1. IP, crab cavity alignment and orbit control
R. De Maria
Thanks for input, suggestion and discussions to G. Arduini, V. Baglin, N. Biancacci, L. Bottura, H. Burkhardt, R. Calaga, O. Capatina, H. Durand, S. Fartoukh, P. Fessia, M. Fitterer, F. Galan, D. Gamba, B. Gorini, M. Giovannozzi, H. Prin, D. Ramos, B. Salvant, K. Sjobaek, M. Sosin, .
81st HiLumi WP2 Meeting 24/11/2016

2. Tunnel layout flexibility is more and more frozen.
Status
Experiment are looking at the mechanical structure of the inner tracker and alignment needs.
Vacuum is the process of defining interfaces and is gathering specifications. Similarly for survey.
Tunnel layout flexibility is more and more frozen.
Project asked to reduce the number of correctors (MCBYs) to limit work load (reuse Q4 assembly as is).
R. De Maria, 81st WP2 Meeting, 24/11/2016

3. Motivation of the tal
Make sure the baseline for orbit gymnastic and alignment needs is consistent between specifications, operational procedures, hardware requirements (bellows, jaks and cryogenic- SC- RF- links).
TCC mandated to study scenarios with reduce the number of orbit correctors:
will affect on the range of orbit manipulations
Impact more or less severe depending on the number of installed cavities and Q4 replacement with MQYY.
R. De Maria, 81st WP2 Meeting, 24/11/2016

4. History
HLLHCV1.0: HL-LHC Layout and Optics Models for 150 MM NB3SN Triplets and Local Crab-Cavities, CERN-ACC , :
2xMCBRD(D2)-2xMCBYY(Q4)-1xMCBY(Q5)
Crossing Scheme and Orbit Correction in IR1/5 for HL-LHC, CERN-ACC :
2xMCBRD(D2)-2xMCBYY(Q4)-3xMCBY(Q5) in HLLHCV1.1, crab knobs, alignment on closed orbit
HLLHCV1.2, 53rd WP2 Meeting
As HL-LHCV1.1 with additional 2 mm IP offset knob
R. De Maria, 81st WP2 Meeting, 24/11/2016

5. General information
IP and crab cavities have strict transverse position constraints
IP has to be centered around the inner tracker as much as possible to save radiation and maximize event reconstruction (± 1 mm tolerated, can we quantify the losses?)
Crab cavities electrical centered can be aligned at best within ± 0.5 mm then should be centered as much as possible to avoid large beam loading. To save orbit corrector strength, crab cavity should be aligned around the crossing bump therefore bellows between cryomodules needs to be flexible.
Experiments would like to re-align the beam as soon as they have first luminosity data (e.g. first technical stop) to optimize the IP position with respect to the inner tracker.
Ground motion and mechanical drift has to be expected and compensated every year (ideally to avoid large intervention that require multiple passages). After realignment it is expected to still have 1 mm of uncertainty (see EYETS experience).
Triplet remote alignment with beam was proved this year. It is an important feature to keep and enhance for HL-LHC.
R. De Maria, 81st WP2 Meeting, 24/11/2016

6. Crab cavity – Beam loading
Crabbing plane:
1 mm per cavity static transverse offset allowed in the crab plane.
Up to 2 mm for transient of few milliseconds
In the non crabbing plane:
5 times more allowed for the main mode. HOM not yet considered.
Are HOM a problem in the non-crossing plane? Do we need simulation to validate operation with 5 mm offset in the non crossing plane?
R. Calaga
R. De Maria, 81st WP2 Meeting, 24/11/2016

7. Target for cryomodule alignment
Two consecutive cavity in the same cryomodule can be aligned (e. m. center) within ± 0.5 mm
Each cryomodule could be aligned as a whole, but magnitude to be defined from beam requirements and hardware constraints.
Alignment stability and reproducibility to be measured during the SPS test.
R. Calaga
R. De Maria, 81st WP2 Meeting, 24/11/2016

