Abstract
Using the singly and doubly ionized helium beams as well as a beam from our electrostatic generator, we have studied the low-lying level structure of in the and reactions, respectively. We found one excited state at 666±4 kev in addition to most other states previously discovered in the self-conjugate reaction which presumably yields only states having . We believe this state to be the analog of the ground states of the two neighboring even-even nuclei forming the triplet at . By various coincidence experiments, this state is found to decay by a 73-kev transition, having a probable half-life of 0.014 μsec, to the first-excited state of at 593 kev, which in turn decays to the ground state with a half-life of 0.266±0.010 μsec. With the plausible assignment of for the 593-kev state ( being completely ruled out by the half-life) this would represent a pure —pure cascade, whose strengths would be 0.0045 and 0.0077 single-particle units, respectively. The location of the first state occurs exactly as expected from a systematic study of the series Coulomb-energy differences, lending additional support to the , assignment.
We observed proton groups to most previously known states, and one new one at 3.75 Mev. A number of higher energy gamma rays were found in coincidence with those already mentioned which we can interpret within the framework of known excited states.
- Received 7 May 1958
DOI:https://doi.org/10.1103/PhysRev.111.1303
©1958 American Physical Society