Calibration error of the Geiger counter

Geiger counter (Radiation measurement)

Radiation dose observed by instruments such as iMetry is sum of background(environmental radiation) and the radiation generated from the sample.
In case of dose obtained with iMetry, Radiation dose will be simple sum, still there may be some linearity error.

To know the radiation of the sample strictly, you need Environmental Geiger Counter shielded with lead.

Geiger counter (dose) calibration

  • To (dose) calibrate a Geiger counter, a Cs137 test nuclide and a calibrated dosimeter are required.
  • In theory, in fully shielded environment, dose from a point radiation source decreases in inverse proportion to the square of the distance.
  • Therefore, with a correctly calibrated radiation meter, if you measure radiation dose including the background in 5cm and 10cm distance from a point radiation source, and subtracting the same background from both values, the latter becomes 1/4 of the former, at least in theory.
  • In the real world, due to attenuation by the air and a sensor shape factor, results may not necessarily match the theory. Error due to the linearity of the radiation dose may also occur.
    To reduce the effects of linearity of the radiation dose and get better result, measure in small enough spam, and calibrate in neighboring dose to the target dose.

  • In addition, If there is a monitoring post in the neighborhood, measuring the cpm near the monitoring post and calibrating to the displayed dose (μSv/h) can be a simple way of calibration. iMetry works with a single calibration point, this might be the most simple, accurate, and doubtless DIY way of re-calibration.

  • 最終更新:2013-06-18 18:38:05