How To Calibrate A CD V-700 Geiger Counter

How To Calibrate A CD V-700 Geiger Counter With operational check source or Americium-241

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[intercomsec]

Specifically I have a couple of counters and ionisation instruments that are calibrated annually by a government approved test lab. Other instruments (including those I build myself) are tested using a pulse generator referring to the tube characteristics.

As to Google, a useful tool, but hardly infallible, I prefer my 45 years in science education and research.

[RADIATIONDOMINATION]

@intercomsec GTFO!!!!

[john762x39]

I think you messed up your calibration . Are you taking into account the Half life decay of the check source.

lead-210 (Ra D) which has a 22 year half-life How old is your meter?

[RADIATIONDOMINATION]

@john762x39 my check source is du or delpeted uranium which has a half life of over 20,000,000 years!!!

[InfernalSatan]

can you please list the calibration value for both the check source and the americium? Thanks

[RADIATIONDOMINATION]

@InfernalSatan the americium value is 1-1.5 milli renkins hr and the check source is 2.0 milli renkins hr.

[intercomsec]

its actually Roentgen or milliroentgen after William Conrad Roentgen.

Remember different makes had different sources with different half-lives (the manuals are frequently incorrect as to the type of source). Remember also these instruments are over 40 years old, therefore the sources may or may not have significantly reduced levels. The only way to fully calibrate a counter is to use a fully referenced source, with specific source/tube geometry.

[vanamonde2]

You can't calibrate a CD V-700 this way. The CD V-700 is calibrated with a Cesium 137gamma radiation source with the probe closed. Remember a CD V-700 MEASURES gamma and only DETECTS beta. You are saying you are measuring mr/Hr and you aren't you are only seeing CPM that way not a mr/Hr measurement.

[gbmilan]

john762x39 is actually correct! It clearly states in the instruction manual for the Anton Electronics Model 6 CDV-700 that the half life of the check source (Radium D+E) is approximately 22 years and considering that the Anton Model 6 was only in production from 1960-1961 I would say that your check source has already decayed past the time of accurate calibration.

[antiprotons]

I just wanted to mention a side note about Am241 vs DU. The gamma emergy for Am241 is primarily under 60 keV, just like U-238, but the U-238 will contain many higher energy decay products, like Bi214 and Pb214, each providing various ranges of energy even in excess of 1 MeV. That means that an Am241 calibration will be a somewhat short of accurate. Have you considered trying a Cs137 gamma only calibration?

[SCUBACUBA]

@intercomsec Wow, someone got an A in Google searching skills.

Please explain your specific source/tube geometry calibration tool.

You sound like you really know your radiation meters.

[antiprotons]

Hey thanks for the info!!!  I am buying a cdv700 and this will be helpful