ZnS:Cu In Electron Beam From Home Made Cathode Ray Tube
Note: Further examination shows that the glow is most likely caused by low energy x-rays and not electrons making it out. The tube glowing white indicates that the pressure was not low enough to reach 60keV in kinetic energy for the electrons.
A quick test where a ZnS:Cu coated piece of tape is placed in front of the window of a cathode ray tube. The voltage is about 60kV so a lot of electrons are getting stopped by the aluminium foil window itself sadly. The vacuum is pulled down to 0.5Pa.