Bialkali Cathode Process Program Small window cathode development

Bialkali Cathode Process Program Small window cathode development, 1. 22” samples - Process samples to optimize QE and bandpass -Na 2 KSb, K 2 Cs. Sb cathodes - Use several substrate materials, Si. O 2, verify B 33 - Test Mg. O/ITO/conductor underlayer for cathodes Large size window cathode study, 8” windows. - Study source alkali design for large cathodes - Develop techniques to make larger area uniform QE - Optimize cathode QE levels - Test metal/ITO conductor underlayer for cathodes - Test metalization and sealing techniques 1

1. 22” Substrate Sample test Bialkali Cathodes. Small sample test runs, 1. 22” - Substrate material tests - Fused silica and B 33 - ITO and Mg. O ALD layers Preparing 2 nd run in small tank used to process Bialkali cathodes (1. 22”). Can now deposit 4 simultaneous samples/1 cathode shoot. 2 2

ALD ITO/Mg. O Layer Properties for Windows 1. 22” samples Red Quartz Black Quartz + ITO 4. 5 nm Blue Quartz +ITO + Mg. O 5 nm 1. 22” samples deconvloved Blue ITO 4. 5 nm Black ITO + Mg. O 5 nm Samples coated by Joe Libera, measured by Lisa Pawlowicz Our resistance measurements give about 104 to 105 Ohms/sq, So very much comparable to CERN. Braem, NIMA 2003 3

Cathode Process Equipment Status Large 16” flange tank, takes full size windows (8. 7”) to test -Quantum efficiency -QE Uniformity Evaporation tooling for 8. 7” -Seal tests Windows and 8” MCPs. Status - design done, being welded up Status, done except for one part 4

8” Tube and Cathode Process Tank System 3” window test article on metal frame with Indium seal Indium wells and ceramic frames for detector window seal tests are on order, Will need to be brazed before seal tests. UHV 18” process Chamber: Status: - chamber in fab - due Sept, other hardware mostly in house. 5

Cathode/Substrate Factoids - Wet cleaning of ITO / Mg. O ALD coat is OK - Oxygen plasma cleaning of ITO / Mg. O is NOT OK - Proper pre cleaning of window substrates essential and includes precautions for handling - ITO 4. 5 nm has UV transmission and conductivity as predicted - Mg. O 5 nm UV transmission is good - No problems with inconel evaporated borders good adhesion/conduction 6