8. Survey Local ground motion during a run/long term:
Area above D2-Q4 may have much larger movement due to tunnel above.
Triplet area not stable already now.
Present LHC alignment of the triplets
manual vertical ± 20 mm, today much smaller today due to load sensors
manual horizontal ± 20 mm
remote ± 2 mm h/v limited for safety of the bellows
HL-LHC
Range to be specified.
Remote alignment with beam up to Q5 for the magnets.
Not clear strategy for collimators, BPM, TAXS, TAXN fixed masks.
H. Durand
TAXN and fixed mask must be aligned with the magnets for protection and aperture. Only small residual of ground motion ~1 mm accounted for aperture.
R. De Maria, 81st WP2 Meeting, 24/11/2016

9. Alignment around point 5
D. Missiaen
A. Behrens Q7 Q8
Q10 Q7
R. De Maria, 81st WP2 Meeting, 24/11/2016 Q8
Beam position 2016
Q10
Origin CMS coordinate system
2mm
TAS YCMS = -0.6 mm
TAS YCMS = -1.6mm
Center Pixel detector YCMS = -1.1mm

10. Survey-fiducialization tolerances
Ground motion
Fiducializaton r
[mm] h v
TAXS (*)
2.0
0.5
Triplets
0.6
1.0
BPMs
2.5
TAXN (*)
0.84
0.36 D1
D2/Q4/Q5
0.9 h v r
Values from J. Jeanneret, LHC rep 1007.
To be re-validated by Survey, WP3, WP8 teams.
Values for experimental beam pipe under discussions.
R. De Maria, 81st WP2 Meeting, 24/11/2016

11. Baseline orbit corrector layoutQ1 HV
Q2a
Q2b HV Q3 HV CP D1
B1(E) D2 H V C C H V H V Q4 H V H Q5
MBRD V H C C V H V H
MQY V H V
MQY
B2(I)
Type
Number
Strength
MCBXFB 2
2.5 Tm
MCBXFA 1
4.5 Tm
MCBRD
5 Tm
MCBY.4
4 (1.9K)
2.8 Tm
MCBY.5
3 (1.9K)
Baseline design to
Save aperture by closing crossing bump closer to the IP
Provide knobs for adjusting orbit at the crab cavities independently from the IP
Naturally compatible with 4 cavities and crab kissing, due to HV alternation between B1/B2.
R. De Maria, 81st WP2 Meeting, 24/11/2016

12. Nominal crossing bump Baseline closed in MCBY.4 (acby.4=0.2 acbrd)
Beam 1
Beam 2
Impact on crab cavity alignment D2 AB CD Q4
Crossing angle:
x,y: ±1.15 mm (Beam 1, AB)
x,y: ±(-0.5) mm (Beam 2, AB)
For cryomodules:
average offset 0.3 mm
shear 1.65 mm AB CD
R. De Maria, 81st WP2 Meeting, 24/11/2016

13. Crab cavity knobs definitions
Orbit gymnastic at the crab cavity location without modifying the orbit at the IP
ccp: shift both beams in the same direction at the crab cavities using MCBX123-MCBRD-MCBY.4-MCBY.5. (e.g. correct a drift of a cryomodule)
ccm: shift both beams in the opposite direction at the crab cavities using MCBX3-MCBRD-MCBY.4-MCBY.5 (e.g. correct Beam1- Beam2 separation)
ccs: shift position of one cryomodule with respect to the next for the same beam. (e.g. correct for cryomodule alignment in 4 cavity configuration)
R. De Maria, 81st WP2 Meeting, 24/11/2016

14. Orbit knobs - offset Beam 1 Beam 2
IP Offset knob: x,y= ±2 mm same for the two beams to accommodate alignment needs of the experiments with machine realignment, besides crab cavities.
IP offset:
x,y: ±3.4 mm (Beam 1, CD),
x,y: ±1mm (Beam 2, CD),
For cryomodules:
avg. offset 1.2 mm
shear 2.2 mm D2 AB CD Q4 AB CD
R. De Maria, 81st WP2 Meeting, 24/11/2016

