| T O P I C R E V I E W |
| gazinbali |
Posted - 05/04/2012 : 01:15:46
ok im new to this.. seems there are Grays, millisieverts, Microsieverts REMS RADS, Curies, Bequerels etc etc etc...now I have CPS counts per second..
How is anyone supposed to make sense of all this ??
Is there a chart or some source of definitive info to explain?
Im looking at the GQ GMC-300 digital Geiger Counter but im confused because different tubes give different results.. so maybe one tube says Im getting 50Msv/Hr another says 20Msv/Hr so who do i believe and how do I choose the correct tube?
How do I calibrate a different tube?
What is the maximum radiation level this device will measure in SV
I look forward to someone emailing me a reply
many thanks
gary
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| 4 L A T E S T R E P L I E S (Newest First) |
| Radman96 |
Posted - 05/14/2012 : 13:33:03
The most commonly used dose rate in the US is REMs and RADs. REM stands for Roentgen equivalent Man (The dose the human body sees). RAD stands for RAdiation Dose (General radiation measurement). They both are the same. 1 Rad = 1 Rem. This is only for Gamma and X-ray measurement only. Many geiger counters here in the USA have the scale calibrated in R/hr and CPM.
CPM stands for Counts Per Minute. It is for Alpha and Beta only. It's the number of particles that enter the GM tube per minute.
The difference? Gamma/X-ray's are light. They're actual photons. Alpha's and Beta's are particles. Not light.
That's how the US does it (We always like to have our own units, even if it complicates everything ;-) )
Sieverts, Curies, Grays are all Metric units. I understand little about anything other that Sieverts. They're just like RADs, but on a different scale. Ex: 0.5 Millirems = 0.05 Millisieverts
CPM and Sieverts are the most common used scales around the world.
A good PDF to read on the subject (Not mine): h**p://www.bt.cdc.gov/radiation/pdf/measurement.pdf
hope it Helps!
-Alex |
| horseflesh |
Posted - 05/14/2012 : 13:03:29
I believe that calibration only helps you get a real number if you are testing the same kind of source.
So, if you calibrate your device from a Cs-137 source, and then try to check the uSv reading in an X-ray machine, the value will be meaningless. Different sources have different types of activity.
You can use CPS to evaluate the relative activity of various sources but I am afraid there is no way to get a reliable reading in SI units that is meaningful across many kinds of sources.
If I am wrong, I look forward to being corrected with details that I can use. :)
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| gazinbali |
Posted - 05/13/2012 : 07:15:58
This is a technical forum... is this the best answeri can get??
Mods.. can you please answer the questions in my post..
Thanks |
| ZLM |
Posted - 05/05/2012 : 20:51:39
CPS and CPM are relative value and they are depending on tube. But they are directly related to the rediation level. |
