MARS Calculations for MIPP(FNAL-E907) Shielding Assessment

We present the results of MARS calculations of beam induced radiation in the MIPP beamline for MIPP shielding assessment. 1 Model In order to estimate the beam induced effects for MIPP running conditions a model of the MIPP beam line and beam enclosure has been established within the MARS14 framework [1]. The optics of the beam line is governed by an “optics” file that is an output of the MAD code [2]. The MAD “optics” file is read and translated to MARS14 format by the recently improved and refined MAD-MARS Beam Line Builder (MMBLB) [3]. The use of the MMBLB makes it possible to easily synchronize changes in both the MAD and MARS14 models. Two views of the system studied are shown in Fig. 1 and 2, which depict the MIPP beamline in the MC6 hall. Shown are a segment of the primary beamline leading up to the primary target cage followed by the secondary beamline. The MAD-like axis orientation has been used for the MARS14 model, that is the axis Y points upwards and Z – downstream. This axis convention is not native to MARS14, where the axis X points upwards. This leads to cross-section plots rotated by π/2 clock-wise for all such plots in this document. A number of simplifications have been made in the model. Concrete magnet stands have not been included. The stands represent a significant amount of material and should result in even smaller radiation doses in the system when accounted for. Effects of the gaps between concrete blocks that form the walls of the beam enclosure in MC6 have not been studied. Such gaps may result in higher dose rates, especially in places where walls are relatively thin (roof of MC6). The following material densities are used. The density ρ for shielding steel is taken to be 7.2 g/cc, which is 92% of the nominal one. This takes into account the gaps between the shielding sheets. The density ρ for soil is taken to be 2.24 g/cc, that of Fermilab wet dirt. The heavy concrete has the density of 4 g/cc and the same chemical composition as