Mon·Nov 14, 2016Monday·November 14, 2016

1. 01*

   Determination of the scalar polarizabilities of the proton using beam asymmetry ${\Sigma }_3$ in Compton scattering

   V. Sokhoyan · E. J. Downie · E. Mornacchi · J. A. McGovern · N. Krupina · F. Afzal · J. Ahrens · C. S. Akondi · J. R. M. Annand · H. J. Arends · R. Beck · A. Braghieri and 64 other authors

   The scalar dipole polarizabilities, ${\alpha }_{E1}$ and ${\beta }_{M1}$, are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton polarizabilities were determined by fitting to unpolarized proton Compton scattering cross section data. The measurement of the beam asymmetry ${\Sigma }_3$ in a certain kinematical range provides an alternative approach to the extraction of the scalar polarizabilities. At the Mainz Microtron (MAMI) the beam asymmetry was measured for Compton scattering below pion photoproduction threshold for the first time. The results are compared with model calculations and the influence of the experimental data on the extraction of the scalar polarizabilities is determined.

   nucl-exEPJA(2017)·38 citations
2. 02*

   Robust Geo-neutrino Results

   Steve Dye🇺🇸

   Geo-neutrino observations probe the quantities and distributions of terrestrial heat-producing elements uranium and thorium. The quantities of these elements gauge global radiogenic power, offering insights into the origin and thermal history of the Earth. The distributions reveal the initial partitioning and subsequent transport of these trace elements between metallic core, silicate mantle, and crust types. Ongoing observations at underground sites in Japan and Italy record the energies but not the directions of geo-neutrinos from uranium and thorium. Without directions pointing back to source regions, disentangling the signals from various reservoirs requires resolution of differing rates or energy spectra at separate sites. Due to limited statistics and site contrast, however, the observations at Japan and Italy do not yet measure distinct rates or energy spectra. Further analyses of the observations that derive fluxes, determine a signal from the mantle, and assess the global radiogenic power of uranium and thorium, depend on geochemical assumptions and model predictions. This letter discusses opportunities for eliminating or minimizing these dependencies through observations at dissimilar sites, producing robust geo-neutrino results.

   ↳ physics.geo-phnucl-ex2 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.