The standard test method ASTM E545-19 is used to determine quantitative data on neutron beam and image system parameters that influence film exposure and, as a result, image quality. In addition, Beam Purity Indicator (BPI) is used to check the neutron radiography quality on a day-to-day basis. The BPI is developed and tested using gadolinium conversion screens and single-emulsion silver-halide films exposed combined in a neutron imaging beam.
In the ASTM E545-19 test, a beam of radiation is directed perpendicularly on the film plane. Firstly, a conversion screen is used that responds to neurons of thermal energy; exposure contributors are also calculated. Then, the value of G, H, and sensitivity level is determined. Finally, neutron radiography was determined, and images of wire were compared visually in BPI.
Effective thermal neutron content,
NC = × 100
Effective scattered neutron content
S = (∆DB/DH) × 100
Effective gamma content,
γ = (DT – lower DL)/DH × 100
Effective pair production content,
P = (∆DL/DH) × 100