Shielding Design of the PANDA Spectrometer at the Munich High-Flux Reactor FRM-II

The start-up of the Munich high-flux reactor FRM-II is going on. At the beam tube SR-2 the spectrometer PANDA has been installed. It is a three-axis neutron spectrometer looking onto a slightly under-moderated cold neutron source. For polarization analysis PANDA is equipped with a vertical cryo-magnet producing fields up to 14.5 Tesla at the sample. To get an appropriate shielding of the high-intensity instrument one had to take into account the large cross-section of the primary beam, several restrictions using magnetic materials, limitations in loading the site and, finally, one had to keep the lateral extent of the shielding small to allow for high scattering angles. The shielding has been designed on the base of results which were achieved by the combined use of both the Monte Carlo code MCNP-4B2 and an analytical method based on one-dimensional dose transmission functions.