Lifetime Measurement of Doubly Excited States in Helium Atom by Beam-Foil Technique

Lifetimes of six doubly excited states in He were measured by means of the beam-foil technique. One of them is a new data, and the others are compared with the previous beam-foil data and the theoretical calculations. The reduction of experimental error was achieved by designing the well reproducible foil-drive mechanism and by applying the deconvolution procedure to the data treatment. The beam velocity after passage through the foil was determined by observing the zero field quantum beat with the accurately known fine structure separation.