15. HL-LHC IR orbit knobs
Sep.
Knob
Crossing
Crab shift
knob
Crab slope
Offset
[mm]
TAXS
0.75
6.15
0.0
2.0
MQXFA.1
11.1
2.45
MQXFB.2
1.19
16.8
0.19
3.50
MQXFA.3
0.82
17.0
0.41
2.72
MBXF
0.47
15.4
2.10
TAXN
0.17
5.44
2.83
MBRD
0.11
3.26
0.98
0.00
3.07
MCBRD
0.06
1.71
1.0
0.05
3.14
ACFCA.A
0.03
1.15
0.13
3.25
ACFCA.B
0.02
1.09
0.15
3.27
ACFCA.C
0.01
0.24
3.36
ACFCA.D
0.69
0.26
3.38
TCLMB.4
0.31
0.42
3.44
MCBY
0.16
0.46
3.49
MQY
0.9
0.44
3.30
TCLMB.5
0.8
2.73
MCBY[HV].5
0.3
2.64
MQY.5
2.39
TCLMC.6
1.7
MCBC[HV].6
1.4
MQML.6
1.39
x: crossing angle ±295 μrad (for ref.) s: separation ±0.75 mm (for ref.) ccp: locally offset beams at crabs ±0.5 mm ccm: locally separate beams at crabs ±0.5 mm ccs: locally offset between consecutive crabs ±0.25 mm (for 4 cavities option) offset: change IP position ±2 mm
R. De Maria, 81st WP2 Meeting, 24/11/2016

16. Orbit corrector budget
IP crossing, separation, offset (x: ±295 μrad, , s: ±0.75 mm, o: ±2.0 mm)
beam based alignment of crab cavities: ccp, ccm (shift): ±0.5 mm, ccs (slope): ±0.25 mm
IT alignment and transfer function errors (err): ±0.5 mm transverse, ±10 mm longitudinal, ±2x10-3 relative gradient error, ±2x10-3 D2 relative field error (±2 σ from uniform errors).
orbit correction from the arc (from LHC data to confirmed): arc 0.7 Tm;
lumi scan knobs (single beam IP shift for 100μm)
x-scheme [Tm]
cc alignment [Tm]
err [Tm]
arc [Tm]
lumi [Tm]
summary [Tm]
name x s o
ccp
ccm
ccs
err
arc*
lumi
Tot
max
margin [%]
MCBX1
0.10
0.08
1.05
0.20
0.92
2.27
2.5
9.2
MCBX2
0.38
1.40
2.15 14
MCBX3
2.12
0.94
0.45
0.15
0.78
4.45
4.5
1.0
MCBRD4
3.17
0.28
0.46
0.11
0.35
0.34
4.71 5
5.8
2xMCBY4
1.28
0.04
0.48
0.84
5.0
5.6
10.8
MCBY5.S
0.17
0.44
0.41
1.46
2.8
47.9
MCBY5
0.7 75
MCBC6
0.60
1.30
2.1 47
MCBC7
1.10
1.80 35
R. De Maria, 81st WP2 Meeting, 24/11/2016
*to be reviewed

17. Alignment needs for baseline scenario
For ± 2 mm IP offset with beam crab cavity cryomodules needs to aligned to
from survey ±4.5 mm
from adjacent cryomodules 3.9 mm
Beam can absorb additional crab cavity drift: ±0.5 mm cpp, ccm and ±0.25 mm ccs (in 4 cavities)
In case of 2 cavities cpp and ccm have larger range.
New vacuum modules with deformable RF bridge could be designed if needed to accommodate a transverse movement of ~ 5 mm  coordination is needed with WP2, WP4 and WP15
C. Garion, V Baglin, HiLumi meeting 216
R. De Maria, 81st WP2 Meeting, 24/11/2016

18. Mitigate static cryomodule offset due to crossing bump
Options
Mitigate static cryomodule offset due to crossing bump
Implement IP shift with triplet re-alignment
Profit from frozen crossing plane between IRs
R. De Maria, 81st WP2 Meeting, 24/11/2016

