Decay of Nb94 and Nb94m

Gamma rays in Mo94 following the decay of Nb94 have been studied using coincidence and directional correlation measurements. The 700 keV transition was found to be in coincidence with the 873 keV gamma ray. The intensity of the crossover transition of 1573 keV was found to be less than 0.1 % of the 873 keV gamma ray intensity. The directional correlation of the 700 keV - 873 keV cascade was measured and the corrected expansion coefficients were found to be A2 = 0.0965 +/- 0.0076 and A4 = 0.019 +/- 0.011. These data indicate spins of 4 and 2 for the 1573 keV and 873 keV levels, respectively. Gamma rays following the decay of Nb94m were studied with proportional and scintillation counters. The conversion coefficient [alpha]K of the 42 keV gamma ray in the decay of 6.6 min Nb94m was measured to be 1600 +/- 350 and the branching ratio of the transition from Nb94m to the 873 keV level of Mo94 was found to be 0.19 +/- 0.03 %. The intensity ratio of the 600 keV beta ray to the 1.3 MeV beta ray in the decay of Nb94m was determined to be 3.0 +/- 0.6 %. These measurements support a spin and parity of 3- for the isomeric state.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32305/1/0000373.pd

Afterheat calculations for the HTGR

Afterheat rates were calculated for the HTGR utilizing new input information. The new afterheat results are a few percent higher than the HTGR afterheat results previously obtained in the 100-to 10,000-sec time range and are 11 to 15% higher than the previous results in the one-day to ten-days time range. The uncertainties were studied in the time region from 100 sec to ten days. The new results were also compared with calculations at other laboratories. The gamma-ray spectra were computed at several shutdown times for future applications in shielding studies. Previous afterheat calculations for the HTGR are completely replaced and updated. (auth

Energy levels of As77

The gamma rays of As77 following beta decay of were investigated using coincidence techniques. General features of the level structure were found to be in substantial agreement with the work of previous investigators. Additional complexity was found in the level structure above 2 MeV. Relative intensities of the gamma transitions are reported.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32253/1/0000315.pd

Decay of Se81m and Se81

The gamma rays in Se81 and Br81 following the decay of Se81m and Se81 were studied with a magnetic spectrograph. Three internal conversion lines were observed in these measurements. Gamma-ray spectra taken with a NaI(Tl) detector indicated a transition at 30 keV in addition to previously reported gamma rays. Measurements were made of spectra of gamma rays in coincidence with gamma rays in five energy regions. The results indicate levels at 280 keV, 560 keV and 832 keV in Br81 and agree with the main features of the decay scheme proposed by Krause et al. Beta-gamma coincidence measurements showed that the 560 keV level in Br81 is a different level than the 550 keV level which is excited in (p, [gamma]) and ([gamma], [gamma]') reactions. Intensities of the transitions were computed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32287/1/0000354.pd