Annihilation radiation Annihilation radiation Annihilation radiation is a term used in Gamma spectroscopy for the gamma radiation produced when a particle and its antiparticle collide and annihilate. Most commonly, this refers to 511-keV gamma rays produced by a normal (negative) electron colliding with a positron. Annihilation radiation is not monoenergetic, unlike gamma rays produced by radioactive decay. The production mechanism of annihilation radiation introduces Doppler broadening. The annihilation peak produced in a gamma spectrum by annihilation radiation therefore has a higher full width at half maximum (FWHM) than other gamma rays in spectrum. The difference is more apparent with high resolution detectors,
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