Cross-section measurement for an optimized Cu production at an 18 MeV medical cyclotron from natural Zn and enriched Zn solid targets.

The availability of novel medical radionuclides is a key point in the development of personalised nuclear medicine. In particular, copper radioisotopes are attracting considerable interest as they can be used to label various molecules of medical interest, such as proteins and peptides, and offer two of the most promising true theranostic pairs, namely Cu/Cu and Cu/Cu. Although Cu (t = 12.7006 h, β: 17.6%, β: 38.5%) is nowadays the most commonly used as a diagnostic radionuclide, Cu (t = 3.339 h, β: 61%) features more favourable nuclear properties, such as a higher positron decay fraction and the absence of β emissions. To date, the production of Cu has been carried out irradiating highly enriched Ni targets with a low energy proton beam. However, the use of the very expensive Ni targets requires an efficient recovery of the target material and makes this method quite inconvenient. Another promising production route is the proton irradiation of natural Zn or enriched Zn targets, exploiting the (p,α) nuclear reaction. Along this line, a research program is ongoing at the Bern medical cyclotron, equipped with an external beam transfer line and a solid target station. In this paper, we report on cross-section measurements of the Zn(p,α)Cu nuclear reaction using natural Zn and enriched Zn material, which served as the basis to perform optimized Cu production tests with solid targets.