Thu·Oct 15, 2015Thursday·October 15, 2015

1. 01*

   New formulae for the $(-2)$ moment of the photo-absorption cross section, ${\sigma }_{{}_{-2}}$

   Nico Orce🇨🇦

   Two new formulae for the $(-2)$ moment of the photo-absorption cross section, ${\sigma }_{{}_{-2}}$, have been determined, respectively, from the 1988 compilation of Dietrich and Berman and a mass-dependent symmetry energy coefficient, $a_{sym}(A)$. The data for $A\gtrsim 50$ follow, with a {\small $RMS$} deviation of 6\%, the power-law ${\sigma }_{{}_{-2}}=2.4A^{5/3}$$\mu$b/MeV, which is in agreement with Migdal's calculation of ${\sigma }_{{}_{-2}}=2.25A^{5/3}$$\mu$b/MeV based on the hydrodynamic model and the ${\sigma }_{{}_{-2}}$ sum rule. The additional inclusion of $a_{sym}(A)$ provides a deeper insight to the nuclear polarization of $A\geqq 10$ nuclei.

   nucl-exnucl-thPRC(2015)·21 citations
2. 02*

   Nuclear polarization effects in Coulomb excitation studies

   Nico Orce🇨🇦

   New polarization potentials have been determined based on: 1) the latest photo-neutron cross section evaluation and a missing factor of two in previous work, and 2) the mass dependency of the symmetry energy, $a_{sym}(A)$. The magnitude of the first one is 35\% stronger than the currently accepted polarization potential. The second one opens up the possibility for a parameter-free polarization potential. Both polarization potentials are essentially the same for heavy nuclei. The polarization effect on quadrupole collectivity is more substantial than previously assumed for light nuclei. Particular cases are discussed where long-standing discrepancies between high-precision Coulomb-excitation and lifetime measurements still remain. A solution to the long-standing discrepancy between $B(E2;0_1^{+}\to 2_1^{+})$ values determined in ${}^{18}$O by several Coulomb-excitation studies and a high-precision lifetime measurement is provided in favor of the latter. Polarization effects in light nuclei also influence the determination of spectroscopic quadrupole moments in Coulomb-excitation measurements. The hindrance of polarizability observed in the photo-neutron cross section for single-closed shell nuclei is calculated to have a negligible effect on quadrupole collectivity, within the existing experimental uncertainties.

   nucl-exnucl-th0 citations
3. 03*

   Development of holmium-163 electron-capture spectroscopy with transition-edge sensors

   M. P. Croce🇺🇸 · M. W. Rabin🇺🇸 · V. Mocko🇺🇸 · G. J. Kunde🇺🇸 · E. R. Birnbaum🇺🇸 · E. M. Bond🇺🇸 · J. W. Engle🇺🇸 · A. S. Hoover🇺🇸 · F. M. Nortier🇺🇸 · A. D. Pollington🇺🇸 · W. A. Taylor🇺🇸 · N. R. Weisse-Bernstein🇺🇸 and 7 other authors

   Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (QEC < 3 keV) and short half-life (4570 y) of 163Ho make it attractive for high-precision electron capture spectroscopy (ECS) near the kinematic endpoint, where the neutrino momentum goes to zero. In the ECS approach, an electron-capture-decaying isotope is embedded inside a microcalorimeter designed to capture and measure the energy of all the decay radiation except that of the escaping neutrino. We have developed a complete process for proton-irradiation-based isotope production, isolation, and purification of 163Ho. We have developed transition-edge sensors for this measurement and methods for incorporating 163Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of 163Ho. We present our work in these areas and discuss the measured spectrum and its comparison to current theory.

   ↳ physics.ins-detnucl-exJ.Low Temp.Phys.(2016)·56 citations
4. 04*

   Shedding Light on the EOS-Gravity Degeneracy and Constraining the Nuclear Symmetry Energy from the Gravitational Binding Energy of Neutron Stars

   Xiao-Tao He🇨🇳 · F. J. Fattoyev🇺🇸 · Bao-An Li🇺🇸 · W. G. Newton🇺🇸

   A thorough understanding of properties of neutron stars requires both a reliable knowledge of the equation of state (EOS) of super-dense nuclear matter and the strong-field gravity theories simultaneously. To provide information that may help break this EOS-gravity degeneracy, we investigate effects of nuclear symmetry energy on the gravitational binding energy of neutron stars within GR and the scalar-tensor subset of alternative gravity models. We focus on effects of the slope $L$ of nuclear symmetry energy at saturation density and the high-density behavior of nuclear symmetry energy. We find that the variation of either the density slope $L$ or the high-density behavior of nuclear symmetry energy leads to large changes in the binding energy of neutron stars. The difference in predictions using the GR and the scalar-tensor theory appears only for massive neutron stars, and even then is significantly smaller than the difference resulting from variations in the symmetry energy.

   ↳ nucl-thastro-ph.SRgr-qcnucl-exEPJ Web Conf.(2016)·0 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.