The quality of a neutron radiographic image is dependent upon many factors. The L/D ratio is one of those factors and constitutes a numerical definition of the geometry of the neutron beam. The L/D ratio required for a specific neutron radiographic examination is dependent upon the thickness of the specimen and the physical characteristics of the particular element of interest. Use of this test method allows the radiographer and the user to determine and periodically check the effective collimation ratio.

1. Scope

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 collimator system. The values derived by this technique should be more accurate than those based on physical measurements, particularly for poorly defined apertures.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

E748 Practices for Thermal Neutron Radiography of Materials

E1316 Terminology for Nondestructive Examinations

Keywords

beam collimation; L/D ratio; neutron radiography; radiographic unsharpness; umbral shadow; L/D ratio; Neutron radiographic testing; NU (no umbra) technique; Radiographic examination; Umbra;

ICS Code

ICS Number Code 19.100 (Non-destructive testing)

Citing ASTM Standards

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