SALT LAKE CITY — Several years ago Steve McCown was watching CNN and saw a story about suspected terrorists crossing from Mexico to the U.S. with plans to deploy a dirty bomb — a device that pairs conventional explosives with radioactive material.
"As a patriotic American it concerned me, and I thought, ‘Well, what can I do?' " McCown said. "How can we detect those folks when we really don't know where they are?"
McCown, Director of Digital Services at Bonneville International, was working in cyber security at the time. He was a research scientist at the Idaho National Laboratory (INL), a federal research complex in Idaho Falls, working on cyber security projects involving cell phones.
Can a cell phone, he wondered, be used somehow to detect radioactivity and track a dirty bomb?
As it turned out, it can.
Cell phones have cameras, and camera sensors react to radioactivity. High-energy particles strike a sensor array and register as small bright pinpoints or thin streaks of light.
The more people that have the (app) … the tighter the detection grid becomes. Personally, I would love to have every first responder in the country to have this application.
McCown and a team at INL developed an app, named CellRAD, to turn a cell phone into a Geiger counter. They now hope to distribute it to first responders like police and firefighters who might not have access to expensive radiation detectors.
"The important thing about this innovation is that they're passive sensors," said Scott Brown, an engineer at INL, explaining that the application runs continuously in the background. "(First responders) can go about their regular day and only be interrupted if there is an incident they need to respond to."
The developers say the application is not as sensitive as a dedicated radiation detector, but it works well enough to alert users to dangerous levels of radiation.
There are already commercially-available apps that turn cell phones into Geiger counters, such as Wikisensor and GammaPix. In Germany, Rolf-Deiter Klein developed one in response to the Fukushima disaster.
"(I) looked around at Geiger counters and thought, first, it's very difficult to get them here in Germany — all were sold out — and thought there might be another way to detect this radioactivity," Klein said.
Cell phones have cameras and camera sensors react to radioactivity.
High energy particles strike a sensor array and register as small bright pinpoints or thin streaks of light.
An app may not be as sensitive as a dedicated radiation detector, but it works well enough to alert users to dangerous levels of radiation.
What makes the INL app different is its power in numbers. If CellRAD is running on numerous cell phones, each phone can send its readings to a central server, which creates a map of hot spots.
"That allows the responders to create a walking, moving network," said Carl Kutsche, who manages the project for INL. He calls it a radiation detection grid.
"The more people that have the (app) … the tighter the detection grid becomes," he said. "Personally, I would love to have every first responder in the country to have this application."
Kutsche said a national grid could be used to track terrorists with nuclear material or, in the case of a nuclear accident, to map danger areas.
"For example, in the Fukushima nuclear accident, you had first responders saying, ‘You know we need to get away from this plant,' " said Joshua Cogliati, nuclear engineer and computer scientist. "And sometimes people drove away from the plant, but into a higher radiation region. You'd be able to know … that's not where we want to send people."
Kutsche said INL will probably try the system out on a limited basis, with one police or fire department and scale up from there. He said there are no plans to distribute the app to the general public.