ABSTRACT
The first observation of beta-delayed alpha decay dates back to the first days of nuclear physics and the work of Rutherford on naturally occurring radioactive series. 1 The modern era in the field, though, began in the early 1960s with the discovery 2 and first characterization 3 of beta-delayed proton radioactivity. Since then, the growth in the number of known precursors, particularly of proton precursors, has been remarkable. At the time of the first review by Goldanskii 4 in 1966, ten proton precursors were (barely) known; by 1974, the review article by Hardy 5 listed 26; and in 1977 Cerny and Hardy 6 knew of 42. Today, there are 97 delayed proton precursors tabulated in this review, including some that emit alpha particles as well. There are also 17 precursors known only to emit alphas.
