Proton-induced production of residual radionuclides in lead at intermediate energies

Abstract

Integral excitation functions for the production of residual nuclides are basic quantities for the calculation of radioactive inventories of spallation targets in spallation neutron sources and in accelerator-driven devices for energy amplification or for transmutation of nuclear waste. We present comprehensive measurements of such data for the proton-induced production of residual nuclides from lead for proton energies between 64.8 MeV and 2.6 GeV. About 2000 individual cross-sections for 127 reactions were determined by means of off-line γ-spectrometry. The phenomenology of excitation functions which exhibit clearly distinguishable reaction modes like multi-fragmentation, three different types of asymmetric and symmetric fission and deep spallation is discussed. The experimental data are compared with calculations based on an intranuclear cascade/evaporation model in form of the LAHET code system. Together with earlier model exercises this comparison demonstrates the necessity for further improvements of models and codes if medium-energy activation cross-sections for applications shall be reliably predicted by theory. Today, experimental investigations remain indispensable.