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Primary standards

Primary standard measuring facilities for the realization of the unit of air kerma:

A: Free-air ionization chambers for X-radiations between 7.5 kV and 400 kV
  

Designation Type Energy range Expanded uncertainty
(k = 2)
PK100 Parallel-plate ionization chamber 7.5 kV - 150 kV 0.62 %
FK Cylindrical ionization chamber 30 kV -300 kV 0.60 %
PK 400 Parallel-plate ionization chamber 50 kV - 400 kV 0.65 %



B: Cavity ionization chambers for 137Cs- and 60Co gamma radiation
 

Designation Type Measurement volume Expanded uncertainty
(k = 2)
60Co 137Cs
HRK-1 Cylindrical chamber 0.5539 cm3 0.46 % 0.44 %
HRK-2 Cylindrical chamber  1.5190 cm3 0.42 % 0.40 %
HRK-3 Flat chamber 6.138 cm3 0.45 % 0.42 %