22/02/15

am    Testing various grounding configurations for the connection between the DSSSD and the FEE64 modules.

15.45 Obtaining error messages from Merger TTY console (see attachment 1)

1700: Summary of AM testing of grounding configurations.

           Set up system as it was when we left last night to check reproducibility -> peak FWHMs all same to within 10%.

           Throughout tests yesterday, nnaida8 was consistently worse than the other nnaida, why? Can it be improved?

           Most obvious difference between 8 and the rest was that the nose was grounded through nnaida8.

           Removed nose grounding cable and left to hang -> no appreciable difference in FWHMs.

           It was then attached to the Cu piping using a croc clip -> no change.

           Connected to nnaida6 -> no change.

           The heavy duty Cu braiding was removed from all nnaida and the pulser FWHM in all nnaida increase significantly.

                 => clearly the braiding is helping.

           Put Cu braiding back in place and added shielding plates to nnaida1,3,8 (kapton in way on nnaida5/6, also useful as a reference point).

           Each shield plate was fit onto the set screws with two spacers and sat over the kaptons, black tape was put over the vias to prevent them touching the plates.

           No change with respect to the first measurements this morning.

                 => the grounding changes implemented today have had no effect at the current noise level, but that is not to say they may not have an effect in combination with production detectors, new kaptons etc.

1715: Tested the new USB mains power switches for function (without load). All seem to function correctly and are controllable from the RPi.