Mon·Sep 21, 2020Monday·September 21, 2020

1. 01*

   Consistency of nucleon-transfer sum rules in well-deformed nuclei

   B. P. Kay🇺🇸 · J. P. Schiffer🇺🇸 · S. J. Freeman🇬🇧 · T. L. Tang🇺🇸 · B. D. Cropper🇬🇧 · T. Faestermann🇩🇪 · R. Hertenberger🇩🇪 · J. M. Keatings🇬🇧 · P. T. MacGregor🇬🇧 · J. F. Smith🇬🇧 · H.-F. Wirth🇩🇪

   Nucleon-transfer sum rules have been assessed via a consistent reanalysis of cross-section data from neutron-adding ($d$,$p$) and -removing ($d$,$t$) reactions on well-deformed isotopes of Gd, Dy, Er, Yb, and W, with $92\le N\le 108$, studied at the Niels Bohr Institute in the 1960s and 1970s. These are complemented by new measurements of cross sections using the ($d$,$p$), ($d$,$t$), and ($p$,$d$) reactions on a subset of these nuclei. The sum rules, defined in a Nilsson-model framework, are remarkably consistent. A single overall normalization is used in the analysis, which appears to be sensitive to assumptions about the reaction mechanism, and in the case of sums using the ($d$,$t$) reaction, differs from values determined from reactions on spherical systems.

   nucl-exPRC(2021)·4 citations
2. 02*

   Experimental Study of Neutron Formation in X-Ray Discharge: Is There a Challenge to Standard Model?

   Max I. Fomitchev-Zamilov🇺🇸

   In this paper we examine the puzzle of neutron formation in atmospheric discharge. While conventional explanation relies on photonuclear reactions, voltages used to recreate such discharges in the lab (1 MV) are thought to be not high enough to accelerate electrons beyond the threshold of photonuclear reactions (10.5 MeV). We have proposed a solution to the neutron formation puzzle and point out that rapidly changing magnetic vector potential creates strong electrokinetic field that can accelerate free electrons to energies that are much higher than what is possible with the voltage of the discharge. We report on the development of highly sophisticated and extremely sensitive neutron detector system that can reliably detect neutron fluxes smaller than 0.1 CPS above background and is completely impervious to EM noise. Finally, we present measurements of weak yet statistically significant neutron fluxes originating from sustained 20-30 kV / 20-30 mA X-ray producing discharge in dilute atmosphere.

   nucl-ex0 citations
3. 03*

   New equations of state constrained by nuclear physics, observations, and QCD calculations of high-density nuclear matter

   S. Huth🇩🇪 · C. Wellenhofer🇩🇪 · A. Schwenk🇩🇪

   We present new equations of state for applications in core-collapse supernova and neutron star merger simulations. We start by introducing an effective mass parametrization that is fit to recent microscopic calculations up to twice saturation density. This is important to capture the predicted thermal effects, which have been shown to determine the proto-neutron star contraction in supernova simulations. The parameter range of the energy-density functional underlying the equation of state is constrained by chiral effective field theory results at nuclear densities as well as by functional renormalization group computations at high densities based on QCD. We further implement observational constraints from measurements of heavy neutron stars, the gravitational wave signal of GW170817, and from the recent NICER results. Finally, we study the resulting allowed ranges for the equation of state and for properties of neutron stars, including the predicted ranges for the neutron star radius and maximum mass.

   ↳ nucl-thastro-ph.HEnucl-exPRC(2021)·108 citations
4. 04*

   High-accuracy calculation of the deuteron charge and quadrupole form factors in chiral effective field theory

   A. A. Filin🇩🇪 · D. Möller🇩🇪 · V. Baru🇩🇪 · E. Epelbaum🇩🇪 · H. Krebs🇩🇪 · P. Reinert🇩🇪

   We present a comprehensive analysis of the deuteron charge and quadrupole form factors based on the latest two-nucleon potentials and charge density operators derived in chiral effective field theory. The single- and two-nucleon contributions to the charge density are expressed in terms of the proton and neutron form factors, for which the most up-to-date empirical parametrizations are employed. By adjusting the fifth-order short-range terms in the two-nucleon charge density operator to reproduce the world data on the momentum-transfer dependence of the deuteron charge and quadrupole form factors, we predict the values of the structure radius and the quadrupole moment of the deuteron: $r_{\mathrm{str}}=1.9729\begin{array}{c}+0.0015\\ -0.0012\end{array}\text{fm},Q_d=0.2854\begin{array}{c}+0.0038\\ -0.0017\end{array}{\text{fm}}^2.$ A comprehensive and systematic analysis of various sources of uncertainty in our predictions is performed. Following the strategy advocated in our recent publication Phys. Rev. Lett. 124, 082501 (2020), we employ the extracted structure radius together with the accurate atomic data for the deuteron-proton mean-square charge radii difference to update the determination of the neutron charge radius, for which we find: $r_n^2=-0.105\begin{array}{c}+0.005\\ -0.006\end{array}{\text{fm}}^2$. Given the observed rapid convergence of the deuteron form factors in the momentum-transfer range of $Q\simeq 1-2.5$ fm${}^{-1}$, we argue that this intermediate-energy domain is particularly sensitive to the details of the nucleon form factors and can be used to test different parametrizations.

   ↳ nucl-thhep-phnucl-exPRC(2021)·62 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.