High Range Handheld Radiation Monitor

The HR HRM is a small, self-contained gamma ray and thermal neutron radiation detector for use in the interdiction and localization of nuclear materials. It is a derivative of the HRM designed to search for and localize gamma radiation sources in environments with exposure rates up to 88 R/hr (+/- 40% at 662keV).  While the HR HRM is not sensitive enough to detect kilogram quantities of SNM, it is well suited to precisely locate large gamma sources, such as those that might be used in the construction of a Radiological Dispersal Device (RDD).  All functions of the HR HRM are otherwise the same as the standard HRM.

As a fully militarized and ruggedized high range nuclear search instrument, the HR HRM is in a class of its own.  Unlike commercial-grade instruments currently available, the HR HRM can be carried on a parachute jump, can be used by divers underwater, and can be easily employed by gloved and equipped operators in a full range of tactical and environmental conditions. As an instrument for the detection of gamma and neutron radiation at standoff range, the HR HRM has long been established as the gold standard handheld to localize RDDs for elite Military, Law Enforcement, and Federal Agency operators.

For sensing, the HR HRM employs a high-quality photomultiplier tube and a cesium iodide scintillator combined with a high-pressure Helium-3 filled proportional counter. It is the size of a flashlight and is intended to be handheld or worn on the operator’s belt, leg, or arm in the nylon holster provided.



The HRM and HR HRM are unique as the only fully militarized and proven handheld radiation detector available as commercial equipment. Their cases are machined out of a solid block of high-impact resistant plastic, and all penetrations are O-ring sealed. They have been engineered and tested to operate at extreme temperatures, at extreme altitudes, and underwater. They have survived all manner of practical drop and shock testing. They can go anywhere the operator goes and can be quickly decontaminated without special care.


Radiation Type Gamma, Neutron
Gamma Detector Type Cesium Iodide Scintillator
Detector Size 3.2mm³
Sensitivity 0.002 cps per µR/h at Cs-137 (662keV)
Neutron Detector Type Helium-3 Proportional Counter
Detector Size 1.81 in³ (122 psi)
Sensitivity 10.5 cps/nv
Integration Time <1 Second
Size 21.1 cm x 5.1 cm x 3.0 cm
Weight 346g with Battery
Battery CR123A
Battery Life (Operating) 1 Month
Environmental Protection Shock, Vibration, and Drop Resistant; Waterproof to 66 ft
Temperature Range -25º to 50º C
Indicators Visible, Audible, Vibration
Operational Availability 0.999