== Production ==

== Production ==

- The pictures linked above, show the configuration of the first chamber package and the testing set-up. After taking the wire frame form the vacuum chamber (vacuum went down to ~6 10^-6 tor) we checked that the frame was no longer conductive and we installed it again in the package. First we had Lexan sheet on the top, than we replaced it with the second cathode and the second end window. The package has no detectable gas leakage and we bubble it with a flow of 20-40 ccpm. On three of the HV sectors (out of four) we were able to apply HV up to 2300V and -500V sense/field with current less than 100 uA. The fourth HV sector shows high current so far: ~500 uA at 2000V/-500V. It may improve, but if not, it will require cleaning. In any case the chamber is operational and we tested all the channels with a scope with differential probe. In the moment we see signals from all the channels (both wires and strips) except one cathode channel on the bottom cathode which connectors are close to a metal pin. We suspect it was damaged when prying the wire frame with a screw driver when it was taken to be put in the vacuum chamber. The pins are very tight (compared to the prototype) and the only way to take a frame out was to rotate the pins while lifting the frame; for that you need to unscrew the hubs from the jig plate. Bill will work on designing pins that are easily removable. Before, there were also another two channels on the top cathode not showing signals but after bending a little the cathode periphery at the daughter card it started working (has to be investigated!).  At the beginning of the tests most of the noise was coming from the chamber itself, but later it improved. Generally, the pick-up noise is much lower than on the full-scale prototype. Could be because of the new design cathode shielding, and/or because Blue Crab is less noisy than 126.   

- The pictures linked above, show the configuration of the first chamber package and the testing set-up. After taking the wire frame form the vacuum chamber (vacuum went down to ~6 10^-6 tor) we checked that the frame was no longer conductive and we installed it again in the package. First we had Lexan sheet on the top, than we replaced it with the second cathode and the second end window. The package has no detectable gas leakage and we bubble it with a flow of 20-40 ccpm. On three of the HV sectors (out of four) we were able to apply HV up to 2300V and -500V sense/field with current less than 100 uA. The fourth HV sector shows high current so far: ~500 uA at 2000V/-500V. It may improve, but if not, it will require cleaning. In any case the chamber is operational and we tested all the channels with a scope with differential probe. In the moment we see signals from all the channels (both wires and strips) except one cathode channel on the bottom cathode which connectors are close to a metal pin. We suspect it was damaged when prying the wire frame with a screw driver when it was taken to be put in the vacuum chamber. The pins are very tight (compared to the prototype) and the only way to take a frame out was to rotate the pins while lifting the frame; for that you need to unscrew the hubs from the jig plate. Bill will work on designing pins that are easily removable. Before, there were also another two channels on the top cathode not showing signals but after bending a little the cathode periphery at the daughter card it started working (has to be investigated!).  At the beginning of the tests most of the noise was coming from the chamber itself, but later it improved. Generally, the pick-up noise is much lower than on the full-scale prototype. Could be because of the new design cathode shielding, and/or because Blue Crab is less noisy than 126.