AT1125 and AT1125A Radiation Monitors

Portable high-sensitivity Radiation Monitors are designed to search for and detect sources of gamma radiation, measure ambient gamma radiation dose equivalent rate, alpha and beta particle flux density from flat contaminated surfaces, as well as for radiometric monitoring of radionuclides in samples using 0.5-litre Marinelli beaker.
For radiometric radionuclide content monitoring in samples the following Monitor design variants are possible:
1) 137Cs monitoring
2) 137Cs and 134Cs + 137Cs monitoring
3) 131I, 137Cs and 134Cs + 137Cs monitoring
  • Multiple functions
  • High sensitivity
  • Field operation capability over a wide temperature range
  • Integrated system for measurement path LED stabilization
  • Threshold level crossing alarm
  • Memory function for up to 100 measurement results
  • Writing, storing and transmitting measurement data into PC via RS232 or USB (adapter) interface


  • Search, detection and localization of ionizing radiation sources
  • Radiation monitoring of environment, areas, facilities, raw products and materials
  • Rapid radiation monitoring of 137Cs content in wild-growing mushrooms and berries
  • Dosimetric and Radiometric monitoring of manufacturing facilities
  • Scrap metal radiation monitoring

By equipping Radiation Monitors with NaI(Tl)-scintillation detector high sensitivity and ability to rapidly respond to minor changes in radiation background can be achieved. Thus the instruments allow high-accuracy dose rate measurement in a wide range of gamma energies due to "Spectrum-Dose" correction functions in the energy range from 0.05 to 3 MeV.
Apart from scintillation detector AT1125A Radiation Monitor is equipped with a Geiger-Muller tube, that significantly expands the range of ambient gamma radiation dose equivalent rate measurement.
This device features a possibility of sample radiometric radionuclide content monitoring with lead protection unit indoors and express-testing in field environment without lead protecting unit.


Sample monitoring with lead protection unit Sample express monitoring in field environment
The Radiation Monitros can be delivered with an external BDPS-02 Smart Probe, designed for measuring alpha and beta particle flux density from flat contaminated surfaces, gamma and X-radiation ambient dose equivalent and ambient dose equivalent rate.

External BDPS-02 Smart Probe connection       PC connection




Scintillator NaI(Tl) Ø25x40mm


Scintillator NaI(Tl) Ø25x40mm, Integrated Geiger-Muller counter tube


End-type 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


     АТ1125, АТ1125А




Energy range of registered X-ray and gamma radiation


     АТ1125, АТ1125А

50keV ... 3MeV


20keV ... 3MeV

Energy dependence of sensibility


     Energy range from 50keV to 3MeV


     Energy range from 20keV to 3MeV (BDPS-02)


Flux density measurement range


     Alpha particles (BDPS-02)

2.4 ... 1·106 particle/(min·cm2)

     Beta particles (BDPS-02)

6 ... 1·106 particle/(min·cm2)

Maximum energy range of detected beta particles spectrum



155keV ... 3.54MeV



     АТ1125, АТ1125А


          to 137Cs gamma radiation

350 cps/µSv·h-1

          to 241Am gamma radiation

3800 cps/µSv·h-1



          to 137Cs gamma radiation

6.6 cps/µSv·h-1

Radionuclide specific activity measurement range using 0.5 litre Marinelli beaker


     With Protection Unit

50 ... 105 Bq/kg

     W/o Protection Unit

100 ... 105 Bq/kg

Intrinsic error of radionuclide specific activity measurement

± 20 %

Count rate measurement range

1 ... 105s-1

Natural radiation gamma background (0.1µSv/h) measurement time with ±20% statistical error (Р=0.95)


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


Power supply

Internal rechargeable Ni-MH battery or AC power adapter

Operation mode setup time


Protection class






Working temperature range


Relative humidity with air temperature ≤35оС without сondensation


Overall dimensions, weight


     AT1125, AT1125A

258x85х67 mm, 1.0 kg


138x86x60 mm, 0.3 kg

     Protection unit

Ø150x155 mm, 10.5 kg

AТ1125 and AТ1125A Radiation Monitors meet Safety standard requirements: IEC 61010-1:1990
EMC requirements: EN 55022:1998+А1:2000+А2:2003, EN 55024:1998+A1:2001+A2:2003, IEC 61000-4-2:2001, IEC 61000-4-3:2008

Design and specifications are subject to change without notice

Download brochure1.31 MB