Anomalous cross sections for (p,n) reactions producing the isomers /sup 114m/sub 2//In(T/sub 1/2/=42 msec) and /sup 116m/sub 2//In(T/sub 1/2/=2. 16 sec). [Excitation, 4 to 9 MeV]

To elucidate isomerism, the excitation functions of (p,n) reactions and their cross sections producing /sup 114m/sub 2//In and /sup 116m/sub 2//In isomers at 4 to 9 MeV are examined. It was found that the ground states of /sup 114/In and /sup 116/In have I/sup ..pi../ = 1/sup +/; the 5 /sup +/ and 8/sup -/ isomeric states have configurations of (p(g/sub 9/2//sup -1/)n (s/sub 1/2/ + d/sub 3/2/)) and (p(g/sup -1//sub 9/2/)n(h/sub 11/2/)) types respectively. The second isomeric level is a member of a multiplet having spins from 1/sup -/ to 10/sup -/, which has the lowest excitation energy. The selection rule for the orbital angular momentum j heavily suppresses the transitions between levels having h/sub 11/2/ and (s/sub 1/2/ + d/sub 3/2/) neutron orbitals. This leads to a gamma cascade within the multiplet, i.e., to population of the 8/sup -/ isomer. Therefore, the (p,n) reactions resemble (n, ..gamma..) results in previous work in having the excitation cross section for the 8/sup -/ isomer as the cross section for excitation of the entire multiplet. This hypothesis is confirmed by previous direct spectroscopic observations on /sup 116/In, in which members of the (p(g/sup -1/ /sub 9/2/)n(h/sub 11/2/)) multiplet from 3/sup -/more » to 9/sup -/ were observed. Results similar to those obtained here can serve as a basis for including the selection rule for the orbital angular momentum j in the theoretical procedure for deexcitation via gamma-ray cascade. Here interest attaches to the differences in the excitation cross-sections for the second isomeric states of /sup 114/In and /sup 116/In. (JFP)« less