| T O P I C R E V I E W |
| Callisto |
Posted - 10/25/2012 : 05:29:14
where can I find the datasheet of the M4011 ?
Measurements of the my GMC 300 are not consistent with actual measurements |
| 4 L A T E S T R E P L I E S (Newest First) |
| ZLM |
Posted - 03/11/2016 : 11:23:07
For the tube noise 0.2cps means average. The true value can be 0 - 24. The calibration process should cover this variation.
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| Nudnik |
Posted - 03/11/2016 : 03:55:08
According to government sources we have a background of 77nSv/h ( h**p://sfws.lfrz.at/)
According to the data sheet tube noise is at 0.2cps which is 12cpm.
At the given background radiation of 77nSv/h my GMC320 shows 19cpm.
Now, if I take the tube noise into consideration this would mean 19 - 12 = 7cpm = 77nSv/h
So, either tube noise data are wrong or the tube is crap (at least unusable for background measurement)
Am I missing something?
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| Craig |
Posted - 01/21/2015 : 21:36:37
Hi Callisto and Benezi.
Yes: that should be the very first question.
By Googling M4011 + specifications, you end up with incomplete specifications such as at:
> h**p://m.aliexpress.com/item-desc/1790161282.html
--and GQ's own posted specs at:
> h**p://www.ebay.com/itm/New-High-Sensitivity-M4011-Geiger-Counter-Tube-/260835055100?hash=item3cbafb15fc&pt=LH_DefaultDomain_0#ht_928wt_862
* We get a noise figure of "0.2cps" = 12cpm (which no one wants to talk about), but nowhere do we see the stated gamma sensitivity. I see companies which use LND G-M tubes stating sensitivity in a calibrated 1000uR/hr field of cesium-137 radiation --which lobs the count way above any contested levels of internal noise and/or local "background" levels. Those of us doing low level background monitoring then interpret (say) a spec of 3500cpm at 1000uR/hr --to meaningfully indicate 10 uR/hr (0.10 uSv/hr) at 35cpm.
* For what it's worth, using GeigerGraph-4.3 software and the GQ supplied USB adapter cable, I carefully compared the response of a GMC-200 to a Medcom "Inspector" Geiger counter --in a typical (one meter above the ground) outdoor field of background radiation here --and came up with 16cpm at 0.10 uSv/hr --for what I take to be gamma --but who knows what percentage is actually cosmic/muons and internal G-M tube noise? At least that 16cpm should put you on the same page with everyone else --confused as we all might be about what we're actually counting.
* It appears that GQ Electronics software sets an M4011 tubes response to 10 uR/hr at 20cpm. (I don't think the difference is a big deal.)
Craig
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| Benezi |
Posted - 11/12/2014 : 14:51:43
A datasheet of the M4011 would help a lot!
Does anyone knows a source?
Thanks a lot,
Benedikt |
