Fri·Nov 22, 2019Friday·November 22, 2019

1. 01*

   Axial-vector weak coupling at medium momentum for astro neutrinos and double beta decays

   Hiroyasu Ejiri🇯🇵

   Neutrino nuclear responses associated with medium momentum transfer of q=20-80 MeV for astro neutrinos and double beta decays were studied by using charge exchange reactions on Te128 and Te130. Gamow-Teller and spin dipole nuclear matrix elements are found to be reduced with respect to the pnQRPA matrix elements by the coefficient of around 0.35. The reduction is discussed in terms of the quenching of axial vector coupling (g_A).

   nucl-exnucl-thJ.Phys.G(2019)·10 citations
2. 02*

   The PanEDM Neutron Electric Dipole Moment Experiment at the ILL

   David Wurm🇩🇪 · Douglas H. Beck🇺🇸 · Tim Chupp🇺🇸 · Skyler Degenkolb🇫🇷 · Katharina Fierlinger🇩🇪 · Peter Fierlinger🇩🇪 · Hanno Filter🇩🇪 · Sergey Ivanov🇩🇪 · Christopher Klau🇩🇪 · Michael Kreuz🇫🇷 · Eddy Lelièvre-Berna🇫🇷 · Tobias Lins🇩🇪 and 15 other authors

   The neutron's permanent electric dipole moment $d_n$ is constrained to below $3\times 10^{-26}e\text{cm}$ (90% C.L.) [ arXiv:hep-ex/0602020, arXiv:1509.04411 ], by experiments using ultracold neutrons (UCN). We plan to improve this limit by an order of magnitude or more with PanEDM, the first experiment exploiting the ILL's new UCN source SuperSUN. SuperSUN is expected to provide a high density of UCN with energies below 80 neV, implying extended statistical reach with respect to existing sources, for experiments that rely on long storage or spin-precession times. Systematic errors in PanEDM are strongly suppressed by passive magnetic shielding, with magnetic field and gradient drifts at the single fT level. A holding-field homogeneity on the order of $10^{-4}$ is achieved in low residual fields, via a high static damping factor and built-in coil system. No comagnetometer is needed for the first order-of-magnitude improvement in $d_n$, thanks to high magnetic stability and an assortment of sensors outside the UCN storage volumes. PanEDM will be commissioned and upgraded in parallel with SuperSUN, to take full advantage of the source's output in each phase. Commissioning is ongoing in 2019, and a new limit in the mid $10^{-27}e\text{cm}$ range should be possible with two full reactor cycles of data in the commissioned apparatus.

   ↳ physics.ins-dethep-exnucl-exEPJ Web Conf.(2019)·61 citations
3. 03*

   Fission of super-heavy elements: ${}^{132}$Sn-plus-the-rest, or ${}^{208}$Pb-plus-the-rest ?

   C. Ishizuka🇯🇵 · X. Zhang🇨🇳 · M.D. Usang · F.A. Ivanyuk · S. Chiba🇯🇵

   In this work we try to settle down the controversial predictions on the effect of doubly magic nuclei ${}^{132}$Sn and ${}^{208}$Pb on the mass distributions of fission fragments of super-heavy nuclei. For this we have calculated the mass distribution of super-heavy nuclei from ${}^{286}$Cn to ${}^{306}$122 within the dynamical 4-dimensional Langevin approach. We have found that in "light" super-heavies the influence of ${}^{208}$Pb on the mass distributions is present but negligible small. In "heavy" super-heavies, Z=120-122, the (quasi)symmetric peaks and strongly asymmetric peaks at fragment mass $A_F$ close to $A_F$=208 are of comparable magnitude.

   ↳ nucl-thastro-ph.HEnucl-exPRC(2020)·22 citations
4. 04*

   Characterization of TRIGA RC-1 neutron irradiation facilities for radiation damage testing

   Davide Chiesa🇮🇹 · Mario Carta · Valentina Fabrizio · Luca Falconi · Angelo Grossi · Massimiliano Nastasi🇮🇹 · Mario Palomba · Stefano Pozzi🇮🇹 · Ezio Previtali🇮🇹 · Pier Giorgio Rancoita · Barbara Ranghetti · Mauro Tacconi

   This paper presents the results of neutron flux measurements at two irradiation facilities of the TRIGA Mark II reactor at ENEA Casaccia Research Center, Italy. The goal of these measurements is to provide a complete characterization of neutron irradiation facilities for accurate and precise dose evaluation in radiation damage tests and, more generally, for all applications that need a good knowledge of neutron flux in terms of intensity, energy spectrum and spatial distribution. The neutron activation technique is used to measure the activation rates of several reactions, chosen so to cover the whole energy range of neutron flux spectrum. A multi-group neutron flux measurement is obtained through an unfolding algorithm based on a Bayesian statistical model. The obtained results prove that this experimental method allows to measure the total neutron flux within 2% statistical uncertainty, and to get at the same time a good description of its energy spectrum and spatial distribution.

   ↳ physics.ins-detnucl-exphysics.app-phEur.Phys.J.Plus(2020)·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.