EMISSION PROBABILITIES FOR THE 5.449-MEV ALPHA-PARTICLES AND 241-KEV GAMMA-RAYS IN THE RA-224-RN-220 DECAY

The emission probability P// alpha //1 for the 5. 449-Mev alpha particles, which in the decay of **2**2**4Ra populate the 241-kev level in **2**2**0Rn, was measured using **2**2**4Ra sources produced by recoil implantation from **2**2**8Th and Si surface-barrier detectors. Additionally, the 241-kev gamma -ray emission probability, P// gamma //(//2//4//1//) was measured using **2**2**8Th sources and a calibrated high-purity Ge detector. A pair of deduced values, P// gamma //(//2//4//1//), P// alpha //1, was obtained from the measured data of P// alpha //1 and P// gamma //(//2//4//1//), respectively. The weighted mean of the measured and deduced data yielded the results of P// alpha //1 equals 0. 0507 plus or minus 0. 0005 and P// gamma //(//2//4//1//) equals 0. 0400 plus or minus 0. 0007. The quoted overall uncertainties correspond to the 68% confidence limits for the mean with an effective number of degrees of freedom equal 5.