Proton radioactivity - Spherical and deformed

The proton drip line defines one of the fundamental limits to nuclear stabi lity. Nuclei lying beyond this line are energetically unbound to the emissi on of a constituent proton from their ground states. This phenomenon is kno wn as proton radioactivity. For near-spherical nuclei in the region of the drip line between Z = 69 (Tm) and Z = 81 (Tl), proton decay transition rate s have been shown to be well reproduced by WKB calculations using spectrosc opic factors derived from a low-seniority shell model calculation. Another approach using spectroscopic factors obtained from the independent quasipar ticle approximation has also proved successful in this region. These interp retations have allowed the extraction of nuclear structure information from nuclei well beyond the proton drip line. The race-earth proton emitters Ho -141 and Eu-131 have recently been observed, and their decay rates can only be explained by assuming large deformation for these nuclei. In addition t o providing information on the wavefunctions and deformations of these nucl ei, these results offer the opportunity to study the phenomenon of quantum mechanical tunneling through a deformed potential barrier.