Energy and projectile dependence of nuclear alignment in fusion-evaporation reactions

Nuclear alignment attenuation coefficients of excited levels in 67Ga have been measured via the reactions 64Zn + α and57Fe + 12C for incident energies between 9 and 22 MeV and 32 and 48 MeV, respectively. The data were deduced from angular distributions of four pure electric quadrupole transitions in 67Ga. For the heavy-ion induced reaction a slight decrease of alignment with incident energy has been observed while there is a strong energy dependence of nuclear alignment for the α-induced reaction due to the feeding mechanism. The attenuation coefficients are consistent with the Gaussian magnetic substate population hypothesis except where direct and cascade feeding compete with comparable intersities.