The fiber optic dosimeter on the Navigational Technology Satellite 2

A fiber-optic radiation dosimeter has been developed that utilizes the darkening induced in silicate glasses by ionizing radiation. A small, light weight, low-power consuming dosimeter package was deployed on the Navigational Technology Satellite 2. Observed real-time accumulated absorbed dose behind three shield thicknesses for the period July 1977 - June 1978 are compared with both the AE4 and the AEI7 particle fluence models for outer zone trapped electrons. The observations indicate little shielding improvement above three g/sq cm due to the presence of bremsstrahlung generated within the shielding and give evidence of a harder energy spectrum than predicted by these models. Occasional large dose rate fluctuations may correlate with sunspot activity during late 1977 and early 1978.