Radiation shielding for the Main Injector collimation system

The results of Monte Carlo radiation shielding studies performed with the MARS15 code for the Main Injector collimation system are presented and discussed. A Proton Plan was developed recently at Fermilab for the benefit of the existing neutrino programs as well as to increase anti-proton production for the Tevatron programs [1]. As a part of the plan, the intensity of proton beams in the Main Injector (MI) should be increased by means of slip-stacking injection. In order to localize beam loss associated with the injection, a collimation system was designed [2] that satisfies all the radiation and engineering constraints. The system itself comprises a primary collimator and four secondary ones to which various masks are added. It is assumed that beam loss at the slip-stacking injection is equal to 5% of total intensity which is 5.5 x 1013 protons per pulse [2]. As far as pulse separation is 2.2 seconds, one has (5.5 x 1013/2.2) x 0.05 = 1.25 x 1012 protons interacting per second with the primary collimator. In the paper the geometry model of the corresponding MI region and beam loss model are described. The model of the region was built by means of the MAD-MARS Beam Line Builder (MMBLB) [3] using results of the collimation studies [2]. The results of radiation shielding calculations performed with the MARS15 code [4] are presented