Researchers at Massachusetts Institute of Technology in Cambridge have simulated the emission of Cerenkov radiation by a moving charged particle in a two-dimensional photonic crystal. Based on their findings, which appear in the Jan. 17 issue of Science, they propose that the phenomenon may lead to more sensitive particle detectors and to the development of unique sources of radiation.According to their models, the relationship of the charge velocity to the speed of light in a periodic structure produces four distinct types of Cerenkov radiation, including a backward-pointed, reversed radiation cone unique to photonic crystals. They calculate that the emissions should be observable, opening the door to alternatives to scintillation counters and cloud chambers.