Wed·Sep 24, 2014Wednesday·September 24, 2014

1. 01*

   Upper limit on the cross section for reactor antineutrinos changing 22Na decay rates

   R.J. de Meijer (1,2)🇳🇱 · S.W. Steyn (3) ((1) Stichting EARTH, the Netherlands, (2) Department of Physics, University Western Cape, South Africa, (3) Eskom, Koeberg, South Africa)

   In this paper we present results of a long-term observation of the decay of 22Na in the presence of a nuclear fission reactor. The measurements were made outside the containment wall of and underneath the Koeberg nuclear power plant near Cape Town, South Africa. Antineutrino fluxes ranged from ~5*10^11 to 1.6*10^13 cm^-2 s^-1 during this period. We show that the coincidence summing technique provides a sensitive tool to measure a change in the total decay constant as well as the branching ratio between EC and beta+ decay of 22Na to the first excited state in 22Ne. We observe a relative change in count rate between reactor-ON and reactor-OFF equal to (-0.51+/-0.11)*10^-4. After evaluating possible systematic uncertainties we conclude that the effect is either due to a hidden instrumental cause or due to an interaction between antineutrinos and the 22Na nucleus. An upper limit of ~0.03 barn has been deduced for observing any change in the decay rate of 22Na due to antineutrino interactions.

   nucl-exastro-ph.HEphysics.ins-det6 citations
2. 02*

   S$\pi$RIT: A time-projection chamber for symmetry-energy studies

   R. Shane🇺🇸 · A. McIntosh🇺🇸 · T. Isobe🇯🇵 · W.G. Lynch🇺🇸 · H. Baba🇯🇵 · J. Barney🇺🇸 · Z. Chajecki🇺🇸 · M. Chartier🇬🇧 · J. Estee🇺🇸 · M. Famiano🇺🇸 · B. Hong🇰🇷 · K. Ieki🇯🇵 and 16 other authors

   A Time-Projection Chamber (TPC) called the SAMURAI Pion-Reconstruction and Ion-Tracker (S$\pi$RIT) has recently been constructed at Michigan State University as part of an international effort to constrain the symmetry-energy term in the nuclear Equation of State (EoS). The S$\pi$RIT TPC will be used in conjunction with the SAMURAI spectrometer at the Radioactive Isotope Beam Factory (RIBF) at RIKEN to measure yield ratios for pions and other light isospin multiplets produced in central collisions of neutron-rich heavy ions, such as ${}^{132}$Sn + ${}^{124}$Sn. The S$\pi$RIT TPC can function both as a TPC detector and as an active target. It has a vertical drift length of 50 cm, parallel to the magnetic field. Gas multiplication is achieved through the use of a multi-wire anode. Image charges are produced in the 12096 pads, and are read out with the recently developed Generic Electronics for TPCs.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2015)·77 citations
3. 03*

   Systematics of intermediate-energy single-nucleon removal cross sections

   J.A. Tostevin🇬🇧 · A. Gade🇺🇸

   There is now a large and increasing body of experimental data and theoretical analyses for reactions that remove a single nucleon from an intermediate-energy beam of neutron- or proton-rich nuclei. In each such measurement, one obtains the inclusive cross section for the population of all bound final states of the mass A-1 reaction residue. These data, from different regions of the nuclear chart, and that involve weakly- and strongly-bound nucleons, are compared with theoretical expectations. These calculations include an approximate treatment of the reaction dynamics and shell-model descriptions of the projectile initial state, the bound final states of the residues, and the single-particle strengths computed from their overlap functions. The results are discussed in the light of recent data, more exclusive tests of the eikonal dynamical description, and calculations that take input from more microscopic nuclear structure models.

   ↳ nucl-thnucl-exPRC(2014)·160 citations
4. 04*

   Dihadron Fragmentation Functions and Transversity

   Marco Radici🇮🇹 · A. Courtoy🇧🇪 · Alessandro Bacchetta🇮🇹

   We present preliminary results for an updated extraction of the transversity parton distribution based on the analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets in collinear factorization. Data for proton and deuteron targets by HERMES and COMPASS allow for a flavor separation of the valence components of transversity, while di-hadron fragmentation functions are taken from the semi-inclusive production of two pion pairs in back-to-back jets in $e^{+}{e}^{-}$ annihilation. The latter data from Belle have been reanalyzed using the replica method and a more realistic estimate of the uncertainties on the chiral-odd interference fragmentation function has been obtained. After encoding this piece of information into the deep-inelastic scattering cross section, the transversity has been re-extracted by using the most recent and more precise COMPASS data for proton target. This picture represents the current most realistic estimate of the uncertainties on our knowledge of transversity. The preliminary results indicate that the valence up component seems smaller and with a narrower error band than in previous extraction.

   ↳ hep-phhep-exnucl-exnucl-thEPJ Web Conf.(2015)·2 citations
5. 05*

   And there was light

   C.A. Bertulani🇺🇸

   I discuss the use of light as a collection of real and virtual photons to study lingering questions in particle and nuclear physics.

   ↳ nucl-thhep-phnucl-exAIP Conf.Proc.(2015)·4 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.