19. Alternatives on crossing bump
Corrector strength as a function of orbit at the crab cavities.
M. Fitterer, CERN-ACC
Crossing angle can be always reduced without having impact on the orbit at the crab cavities.
One can also have x=0, px≠0 in the middle of a cryomodule and close the crossing bump in Q5-Q6 at the cost of aperture in Q4 and with only 2 cavities options. Not an option for flat beta*.
R. De Maria, 81st WP2 Meeting, 24/11/2016

20. IP shift with triplet re-alignment
Ig (TAXS)-triplet-D1 can be realigned remotely quickly by the same amount:
IP shift without using MCBX and loosing aperture in the triplet and with smaller loss in Q4.
Both cryomodule needs to be realigned by same amount and direction (at least no shear)
The residual orbit offset can be absorbed from:
Q4 to Q5 using all margins for MCBY in the baseline
Q4 to Q6-Q7 to gaining margin in MCBY and the cost of MCBC (and still keeping overall more margin)
In general being able to align also independently the triplet remotely with beam brings important operational advantages and performance increase.
R. De Maria, 81st WP2 Meeting, 24/11/2016

21. Profit from frozen crossing plane between IRs
Reusing the present LHC Q4 with 3 correctors MCBYA/B implies having one beam and of one side with 1 corrector in the crossing plane (i.e. if B1 Left has HVH, B2 Left has VHV).
In the crossing plane one could cope with one corrector (at 1.9 K)
If dropping option for 4 cavities
use reduced offset knob with triplet alignment closed in Q6-Q7 or drop offset knob and rely on full mechanical realignment completely (then also 4.5 K possible)
or close the crossing bump in Q7 (complicates operations)
Parallel separation plane needs only one corrector (4.5 K) if:
no alignment needed for the crab cavities
3xMCBY (at 4.5 K) can be used in Q4 if:
Introducing a new MCBY type HH and VV and install in IR1/IR5 respectively (or viceversa)
Exchange existing Q4 from IR1 to IR5 if and when exchanging the cross plane between IR1 and IR5
Build and install MQYY + 2xMCBYY if and when crab kissing will be implemented
R. De Maria, 81st WP2 Meeting, 24/11/2016

22. Orbit corrector budget
IP crossing, separation, offset (x: ±295 μrad, , s: ±0.75 mm, o: ±2.0 mm)
beam based alignment of crab cavities: ccp, ccm (shift): ±0.5 mm, ccs (slope): ±0.25 mm
IT alignment and transfer function errors (err): ±0.5 mm transverse, ±10 mm longitudinal, ±2x10-3 relative gradient error, ±2x10-3 D2 relative field error (±2 σ from uniform errors).
orbit correction from the arc (from LHC data to confirmed): arc 0.7 Tm;
lumi scan knobs (single beam IP shift for 100μm)
x-scheme [Tm]
cc alignment [Tm]
err [Tm]
arc [Tm]
lumi [Tm]
summary [Tm]
name x s o
ccp
ccm
ccs
err
arc*
lumi
Tot
max
margin [%]
MCBX1
0.10
0.08
1.05
0.20
0.92
2.27
2.5
9.2
MCBX2
0.38
1.40
2.15 14
MCBX3
2.12
0.94
0.45
0.15
0.78
4.45
4.5
1.0
MCBRD4
3.17
0.28
0.46
0.11
0.35
0.34
4.71 5
5.8
2xMCBY4
1.28
0.04
0.48
0.84
5.0
5.6
10.8
MCBY5.S
0.17
0.44
0.41
1.46
2.8
47.9
MCBY5
0.7 75
MCBC6
0.60
1.30
2.1 47
MCBC7
1.10
1.80 35
R. De Maria, 81st WP2 Meeting, 24/11/2016
*to be reviewed

23. Conclusion For IP offset
the baseline relies on crab cavities to have flexible bellows, can be realigned during a technical stop in the range ±3.4 mm
If triplet-D1 can be aligned as quickly, the range of alignment of the crab cavities reduces to ± 2 mm and improves in β* reach.
Small orbit adjustment at crab cavities are possible independently on the position of the IP to absorb ground motion or other imperfections.
A reduction of orbit correctors has impact on flexibility and robustness and require two new MCBY types.
R. De Maria, 81st WP2 Meeting, 24/11/2016

