Once values of the decay index for a particular nuclide are obtained and a particular value is agreed upon, this value is generally accepted. Usually no further measurements are taken. The terminology is such that no change with time is expected. Note the quantity, l , is called the nuclear decay constant . Hence it is easy to see why a slight change in decay rate, if it exists, could have been overlooked during the past fifty years.
External parameters can effect slight changes in the nuclear decay rate.
B. Dudley's hypothesis. 11 Dudley rejects the idea that radioactive decay is completely spontaneous and instead hypothesizes that neutrinos from the neutrino sea, which has been suggested by others, trigger radioactive decay. Radiohalos are minute concentric rings of discoloration in minerals such as mica formed by alpha ray bombardment from radioactive inclusions. Radiohalos give evidence that decay rates vary with time. Some researchers believe otherwise.