Experimental searches for rare alpha and beta decays

The current status of the experimental searches for rare alpha and beta decays is reviewed. Several interesting observations of alpha and beta decays, previously unseen due to their large half-lives (10 15 -10 20 yr), have been achieved during the last years thanks to the improvements in the experimental techniques and to the underground locations of experiments that allows to suppress backgrounds. In particular, the list includes first observations of alpha decays of 151 Eu, 180 W (both to the ground state of the daughter nuclei), 190 Pt (to excited state of the daughter nucleus), 209 Bi (to the ground and excited states of the daughter nucleus). The isotope 209 Bi has the longest known half-life of T1/ 2 10 19 yr relatively to alpha decay. The beta decay of 115 In to the first excited state of 115 Sn (Eexc = 497.334 keV), recently observed for the first time, has the Q beta value of only (147 +/- 10) eV, which is the lowest Q beta value known to-date. Searches and investigations of other rare alpha and beta decays (48 Ca, 50 V, 96 Zr, 113 Cd, 123 Te, 178m2 Hf, 180m Ta and others) are also discussed.