Institute for Theoretical Atomic, Molecular and Optical Physics between AMO theory and experiment and promoting AMO theory within the general physics community. It has been involved in some capacity in most of the National Research Council target areas, i.e. precision measurements and tests of fundamental laws, ultracold physics, the development and application of ultra-intense, short wavelength light sources, ultra-fast quantum control of atoms, molecules and electrons, nanoscience, and quantum information science. The Institute is sponsored by the National Science Foundation, the Smithsonian Institution, the Center for Astrophysics and Harvard University. The Armstrong Report in 1987 on "The State of Theoretical Atomic, Molecular and Optical Sciences in the United
Radiation length beyond leptons and photons, the presence of the stronger hadronic and nuclear interaction makes it a far less interesting characterisation of the material; the nuclear collision length and nuclear interaction length are more relevant. Comprehensive tables for radiation lengths and other properties of materials are available from the Particle Data Group Radiation length In physics, the radiation length is a characteristic of a material, related to the energy loss of high energy particles electromagnetically interacting with it. In materials of high atomic number (e.g. W, U, Pu) the electrons of energies >~10 MeV predominantly lose energy by bremsstrahlung, and high-energy