NEUTRON GENERATION IN AN EXTENDED CU TARGET IRRADIATED WITH 22 AND 44GEV CARBON-IONS (PRELIMINARY-RESULTS)

An extended Cu target was centrally irradiated with 22 and 44 GeV carb on ions for about 11 and 15 hours, respectively. The upper side of the target was in contact with a paraffin block for the moderation of sec ondary neutrons. Small holes in the moderator were filled with lanthan um salts (LaCl3.7H(2),O) where the neutrons induced the La-139 (n, gam ma) La-140 reaction. The beta-decay of La-140(40h) was followed using radiochemical methods. The yields for the formation of La-140 agree wi thin large errors with other experiments on extended targets carried o ut at the LHE, JINR (Dubna). To a first approximation, the breeding ra te of La-140 doubles when the C-12 energy is increased from 22 to 44 G eV. If results at 44 GeV are compared to those at 22 GeV, there cannot be excluded an excess of (20 +/- 7)% in the experimentally observed L a-140 production over theoretical estimates. A definite conclusion in this respect must await further experimental and theoretical work. The se experiments are the beginning of a research program to develop a su bcritical reactor with neutron fluxes sufficiently high to permit the TRANSMUTATION of long-lived radioactive waste into short-lived or stab le nuclei. Such transmutation would considerably relieve the ecologica l problems related to the final deposition of radioactive waste.