Measuring a big bang

A bomb-proof thermometer has been developed by British scientists. Gavin Sutton and colleagues at the National Physical Laboratory near London says that the new high-speed thermometer can measure the temperature within an explosion without being damaged by the detonation. The shockwave, heat, soot and debris from an explosion can damage normal thermometers but thermocouple type thermometers are too slow to react to allow scientists to model explosions accurately. However, an optical fiber 400 micrometers across, protected from the blast by a sand-packed steel tube with one open end can detect thermal radiation at four wavelengths taking measurements 50000 times a second and has been calibrated to 3000 Kelvin. The lab tests involved temperatures above this temperature and the only damage done was a small amount soot off the end of the optic fiber says Sutton. "We easily removed that with alcohol and a Q-tip," he says.