Abstract
-decay branching ratios were obtained for high- and low-spin isomers in . These activities were produced by bombarding with ions, respectively, accelerated in the Oak Ridge isochronous cyclotron. With the use of a gas-jet-capillary transport system it was possible to do -particle, x-ray, and -ray counting simultaneously. Branching ratios were deduced in the main by determining the number of x rays emitted and then applying appropriate correction factors to obtain the total number of electron-capture and positron decays. For , where the -ray spectral measurements could be used to extract information concerning their decay to , it was possible to deduce alternate, and thus independent, -decay branching ratios. (Incidentally, our results confirm those of Ward and Neiman for the decay of the high-spin isomer to levels in .) Within error limits the two sets of ratios for were found to be in agreement. For the two cases, i.e., 35.6-sec and 9.3-min , where experimental -decay branches had been previously measured our data agree with the earlier results. -decay reduced widths were calculated by using the formalism developed by Rasmussen and compared with values for neighboring even-even nuclei, which can be taken to represent unhindered decay. The present study is the first systematic investigation of -decay rates for a series of isotopes of an odd- element in the rare earth region. It was found that, as for odd- isotopes in the heavy-element region, the -decay reduced widths range from those of even-even nuclei down to much smaller values.
RADIOACTIVITY ; , , , ; measured -decay branching ratios; deduced -decay rates. deduced levels, , .
- Received 19 February 1974
DOI:https://doi.org/10.1103/PhysRevC.10.296
©1974 American Physical Society