F. H. Newman’s research while affiliated with University of Exeter and other places

KLEMPERER1 has recently shown that 19K40 is very probably the source of the natural beta-radioactivity of potassium. This supports the suggestion put forward by the authors2 based on Fermi's failure to observe induced beta-radioactivity when calcium is bombarded with neutrons. Klemperer also suggested that 37Rb86 is similarly the source of the natural beta-radioactivity of rubidium. The effects observed when rubidium, yttrium and strontium are bombarded with neutrons support this suggestion as follows.

RADIOACTIVITY induced by proton, diplon, neutron and alpha-particle bombardment can be explained on the hypothesis that the nuclear structure of stable isotopes consists of alpha-particles, neutrons and diplon. Missing isotopes of mass number less than twice the atomic number contain, on this theory, a free proton in addition to the other nuclear components1. Such nuclei are unstable and radioactive, emitting positrons. They may be produced artificially by bombarding appropriate stable isotopes with protons, diplons or alpha-particles but, being short-lived, have not at present been detected. These positron radioactive isotopes will only be found among elements below scandium in the periodic table, and are of the structural type, for example, 7N13 (3alpha + p), 6C11 (2alpha + D + p), 15P30 (7alpha + p + n).