24. Open Points
Expected range and time scale of IP alignment with respect to the triplet needed due to:
internal mechanical movement of the detector
ground motion of the cavern with respect to the triplet
Expected range of alignment needed due to
short range ground motion between triplet area, D2-Crab area, Q5-Q7 area, arc.
mechanical realignment of cryostats and other equipment
How often do we need to realign, what and by how much.
The range of alignment allowed by cryomodule:
with respect to the tunnel
with respect to a neighbor cryomodule or magnet
R. De Maria, 81st WP2 Meeting, 24/11/2016

25. Backup
R. De Maria, 81st WP2 Meeting, 24/11/2016

26. Orbit corrector budget (ip to ccp)
IP crossing, separation, offset (x: ±295 μrad, , s: ±0.75 mm, o: ±0.5 mm)
beam based alignment of crab cavities: ccp (±1.3 mm), ccm (±0.5 mm), ccs (±0.0 mm)
IT alignment and transfer function errors (err): ±0.5 mm transverse, ±10 mm longitudinal, ±2x10-3 relative gradient error, ±2x10-3 D2 relative field error (±2 σ from uniform errors).
orbit correction from the arc (from LHC data to confirmed): arc 0.7 Tm;
lumi scan knobs (single beam IP shift for 100μm)
x-scheme [Tm]
cc alignment [Tm]
err [Tm]
arc [Tm]
lumi [Tm]
summary [Tm]
name x s o
ccp
ccm
ccs
err
arc*
lumi
Tot
max
margin [%]
MCBX1
0.1
0.08
0.26
0.52
0.92
1.80
2.5
27.9
MCBX2
0.10
1.4
2.12
15.4
MCBX3
0.2
0.24
1.17
0.15
0.78
4.46
4.5
1.0
MCBRD4
3.17
0.00
0.73
0.11
0.35
4.51 5
9.8
2xMCBY4
1.28
0.04
1.25
0.48
3.91
5.6
30.2
MCBY5.S
1.14
0.44
1.63
2.8
41.9
MCBY5
0.7
0.34
1.04
62.9
MCBC6
1.19
2.1
43.3
MCBC7
0.28
0.98
65.2
R. De Maria, 81st WP2 Meeting, 24/11/2016
*to be reviewed

27. Orbit corrector budget (cheap)
IP crossing, separation, offset (x: ±295 μrad, , s: ±0.75 mm, o: ±0.5 mm)
both plane alignment of crab cavities: ccp, ccm (shift): ±0.5 mm, ccs (slope): ±0.25 mm
IT alignment and transfer function errors (err): ±0.5 mm transverse, ±10 mm longitudinal, ±2x10-3 relative gradient error, ±2x10-3 D2 relative field error (±2 σ from uniform errors).
orbit correction from the arc (from LHC data to confirmed): arc 0.7 Tm;
lumi scan knobs (single beam IP shift for 100μm)
x-scheme [Tm]
cc alignment [Tm]
err [Tm]
arc [Tm]
lumi [Tm]
summary [Tm]
name x s o
ccp
ccm
ccs
err
arc*
lumi
Tot
max
margin [%]
MCBX1
0.1
0.08
0.26
0.2
0.92
1.48
2.5
40.7
MCBX2
0.10
1.4
1.80
28.2
MCBX3
2.12
0.24
0.45
0.15
0.78
3.74
4.5
17.0
MCBRD4
3.63
0.00
0.28
0.11
0.34
4.51 5
9.8
MCBY4.S
0.9
0.04
0.35
0.48
2.41
2.8
13.9
MCBY4
0.7
0.90
67.9
MCBY5.S
0.44
67.1
MCBY5
0.70
75.0
MCBC6
0.85
2.1
59.5
MCBC7
0.98
65.2
R. De Maria, 81st WP2 Meeting, 24/11/2016
*to be reviewed