Excitation function and isomeric cross-section ratio for the ⁶¹Ni(p,α)⁵⁸Co^m,g process

Excitation functions were measured by the stacked-foil technique for ⁶¹Ni(p,α)⁵⁸Co^m and ⁶¹Ni(p,α)⁵⁸Co^m+g reactions using 88.84% enriched ⁶¹Ni from threshold up to 18.6 MeV. Thin samples of ⁶¹Ni were prepared by electrodeposition on gold foils. The radioactivity of the activation products was determined via high resolution x- and γ-ray spectrometry. From the measured experimental data isomeric cross-section ratios [σ_m/σ_m+g] were deduced. Statistical model calculations taking into account precompound effects were performed for the strong ⁶¹Ni(p,xn) channels as well as for the weak ⁶¹Ni(p,α) process. The experimental ⁶¹Ni(p,xn) and ⁶¹Ni(p,α) excitation functions are described well by the calculation over the whole investigated energy range. The isomeric cross-section ratio for the isomeric pair ⁵⁸Co^m,g formed in the ⁶¹Ni(p,α) process is also reproduced well by the model calculation, provided the input level scheme and the spin distribution are properly taken into account.