The Sentry – Gamma X-Ray Alarming Dosimeter / Ratemeter

The Radiation Alert® Sentry is a Personal Alarming Dosimeter / Ratemeter designed to ensure the safety of personnel that work in occupations with potential x-ray or gamma exposure.

The pocket sized unit has built in memory for recording data points for tracking accumulated exposure. The Sentry Software option enables you to generate incident reconstruction for analysis. The software also permits you to easily set the vibrating and audio alert to your desired levels for dose and dose rate.

 Use the audio switch to choose between audible clicks or a discreet silent mode. The Sentry can be augmented with the use of headphones.



Uncompensated GM Tube

Switch Functions

Power, Audio Clicks On/Off, Vibrate & Audible Alert, Silent Vibrating Only Alert

Operating Range

Dose Rate: .1 – 15 R/hr

 Accumulated Dose: .1 – 65 R

Dose Rate Linearity

Better than ±15% up to 15 R

Energy Response

 Down to 30 KeV

Gamma Sensitivity

1.5 cps/mR/hr referenced to Co-60

Audible Alarms

 90db @ 1 ft.

• accumulated dose

• dose rate

Alarm Thresholds

Dose Alarm Default 500 mR

Rate Alarm Default 50 mR/hr

Alarm and warning levels are user selectable with Optional Sentry Software.


Headphone Connector, Internal Serial Header connector (cable comes w/ Optional Sentry Software).

Power Requirements

9 Volt Battery. Typical battery life is 1500 hrs at background.

Temperature Range

-20° – + 50°C (-4° – +122°F)


88 g (3.1 oz.)

 8.3 oz w/ Xtreme Boot Option


3.8 x 2.4 x 1 in (96.5 x 70 x 25.4 mm)


  • Carrying Case
  • SentryCom Software

Pictured to the right, the optional Sentry Com Software enables you to set the values for dose and dose rate alarms and warnings, set the Cal Factor, and the data logging frequency. It also allows the user to download the accumulated dose data, which includes time and date stamp, exposure, and power cycle identifiers (shows all zeros for data point when unit is turned off and on) for analysis.