Two corrections to what I wrote: There are any number of decay modes, and the ones that seem to be of > interest to the authors are beta (+/-) decays, as far as I can tell. >
I think they're also looking at electron capture. > One graph shows an unmistakable annual period in the decay of 36Cl [2] > (although the source of the variation may be the effects of annual changes > in temperature and pressure on instruments, for example). > Eric Norman in [1] clarifies that the graph that shows the annual period is of the ratio of the decay of 32Si to 36Cl, rather than of the decay of 36Cl. He mentions the possibility that this variation could be due to differences in the sensitivity of a G-M counter to these two isotopes as a result of changes in temperature and humidity over the course of the year. [1] http://arxiv.org/pdf/1208.4357v1.pdf
