a Geiger ionization chamber contains 60 cubic cm of air and records 500 mR/min. calculate (a). the current produce by the chamber (b). the total number of ion pairs produced per hour of exposure.
please answer, thank you!,
To calculate the current produced by the Geiger ionization chamber and the total number of ion pairs produced per hour of exposure, we need to know the conversion factor between current and radiation exposure.
(a) Calculating the current produced by the chamber:
- First, convert the recorded exposure of 500 milliroentgens per minute (mR/min) into coulombs per kilogram (C/kg). The conversion factor can be obtained from the instrument's calibration or look up the appropriate conversion factor.
- Let's assume that the conversion factor is 1 mR = 10 μC/kg (microcoulombs per kilogram). Therefore, we have 500 mR/min x (10 μC/kg / 1 mR) = 5000 μC/(kg⋅min).
- Since we want to find the current produced per minute, we divide the result by 60 to get the current in microamps (μA). 5000 μC/(kg⋅min) / 60 min = 83.33 μA.
So, the current produced by the chamber is approximately 83.33 microamps (μA).
(b) Calculating the total number of ion pairs produced per hour of exposure:
- We need to use the concept of ionization constant, which represents the average number of electron-ion pairs produced per unit exposure (in this case, per unit radiation exposure from the air in the chamber).
- The ionization constant for air is approximately 2.58 x 10^7 ion pairs per C/kg.
- Multiply the ionization constant by the radiation exposure in coulombs per kilogram (C/kg) for the given exposure rate of 500 mR/min. The exposure in C/kg is 500 mR x (10 μC/kg / 1 mR) = 5000 μC/kg.
- Now, we can calculate the total number of ion pairs produced per hour of exposure. Multiply the ionization constant (2.58 x 10^7 ion pair/C/kg) by the exposure in C/kg per hour: 2.58 x 10^7 ion pair/C/kg x 5000 μC/kg x (1 C / 10^6 μC) x 60 min.
- Simplifying, we have (2.58 x 10^7) x (5000 x 10^-6) x 60 ion pairs/hour.
Therefore, the total number of ion pairs produced per hour of exposure is approximately 7,740 ion pairs/hour.
So, the current produced by the chamber is approximately 83.33 μA, and the total number of ion pairs produced per hour of exposure is approximately 7,740 ion pairs/hour.