WHAT DOES THE LARGE AREA TELESCOPE (LAT) DO AND HOW DOES IT WORK?
The LAT detects gamma rays by using Einstein’s famous E = mc2 equation in a technique known as pair production. When a gamma ray, which is pure energy, slams into a layer of tungsten in the detector, it can create a pair of subatomic particles (an electron and its antimatter counterpart, a positron). The direction of the incoming gamma ray is determined by projecting the direction of these particles back to their source using several layers of high-precision silicon tracking detectors. A separate detector, called a calorimeter, absorbs and measures the energy of the particles. Since the energy of the particles created depends on the energy of the original gamma ray, counting up the total energy determines the energy of that gamma ray. Because the LAT in orbit is bombarded by many more particles than gamma rays, it wears a “hat” – a third detector that produces a signal when a particle, but not a gamma ray, goes through it. The combination of no signal in this outer detector (“the dog t
