Bundels, A.; Ott, K.: Calculation of High Energy Neutron Corrections for Albedo Dosimeters at BESSY. In: Proceedings of the 10th International Workshop on Radiation Safety at Synchrotron Radiation Sources : MAX IV Laboratory, Lund University, Sweden, 22-24 May 2019. Lund University, MAX IV Laboratory, 2020, p. 21-28
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At synchrotron light sources like BESSYII a considerable part of the exposition consists of high energy neutrons with E > 10 MeV. The detection of neutrons with common Leake or Anderson-Braun monitors require the thermalization of neutrons resulting in a high energy limit of 10 – 20 MeV. We found solutions for this problem in our development of lead moderators that increase the upper detection limit to several GeV [1] and by the calculation of correction factors for our neutron spectra [2, 3]. The correction factor between 2 and 3 (depending on shielding) makes it necessary to consider the situation for Albedo-dosimeter too. These dosimeters which are in usage for personal dosimetry at BESSYII also require thermal energies for neutron detection. In contrast to the ambient dosimetry where the fluence to dose conversion coefficients H*(10) [4] have been calculated up to the TeV range [5], the conversion coefficients Hp(10) for the personal dosimetry have been tabulated only up to 20 MeV [4] and have been calculated more recently by Olsher et al [6] up to 250 MeV. We present in this work our approach to calculate the correction factors for Albedo-dosimeters using FLUKA [7,8] calculations of the neutron spectra in the experimental hall at BESSYII and PTB neutron reference spectra for neutron sources [9] to calculate the Albedo-dosimeter response function [9] from relative in absolute units.