Temperature compensation for Geiger tube

[sebswed]

Hi there.

Does anyone know if the accuracy of a GM tube can be improved with a temperature variable in the calculation?
If yes, does someone on the forum know the equation?

I'm using an M4011 tube.

Kind regards,
Sebastiaan

 

[hevans1944]

Show us the calculation without a temperature variable.

 

[sebswed]

The calculation that I am using today and which I have verified by comparing the readings to my store bought is:

cLog = 18 (Interval period in seconds, recommended value 15-60. (calculate CPM based on xx seconds) 18 seconds makes nice 1 hour graph based on available pixels)
cMax = 60 (Maximum logging period = 1 minute (CPM = clicks per minute))
GEIGER_Calibrate = 151.50
Multiplier = cMax / cLog
cpm = intervalCounts * Multiplier (intervalCounts = counts during this interval)
uSvh = cpm / GEIGER_Calibrate

As I have both humidity and temperature available as variables I was just wondering if this could be used to improve the calculations.

 

[hevans1944]

As I have both humidity and temperature available as variables I was just wondering if this could be used to improve the calculations.

That would depend on whether or not you can find a relationship between humidty and GM pulse rate, or between temperature and GM pulse rate using a known radiation calibration source placed at a fixed distance from the entrance aperture of a Geiger-Muller tube.

The energies of the radiation to which the GM tube is sensitive would seem to preclude any humidty effect, and GM tubes are not sensitive to temperature AFAIK, except possibly temperature might affect quenching time between pulses, thereby limiting the maximum counting rate. That would not be a "calibration" issue since a pulse either occurs or not in response to an ionizing event.

It would be interesting to set the GM tube inside an environmentally controlled chamber with a radiation source and take some statistics as the humidity and temperature are varied. I couldn't find anything on the Internet describing this experiment, but that's what you would have to do to obtain the "correction" factors for your data collection system.