CNR—the new beamline for cold neutron imaging at the Swiss spallation neutron source SINQ

摘要

Based on the very good experience and knowledge gained with thermal neutron radiography at NEUTRA, novel capabilities can be predicted for a new beamline with cold neutrons: Micro tomography, neutron phase contrast imaging, contrast enhanced radiography, improved quantification of tracer elements and energy selective neutron imaging. The two main conditions for high-quality neutron imaging—radiography, tomography and especially for neutron phase contrast imaging—are a high beam collimation and a sufficiently high neutron flux. In order to obtain as many cold neutrons as possible from the source, neutron guides are normally used. We have examined whether guides in the accessible parts of the beam channel for CNR could enhance the performance of the instrument. Our findings are (1) that the enhanced divergence provided by the guide is not matched to the collimation or L/D ratio planned for the instrument and (2) the extended image size provided by the guide is not homogeneously illuminated. It has therefore been decided not to use guides inside the target block. The new radiography beam line CNR for imaging with cold neutrons will be installed at channel 52 of the spallation neutron source SINQ. It will have a direct view onto the liquid deuterium cold source. The installation is planned for the annual shutdown period—spring 2005. When operational, the CNR facility will be available for the NR community in the same way as the NEUTRA station.