Production of 99 Mo and 64 Cu in a mixed field of photons and neutrons in a clinical electron linear accelerator

The medical isotopes 99 Mo and 64 Cu were produced via the dual routes of 100 Mo(γ,n) 99 Mo + 98 Mo(n,γ) 99 Mo and 65 Cu(γ,n) 64 Cu + 63 Cu(n,γ) 64 Cu reactions from nat Mo and nat Cu targets via irradiation with bremsstrahlung + neutrons field using a 15MV clinical electron linear accelerator ( linac). The activities of 99 Mo and 64 Cu measured by off-line γ-ray spectrometry were 1.05 and 13.5 Bq per gram of nat Mo and nat Cu per gray-second irradiation. Fluka calculations estimate 28.77 ± 5.5 and 33.35 ± 6.33% contribution to 99 Mo and 64 Cu yield, respectively due to the secondary co-produced neutrons by (γ,n) reactions in the linac head. The 64 Cu yield is observed to increase up to 46% after moderation of the neutrons with varying thickness of a solid water phantom. This study suggests the possibility of irradiating natural targets of Mo and Cu in an electron linac to produce 99 Mo and 64 Cu as a cost saving measure for medical applications.