Kick Response Measurements 03052017 V plane Hplane TI2 LHC It was realised that the coupled TI28LHC ring optics model which is part of the SPS LSA system was not updated after moving to ATS optics ID: 783160
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Slide1
Kick response measurement and Setup Protection Element
Slide2Kick Response Measurements 03/05/2017
V
-plane
H-plane
TI2
LHC
It was realised that the coupled TI2(8)-LHC ring optics model (which is part of the SPS LSA system) was not updated after moving to ATS optics
a new model was generated (not propagated) and checked
wrt
03/05 measurements
problem persisted!
TI8
LHC
Found a disagreement between BPM readings and model for both lines looking like a phase shift when entering the LHC ring
Slide3Q20 TL- ATS LHC Optics Matching Checks
TL optics correctly updated since 2012* after change from Q26 to Q20 (checked quadrupole strengths in LSA and ok)
2012 TL optics matched
wrt
ATS LHC optics.
TI2
LHC (ATS)
TI8
LHC (ATS)
* E. Gianfelice’s optics checked and revised by M. Fraser and F. Velotti
Slide4TI2(8)-LHC Operational and MADX Optics model
H-plane
V
-plane
TI2-LHC:
correct model
(TL quads and MQY5.L2B1 strengths
ok
, initial conditions ok
) TI8-LHC: wrong model (MQY5.R8B2 strengths
ok, TL quads strengths and x,xp initial conditions not ok). Not clear if the wrong TL optics was used when generating the new combined model.H-plane
V-plane
TI2
LHC
TI8
LHC
b
-beating!
We corrected the optics model for TI8 but the
problem persisted!
Slide5Finally…..
We realised that the kick response measurement was done with the subtract closed orbit option flagged
need to run in
inject&dump
>0 turns to get BPM data fake measurement in the LHC.
We repeated the kick response measurement with correct TI8 model and settings on 08/05/2017
Slide6Kick Response Measurements 08/05/2017
V
-plane
H-plane
TI2
LHC
TI8
LHC
Excellent agreement between measurements and model!
One more lesson learnt, important check to (correctly)
repeat after every YETS!
Slide7Setup protection elements: TCDIs
LHC golden orbit defined
Steering of the lines by minimising injection oscillations
golden trajectory
Alignment of TCDIS
with automatic tool (upgraded version now available not tested yet). No
inject&dump but accumulate pilots in the LHC (no need to wait for XPOC check beam at every cycle)New settings and thresholds in database
Slide8TCDI Validation
TI8 Horizontal
TI8 Vertical
Online measurements
Slide9TCDI Validation
TI8 Horizontal
TI8 Vertical
Online measurements
TI2 Horizontal
TI2 Vertical
Data post-processing
Slide10Setup protection elements: TDIs
LHC golden orbit defined
Angular alignment for each jaw
Same angle and beam centre as last year within 100
urad and 100 um
Slide11TDI Validation
Measured beam size in agreement with theoretical one within <100 um
TCLIB too close to the beam (confirmed by
lossmaps
). Beam size at TCLIB checked with x-measurements method
gap adjusted (now at 7.6 nominal sigma) and checked with
lossmaps
.