Monitor reactions in Al-foils for high energy proton beams bombarding a thick target

During the bombardment of U and Pb targets (each 21 cm thick) with protons of energy 1.0 and 1.5 GeV, the reactions Al-27(p, 3pn)Na-24 and Cu-nat.(p, X)Na-24 were studied as monitor reactions. The influence of Al-27(n, alpha) Na-24 on the monitor reaction Al-27(p, 3pn)Na-24 was investigated experimen tally and theoretically. In order to avoid the influence of(n, alpha) react ion, placing of the Al-monitors 35 cm upstream the massive targets is recom mended. This method may be used in Accelerator-Driven-Transmutation (ADT) s tudies of long-lived nuclear waste, where one always uses a massive heavy e lement target irradiated with protons at about 1 GeV. The experiments were performed at the Laboratory of High Energies, JINR, Dubna, Russian Federati on. (C) 1999 Elsevier Science B.V. All rights reserved.