The PMT is the ET 9823QKB04 (14 stage, quartz window, etc.) Base model number is C638KFP (Divider A-ish, positive HV, etc) It's a vendor supplied base, so there was no need to do a damage assessment. Just stay below the max gain of 1.5E8 and/or the max HV of 2500V. Donal has the test ticket data at https://hallcweb.jlab.org/doc-private/ShowDocument?docid=794 .
