- Joined
- Jul 4, 2008
- Messages
- 2,499
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- 113
Well, all this talk over the leaking of Fukushima daiichi （福島第一原子発電所）facility I though it would be interesting to dust off the geiger counters and give them some exercise.
I am measuring a test sample of Ra226 here with a pancake probe. 0.1mR/hr or 1uSv/hr
On this 3" probe the sample gives about 13,500CPM. ~3.5-4.0mR/hr Beta eq. ~40uSv/hr.
My Giegercounter with scintillation preamp installed was a custom build by GEOS electronics. It is a very rare and extremely specialized counter. It can run NaI/Tl scintillation detectors from 900-1200V and has variable HV!
The big box with blue and silver is a homebuilt scaler. The inverse square wave pulses are sent to the totalizer and recorded as an ionization event. Total amount of clicks = total dose rate for a given amount of time. I usually set it to 1 minute.
This cost me a pretty penny to build, about $350!
While we are on the subject of radiation and Japan. the amounts seen in B.C.and California from the leaking power plant are in the nSv/hr range or possibly 1 or 2 CPM difference before and after the disaster.
I haven't tested the seaweed around Tofino yet, but it would be interesting to see the counts. doubtful they would be able to be detected.
I am measuring a test sample of Ra226 here with a pancake probe. 0.1mR/hr or 1uSv/hr
On this 3" probe the sample gives about 13,500CPM. ~3.5-4.0mR/hr Beta eq. ~40uSv/hr.
My Giegercounter with scintillation preamp installed was a custom build by GEOS electronics. It is a very rare and extremely specialized counter. It can run NaI/Tl scintillation detectors from 900-1200V and has variable HV!
The big box with blue and silver is a homebuilt scaler. The inverse square wave pulses are sent to the totalizer and recorded as an ionization event. Total amount of clicks = total dose rate for a given amount of time. I usually set it to 1 minute.
This cost me a pretty penny to build, about $350!
While we are on the subject of radiation and Japan. the amounts seen in B.C.and California from the leaking power plant are in the nSv/hr range or possibly 1 or 2 CPM difference before and after the disaster.
I haven't tested the seaweed around Tofino yet, but it would be interesting to see the counts. doubtful they would be able to be detected.
