Mon·Jun 11, 2018Monday·June 11, 2018

1. 01*

   The ${}^7$Be($\mathbf{n},\mathbf{p}$)${}^7$Li reaction and the Cosmological Lithium Problem: measurement of the cross section in a wide energy range at n_TOF (CERN)

   L. Damone🇮🇹 · M. Barbagallo🇮🇹 · M. Mastromarco🇮🇹 · A. Mengoni🇮🇹 · L. Cosentino🇮🇹 · E. Maugeri🇨🇭 · S. Heinitz🇨🇭 · D. Schumann🇨🇭 · R. Dressler🇨🇭 · F. Käppeler🇩🇪 · N. Colonna🇮🇹 · P. Finocchiaro🇮🇹 and 146 other authors

   We report on the measurement of the ${}^7$Be($n,p$)${}^7$Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n\_TOF facility at CERN. This reaction plays a key role in the lithium yield of the Big Bang Nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and showed a large discrepancy between each other. The measurement was performed with a Si-telescope, and a high-purity sample produced by implantation of a ${}^7$Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low-energy, relative to current evaluations, in the region of BBN interest the present results are consistent with the values inferred from the time-reversal ${}^7$Li($p,n$)${}^7$Be reaction, thus yielding only a relatively minor improvement on the so-called Cosmological Lithium Problem (CLiP). The relevance of these results on the near-threshold neutron production in the p+${}^7$Li reaction is also discussed.

   nucl-exPRL(2018)·77 citations
2. 02*

   2K(2\nu)-Capture in Xe-124: Results of Data Processing for an Exposure of 37.7 kg x day

   Yu.M.Gavriljuk · A.M.Gangapshev🇷🇺 · V.V.Kazalov🇷🇺 · V.V.Kuzminov🇷🇺 · S.I.Panasenko · S.S.Ratkevich🇺🇦 · D.A.Tekueva🇷🇺

   The results of the experimental search for two-neutrino $2K$-capture in ${}^{124}$Xe with a large copper proportional counter obtained by processing the data for an exposure of 37.7 kg$\times$day are presented. The experimental setup is located at the Underground Low-Background Laboratory of the Baksan Neutrino Observatory at a depth of 4900 m w.e. The combination of methods of selection of useful signals with a unique set of characteristics and the event topology taken into account allowed us to suppress the background in the energy region of interest. A new half-life limit for $2K(2\nu )$-capture in ${}^{124}$Xe was determined: T${}_{1/2}\ge 7.7\cdot 10^{21}$ yrs (90\% C.L.).

   nucl-exphysics.ins-detPhys.Part.Nucl.(2018)·7 citations
3. 03*

   No correlation between Solar flares and the decay rate of several $\beta$-decaying isotopes

   J.R. Angevaare🇳🇱 · L. Baudis🇨🇭 · P.A. Breur🇳🇱 · A. Brown🇨🇭 · A.P. Colijn🇳🇱 · R.F. Lang🇺🇸 · A. Massafferri🇧🇷 · J.C.P.Y. Nobelen · R. Perci · C. Reuter🇺🇸 · M. Schumann🇩🇪

   We report on finding no correlation between the two strongest observed Solar flares in September 2017 and the decay rates of ${}^{60}$Co, ${}^{44}$Ti and ${}^{137}$Cs sources, which are continuously measured by two independent NaI(Tl) detector setups. We test for variations in the number of observed counts with respect to the number of expected counts over multiple periods with timescales varying from 1 to 109 hours around the Solar flare. No excess or deficit exceeds the 2$\sigma$ global significance. We set a conservative lower limit on the decay rate deviation over an 84-hour period around the two correlated Solar flares in September 2017 to $0.044\%$ with 2$\sigma$ confidence. A fractional change of $0.1\%$ in the decay rate of ${}^{54}$Mn over a period of 84 hours was claimed with 7$\sigma$ significance during multiple Solar flares in December 2006. We exclude such an effect at 4.7$\sigma$ significance.

   nucl-exastro-ph.SRAstropart.Phys.(2018)·5 citations
4. 04*

   Comment on "Measurement of the $Q^2$ Dependence of the Deuteron Spin Structure Function $g_1$ and its Moments at Low $Q^2$ with CLAS"

   Vadim Lensky🇩🇪 · Franziska Hagelstein🇨🇭 · Astrid Hiller Blin🇩🇪 · Vladimir Pascalutsa🇩🇪

   We argue that the recently published CLAS results on the deuteron spin polarizability ${\gamma }_0$ [Adhikari {\it et al.}, Phys.\ Rev.\ Lett.\ {\bf 120}, 062501 (2018)], as well as their comparisons with chiral perturbation theory ($\chi$PT), are misleading. In reality, the deuteron polarizability is larger by 4 orders of magnitude, as demonstrated here by a novel calculation in pionless EFT. The CLAS paper, on the other hand, presents only a tiny correction to it, based on a partial evaluation of a sum rule for ${\gamma }_0$. The sum rule is assumed to have the same form as for the nucleon; we argue it does not. Moreover, their "test of $\chi$PT" tacitly involves assumptions which, as we demonstrate, may not be valid at the claimed accuracy.

   ↳ nucl-thhep-phnucl-ex4 citations
5. 05*

   Extended Skyrme interactions for transport model simulations of heavy-ion collisions

   Rui Wang🇨🇳 · Lie-Wen Chen🇨🇳 · Ying Zhou🇨🇳

   Based on an extended Skyrme interaction that includes the terms in relative momenta up to sixth order, corresponding to the so-called Skyrme pseudopotential up to next-to-next-to-next-to leading order (N3LO), we derive the expressions of Hamiltonian density and single nucleon potential under general non-equilibrium conditions which can be applied in transport model simulations of heavy-ion collisions induced by neutron-rich nuclei. While the conventional Skyrme interactions, which include the terms in relative momenta up to second order, predict an incorrect behavior as a function of energy for nucleon optical potential in nuclear matter, the present extended N3LO Skyrme interaction can give a nice description for the empirical nucleon optical potential. We also construct three interaction sets with different high-density behaviors of the symmetry energy, by fitting both the empirical nucleon optical potential up to energy of $1$ GeV and the empirical properties of isospin asymmetric nuclear matter. These extended N3LO Skyrme interactions will be useful in transport model simulations of heavy-ion collisions induced by neutron-rich nuclei at intermediate and high energies, and they can also be useful in nuclear structure studies within the mean-field model.

   ↳ nucl-thastro-ph.SRhep-phnucl-exPRC(2018)·31 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.