ALPHA-PARTICLE AND ELECTRON-CAPTURE DECAY OF (209)PO

Gamma-ray and K alpha X-ray emissions have been measured from a very p ure Po-209 source containing less than 0.13% Po-208 activity and no de tectable Po-210 (less than or equal to 2 X 10(-4)%). The alpha-particl e emission rate for this source has previously been determined. Data a re presented that confirm alpha decay to the Pb-205 excited level at 2 62.8 keV, with an alpha-particle emission probability (+/-standard unc ertainty) of 0.00559+/-0.00008. The ratio of K-shell electron capture to total electron capture for the second forbidden unique electron cap ture decay to the 896.6 keV level in Bi-209 was determined to be 0.594 +/-0.018. The electron capture decay fraction was found to be 0.00454/-0.00007, while the probabilities per decay for the 896.6, 262.8, and 260.5 keV gamma rays and the Bi K alpha and Pb K alpha X-rays were me asured as 0.00445+/-0.00007, 0.00085+/-0.00002, 0.00254+/-0.00003, 0.0 0202+/-0.00005, and 0.00136+/-0.00005, respectively.