Improvement on design of target by the SHIELD code and it's applications to some complicated spallation targets

The technique of the geometric design and graphic displaying of GEANT3 is a dopted in the SHIELD code. Some examples of complicated spallation targets are designed and discussed. With the proton beam energy of 150MeV, our resu lts show that the best thickness of W spallation target is 5cm; 5.0-5.8 neu trons can be produced per GeV of beam energy for properly designed W target ; the material damage and the radiation deposits are concentrated in the be am axes of about 2 cm long; scattered proton beam may alleviate the concent ration, but may also lower the neutron production.