Related papers: Electron capture strength on odd-A nucleus $\mathb…
We propose a new model to calculate stellar electron capture rates for neutron-rich nuclei. These nuclei are encountered in the core-collapse of a massive star. Using the Shell Model Monte Carlo approach, we first calculate the finite…
Electron captures on nuclei play an essential role for the dynamics of several astrophysical objects. The capture rate can be derived in perturbation theory where allowed nuclear transitions (Gamow-Teller transitions) dominate, except at…
We calculate Gamow-Teller strength distributions for $\beta \beta$-decay nuclei $^{76}$Ge and $^{82}$Se using the deformed pn-QRPA model. We use a deformed Nilsson basis and consider pairing correlations within the deformed BCS theory.…
Background: The strength of electron capture for medium mass nuclei has a significant effect on the evolution of supernovae. There is insufficient knowledge of these strengths and very little data for important radioactive nuclei. Purpose:…
We investigate even-even nuclei in the $A\sim70$ mass region within the framework of the proton-neutron quasi-particle random phase approximation (\mbox{pn-QRPA}) and the interacting boson model-1 (\mbox{IBM-1}). Our work includes…
Electron-capture rates at different density and temperature conditions are evaluated for a set of pf-shell nuclei representative of the constituents in presupernova formations. The nuclear structure part of the problem is described within a…
We present shell model calculations of electron capture strength distributions in A=28 nuclei and computations of the corresponding capture rates in supernova core conditions. We find that in these nuclei the Brink-Axel hypothesis for the…
We propose a new method to calculate stellar weak-interaction rates. It is based on the Thermo-Field-Dynamics formalism and allows the calculation of the weak-interaction response of nuclei at finite temperatures. The thermal evolution of…
Gamow-Teller (GT) strength in $^{40}$Ar is studied by shell-model calculations with monopole-based universal intearction, which has tensor components of $\pi$\rho$-meson exchanges. Calculated GT strength is found to be consistent with the…
We present Gamow-Teller strength distributions from shell model Monte Carlo studies of fp-shell nuclei that may play an important role in the pre-collapse evolution of supernovae. We then use these strength distributions to calculate the…
Weak rates in nickel isotopes play an integral role in the dynamics of supernovae. Electron capture and $\beta$-decay of nickel isotopes, dictated by Gamow-Teller transitions, significantly alter the lepton fraction of the stellar matter.…
We calculate supernova electron capture and beta decay rates for various pf-shell nuclei using large-scale shell model techniques. We show that the centroid of the Gamow-Teller strength distribution has been systematically misplaced in…
Gamow-Teller (GT) strength distributions (B(GT)) in electron-capture (EC) daughters stemming from the parent ground state are computed with the shell-model in the full pf-shell space, with quasi-particle random-phase approximation (QRPA) in…
Charge-changing transitions play a significant role in stellar weak-decay processes. The fate of the massive stars is decided by these weak-decay rates including lepton (positron and electron) captures rates, which play a consequential role…
We investigate the Gamow-Teller strength distributions in the electron-capture direction in nuclei having mass A=90-97, assuming a 88Sr core and using a realistic interaction that reasonably reproduces nuclear spectroscopy for a wide range…
The structure and the weak interaction mediated rates of the heavy waiting point (WP) nuclei $^{80}$Zr, $^{84}$Mo, $^{88}$Ru, $^{92}$Pd and $^{96}$Cd along $N = Z$ line were studied within the interacting boson model-1 (\mbox{IBM-1}) and…
We investigate the Gamow-Teller (GT) transition strength distributions in the light carbon isotopes $^{12,14,16}$C within the framework of the deformed quasiparticle random-phase approximation (DQRPA). Nuclear deformation is explicitly…
We developed the deformed proton-neutron quasiparticle random phase approximation (QRPA) and applied to the evaluation of the Gamow-Teller (GT) transition strength distributions including high-lying excited states, which data becomes…
A detailed model for the calculation of beta decay rates of the $fp$ shell nuclei for situations prevailing in pre-supernova and collapse phases of evolution of the core of massive stars leading to supernova explosion has been extended for…
Proton-neutron quasi-particle random phase approximation (pn-QRPA) theory has recently being used for calculation of stellar weak interaction rates of $fp$-shell nuclide with success. Neutrino losses from proto-neutron stars play a pivotal…