| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1988: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
1. A high purity germanium detector and a 4pibeta pressurized proportional counter using a live-timed bi-dimensional data acquisition system were used for measurement of gamma-ray emission probability.
2. When the disintegration rate of ^<60>Co and ^<134>Cs, which decay by beta^- particle emission, were measured by this system, the results agreed with those measured by conventional method. The disintegration rate of ^<57>Co which decays by electron capture can be easily measured by application of two-dimensional efficiency extrapolation method.
3. Measurement of disintegration rate for ^<152>Eu was carried out for determination of gamma-ray detection efficiency. ^<152>Eu decays via beta^- -particle emission and electron capture accompanied by a substantial fraction of conversion electrons, which complicate standardization, but accurate disintegration rate can be determined by two-dimensional efficiency extrapolation method.
4. Disintegration rate of ^<133>Ba depended slightly on the gate
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set in the 47pibeta-gamma coincidence counting using a NaI(T1) scintillator. The reason is probably large internal conversion electrons instead of the 53 keV gamma-rays; therefore, two-dimensional efficiency extrapolation method was applied. Five combinations of gamma-rays gave good results.
5. The emission probability for the 1.52 MeV gamma-ray of ^<42>K was determined to be 0.1808<plus-minus>0.0009. The present result has an uncertainty smaller than the past results by factor of two, and that is small enough to consider the application of ^<42>K which can be "milked" from ^<42>Ar.
6. ^<86>Rb transits directly to the ground level of ^<86>Sr with probability of about 0.9, and the 1077 keV gamma-ray from the excited level is emitted following emission of beta-ray with about 0.1 of emission probability. To determine the emission probability of the gamma-ray, it is required the measurement of beta branching ratio or of the disintegration rate and gamma-ray intensity. The present work showed the good result for the emission probability of the 1077 keV gamma-ray, O.0888<plus-minus>O.0003.
7. A large amount transition from ^<103>Ru go through the 40 keV metastable level that has half-life of 56 min and the transition has a large internal conversion coefficient. There is a problem concerning with existence of beta transition to the 40 keV level or ground level. The present result for emission probability for the 497 keV gamma-ray showed that the beta transition to the ground level is 0.0072<plus-minus>0.0062 and that the beta transition to the 40 keV level is nothing. Less
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