Crystal Technique for Measuring Cyclotron Beam Energies

A lithium fluoride crystal when irradiated with deuterons from a cyclotron develops a yellow color; if the deuterons are stopped within the crystal, there is a sharp demarcation in color between the irradiated and unirradiated portions. It has been found that the measurement of the depth of penetration of the color into lithium fluoride can be used to determine accurately (±0.1 Mev at 20 Mev, ±0.2 Mev at 10 Mev) and rapidly the energy of deuterons in a cyclotron beam. A single exposure of a crystal to the deuteron beam allows one to determine not only the energy of the deuterons but also the angular orientation of the beam trajectories.