Applications and characteristics of imaging plates as detector in neutron radiography at SINQ

Imaging plate technique is a commonly accepted method in many fields as in medicine, biology and physics for detection of the distribution of beta- an d gamma-radiation or X-rays on large areas. Recently a new type of imaging plate sensitive to neutrons has been developed. The storage layer is doped with gadolinium, which, after absorption of neutrons, produces radiation de tectable by the same sensitive crystals used in conventional imaging plates . At the spallation neutron source, SINQ, at the Paul Scherrer Institut (CI I) some of the characteristics of the neutron radiography station in combin ation with the imaging plate technique were investigated. The intensity dis tribution of the source was measured to check the accuracy for quantificati on of the image data. Also, the reproducibility of results obtained by this detection system was stated. For a test object, the high selectivity for d ifferent neutron absorption is demonstrated at details with low contrast. T he obtainable spatial resolution was determined recording an image of a gad olinium edge, from which the line spread function and the modulation transf er function can be calculated. By use of conventional X-ray sensitive imagi ng plates the exposure time for a indirect detection method using a dyspros ium foil can be reduced significantly. For the measurement of the latent im age in the neutron activated foil it is sufficient to excite the imaging pl ate by the radiation of the isotope Dy-165m With a Short life time. The pos sibility to measure effective cross-sections of materials with pretty stron g absorption by imaging plates as detector because of their high dynamic ra nge was proved as well. (C) 1999 Elsevier Science B.V. All rights reserved.