Multielectron SEFs for nuclear reactions involved in advanced stages of stellar evolution

Abstract

Multi-electron screening effects encountered in laboratory astrophysical reactions are investigated by considering the reactants Thomas-Fermi atoms. By means of that model , previous studies are extended to derive the corresponding screening enhancement factor (SEF), so that it takes into account ionization, thermal, exchange and relativistic effects. The present study, by imposing a very satisfactory constraint on the possible values of the screening energies and the respective SEFs, corrects the current (and the future) experimental values of the astrophysical factors associated with nuclear reactions involved in advanced stages of stellar evolution.

Screenedαdecay in dense astrophysical plasmas and superstrong magnetic fields

“…According to that figure the Coulomb potential practically vanished at distances further than three screening radii (see next sections and Ref. [2]). …”

“…The SEFs for heavy nuclei has been calculated in a paper [2] dealing with astrophysical nuclear reactions experiments. Actually the derived formulas are particularly relevant here since the atoms involved in alpha decay are always multielectronic.…”

“…We will now define the two major limits of our study whose validity and plausibility has been firmly established [2] in the study of multielectron screening effects in astrophysical reactions. Namely, if the nucleus belongs in a neutral atom we should distinguish two modes of decay:…”

“…The energy shift is usually much smaller than the kinetic energy E α imparted on the alpha particle due to the rearrangement of nucleons and can be calculated in the framework of the Thomas-Fermi theory [2]. According to previous studies [3] we can always define a screening enhancement factor (SEF) so that…”

Screening enhancement factors for laboratory CNO and rp astrophysical reactions

“…[3] can be very easily applied to the study of alpha-induced reactions where corrections are expected to be just as important.…”