Abstract
Detailed experimental neutron data relevant to the design of the target station of neutron spallation sources have been gathered by the NESSI-collaboration at the COSY accelerator in FZ Jülich. Numerous neutron multiplicity distributions and reaction probabilities have been measured for 0.4 to 2.5 GeV protons bombarding highly segmented target blocks from Pb, Hg and W of up to 35 cm in length and 15 cm in diameter with the intention to provide a comprehensive data base for the improvement and validation of existing reaction simulation codes.