Electromagnetic radiation (or "extreme") ultraviolet. UV, with X-ray and gamma radiation, are referred to as ionizing radiation due to the ability of photons of this radiation to produce ions and free radicals in materials (including living tissue). Since such radiation can severely damage life at energy levels that produce little heating, it is considered far more dangerous (in terms of damage-produced per unit of energy, or power) than the rest of the electromagnetic spectrum. The heat ray is an application of EMR that makes use of microwave frequencies to create an unpleasant heating effect in the upper layer of the skin. A
The Racah Institute of Physics first nuclear experimentalist measuring very long lived radionuclides as well as extremely short lived nuclear states. In the early sixties his interests shifted to the newly discovered Mossbauer effect, and established a research group which turned Jerusalem into a world center in this field. Many graduates of the Racah Institute (and the physics departments which preceded it) became leading professors and scientists (including a Nobel Laureate) in Israel and all over the world. During its existence the Institute enjoyed visits of many important physicists from all over the world. Niels Bohr, Paul Dirac, Wolfgang Pauli, Robert Oppenheimer, John Wheeler and