Experimental and theoretical study of the yields of residual product nuclei produced in thin targets irradiated by 100-2600 MeV protons (2003)

The objective of the project is measurements and computer simulations of independent and cumulative yields of residual product nuclei in thin targets relevant as target materials and structure materials for hybrid accelerator-driven systems coupled to high-energy proton accelerators. The yields of residual product nuclei are of great importance when estimating such basic radiation-technology characteristics of hybrid facility targets as the total target activity, target 'poisoning', buildup of long-lived nuclides that, in turn, are to be transmuted, product nuclide (Po) alpha-activity, content of low-pressure evaporated nuclides (Hg), content of chemically-active nuclides that spoil drastically the corrosion resistance of the facility structure materials, etc. In view of the above, radioactive product nuclide yields from targets and structure materials were determined by an experiment using the ITEP U-10 proton accelerator in 51 irradiation runs for different thin targets: sup 1 sup 8 sup 2 sup , sup 1 sup 8 sup 3 sup , sup 1 sup 8 sup 4 sup , sup 1 sup 8 sup 6 W at proton energies 0.2, 0.8, and 1.6 GeV; sup n sup a sup t W, sup 5 sup 6 Fe, sup 5 sup 8 Ni, and sup 9 sup 3 Nb at 2,6 GeV; sup 2 sup 3 sup 2 Th, sup n sup a sup t U, at 0.1, 0.2, 0.8, and 1.6 GeV; sup 9 sup 9 Tc, at 0.1, 0.15, 0.2, 0.8, 1.0, 1.2, 1.4, 1.6, and 2.6 GeV; sup 5 sup 9 Co and sup 6 sup 3 sup , sup 6 sup 5 Cu at 0.2, 1.2, 1.6, and 2.6 GeV; sup n sup a sup t Hg at 0.1, 0.2, 0.8, and 2.6 GeV and, additionally, sup 2 sup 0 sup 8 Pb at 1.0 GeV. As a result, 4315 cumulative and independent yields of residual radioactive product nuclei, whose lifetimes range from 8 minutes to 32 years, have been measured. Besides, the monitor sup 2 sup 7 Al(p,x) sup 2 sup 4 Na and sup 2 sup 7 Al(p,x) sup 7 Be reaction cross sections have been measured at proton energies from 0.07 GeV to 2.6 GeV. The experimental nuclide yields were determined by the direct gamma-spectrometry method. The gamma-spectrometer res 1.8 at the 1332 keV gamma-line. The experimental gamma-spectra were processed by the GENIE2000 code. The gamma-lines were identified, and the cross sections calculated, by the ITEP-developed SIGMA code using the PCNUDAT database. The proton fluence was monitored by the sup 2 sup 7 Al(p,x) sup 2 sup 2 Na reaction. Some of the results have been compared with the data obtained elsewhere, in particular with the recent GSI inverse kinematics experiments. The measured data are compared with the simulations by the LAHET, CEM95, CEM2k, LAQGSM, CASCADE, CASCADE/INPE, YIELDX, HETC, and INUCL codes. The predictive power of the tested codes is different but was found to be satisfactory for most of the nuclides in the spallation region, though none of the benchmarked codes agree well with the data in the whole mass region of product nuclides and all should be improved further. On the whole, the predictive power of all codes for the data in the fission product region is worse than in the spallation region; therefore, development of better models for fission-fragment formation is of first priority.