T-474 phone conference

Monday 13 november 2006, 09:30 SLAC time, 17:30 UK time

discussion material

• New BPM design : Reference cavity output vs position
• mover system
• analysis
• Call for papers for PAC, see email mike
• T474 agenda on Mike's meeting page from today

minutes

Minutes of the 13.11.2006 phone conference
++++++++++++++++++++++++++++++++++++++++++

- Alexey gave some comments on the link he sent around 
  (https://www.hep.ucl.ac.uk/elog/Alexey's+logBook/49). He is trying
  to estimate how stable the beam has to be so the reference cavity
  is not a cause of systematics for the position measurement.
  The plots he shows are basically the change of the amplitude of the
  monopole mode signal wrt the beam offset in mm. (sort of dipole mode
  component slipping in...). We prob need about 0.1%, which means +/- 2
  mm. This should be no problem. 

- We decided to place the new Q cavity outside of the chichane, at the 
  location where 3BPM4 is now. Ray needs the dimensions of the Q
  cavity for designing a support. In more detail, he needs to know the
  flange type and flange to flange distance together with a layout of
  the bolding holes. Alex mentioned that the cavity will be some sort
  of "brick" shape. 
  We need to have a piece ready to close the beampipe in case the
  cavity is delayed.

- We discussed the position of the end switched on the horizontal
  stages. For the vertical stages it is no problem as the travel range
  is only 5 mm. On the horizontal ones we want the end switches set so 
  that the stages still get a couple of mm travel range at the beam
  offsite of 5mm, so prob +/- 10mm would be sufficient with then 
  real mechanical stops one or 2 mm further for machine protection in a
  worst case scenario.

- We need a long ethernet cable to be run down to the end station at
  mid-chicane location.

- Mark reported on analysis progress. 
  o It seems the non linearities he observed and reported on earlier
    are due to badly determined frequencies and decay constants.
  o He did work on orbit fitting using an SVD algorithm that regresses
    agains all the position BPM. Yury commented that we prob. should
    take BPM24 into account in the regression as well. 
  o Mark finds 2-3 um of orbit resolution for the whole system, this
    still needs to be understood in terms of individual resolutions of
    the BPMs. Stewart proposes to write a little toyMC to check this. 

- We want to have a contribution to the PAC conference for T474, so we
  need to come up with an abstract. Deadline is on wednesday 13 dec.

- Alex asks how long the safety checks that need to be done for the
  electronics will take. Mike tells this should be pretty quick. But
  it would be helpfull if they can be provided with block diagrams 
  showing voltages and currents, grounding etc...

- There will be a spectrometer meeting on thrusday for the UK guys,
  where we will come up with a list of analysis tasks. 

- Mark Slater sends around a first draft for the paper :
  http://cvs.hep.ucl.ac.uk/viewcvs/esaBpmNote/?cvsroot=LC+Energy+Spectrometer