Geiger Counter/Spectrometry of pavement stone

Spectrometry of pavement stone in front of an old station

Some stones such as granite and marble are known to have natural radiation. So, on stone pavements, often seen in European cities, radiation dose become relatively higher.
iMetry is superior to normal market available Geiger counters for being capable of basic nuclide identification, with that, you can reveal some specific radiation is derived from stones, or radon contained in the stones, or from radioactive cesium.
Generally speaking, of course depends on the situation, but if some 0.1μSv/h~0.25μSv/h radiation is observed on stone pavements like marble, main driver of the radiation is mostly radon derived from the marble.
Of course we cannot say cesium, said to have fallen to the ground up to 10000Bq/m^2 level in Kanto area, Japan, after Fukushima NPP accident, will not detected at all... but please be careful not to mistake Rn-222 series radiations when you measure on stone pavement.


Dose measurement with iMetry

iMetry showed 0.2064μSv/h, when measured on the stone pavement.
This is 4 times higher than background, assuming background in Kanto, Japan is 0.04~0.06μSv/h

Spectrum with iMetry

4 hours of measurement gave this spectrum.
Apparently different from spectrum of Cs137 or Cs134 and Cs137, similar to that of spectrum of marble. So, this is considered to be naturally occurring radiation.

Some energy peaks observed, possibly 295, 352, 609, 1120, 1765keV derived from Rn-222 and 1461keV from K-40.

iMetry is calibrated with 356keV and 661keV by default, when we added these energy peaks listed above, they are almost in one line. This may also support that observed radiation is derived from Rn-222.
In addition, adding energy calibration points will increase energy accuracy in later measurements.

  • 最終更新:2013-06-14 13:00:58