Level density sensitivity in deuteron-induced production of medically relevant Cu and Ga radionuclides from Ni and Zn targets

Abstract

Cu and Ga isotopes produced using accelerators support PET imaging, legacy scintigraphic imaging, and emerging theranostic strategies. Therefore, in this work, we theoretically calculated their accelerator-based formation cross sections using the TALYS code. A modified TALYS implementation of the collective semi-classical Fermi gas model (CSCFSGM) is benchmarked against six standard TALYS level density prescriptions for eight medically relevant or production adjacent residual reaction channels: 58 Ni(d,n) 59 Cu, 60 Ni(d,2n) 60 Cu, 60 Ni(d,n) 61 Cu, 64 Ni(d,2n) 64 Cu, 64 Zn(d,n) 65 Ga, 66 Zn(d,2n) 66 Ga, 66 Zn(d,n) 67 Ga, and 68 Zn(d,2n) 68 Ga. Theoretical residual production curves were interpolated to the measured energies and compared with reduced chi-square, coefficient of determination, mean weighted deviation, and relative variance. The results show that the level density choice is a non-negligible component of production route assessment. CSCFSGM improves selected one neutron emission channels, especially 60 Ni(d,n) 61 Cu and 64 Zn(d,n) 65 Ga, but it overpredicts 58 Ni(d,n) 59 Cu and underpredicts several high yield two neutron channels. For the production relevant 64 Ni(d,2n) 64 Cu and 68 Zn(d,2n) 68 Ga reactions, CTM and GSM, respectively, provide the most favorable native TALYS comparisons. The novelty of the work is an archive level, model to data benchmark that links nuclear level density sensitivity directly to Cu/Ga medical radionuclide production and impurity assessment channels. The study indicates that TALYS based production evaluations should report the selected level density prescription and treat it as a source of model uncertainty.