Study of bare atom beta decay and a low energy resonance state relevant to nuclear astrophysics

Abstract

In our theoretical programme on the study of bare atom and#946;and#8722; decay, we have calculated newlineterrestrial and#946;and#8722; decay rates of some fully ionized (bare) atoms in the mass range Aand#8776; 60 240 newlinefor the decay to both continuum and atomic bound states. Decay rates to continuum and newlineatomic bound states have been calculated separately to reveal the importance of the later. newlineThe latest experimental data have been used for nuclear and atomic observables, such as and#946;and#8722; newlinedecay Q-values, ionization energies, neutral atom and#946;and#8722; decay branchings, and neutral atom newlinehalf-lives, as inputs. and#946;and#8722; decay rates for decay to continuum and bound states, along with newlinethe decay rate enhancement factor arising due to bound state decay, have been calculated newlineand compared with the previously calculated and experimental values, if available. The newlinetotal decay rate calculated for bare atoms might be helpful to set a limit for the maximum newlineenhancement due to bound state decay. The changes in branching in bare atom compared to newlinethat in the neutral atom have been found. Branching flip for a few cases has been obtained newlinefor the first time. These changes in branching and branching flip have been explained with newlineproper reason. newlineNext we have calculated and#946;and#8722; decay rates to continuum and atomic bound states, from newlineground/isomeric levels and excited nuclear levels, of some fully ionized atoms (A = newline59 81) in the stellar s-process conditions (free electron number density newlinene = 1026/cm3 1027/cm3 and temperature T = 108 K 5×108 K). The importance of the newlinebound state and#946;and#8722; decay in stellar situations has been shown explicitly. In this calculation, we newlinehave established the existence of bare atoms for the above mass range for the physical newlinesituations mentioned, by solving the Saha ionization equation taking into account the newlineionization potential depression (IPD). Total and#946;and#8722; decay rates (bound state plus continuum newlinestate) have been calculated using IPD corrected neutral atom Q-value as a function of newlinedensity and temperature. A comparison of stellar and#946;and#8722; half-lives with neutral atom half-lives newlinehas been presen