iMetry Spectrometry/Geiger Counter case study

  • One thing noteworthy is radon, and its gamma ray spectrum, especially from the daughter nuclide of Rn-222. In latest luxury hotels in Western countries and China (Often uses large amounts of granite and marble, maybe their procurement cost is low?), or even in Japan, old temples, entrance of a luxury high-rise building, old station square, stone steps, stone pavement, stone statue is heavy use of marble. In such facilities, relatively high value of radiation 0.1μSv / h ~ 0.25μSv / h derived from radon is observed. In cases of measurement on a stone statue, stone steps, and stone pavement appeared in some weekly magazines, I do not say cesium-derived radioactivity is not contained at all, but the main component of the radioactivity of such cases is often radon origin contained in granite and marble, though can't to be too sure without checking individual spectrum.

  • However, while natural radon and radium is detected in concrete buildings, stone statues, and stone buildings, a situation that in Kanto area, Japan, normal soil is contaminated with cesium of about 10,000 Bq / m ^ 2 order can not be overlooked.
  • When you observe 0.1μSv/h〜0.25μSv/h level radiation dose on stone pavement, stone steps, stone statue or by marble pillars, spectrometry is vital for appropriate measurement, or on the contrary, radon may leak and observed on normal soil. On concrete nor asphalt, even when relatively high value is observed, you must first look at the spectrum individually.
  • In Rome, the background is high rather than Tokyo in the stone-made town for radon.By stone-made rows of houses, the same thing can be said also in Tokyo.


  • Reference link


To have an iMetry Geiger counter/spectromety

  • The maximum usefulness of iMetry is that I131 is detectable by itself at an early stage.
    Due to cumulative effect, I131 will accumulate at extraordinary ratio and damage the thyroid.
  • If I131 is detected, you should immediately evacuate the juvenile, iMetry can help you think and decide yourself whether evacuation is necessary. In such situation, information may also be confused, normal monitoring post and Geiger counter may not help you much.

Around the rainwater flow

Try obtaining a spectrum where is slightly lower than the ambient, rainwater is likely to flow into. It is easy to find a place radioactivity is strong if you set moving average window to one minute in iMetry App.

  • Measurement Sample:
    • 0cm from the ground, approx. 0.2μSv/h, Spectrum showed peak around 600keV derived from Cs134/137 and 800keV derived from Cs134 in around 10 minutes. Measured point's radiation dose at 1m from the ground is 0.07μSv/h, not very high.
      雨水計測.png

Long-time Geiger counter/spectrometry in the concrete building of low-dose


Spectrum peak derived from radon can be detected if you perform long time measurement more than 8 hours in a low-dose concrete building. Please do not mistake the peak to that of cesium.
Background-in-building.jpg

These seem to be 295, 352, 609, 1120, 1765keV spectrum peaks derived from Rn-222. Though 295keV peak is not clear with threshold set to 200.

(From Official page)

Radon in marble Geiger counter/spectrometry


Measured marble used in a building for 4 hours. (The threshold is set to 100)
marble-spectrum.png
They appear to be by 295, 352, 609,1120, 1765keV spectrum peaks by Rn-222. Do not mistake 609keV peak to that of cesium. In this case, clear peak at 1765keV was observed. This may be due to the radiation is derived from marble, not radon in the air.

  • 最終更新:2013-06-14 18:50:27

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