PPT Slide
Target and Production MUTAC 21 July 1999 cdj
The Collaboration has made an extensive study of pion production below 1 GeV for a range of materials and primary proton energies. Recently CERN has contributed to this study essentially by using FLUKA to confirm the US results. A broad summary is presented here.
For proton energies below 3 GeV, pion production is most efficient in a thin target, but a multi-traversal thin target is disfavored because of target lifetime issues.
However, total pion yield is greater from thick targets (1-2 interaction lengths), in which case the yield per MW is essentially constant for energies above 8 GeV.
The pion yield per MW increases with the atomic number of the target but the dependence is weak for elements higher than copper.
The fraction of beam energy deposited per interaction length in a low-Z target is considerably higher than for a high-Z material - due largely to the increased contribution from nuclear fragmentation. This favors high-Z materials due to the resulting lower neutron activation levels in surrounding materials.
Various effects all favor high-Z targets exposed to proton beams at energies above 8 GeV