Design, optimization, and implementation of the new neutron radiography facility at FRM-II

Abstract

A neutron radiography and tomography facility was planned and installed at the new research reactor FRM-II in Munich.This paper describes the designing, optimization, construction, and first applications of this facility.Prior to construction, the whole facility was optimized by computational methods.The facility is based on the principle of a pin hole camera.For reduction of background radiation and neutron leakage from regions around the pin hole, a collimator was developed that provides a circular point spread function and a quadratic illuminated area in the detector plane.The radiation shielding for the facility was optimized with regard to weight, cost, volume, and background radiation at the detector position.Different shielding materials and geometries were taken into consideration for this purpose.With a single pin hole camera high flux at the specimen (low noise level in the projection) and high spatial resolution cannot be achieved simultaneously.A variety of other aperture types and reconstruction algorithms were tested for neutron radiography purposes.Investigations were carried out whether the noise level in projections can be decreased without reduction of resolution.