arXiv subjects

S. Ghinescu

Publications and source records attributed to S. Ghinescu.

4 recordsLinked to original sources

arXiv2026

Updated Results for Kinematic Factors in Double Beta Decays

Accurate calculations of phase space factors (PSFs), electron energy spectra and angular correlations are essential for designing and interpreting double-beta decay (DBD) experiments. These quantities help maximize sensitivity to potential signals, distinguish between different decay modes and interpret the data. In this work we provide updated results for these kinematic factors for two-neutrino ($2\nu\beta\beta$) and neutrinoless ($0\nu\beta\beta$) decay modes, including electron-emission, positron-emission and electron capture transitions. The calculations are performed with an adapted Dirac-Hartree-Fock-Slater method which allows for orthogonality of the wave functions of electrons and positrons in bound and continuum states and incorporates relevant atomic features such us screening, finite nuclear size, exchange corrections and phase shift effects. We provide tables with updated PSFs calculated both in the closure approximation and using the Taylor expansion method, for a large number of DBD isotopes. We discuss the impact of individual atomic corrections and find that our results are in line with predictions reported in recent literature. In some specific cases we find differences between our PSF values and those previously reported which are worth considering for better prediction and interpretation of DBD data. Then, we provide numerical values for $^{76}\text{Ge}$, $^{100}\text{Mo}$, $^{130}\text{Te}$ and $^{136}\text{Xe}$, which are most investigated in current DBD experiments. Similar data for other isotopes are available upon request.

nucl-th↗

arXiv2023

Systematics of neutron emission

Neutron physics is one of the oldest branches of the experimental nuclear physics,but the investigation of the spontaneous neutron emission from the ground state along the neutron dripline is still at its beginning, in spite of the crucial importance for nuclear astrophysics. The proton dripline is much better investigated and a systematics of spontaneous proton half lives corected by the centrifugal barrier (monopole transitions) is given by the Geiger-Nuttall law $\log_{10}T\sim\chi$, where $\chi\sim ZQ^{-1/2}$ is the Coulomb parameter characterizing the outgoing Coulomb-Hankel wave in terms of the daughter charge $Z$ and Q-value. Our purpose is to propose a similar simple systematics of spontaneous neutron half lives, but in terms of the nuclear reduced radius $\rho=\kappa R\sim A^{1/3}Q^{1/2}$, characterizing the "neutral" outgoing spherical Hankel wave. It turns out that the half life in emission of neutral particles is governed by the scaling law $T\sim\rho^{-2}\sim A^{-2/3}Q^{-1}$ for monopole transitions. We evidence the important role of the angular momentum carried by the emitted neutron. The influence of the neutron wave function generated by a Woods-Saxon nuclear mean field is also analyzed.

nucl-th↗

arXiv2023

Self-consistent calculations for atomic electron capture

We present a comprehensive investigation of electron capture (EC) ratios spanning a broad range of atomic numbers. The study employs a self-consistent computational method that incorporates electron screening, electron correlations, overlap and exchange corrections, as well as shake-up and shake-off atomic effects. The electronic wave functions are computed with the Dirac-Hartree-Fock-Slater (DHFS) method, chosen following a systematic comparison of binding energies, atomic relaxation energies and Coulomb amplitudes against other existing methods and experimental data. A novel feature in the calculations is the use of an energy balance employing atomic masses, which avoids approximating the electron total binding energy and allows a more precise determination of the neutrino energy. This leads to a better agreement of our predictions for capture ratios in comparison with the experimental ones, especially for low-energy transitions. We expand the assessment of EC observables uncertainties by incorporating atomic relaxation energy uncertainties, in contrast to previous studies focusing only on Q-value and nuclear level energies. Detailed results are presented for nuclei of practical interest in both nuclear medicine and exotic physics searches involving liquid Xenon detectors ($^{67}\mathrm{Ga}$, $^{111}\mathrm{In}$, $^{123}\mathrm{I}$, $^{125}\mathrm{I}$ and $^{125}\mathrm{Xe}$). Our study can be relevant for astrophysical, nuclear, and medical applications.

nucl-th↗

arXiv2018

Search for $K^{+}\rightarrowπ^{+}ν\overlineν$ at NA62

$K^{+}\rightarrowπ^{+}ν\overlineν$ is one of the theoretically cleanest meson decay where to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN SPS is designed to measure the branching ratio of this decay with 10\% precision. NA62 took data in pilot runs in 2014 and 2015 reaching the final designed beam intensity. The quality of 2015 data acquired, in view of the final measurement, will be presented.

hep-ex↗