ALPHA DECAY OF Bi$sup 210$ ISOMER

Studies were made of the long-lived isomer of Bi/sup 210/, emitting alpha particles of 4935 plus or minus 20 kev with a T/sub 1/2/ = 2.6 x 10/sup 6/ years. The spectrum measured is presented. In addition to the previously observed alpha particles at 4935 plus or minus 20 kev, two new groups of alpha particles with energies 4900 plus or minus 10 and 4640 plus or minus 30 kev were found. The relative intensities of the free alpha transitions are 60, 30, and 10%, respectively. The decay scheme is included. (R.V.J.)