Excitation Functions for Alpha-Induced Reactions on Manganese-55

Excitation functions for the reactions Mn 55 (α, n )Co 58 , Mn 55 (α, 2 n )Co 57 , Mn 55 (α, 3 n )Co 56 , Mn 55 (α, α' n )Mn 54 and Mn 55 (α, 2 p n )Mn 56 were measured by the activation method using a "stacked-foil" technique, the alpha-particle energies ranging from 10 MeV to 40 MeV. Bombardments were made with the alpha-particle beam of 32 MeV and 40 MeV from the 160 cm INSJ cyclotron. The beam was collected in a Faraday cup and measured by a current integrator. After bombardments, manganese, cobalt and iron were chemically separated. The disintegration rates of product nuclei Co 58 , Co 57 , Co 56 and Mn 54 were obtained by the gamma-ray scintillation spectrometry, while that of Mn 56 by a calibrated end-window type Geiger counter. The reaction cross section was found to agree with calculated value for a nuclear radius constant r 0 of 1.7×10 -13 cm. Competition between different reactions was analyzed in terms of the statistical model of nuclear reaction by use of a level density expression of ω= c exp [2( a E ) 1/2 ] and it agrees with the calculated value for a =2 MeV -1 .