Investigation of the Performance of 7LiF:Mg,Cu,P Under Environmental Conditions

The high gamma sensitivity demonstrated by LiF:Mg.Cu,P produced in China and Poland makes it appropriate for environmental applications. Recently a new version of this material has been produced in the United States in both loose chip and encapsulated card form. This study investigates the performance of the US material under conditions designed to simulate environmental insults as described in ANSI Draft Standard N13.29. Twenty dosemeters are placed in an environmental chamber that cycles twice through three 15 day periods of temperature and humidity conditions: -20°C; +50°C with 20% relative humidity; and +50°C with 90% relative humidity. Five randomly selected dosemeters are exposed to a 137 Cs source that will give doses between 0.5 to 10.0 mSv at the beginning, middle, and end of the 90 day test. Two 40 W fluorescent bulbs provide lighting in the chamber. Performance is measured by comparison with the proposed Draft N13.29 performance criteria that would require the absolute value of the bias and standard deviation to each be less than or equal to 0.35, while their sum must be less than or equal to 0.50.