UCB Bialkali Cathode Process Program Small window cathode development, 1.22” samples Process samples to optimize QE and bandpass Na2KSb, K2CsSb cathodes Ready for cathode test run #6, shoot alkalis this week. Testing B33, B33+ITO, B33+MgO/ITO substrates Four sample holder 2 in process chamber 1 B33 2 B33+ITO 1 B33+ITO+MgO in each 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.

Antimony Beads Test Small sample test runs, 1.22” Have SSL bead and new Sb-Pt bead to test. Substrate material tests B33 ITO and MgO ALD layers Preparing 6th run in small tank used to process Bialkali cathodes (1.22”). 2

8” Tube Windows and Body Walls 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. We have a batch of 5mm thick B33 windows to use for seal tests Latest Alumina tube body wall has been metalized and seems to be sufficiently flat Need Indium wells so we can braze assembly then do seal tests