Bialkali Cathode Process Program Small window cathode development, 1.22” samples Process samples to optimize QE and bandpass Na2KSb, K2CsSb cathodes Use several substrate materials, SiO2, verify B33 Test MgO/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 The sensitivity of the activated photocathode is considerably higher, with a quantum efficiency of as high as 37% at about 450 Å and a sensitivity cut off energy of about 6.2 eV. The observed decrease of sensitivity at 988 and 520 Å (and probably not observed at ~670 Å) is likely to correspond to 2xEgap+Eaff,, 4xEgap+Eaff,, and 3xEgap+Eaff,, respectively. A much better spectral continuity of the illumination source is required in order to study the UV absorption fine structure.

1.22” Substrate Sample test Bialkali Cathodes. Small sample test runs, 1.22” Substrate material tests Fused silica and B33 ITO and MgO ALD layers Preparing 2nd run in small tank used to process Bialkali cathodes (1.22”). Can now deposit 4 simultaneous samples/1 cathode shoot. 2

ALD ITO/MgO Layer Properties for Windows 1.22” samples Quartz Quartz + ITO 4.5nm Quartz +ITO + MgO 5nm 1.22” samples deconvloved ITO 4.5nm ITO + MgO 5nm Red Blue Black Black Blue 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

Cathode Process Equipment Status The sensitivity of the activated photocathode is considerably higher, with a quantum efficiency of as high as 37% at about 450 Å and a sensitivity cut off energy of about 6.2 eV. The observed decrease of sensitivity at 988 and 520 Å (and probably not observed at ~670 Å) is likely to correspond to 2xEgap+Eaff,, 4xEgap+Eaff,, and 3xEgap+Eaff,, respectively. A much better spectral continuity of the illumination source is required in order to study the UV absorption fine structure. Large 16” flange tank, takes full size windows (8.7”) to test Quantum efficiency QE Uniformity Seal tests Status - design done, being welded up Evaporation tooling for 8.7” Windows and 8” MCPs. Status, done except for one part

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. The sensitivity of the activated photocathode is considerably higher, with a quantum efficiency of as high as 37% at about 450 Å and a sensitivity cut off energy of about 6.2 eV. The observed decrease of sensitivity at 988 and 520 Å (and probably not observed at ~670 Å) is likely to correspond to 2xEgap+Eaff,, 4xEgap+Eaff,, and 3xEgap+Eaff,, respectively. A much better spectral continuity of the illumination source is required in order to study the UV absorption fine structure. UHV 18” process Chamber:- Status:- chamber in fab - due Sept, other hardware mostly in house.

Cathode/Substrate Factoids Wet cleaning of ITO / MgO ALD coat is OK Oxygen plasma cleaning of ITO / MgO is NOT OK Proper pre cleaning of window substrates essential and includes precautions for handling ITO 4.5nm has UV transmission and conductivity as predicted MgO 5nm UV transmission is good No problems with inconel evaporated borders good adhesion/conduction The sensitivity of the activated photocathode is considerably higher, with a quantum efficiency of as high as 37% at about 450 Å and a sensitivity cut off energy of about 6.2 eV. The observed decrease of sensitivity at 988 and 520 Å (and probably not observed at ~670 Å) is likely to correspond to 2xEgap+Eaff,, 4xEgap+Eaff,, and 3xEgap+Eaff,, respectively. A much better spectral continuity of the illumination source is required in order to study the UV absorption fine structure.