Proton-induced reactions on Fe, Cu, and Ti from threshold to 55 MeV

Theoretical models often differ significantly from measured data in their predictions of themagnitude of nuclear reactions that produce radionuclides for medical, research, and national security applications. In this paper, we compareapriori predictions from several state-of-the-art reaction modeling packages (CoH, EMPIRE, TALYS, and ALICE) to cross sections measured using the stacked-target activation method. The experiment was performed using the Lawrence Berkeley National Laboratory 88-Inch Cyclotronwith beams of 25 and 55MeV protons on a stack of iron, copper, and titanium foils. Thirty-four excitation functions were measured from 4-55 MeV, including the first measurement of the independent cross sections for Fe-nat(p,x)Cr-49,Cr-51, Mn-51,Mn-52m,Mn-52g,Mn-56, and Co-58m,Co-58g. All of the models, using default input parameters to assess their predictive capabilities, failed to reproduce the isomer-to-ground state ratio for reaction channels at compound and pre-compound energies, suggesting issues in modeling the deposition or distribution of angular momentum in these residual nuclei.