a radiation survey meter observed gamma radiation of 150 mR/hr. The air field ionization chamber has a volume of 580 cubic cm. If the electron generated by the radiation in the chamber are swept out by an electric field, what is the current produced?
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The roentgen is the quantity of radiation which liberates by ionisation 1 esu of electricity per 1 cm³ of air under normal conditions of temperature and pressure
1 electrostatic unit of charge (esu) = 3.33•10⁻¹º C
150 mR/hr =150•10⁻³/3600 R/s
It gives q=(150•10⁻³/3600)•3.33•10⁻¹º = 1.4•10⁻¹⁴ C in 1cm³
and total charge in chamber
Q= 1.4•10⁻¹⁴ •580 =8.1•10⁻¹² C.
I=Q/t= 8.1•10⁻¹² A = 8.1 pA