NUCLEAR-DATA RELEVANT TO THE PRODUCTION OF THE POSITRON EMITTING RADIOISOTOPE Y-86 VIA THE SR-86(P,N)-PROCESSES AND (NAT)RB(HE-3,XN)-PROCESSES

Excitation functions were measured by the stacked-foil technique for S r-86(p,xn)Y-86, Y-86m, Y-85, Y-85m- and (nat)Rb(He-3,xn)Y-87, Y-87m, Y -86, Y-86m, Y-85, Y-85m-reactions from threshold to 17.0 MeV in the ca se of protons and up to 34.5 MeV with He-3-particles. Thin samples of 96.3% enriched (SRCO3)-Sr-86 and natural Rb2CO3 of 10 mm diameter and 6-16 mg/cm2 thickness were prepared via a special sedimentation method . Thick target yields of Y-86 were calculated from the measured excita tion functions; the levels of radioyttrium impurities were determined experimentally. The optimum energy ranges for the production of Y-86 v ia the Sr-86(p,n)- and (nat)Rb(He-3,xn)-processes were found to be E(p ) = 14 --> 10 MeV and E3He = 24 --> 12 MeV, with the expected thick ta rget yields of 10.8 mCi (400 MBq)/muAh and 5.2 mCi (190 MBq)/muAh, res pectively. The Sr-86(p,n)-reaction using highly enriched target materi al is recommended for production of Y-86 since it leads to a higher pu rity product, and a small-sized cyclotron is adequate. The isomeric cr oss section ratios for the isomeric pair Y-86m,g in (p,n)- and (He-3,x n)-reactions are briefly discussed.