In-target production of high specific radioactivity [O-15]nitrous oxide bydeuteron irradiation of nitrogen gas

A simple and rapid production method for high specific radioactivity [O-15] N2O has been developed bused on the N-14(d,n)O-15 reaction on high-purity n itrogen gas in a flow-through target irradiated with a 0.5 mu A beam of 7 M eV deuterons. The [O-15]N2O formed during irradiation is selectively concen trated from the target effluent by adsorption on a zeolite during 150 s and subsequently released by rapid heating into a pulse with a full width at h alf maximum of 3.5 s. The radioactivity and specific radioactivity in the p ulse amount to 4 MBq [O-15]N2O and 4.5 x 10(13) Bq/mol respectively with a radiochemical purity >99.95%. A tenfold higher specific radioactivity may b e feasible at larger beam currents, It was shown that stable N2O was also f ormed during irradiation. Based on responses to variations in various param eters during irradiation and on analyses performed on the products, an expl anation is given on the mechanisms of in-target [O-15]N2O and N2O formation , involving reaction of a particular excited state of O-3 with N-2. (C) 200 0 Elsevier Science Ltd. All rights reserved.