| T O P I C R E V I E W |
| Bobakman |
Posted - 11/25/2022 : 11:44:25
Hi folks I am new to the forum and a soon to be GMC 600+ user, just ordered one yesterday.
A little background on myself I started out my career in 1983 as a radiological De-conner at my utilities first Nuclear Power plant. I currently work as an Electrical and Mechanical technician and operator at one of our Combined Cycle natural Gas plants.
I am an avid Vaseline glass antique collector and the GMC 600+ will be a great addition to the UV light.
I know I will have no issue with the general CPM detection for collecting what I would like to know is how accurate is the 600+ compared to the more expensive Thermo Scientific Rad Eye models?
Secondary use for the 600+ will be for safety survey use if/when needed and this is why I ask.
I do have a 10 Micro Curie CS137 check source purchased new back in 1985 so it is well past its half life.
Thanks for any help information that you can provide.
Bob
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| 2 L A T E S T R E P L I E S (Newest First) |
| Bobakman |
Posted - 11/26/2022 : 11:25:48
Thank you Sir. I will review this information.
Bob
quote:
Originally posted by ullix
Accuracy does not depend on the price of a counter, but on the accumulated counts in a measurement. Thus it depends on the sensitivity of a tube and the duration of the measurement.
The radioactive decay is of a Poisson nature. From this it follows that the Standard Deviation is given as square-root(counts). From there Std.Error follows by regular statistics-
How well this translates into a health relevant dose rate in e.g. µSv/h is a different matter. Here it depends on the existence of a proper calibration. For the LND7317 tube in the GMC-600 counter the tube manufacturer has published a value for its Gamma sensitivity. https://www.lndinc.com/products/geiger-mueller-tubes/7317/
While this gives you an idea of the sensitivity of the tube in comparison to other tubes, keep in mind that this specific values is valid ONLY for their Cs-137 setup!
For more insight I suggest my "Potty Training" intro https://sourceforge.net/projects/geigerlog/files/Articles/ as well as the chapter "Appendix G – Calibration" in the GeigerLog manual https://sourceforge.net/projects/geigerlog/files/
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| ullix |
Posted - 11/26/2022 : 00:53:25
Accuracy does not depend on the price of a counter, but on the accumulated counts in a measurement. Thus it depends on the sensitivity of a tube and the duration of the measurement.
The radioactive decay is of a Poisson nature. From this it follows that the Standard Deviation is given as square-root(counts). From there Std.Error follows by regular statistics-
How well this translates into a health relevant dose rate in e.g. µSv/h is a different matter. Here it depends on the existence of a proper calibration. For the LND7317 tube in the GMC-600 counter the tube manufacturer has published a value for its Gamma sensitivity. https://www.lndinc.com/products/geiger-mueller-tubes/7317/
While this gives you an idea of the sensitivity of the tube in comparison to other tubes, keep in mind that this specific values is valid ONLY for their Cs-137 setup!
For more insight I suggest my "Potty Training" intro https://sourceforge.net/projects/geigerlog/files/Articles/ as well as the chapter "Appendix G – Calibration" in the GeigerLog manual https://sourceforge.net/projects/geigerlog/files/
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