- #1
Von Neumann
- 101
- 4
Question:
I'm looking to estimate my total extra exposure (dose above background) by taking into account account roughly how long I was near each source, the strength of the source, and its approximate distance from me. I believe it's useful to use the following equation,
\frac{dD}{dt}=\frac{dD_{0}}{dt}e^{-cx}
where \frac{dD_{0}}{dt} is the dose rate at x=0 and c is the absorption coefficient.
The dose rates measured at x=0 for the 3 sources, as well as the calculated absorption coefficients are
Ba-133: 277 μR/h , c=0.303/in.
Cs-137: 107 μR/h , c=0.375/in.
Co-60: 117 μR/h , c=0.360/in.
*note that the background radiation has been subtracted from the dose rates shown.
So if I take the time t spend near each source as 10 minutes, and the distance from each source as x=0 in. (as I was holding the sources as we varied the distance in the first part of the experiment) I can approximate the exposure as
\frac{dD_{0}}{dt}\cdott
and then sum these for from each source. So therefore I get,
Ba-133: 277 μR/h * (10 min) * (1 h/ 60 min) = 0.0462 mR
Co-60: 107 μR/h * (10 min) * (1 h/ 60 min) = 0.0195 mR
Cs-137: 117 μR/h * (10 min) * (1 h/ 60 min) = .0178 mR
Thus as my total extra exposure I get,
0.0462 mR + 0.0195 mR + 0.0178 mR = 0.0835 mR
Is this reasoning correct? Thank you in advance for any input.
I'm looking to estimate my total extra exposure (dose above background) by taking into account account roughly how long I was near each source, the strength of the source, and its approximate distance from me. I believe it's useful to use the following equation,
\frac{dD}{dt}=\frac{dD_{0}}{dt}e^{-cx}
where \frac{dD_{0}}{dt} is the dose rate at x=0 and c is the absorption coefficient.
The dose rates measured at x=0 for the 3 sources, as well as the calculated absorption coefficients are
Ba-133: 277 μR/h , c=0.303/in.
Cs-137: 107 μR/h , c=0.375/in.
Co-60: 117 μR/h , c=0.360/in.
*note that the background radiation has been subtracted from the dose rates shown.
So if I take the time t spend near each source as 10 minutes, and the distance from each source as x=0 in. (as I was holding the sources as we varied the distance in the first part of the experiment) I can approximate the exposure as
\frac{dD_{0}}{dt}\cdott
and then sum these for from each source. So therefore I get,
Ba-133: 277 μR/h * (10 min) * (1 h/ 60 min) = 0.0462 mR
Co-60: 107 μR/h * (10 min) * (1 h/ 60 min) = 0.0195 mR
Cs-137: 117 μR/h * (10 min) * (1 h/ 60 min) = .0178 mR
Thus as my total extra exposure I get,
0.0462 mR + 0.0195 mR + 0.0178 mR = 0.0835 mR
Is this reasoning correct? Thank you in advance for any input.