Katharina Breunig

Production of no-carrier-added radiobromine: new nickel selenide target and optimized separation by dry distillation

Abstract Nickel(II) selenide (NiSe) was investigated as a new high-current target material for cyclotron production of radiobromine, as it contains a higher amount of selenium and has a lower melting point than the widely used Cu2Se. Using a slanted target system, NiSe was successfully tested up to beam currents of 16 μA so far. With regard to the isolation of no-carrier-added (n.c.a.) radiobromide from the target material, an improved dry distillation device with high yields of 76% – 86% was developed. The implementation of a special custom-made quartz funnel decreased the dead volume of the apparatus and a quartz capillary for trapping the radiobromine allowed to concentrate the radioactivity in a small volume of less than 100 μL of 0.1 M NaOH, ready for immediate subsequent radiosyntheses. Thus, the new apparatus improves the handling of the isolation procedure and the radioactive product. The radiochemical purity of the resulting solution of n.c.a. [*Br]bromide was verified by radio-IC where no other species were detected.

Cross section measurements of 75As(α,xn)76,77,78Br and 75As(α,x)74As nuclear reactions using the monitor radionuclides 67Ga and 66Ga for beam evaluation

Abstract For the production of the medically interesting radionuclides 76Br and 77Br cross sections of α-particle induced reactions on arsenic, leading to the formation of 76,77,78Br as well as to the non-isotopic impurity 74As, were measured from their thresholds up to 37 MeV. Sediments of elemental arsenic were used as targets and irradiated, using the established stacked-foil technique. In order to remove discrepancies of the existing literature data, the cross section ratios of the monitor nuclides 67Ga/66Ga were used for determination of the α-particle energies as well as the effective beam current through all the stacks, thus inferring the experimental cross sections. Compared with the available excitation functions the new data indicate slightly divergent curve shapes. In the case of 76Br the excitation function seems to be shifted to somewhat lower α-particle energies, and also the maximum cross section of the formation of 77Br tends to be slightly lower compared with the curve recommended to date. In the case of a re-evaluation, these new data should be taken into account, as they may contribute to enhance the accuracy of the excitation functions.