Activation of trace elements and impurities: A new ansatz for Monte Carlo calculations

In the framework of activation calculations of accelerator components with Monte Carlo methods, an unsolved problem is to take into account the spallation products of trace elements and impurities in a bulk material. Because of the low probability of spallation reactions with these elements, a large number of primary particles are necessary to obtain some information about their spallation products. A new algorithm for treating high-energy reactions has been implemented into MCNPX 2.5.0 to overcome these deficiencies. With this algorithm, spallation reactions of all constituents of a material will be performed at each high-energy interaction. This leads to the production of spallation products from all elements in a material. We will present examples of how this new methodology influences the outcome of activation calculations.