99 Tc in stars, reactors, and nuclear medicine

The roles of 99g Tc in stars and in nuclear fission reactors and that of 99m Tc in nuclear medicine that were studied using neutrons provided from accelerators are reported. In addition to the critical role of 99g Tc in stars, we also describe the roles of related light nuclei such as 16 O, and experimental studies on keV-neutron capture cross sections of these light nuclei that were performed using keV neutrons provided from a 3.2-MV Pelletron accelerator are reported. The keV-neutron capture cross section of 99g Tc, that is important in studies on the nucleosynthesis of 99 Tc in stars and on the nuclear transmutation of long-lived nuclear wastes produced in fission reactors, were measured. The cross sections of both light nuclei and 99g Tc were measured using a neutron time-of-flight method with a ns-pulsed neutron source from the 7 Li( p , n ) 7 Be reaction and with an anti-Compton γ - ray NaI(Tl) spectrometer. The measurements reported here were compared with the values of recent worldwide evaluated nuclear data libraries. We proposed a method of producing 99m Tc from the 100 Mo( n ,2 n ) 99 Mo reaction, and performed a 99m Tc production experiment using a nat Mo sample and MeV neutrons from the nat C( d , n ) reaction by 40 MeV deuterons at a cyclotron. Calculations for the 99m Tc production with an enriched 100 Mo sample were also performed, and calculated results were compared with the experimental results. Moreover, the thermoseparation of 99m Tc from 99 Mo was discussed. As a result, it was shown that 99m Tc prepared by the thermoseparation using 99 Mo produced by the 100 Mo( n ,2 n ) 99 Mo reaction can be a promising substitute for the fission product 99 Mo.