Importance of the photo-beta process for the synthesis of “p” elements in stellar conditions

In this work, we compare positon capture and photo-beta disintegration probabilities in several stellar conditions.

We show that the second process can be neglected with regard to the first one in strongly endothermic nuclear transitions, whereas photo-beta disintegration can be competitive with positon capture and even can have a greater likelihood than the latter process in weakly endothermic and exothermic transitions.

In the range of temperature we consider here (T ≈ 10⁹ °K), it appears that the lifetime ratio τ(ph)/τ(e_c⁺) against photo-beta disintegration and positon capture is the smallest for densities in the neighbourhood of 10⁶ g/cm³.

Thus, we arrive at the conclusion that the photo-beta process can play a role in the synthesis of two “p” elements at least, ₆₂¹⁴⁴Sm and ₈₀¹⁹⁶Hg, for which the ratios τ(ph)/τ(e_c⁺) are close to 10 and 20, respectively, in the most favourable stellar conditions.