Present status and future needs of nuclear data for high energy accelerator shielding design calculation

With increasing application of high energy accelerators, their shielding design study has become very important. The present study discusses the current status of nuclear data, especially inclusive neutron production cross sections (thin target yields), thick target yields, neutron transmission through shield and cross sections, and activation and spallation cross sections of neutrons and protons. Their experimental and theoretical data are compared and further needs of basic nuclear data for shielding design calculation are described. Nuclear data in high energy regions above 20 MeV, such as double differential neutron production cross section, double differential neutron yield and neutron reaction cross section, are very poor both in number and in accuracy at the present stage. The shielding design calculation requires the comprehensive data set of these cross sections and/or the more accurate computer code to calculate these quantities. Further effort is expected to carry out shielding and cross section experiments using the monoenergetic neutron beam line which is under construction in Takasaki Branch of JAERI (Japan Atomic Energy Research Institute). (N.K.)