U YIELD MEASUREMENT ON [sup.3,4]He-IRRADIATED Th[O.sub.2] TARGETS

The [sup.230]U yield in the direct reactions [sup.232]Th([sup.3]He, 5n)[sup.230]U and [sup.232]Th([sup.4]He, 6n)[sup.230]U on thick Th[O.sub.2] targets irradiated by 65 and 55 MeV nuclei [sup.3,4]He was measured and compared with calculations. The experimental yield of [sup.230]U in the reaction [sup.232]Th([sup.3]He, 5n) [sup.230]U is approximately 10 times higher than the value computed using the constants from TENDL-2019. The experimental yield of [sup.230]U in the reaction [sup.232]Th([sup.4]He, 6n)[sup.230]U the same, to withi n the limits of error, as the computed value. Comparing the experimental and computed yield in the reaction [sup.232]Th([sup.4]He, 6n)[sup.230]U with the cross section obtained by the ALICA program (USA) showed that the computed cross section is incorrect and the prognoses for [sup.230]U production based on it are unsubstantiated. It is concluded that the reactions [sup.232]Th([sup.3]He, 5n)[sup.230]U and [sup.232]Th([sup.4]He, 6n)[sup.230]U are inefficient for [sup.230]U production in the U-150 cyclotron at the NRC Kurchatov Institute in amounts required for clinical applications.