LIFETIME AND GAMMA-DECAY OF ISOMERIC 19-2- STATE IN TI-43

The nucleus Ti43 has been studied by prompt and delayed n-γ and γ-γ coincidences in the bombardment of Ca40 with 20-MeV α particles. A cascade of three γ rays with energies of 114.7, 1094.0, and 1857.7 keV has been observed. The γ cascade is emitted by an isomeric state of 3066.4-keV excitation energy; its mean life has been determined to be τ=810±50 nsec. By measuring the relative intensities of the three γ rays the sequence in the γ decay has been established. The close resemblance of this γ cascade to the one in the mirror nucleus Sc43 leads to the conclusion that the 3066.4-keV state in Ti43 is an isomeric 19/2- state which has the decay scheme 192-→114.7152-(2952.7)→1094.0112-(1857.7) →72-(0). This conclusion is in agreement with the results of measured excitation functions which show that the maximum yield of the 1857.7-keV γ occurs at the lowest α energy and that of the 114.7-keV γ at the highest. The B(E2) value of the 19/2-→15/2- transition in Ti43 is larger by nearly a factor of 2 than the corresponding transition in Sc43. The slightly lower excitation energy (56.9 keV) of the 19/2- state in Ti43 with respect to the corresponding state in Sc43 seems to be at least partially due to Coulomb shifts arising from the two valence protons in Ti43. NUCLEAR REACTIONS Ca40(α, nγ); prompt and delayed n-γ and γ-γ coincidences with Eα=20 MeV. Singles γ-ray spectra: dσdΩ=f(Eα, Eγ). Deduced for Ti43:192-(3066.4keV) →152-(2951.7keV)→112-(1857.7keV)→72-(0), 192- state: τ=(810±50) nsec. © 1978 The American Physical Society.