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The portable high-sensitivity dosimeter-radiometer is designed for search and detection of gamma-ray sources, measurements of the ambient dose equivalent of gamma radiation, flux density of alpha and beta particles with flat-contaminated surfaces, as well as for the rapid estimations of the specific activity of the radionuclide Cs-137 in the samples using Marinelli beaker with volume 0.5L.

Main >>  Dosimetry  >> AT1125

AT1125 and AT1125A
Radiation Monitor




Through the use of scintillation detector NaI(Tl) the device AT1125 has a high sensitivity and ability to react quickly to small variations of background radiation, also it allows to fulfill a dose measurements with high accuracy in a wide energy range of gamma radiation using the correction function "spectrum-dose" in the range 0.05 - 3 MeV.

The dosimeter-radiometer AT1125A additionally has a embedded Geiger-Muller counter, which significantly extends the range of measurement of ambient equivalent dose of gamma radiation.

The device has ability to implement the radiometric estimations of samples for radionuclide content using lead shielding in a laboratory and also for express test in the field field environment without any protective chambers.





Type of detectors

NaI(TI) Ø25x40 mm

End-type Geiger-Muller counter tube

Geiger-Muller counter tube

Ambient gamma and X radiation dose
rate equivalent measurement range

30nSv/h - 300µSv/h

30nSv/h - 100mSv/h

0.1µSv/h - 30mSv/h

Ambient gamma and X radiation dose
equivalent measurement range

10nSv - 10mSv

10nSv -10Sv

0.1µSv ... 1Sv

Intrinsic relative error limit of dose rate and dose measurement




Energy range of registered X-ray and gamma radiation

50keV ... 3MeV

50keV ... 3MeV

20keV ... 3MeV

Flux density measurement range
- Alpha particles (BDPS-02)
- Beta particles (BDPS-02)

2.4-1E6 ​part./(min·
6-1E6 part./(min·

Maximum energy range of detected beta particles spectrum

155keV ... 3.54MeV

to gamma radiation of Cs-137
to gamma radiation of Am-241

350 cps∙h/µSv
3800 cps∙h/µSv

​350 cps∙h/µSv
3800 cps∙h/µSv

6.6 cps∙h/µSv

Radionuclide specific activity measurement range with 0.5L Marinelli beaker (Rel.error ± 20 %)
- with lead shield
- without lead shield

50 - 1E5 Bq/kg
100 - 1E5 Bq/kg

50 - 1E5 Bq/kg
100 - 1E5 Bq/kg

Count rate measurement range



Detection time of the source of Cs-137 with activity 10 kBq at 5 cm distance



Protection class




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