The Triple Coincidence Detection of the Helium 3¹D State Decay

Abstract

The first triple coincidence detection of the scattered energy loss electron and the sequential cascading photons, 667·8 nm 3¹ D → 2¹P and 58·4 nm 2¹P → 1¹S, from the electron impact excitation of the 3¹D state of helium is reported. An experimental method for identification and determination of the triple coincidences and initial results is reported. The measurement is the final experimental step in determining all the information to define completely the excited 3D state.