22s sep 2014

can calib, shows missing wedge

disconnect B326 from ROC.

run calib, same result.

dismount wedge (special screwdriver

on bench, disconnect ext cable, disconnect bias cable

new wedge (312)

connect bias

hook up to roc on the bench

run calib: saw packets coming up, but no ata in histos.
       next round: nothing coming up at all (2x)
       power cycle roc - no dice
       power cycle vme crate: all ok

data base: deassign 326 from SE4 back 3

[found feet fixture, vac pump, roll of Rclad.
Rclad was made Aug 2010. The spec sheet says shelf life 2 years] 

B312 says 'elevated bias current' (when tested at BNL, but
no such note in the FNAL traveler.
-> check bias current

should be < 0.5 uA at 70V when fresh
(currently 8 wedges typically draw 300 uA after exposure 2014)

Itaru's wedge: 0.027 uA at 21V
B312:          0.050 uA at 21V

Switch to Ortec 710
Itaru's 0.29 uA at 70V
B312    1.73 uA at 70V

The readings on this Ortec are suspect - sometimes
the set V on the knob matches the display, sometimes not.

Installed wedge. I rubbed thermal compund on the disk carbon
fabric, and a smooth film on the graphite feet.

Did cal run, B312_cal_3.png. No gross difference between plots (no bias).
Done.