2017 ATS Optics
IR6 Validation
C. Bracco, B. Goddard
Acknowledgments: R. Bruce, S. Redaelli
Optics constraints
• Q4 gradient fixed within maximum ±1%
• Horizontal phase advance MKDsTCDQ 90˚± 4˚
• TCDQ: by,min ≥ 145 m and bx,min ≥ 450m (no more than 10% smaller than present value)
• |Dx| at TCDQ such to maintain required protection and respect collimation hierarchy (e.g. wrt TCTs)
• Avoid TCDQ movement during squeeze  incompatible with BETS and degraded alignment
precision if non-unidirectional (required ±0.1 mm)
• Ideally phase advance MKDTCTs 0˚ or 180 ˚(± 10˚)
Disclaimer:
Optics constraints related to machine aperture (circulating beam) are not treated in this talk (assumed
as part of standard checks performed by ABP team)
No tracking studies, only analytical checks to be complemented with Roderik’s studies.
ATS Injection-Presqueeze Beam 1
TCDQ
<1%
TCDQ
<6%
Q4 gradient OK
Betx and Bety at TCDQ <6% difference for ATS optics  OK
MKD TCDQ phase advance: 94 deg  OK
Dx at TCDQ for ATS -0.52 m instead of 0.52 m  OK (see next slides)
TCDQ
ATS Injection-Presqueeze Beam 2
TCDQ
<2%
TCDQ
<2%
Q4 gradient OK
Betx and Bety at TCDQ <2% difference for ATS optics  OK
MKD TCDQ phase advance: 94 deg  OK
Dx at TCDQ for ATS -0.37 m instead of -0.34 m  OK (see next slides)
TCDQ
Optics at TCDQ during squeeze
Beam 1
+24%
Ok (0.8s difference
in TCDQ setting)
+40%
Ok
Ok
Ok (see next slides)
Beam 2
<5%
16%
<6%
Ok
Ok
Ok
Ok (see next slides)
TCDQ during squeeze to 30 cm at 6.5 TeV (2017)
Movement of TCDQ during squeeze not compatible with BETS!
Strategy: set and keep the TCDQ at the aperture (in mm) corresponding to 7.3
sigma at the end of the squeeze (30 cm) already at the end of the energy ramp 
adapt other collimator setting accordingly
Beam 1: 0.45 s difference
Beam 2: 0.12 s difference
2016 Optics Beam 1 (6.5 TeV, 40 cm b*)
mux(TCTH5)
mux(TCTH1)
8s
TCDQ set at 8.3 snom + 1 snom (betatron)
TCTH1 and TCTH5 set at 9.0 snom - 1 snom (betatron)
Real cut xCut [snom ] @ TCDQ can be calculated from:
x = xCut * snom *cos(mux) + Dx* Dp/p + xdump
Dp/p=4.26e-4’’;
xCut contains optics and alignment errors during the
setup
xdump is the local orbit at the moment of the
asynchronous dump (at present +1.2 mm for TCDQ)
TCDQ 12.1 s
xCut @ TCTs takes into account the phase advance from
the TCDQ and the dispersive contribution
Phase advance wrt TCDQ [deg]
Forbidden zone: phase advance MKD-TCT (TCT-TCDQ+90°)
40°±2° - 140°±2° and 220°±2° - 320°±2°
‘’Momentum spread at top energy = 1.13e-4
Momentum offset = 2e-4
Total Dp/p = momentum offset + 2*momentum spread
ATS squeezed Optics Beam 1 (6.5 TeV, 30 cm b*)
mux(TCTH5)
mux(TCTH1)
7.0 s
TCDQ set at at 7.3 snom + 1 snom (betatron)
TCTH1 and TCTH5 set at at 8.0 snom - 1 snom (betatron)
Real cut xCut [snom ] @ TCDQ can be calculated from:
x = xCut * snom *cos(mux) + Dx* Dp/p + xdump
TCDQ 11.4 s
Dp/p=4.26e-4’’;
xCut contains optics and alignment errors during the
setup
xdump is the local orbit at the moment of the
asynchronous dump (at present +1.2 mm for TCDQ)
xCut @ TCTs takes into account the phase advance from
the TCDQ and the dispersive contribution
Phase advance wrt TCDQ [deg]
Forbidden zone: phase advance MKD-TCT (TCT-TCDQ+90°)
40°±2° - 140°±2° and 220°±2° - 320°±2°
‘’Momentum spread at top energy = 1.13e-4
Momentum offset = 2e-4
Total Dp/p = momentum offset + 2*momentum spread
2016 Optics Beam 2 (6.5 TeV, 40 cm b*)
mux(TCTH1) mux(TCTH5)
8s
TCDQ set at 8.3 snom + 1 snom (betatron)
TCTH1 and TCTH5 set at 9.0 snom - 1 snom (betatron)
Real cut xCut [snom ] @ TCDQ can be calculated from:
x = xCut * snom *cos(mux) + Dx* Dp/p + xdump
TCDQ 12.0 s
Dp/p=4.26e-4’’;
xCut contains optics and alignment errors during the
setup
xdump is the local orbit at the moment of the
asynchronous dump (at present +1.2 mm for TCDQ)
xCut @ TCTs takes into account the phase advance from
the TCDQ and the dispersive contribution
Phase advance wrt TCDQ [deg]
Forbidden zone: phase advance MKD-TCT (TCT-TCDQ+90°)
40°±2° - 140°±2° and 220°±2° - 320°±2°
‘’Momentum spread at top energy = 1.13e-4
Momentum offset = 2e-4
Total Dp/p = momentum offset + 2*momentum spread
ATS squeezed Optics Beam 2 (6.5 TeV, 30 cm b*)
mux(TCTH5)
mux(TCTH1)
7s
TCDQ set at at 7.3 snom + 1 snom (betatron)
TCTH1 and TCTH5 set at at 8.0 snom - 1 snom (betatron)
Real cut xCut [snom ] @ TCDQ can be calculated from:
x = xCut * snom *cos(mux) + Dx* Dp/p + xdump
TCDQ 11.4 s
Dp/p=4.26e-4’’;
xCut contains optics and alignment errors during the
setup
xdump is the local orbit at the moment of the
asynchronous dump (at present +1.2 mm for TCDQ)
xCut @ TCTs takes into account the phase advance from
the TCDQ and the dispersive contribution
Phase advance wrt TCDQ [deg]
Forbidden zone: phase advance MKD-TCT (TCT-TCDQ+90°)
40°±2° - 140°±2° and 220°±2° - 320°±2°
‘’Momentum spread at top energy = 1.13e-4
Momentum offset = 2e-4
Total Dp/p = momentum offset + 2*momentum spread
Conclusions
• The present ATS optics (squeeze down to 30 cm in view of possible 2017
operation) fulfils the main constraints defined for IR6 provided that the
TCDQ settings can be kept unchanged during the full squeeze (to be
confirmed by collimation!)  no BETS and/or mechanical play problem
• The margin between TCDQ and TCT settings is worse wrt 2016 optics due
to the less favourable phase advance but still acceptable
• No major show stopper was identified.
• Further checks have to be performed for the squeeze down to 10 cm b*.