The LRM is a self-contained gamma-ray and neutron radiation detector system for use in the interdiction and location of nuclear materials. It was specifically designed to be used in linear applications, such as the search of vessels and facilities that feature stacks of shipping containers. The LRM consists of a series of individual gamma radiation and neutron detectors on a cable, with a control module at the operator end to supply the display and communicate alarms. When deployed from the top of a stack of shipping containers, the detectors for the LRM are spaced such that a number of detectors are dedicated to measuring each container in the stack.
When gamma rays or neutrons are detected at levels significantly above the natural background, the unit quickly alerts the operator by sounding an audio alarm and employing the graphical display on the handheld control module. The operator can easily locate the radiation source using the duty-cycle based audio alarm, and/or the graphical readout. A bar graph display will locate the source in the vertical axis by showing which detector module is alarming. The LRM can also be used in a total sum mode where the various detectors are summed together to yield one very sensitive radiation detector.