Pickup tube target having an additive therein for reduced resistivity

Claim 1

A PICKUP TUBE COMPRISING AN EVACUATED ENVELOPE HAVING AN ELECTRON GUN IN ONE END THEREOF FOR PRODUCING AN ELECTRON BEAM DIRECTED ALONG A PARTH, A PHOTOEMISSIVE CATHODE IN THE OTHER END OF SAID ENVELOPE, FOR PORDUCING A PHOTOELECTRON IMAGE DIRECTED ALONG A PATH, A TARGET ELECTRODE POSITIONED IN THE PATH OF SAID ELEC TRON BEAM AND IN THE PATH OF SAID PHOTOELECTRON IMAGE AND IN SAID ENVELOPE, SAID TARGET ELECTRODE INCLUDING A FIRST MATERIAL SELECTED FROM THE GROUP COMPRISING MAGNESIUM OXIDE AND ALUMINUM OXIDE AND HAVING A RESISTIVITY GREATER THAN 10**11 OHM-CENTIMETERS, SAID TARGET FURTHER INCLUDING A SUFFICIENT AMOUNT OF A SECOND MATERIAL SELECTED FROM THE GROUP CONSISTING OF GOLD, SILVER, COPPER, ALUMINUM, TITANIUM, ZINC, TIN, LEAD, GALLIUM, SELENIUM, TELLURIUM, GERMANIUM, SILICON AND CARBON SO THAT THE RESISTIVITY OF SAID TARGET IS SUBSTANTIALLY 10**11 OHM-CM., AND MEANS FOR SCANNING SAID BEAM AT A CONVENTIONAL SCANNING RATE CHARACTERIZED BY A RELATIVELY HIGH EFFICIENCY WHEN SAID TARGET HAS A RESISTIVITY OF APPROXIMATELY 10**11 OHM-CENTIMETERS.