Thermal neutron measurement in the STU Mini Labyrinth experiment

Abstract

As part of an international cooperation the research team from the Slovak University of Technology is involved in the development of new radiation shielding experimental workplaces for code verification and demonstration of radiation shielding principles. One of these activities is the so called “Mini Labyrinth” experiment. It is a simple neutron and gamma shielding benchmark, inspired by the ALARM-CF-AIR-LAB-001 ICSBEP experiment. The STU Mini Labyrinth, as its name implies, is a mini version of the original IHEP Labyrinth, currently with dimensions of 96 × 60 × 25 cm. The experimental setup is placed on a special deck in the neutron physics laboratory of STU and uses remote source handling mechanism and video surveillance. It consists of several NEUTRONSTOP C5 shielding blocks (polyethylene with 5% boron), several detector positions and two channels to insert the neutron source and to generate thermal neutrons. The first one is a plastic tank filled with liquid moderator and a second one is a solid graphite prism, which is ideal to produce thermal neutrons. In the previous works of the research team, efforts were made to find the best setup for measurement inside and outside the Mini Labyrinth. It was found out that the 25 cm height was not appropriate, therefore it was increased to 50 cm by adding an extra level of NEUTRONSTOP blocks. This paper brings the results of first measurements performed on the V3-50-R measurement geometry and their comparisons with simulations using the Monaco code from the SCALE 6 system. In this measurement setup, the neutron source is placed inside the graphite prism and the aim is to measure and simulate the thermal neutron count-rate.