Even-odd staggering of the spectroscopic factor as new evidence forαclustering

Abstract

We evidence a staggering effect of the experimental spectroscopic factors corresponding to even-even and odd-mass (odd-mass and odd-odd) $\ensuremath{\alpha}$ emitters. The comparison to the theoretical estimate within the standard Bardeen-Cooper-Schrieffer (BCS) approach reveals a similar staggering, but with a different behavior. It turns out that the ratio between corresponding experimental and theoretical spectroscopic factors is proportional to the experimental reduced decay width. A similar dependence was found in a previous work between the strength of the quadrupole-quadrupole $\ensuremath{\alpha}$-core interaction, describing the $\ensuremath{\alpha}$-decay fine structure and the reduced width. Thus, the even-odd staggering effect in the spectroscopic factor is a new evidence of the $\ensuremath{\alpha}$-clustering phenomenon in medium and heavy nuclei.