Excitation functions of the 89Y(n,n′γ)89Ym and 89Y(n,αγ)86Rbm processes

Excitation functions of the Y-89(n,n' gamma)Y-89(m) and Y-89(n,alpha gamma)Rb-86(m) reactions were measured over the neutron energy range of 6.2 to 14.7 MeV, using the activation technique in combination with off-line gamma-ray spectrometry. Neutrons in the energy range of 6 to 12.4 MeV were produced using the H-2(d,n)He-3 reaction on a D-2 gas target and in the region of 14 MeV at a D-T generator. The half-life of Y-89(m) was redetermined and found to be 15.28+/-0.17 s, i.e., slightly shorter than the literature value of 16.09 s. Statistical model calculations taking into account precompound effects were performed for the strong Y-89(n,n' gamma)Y-89(m) channel as well as for the weak Y-89(n,alpha gamma)Rb-86(m) process. The experimental data for both the reactions are well described by the calculation over the whole investigated energy range. For the Y-89(n,alpha gamma)Rb-86(m,g) process, the isomeric cross section ratio [sigma(m)/(sigma(m) + sigma(g))] was deduced. A comparison with the results of nuclear model calculations showed good agreement. [S0556-2813(98)05210-8].