Beam Based Alignment at ATF

1
Beam Based Alignment at ATF
These slope of kick versus B field is then
plotted versus beam position. The fit gives the
beam position reading at the null of the magnetic
field.
Quad and Skew Quad Shunt BBA Procedure

• BBA Procedure
• make a closed local bump at target BPM
• use quadrupole or sextupole (skew quad) trims
  (?Q)
• make grid scan of bump amplitude and trim setting
• for each bump value make difference orbit w.r.t.
  to trim0
• fit difference orbits for kick (k) at quadrupole
  or sextupole
• for each bump value fit kick vs trim k f (?Q)
  m ?Qb
• - m is offset from magnetic center
• - for some trajectory through the magnet, m
  0
• plot fitted offset vs absolute reading of target
  BPM
• - horizontal intercept is BPM offset

Sample orbit to fit a kick at the Quad under test
Summary of results
BPM Measured X offset (um) Measured Y Offset (um)
1 297.1 7.3 -197.2 6.9
3 129.3 3.4 267.3 14.4
5 372.1 5.1 -474.4 16.8
7 -43.6 5.6 -49.9 3
9 556.8 8.4 39.8 16.2
11 -29.8 2.8 -153 8.1
13 -77.5 7.2 -104.4 17.0
36 108.5 7.5 -813.0 31.9
38 -259.5 6.3 -40.7 10.2
40 12.5 9.7 401.1 13.6
42 -722.0 15.3 -223.5 7.6
44 -359.6 3.2 -669.3 20.3
46 -19.0 25.0 62.2 6.3
48 1239.6 59.7 -416.7 15.5
For each beam position inside the magnet, the
magnet stength is varied and the resulting fitted
kicks are fit versus the beam position.