ASTM-E803 2020

1.1 This test method defines an empirical technique for the measurement of the effective collimation ratio, L/D, of neutron radiography beams. The technique is based upon analysis of a neutron radiographic image and is independent of measurements and calculations based on physical dimensions of the collimation system. The values derived by this technique should be more accurate than those based on physical measurements, particularly for poorly defined apertures.

1.2 This test method covers both the manufacture and use of the device to measure L/D ratios.

1.3 Neutron images for this method can be produced on radiographic film using an appropriate conversion screen as detailed in Guide E748 or a CR screen with appropriate neutron converter. The method has not been validated with images produced by digital detector arrays.

1.4 This test method only applies to neutron beam lines with cold or thermal neutron spectrums.

1.5 Units—The values stated in SI units are to be regarded as standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.