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User name jroche
Log entry time 19:24:34 on October 3,2010
Entry number 333533
This entry is a followup to: 333494
keyword=bpms are working: need harps scan for calibrationThis afternoon, we took some data witht he bpms after Alex Camsonne changed their offset and ther attenuation. We took some data to check that the bpms are functional at the basic level. They are: ie if we change the beam position by +/-2 mm in either the vertical or horizontal positions, we see meaningfull changes in the position recontructed by the analyzer. This said, we need to do a carefull calibration against harps readings.
Some details.
Run 6950, 6951: pedestal runs with no beam and gain set to0. The pedestal values were updated in the database that spot and the dvcs analyzer are readings (two different data bases). the bpms were then returned to auto-gain.
6953: nominal 0,0 beam position as read by epics. beam intensity 5uA
6954: nominal -2,-2 beam position. beam intensity 5uA
6955: nominal -2,-2 beam position, beam intensity 10uA: no staturation
6956: nominal 0,-2 beam position
6957: nominal 2,2 beam position
6958: nominal 2,-2 beam position
The sketch show the comparison between the epic readings and the analyzer outputs. The left column show the data for the bpm A while the rigth shows the readings for bpm B. The four rows shows the results for run 6958, 6957, 6956, 6954 and 6953 from top to bottom. So we are not quite done with taking bpm calibration data but for sure the bpms reading that the analyzer uses do change as the beam moves.
As we had to fiddle with the cables and the attenuators, I suggest we do not cut the calibration exercise short and do take the 9 data points I suggest at the bottom of the sketch. Also whe we took the data this afternoon , I onlyasked MCC to change the beam position at bpmA which they did somehow by changing the angle of the beam (bpm B reading almost did not change). Askig MCC to change positions at bpm A and bpm B simultaneously would be really better if we want to be able to extrat info for bpm B.
FIGURE 1
