AT2327 Alarm dosimeter (AT920, AT920B, AT920P Pedestrian Radiation Monitors)

Stationary pedestrian radiation monitor is designed to detect gamma radiation sources continuously and automatically in a stream of people crossing borders of secure facilities.

Operating principle

Pedestrian radiation monitor is based on a gamma radiation smart probe.
Monitoring process has two stages. During the first stage the monitor powers on and measures natural gamma radiation background. Smart probe controller uses this measured value to calculate and set the threshold radiation level – alarm level. During the second stage the dosimeter continuously monitors gamma radiation, calculates count rate level and compares the values to alarm threshold level. When the set alarm threshold level is exceeded the audio and visual (red light) alarm actuates to inform staff about gamma radiation source detection.
This feature allows creating radiation-monitoring network from multiple pedestrian radiation monitors (up to 32 monitors) controlled by personal computer with bundled dedicated software installed. Then the PC displays status of each connected pedestrian radiation monitor, its location on monitored site plan, keeps records and logs of alarms. Video recorder allows logging of monitored site video frames.


Radiation screening of passing-by people:

  • Public places and institutions
  • Airport, underground system, bus terminal and railway station control points
  • Access control points on nuclear industry objects
  • Border and customs control points


  • 2-second triggering when threshold level is exceeded by 0.05 μSv/h (АТ920), 0.03 μSv/h (AT920B), 0.04 μSv/h (AT920P)
  • Rapid accommodation to radiation background change
  • Sound and light alerts are emitted when the threshold levels are exceeded
  • A monitoring network with several pedestrian radiation monitors can be arranged with the help of dedicated software
  • Mobility and passage formation capability
  • Radiation monitor components self-test function during operation
  • Continuous and casual radiation monitoring
  • Mains/integrated battery operation
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