LCLS Conceptual Design Report - Stanford Synchrotron Radiation ...

L C L S C O N C E P T U A L D E S I G N R E P O R T
summarizes the simulation already described, and every following row represents a new
simulation where the noted error has been increased with respect to Table 8.10.
Table 8.13 Trajectory and phase error sensitivities to simulation input errors. All errors are those of
Table 8.10 unless noted, in which case that error has been approximately doubled in
value. The random seed used is unchanged for purposes of comparison.
Increased input error x rms / y rms [µm] 〈∆φ x〉 / 〈∆φ y〉 [deg]
after 2 nd pass after 3 rd pass after 2 nd pass after 3 rd pass
(using all errors of Table 8.10) 7.0 / 7.8 1.7 / 2.7 318 / 82 82 / 21
2-µm BPM resolution 5.6 / 7.3 2.5 / 5.2 351 / 89 117 / 67
0.1-% rms undulator pole errors 8.0 / 7.8 2.0 / 2.7 544 / 82 350 / 21
100-µm uncorrelated BPM & quad offsets 11 / 14 2.3 / 3.2 721 / 232 112 / 29
0.6-% quad. gradient errors (mean & rms) 6.5 / 8.9 1.5 / 2.7 229 / 104 74 / 22
All errors are returned to their original values for each new run, except for the noted error. As
the table demonstrates in most cases, three iterations of the alignment procedure render the
algorithm fairly insensitive to the precise set of beamline errors. A doubled BPM resolution and
(independently) a more-than-doubled set of pole field errors have a noticeable impact, but the rms
trajectory is still ≤5 µm and the total phase error is