An attempt was made to detect the 2 minute isomeric state in Mn54 reported by Caldwell and Stoddart. Irradiation of pure Mn55 with various energy bremsstrahlung of 12 to 24 Mev. failed to disclose any (γ, n) reactions leading to this state. Iron targets irradiated by 13.5 Mev. neutrons failed to disclose any positron activity of 2 minute half-life resulting from an (n, p) reaction to this state. In view of these experiments we conclude that the existence of the reported isomeric state in Mn54 should not be accepted without reservation.
The isomeric state in Au196 decays to the ground state with an initial M4 transition of energy 175.5 ± 0.5 kev, followed by 148.2 ± 0.5 kev and 188.8 ± 0.5 kev transitions in cascade; a transition of 85.0 ± 0.5 kev is probably also in cascade with these transitions. There is evidence of a weak 135.9 ± 0.5 kev transition converted in Pt, indicating a small electron capture branch in the decay. The half-life of the isomeric state is 9.5 ± 0.3 hours.
Atomic beam magnetic resonance has been used to study the 41-s isomeric state of 109Ag. The measured nuclear spin is 7/2 and the hyperfine interaction constant in the 2S1/2 electronic state is found to be 9550 ± 100 MHz. The special nature of the data also provides a direct evaluation of the nuclear magnetic moment, μI(corr.) = +4.27 ± 0.13 nuclear magnetons. The accuracy, however, is limited by the possibility of power shifts in the observed resonances and the error quoted is an estimate of this uncertainty. The moment is in closest agreement with theory if one assumes the state is the result of the coupling of three quasi-particles.
A pulsed beam of alpha particles was used to excite the 261 keV level in 151Sm through the 148Nd(α,nγ) reaction. This level was found to decay with a 1.4 ± 0.1 μs half-life to the 65.83, 91.53, 147.9, and 175.38 keV states. As has been found for heavier odd-neutron nuclei in this region, this isomeric state is probably the 11/2−[505] Nilsson orbital.
Magnetic moment of the13/2+isomeric state inCu69: Spin alignment in the one-nucleon removal reaction