A lighthouse is built to shed light on rocky waters, the light turning at the top of a tower to illuminate sections of a dark shoreline that might harm incoming boats. Researchers from Los Alamos National Laboratory (LANL) and a company called Quaesta Instruments have drawn from that age-old design and assembled a sort of reverse-lighthouse to detect radiation in an area. Instead of sending light out, a Lighthouse Detector senses when radiation is coming in.

Although most radiation detectors like Geiger counters are omni-directional, the Lighthouse Detector uses a blocking material to allow gamma rays or neutrons to hit a sensor on only one side of the detector. Measurements are taken from all sides, and the Lighthouse Detector sends that information back to a computer that can figure out the direction of the source of radiation. The directional approach to radiation detection also allows the person measuring an area to distinguish between multiple sources of radiation in an area, as well as determine the shape and size of a potentially large area that's emitting radiation.

The detector's ability to ignore background radiation and pinpoint different primary sources of radiation could potentially make it useful to verify materials that are in storage. Alternatively, it can send an alert if certain materials pass a checkpoint. "This applies not only to large power plants or plutonium facilities, it can also extend to cancer centers working with radioactive therapies or academic labs studying materials properties," a report from LANL states.

The latest research on radiation detectors has focused on making them more automated—and more precise. One of these recent developments was RadPiper, a radiation-detecting robot built by Carnegie Mellon University to detect contamination within pipes at a defunct uranium processing facility in Ohio. The Department of Energy estimated that RadPiper would save the Ohio decommissioning process tens of millions of dollars in labor costs, not to mention keeping employees out of a potentially dangerous situation.

The common thread between the Lighthouse Detector and RadPiper is that their precision can speed up cleanup efforts. Highly accurate radiation detectors, preferably placed on top of robots, can pinpoint exactly which areas of a structure are contaminated, allowing cleanup efforts to be focused there, rather than cleaning up a much wider swath of area to greater expense in the hopes of eliminating the radioactive material.

The Lighthouse Detector's creators also hope that the detector will be used to designate "safe" areas. "Conversely, it is just as significant to verify that a specific area is free of radioactive materials," LANL writes. This is possible for the detector to do, "even among high levels of noise."

It's a long way from wearing a strip of unexposed film, a common practice among people who handled radioactive materials in the 1950s. Radiation would expose parts of the film, so workers would know, after the fact, if they had had too much exposure themselves.

Currently, the Lighthouse Detector is a few steps away from being available to the public, but Jonathan Dowell, a LANL scientist and the Lighthouse Detector project lead, tells Ars that the technology is in quite advanced stages. Researchers have tested it at the Trinity Nuclear Test Site in New Mexico, and they plan to run additional tests on the sea floor to show that the machinery works in the most challenging of environments.

Listing image by Los Alamos National Laboratory and Quaesta Instruments