Activation analysis utilizing byproduct neutrons of cyclotron internal target runs

Abstract

The neutron flux generated by the CS-30 cyclotron at Mt Sinai Medical Center during routine internal target runs was characterized by employing various elements as neutron monitors. The characteristic (p, xn) nuclear reactions from internal targets bombarded by 26.5 MeV protons and the cyclotron inner wall bombarded by stray protons produce a neutron flux of approximately 2 × 10 9cm −2 s −1 at energies up to 22 MeV at a point immediately outside the cyclotron vacuum chamber. Samples exposed to neutron fluences up to 5 × 10 14 cm −2 were analyzed with a Ge(Li) detector. Although the detection limits are relatively high (i.e., Au−0.2 μg; In−1 μg; Na−50 μg), this mode of neutron activation analysis is ancillary to other irradiations and allows a large number of samples to be monitored. This approach may provide an alternative to a neutron generator for research activation applications.