLAND-Zen, which is expected to approach the inverted hierarchy regime before future 1-ton experiments probe completely this life-time or effective neutrino-mass regime, which starts at $\approx 2\times 10^{26}$ yr or $\approx 50$ meV.

   nucl-exphysics.ins-det7 citations
2. 02*

   New data on activation cross section for deuteron induced reactions on ytterbium up to 50 MeV

   F. Tárkányi · F. Ditrói🇭🇺 · S. Takács🇭🇺 · A. Hermanne🇧🇪 · A.V. Ignatyuk

   Activation cross sections of deuteron induced reactions on ytterbium for production of ${}^{177g,173,172,171,170,169,167}$Lu, ${}^{177,175,169}$Yb and ${}^{173,168,167,165}$Tm were extended up to 50 MeV deuteron energy. The new data are in acceptable agreement with the earlier experimental data in the overlapping energy region. The experimental data are compared with the predictions of the ALICE-D, EMPIRE-D and TALYS 1.4 (TENDL-2013 on-line library results) codes.

   nucl-exNucl.Instrum.Meth.B(2014)·1 citation
3. 03*

   Strangeness Suppression in q-qbar Creation Observed in Exclusive Reactions

   K.Park · M.D.Mestayer · the CLAS collaboration

   We measured the ratios of electroproduction cross-sections from a proton target for three exclusive meson-baryon final states: $\Lambda K^{+}$, $p{\pi }^0$, and $n{\pi }^{+}$, with the CLAS detector at Jefferson Lab. Using a simple model of quark hadronization we extract q-qbar creation probabilities for the first time in exclusive two-body production, in which only a single q-qbar pair is created. We observe a sizable suppression of strange quark-antiquark pairs compared to non-strange pairs, similar to that seen in high-energy production.

   nucl-exhep-exphysics.data-anPRL(2014)·20 citations
4. 04*

   Calculation of centrality bias factors in $p$+A collisions based on a positive correlation of hard process yields with underlying event activity

   Dennis V. Perepelitsa🇺🇸 · Peter A. Steinberg🇺🇸

   Hard scattering yields in centrality-selected proton-- and deuteron--nucleus ($p$+A) collisions are generally compared to nucleon--nucleon ($NN$) cross-sections scaled to the appropriate partonic luminosity using geometric models derived from an analysis of minimum bias $p$+A interactions. In general, these models assume that hard process rates and the magnitude of the soft event activity in the underlying $NN$ collisions is uncorrelated. When included, these correlations influence the measured yield in a nominal centrality interval, an effect typically referred to as a "centrality bias". In this work, the impact of a positive correlation between the hard scattering yield and the underlying event activity in individual $NN$ collisions is investigated. This correlation is incorporated into the centrality calculations used by ATLAS and PHENIX, both based on a similar Monte Carlo Glauber approach but with different models of the per-collision or per-participant event activity. It is found that the presence of this correlation tends to increase the yield measured in more central events and decrease it in peripheral events. Numerical factors to correct measured yields for the centrality bias effect are calculated for $p$+A collisions at RHIC and the LHC. Reasonable agreement with a previous calculation of these factors by PHENIX is found, despite differences in the implementation of the underlying bias.

   nucl-ex43 citations
5. 05*

   Low-Mass Dielectron Production in pp, p-Pb and Pb-Pb Collisions with ALICE

   Patrick Reichelt (for the ALICE Collaboration)🇩🇪

   The ALICE Collaboration measures the production of low-mass dielectrons in pp, p-Pb and Pb-Pb collisions at the LHC. The main detectors used in the analyses are the Inner Tracking System, Time Projection Chamber and Time-Of-Flight detector, all located around mid-rapidity. The production of virtual photons relative to the inclusive yield in pp collisions is determined by analyzing the dielectron excess with respect to the expected hadronic sources. The direct photon cross section is then calculated and found to be in agreement with NLO pQCD calculations. Results from the invariant mass analysis in p-Pb collisions show an overall agreement between data and hadronic cocktail. In Pb-Pb collisions, uncorrected background-subtracted yields have been extracted in two centrality classes. A feasibility study for LHC run 3 after the ALICE upgrade indicates the possibility for a future measurement of the early effective temperature.

   ↳ hep-exnucl-exJ.Phys.Conf.Ser.(2015)·4 citations
6. 06*

   Parameterization of the statistical rate function for select superallowed transitions

   I.S. Towner🇺🇸 · J.C. Hardy🇺🇸

   We present a parameterization of the statistical rate function, f, for 20 superallowed 0+-to-0+ nuclear beta transitions between T=1 analog states, and for 18 superallowed "mirror" transitions between analog T=1/2 states. All these transitions are of interest in the determination of V_{ud}. Although most of the transition Q_{EC} values have been measured, their precision will undoubtedly be improved in future. Our parameterization allows a user to easily calculate the corresponding new f value to high precision (+/-0.01%) without complicated computing.

   ↳ nucl-thnucl-exPRC(2015)·50 citations
7. 07*

   Signal recognition efficiencies of artificial neural-network pulse-shape discrimination in HPGe $0\nu \beta \beta$-decay searches

   A. Caldwell🇩🇪 · F. Cossavella🇩🇪 · B. Majorovits🇩🇪 · D. Palioselitis🇩🇪 · O. Volynets🇩🇪

   A pulse-shape discrimination method based on artificial neural networks was applied to pulses simulated for different background, signal and signal-like interactions inside a germanium detector. The simulated pulses were used to investigate variations of efficiencies as a function of used training set. It is verified that neural networks are well-suited to identify background pulses in true-coaxial high-purity germanium detectors. The systematic uncertainty on the signal recognition efficiency derived using signal-like evaluation samples from calibration measurements is estimated to be 5\%. This uncertainty is due to differences between signal and calibration samples.

   ↳ physics.ins-detnucl-exEPJC(2015)·7 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.