ISO/ASTM 51401 covers the preparation, testing, and procedure for using the acidic aqueous silver dichromate dosimetry system to measure absorbed doses in water when exposed to ionizing radiation. The system consists of a dosimeter and appropriate analytical instrumentation. For simplicity, the system is referred to as the dichromate system and is classified as a reference standard dosimetry system.
This International Standard describes the spectrophotometric analysis procedures for the dichromate system.
It applies only to gamma-rays, X-rays and high energy electrons provided the following conditions are satisfied:
the absorbed dose range is from 2 times 103 Gy to 5 times 10 4 Gy;
the absorbed dose rate does not exceed 600 Gy/pulse with a pulse repetition rate not exceeding 12,5 Hz, or does not exceed an equivalent dose rate of 7,5 kGy/s from continuous sources;
for radionuclide gamma-ray sources, the initial photon energy is greater than 0,6 MeV;
for bremsstrahlung photons, the initial energy of the electrons used to produce the bremsstrahlung photons is equal to or greater than 2 MeV
for electron beams, the initial electron energy is greater than 8 MeV;
the irradiation temperature of the dosimeter is above 0 °C and below 80 °C.