1. Task 2. 5: Beam-beam studies D. Banfi, J. Barranco, T. Pieloni, A
Task 2.5: Beam-beam studies D. Banfi, J. Barranco, T. Pieloni, A. Valishev
Very-Preliminary results for RLIUP scenarious
Acknowledgments: team for support!

2. b1, b2
30, 7.5 cm sz
7.5 cm
ex, ey
2.5 mm Nb
2736
Collisions at
IP1, IP5

3. Np (1011)
x-angle (mrad)
sep (s)
L (1034)
DA min
1.0
300
8.9
3.0
4.25
1.2
4.3
<4
350
10.4
2.7
5.3
4.0
5.2
1.4
5.4
400
11.9
5.0
1.8
8.2
2.2
12.3
1.6
450
13.4
6.0
6.2
7.7
5.5
2.0
9.4
4.6
500
14.9
5.6
6.7
7.1
6.5
8.8
550
16.4
9.9
6.1

4. Possible scenarios at 7 TeV:
Nb coll
[1011]
e*coll
[mm]
Coll.
Bunch.
IP1,5
Min b*
(xing / sep)
[cm]
B-B
Sep
[s]
Xing
angle
[mrad]
Lpeak
[1034
cm-2s-1]
Llev
Lev.
time
[h]
tlumi
after
Opt. Fill length
Machine
perf eff.
6 h fills [%]
Machine per eff.
opt. fills
[%]
Avg. Peak-pile-up density
[ev./mm]
Target int.
Lumi
[fb-1/year]
PIC
1.38
1.8
2592
40/20 12
296
4.24 -
6.0
26.4
1.42 70
2.22
2736
329
3.62
8.2
6.9
28.5
28.3
1.15
US1
1.9
2.62 10
298
6.37
5.06
1.7
7.2
6.5
43.4
43.3
1.50
170
US2
2.26
15/15
450
17.6
4.3
8.4
57.8
53.6
1.21
270
2.2
2.5
473
21.3
9.0
4.13
10.2
50.6
1.24
30/7.5
335
20.0
8.7
4.57
50.8
<1.30
Bunch length 7.55cm, could be increased to 10cm for pile-up density or more with 2nd harmonic system
b*= 40 cm could be relaxed to gain aperture and pile-up density
B-B sep being evaluated

5. Beam-beam Task 2.5
Is there any filling scheme among those proposed for BCMS that could pose problems for beam-beam effects?
What is the required beam-beam separation for flat optics and no BBLR?
What is the dependence on intensity?
BBLR position vs emittance, flat beam crossing angle with BBLR. Is it compatible with collimation?

6. The filling schemes are ok for us no counter-proposals!
Filling schemes 25 ns
Courtesy B. Gorini
Filling scheme
Total
IP1-5
IP2
IP8
BCMS: 48b 6 Ps inj, 12 SPS inj
2604
2592
2288
2396
Standard: 72b 4 Ps inj, 12 SPS inj
2748
2736
2452
2524
The filling schemes are ok for us no counter-proposals!
Just few Comments!
12 non colliding bunches for IP1 and IP5 experiment needs
In case of instabilities could be problematic! Except if we take head-on collision in IP2 or IP8
Beta* leveling in IP8 but is 1 head-on stability enough? To be tested

7. Filling schemes 25 ns: 48 bunch trains
12 non colliding bunches for IP1 and IP5 experiment needs
In case of instabilities could be problematic! Except if we take head-on collision in IP2 or IP8
Beta* leveling in IP8 but is 1 head-on stability enough? To be tested
Ratio nominal/pacman different needs considerations for optimization/wire

8. Filling schemes 25 ns: 72 bunch trains
12 non colliding bunches for IP1 and IP5 experiment needs
In case of instabilities could be problematic! Except if we take head-on collision in IP2 or IP8
Beta* leveling in IP8 but is 1 head-on stability enough? To be tested
Ratio nominal/pacman different needs considerations for optimization and wire

9. LHC running 2012 LHC runs always above 8 s DA with imperfections!
LHC nominal DA simulations
8-7 s DA for nominal intensity, nom s
1 s reduction for Intensity increase ppb
LHC runs always above 8 s DA with imperfections!
DA from BB and imperfections always behind collimators in LHC.
We have heavy losses at DA of 3-4 s from measurements (D. Kaltchev & W. Herr)
What do we define as GOOD POINT for upgrade scenarios 6 s ? 8 s ? At collimators?

10. Beam-beam DA studies PIC & US1 scenarios (simulations still running)
DA with beam-beam only (4D&5slices and 6D)
No imperfections
No tune scans = no optimization
DA normalized to 2.5 mm
US2
DA with beam-beam (4D&5slices and 6D)
DA with imperfections
Tune scans on-going for 30/7.5 cm Optic
Thanks to Stephane for providing initial mask file

11. PIC: Beam-beam interactions only
40/20 Optics 4D/5 slices BB
40-20cm Optics and beam-beam : 1.4e11
Intensity 1.4e11
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
DA in s (2.5 mm)
Collimators
Tune scan might improve picture
PIC1: 15.8 s first encounter
PIC2: 14.4 s first encounter
PIC
1.38
1.8
2592
40/20 12
296
4.24
2.22
2736
329
3.62
Crossing angle between mrad

12. PIC: Beam-beam interactions only
40-20cm Optics and beam-beam: 1.3 e11
Intensity 1.3e11
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
Collimators
DA in s (2.5 mm)
Tune scan might improve picture
PIC1: 15.0 s first encounter
PIC2: 12.9 s first encounter
PIC
1.38
1.8
2592
40/20 12
296
4.24
2.22
2736
329
3.62
Crossing angle between mrad

13. PIC: Beam-beam interactions only
40-20cm Optics and beam-beam: 1.6 e11
Intensity 1.6e11
Emittance 2.62 mm
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
DA in s (2.5 mm)
Collimators
Tune scan might improve picture
US1: 13.6 s first encounter
Crossing angle between 400 mrad
US1
1.9
2.62
2736
40/20 10
298
6.37
5.06

14. Footprints and FMA Diffusion rate units of tune
296 mrad 1.8 mm 1.38e11
329 mrad 2.2 mm 1.38e11
12 s sep
12 s sep
Proposed Scenarios PIC1 and PIC2

15. Footprints and FMA Diffusion rate units of tune
390 mrad 1.8 mm 1.38e11
390 mrad 2.2 mm 1.38e11
16 s sep
14.3 s sep
355 mrad 2.62 mm 1.6e11
420 mrad 1.54 mm 1.6e11
12 s sep
18.5 s sep

16. 40-30/40-20/40-10 cm Optics Comparison
40/30 Optics BB
40/20 Optics BB
40/10 Optics BB
Preliminary results show:
Larger DA if b* sep plane larger
Leveling with b* should aim to separation plane to improve DA? Reduce crossing angle?
Sharper improvement with larger b* sep plane
Test constant beta ratio leveling
Tune scan needed!

17. Footprints and FMA Diffusion rate units of tune 256 mrad 1.8 mm 1.5e11
40-20 Optics
40-10 Optics
296 mrad 1.8 mm 1.38e11
256 mrad 1.8 mm 1.45e11
40-30 Optics

18. 40-20 cm Optics: Intensity scan 4D
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
Collimators
DA in s (2.5 mm)
Intensity effect not so important for some configurations

19. 40-20 cm Optics: Intensity scan 6D
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
Collimators
DA in s (2.5 mm)
To be understood
Intensity effect not so important for some configurations

20. 15 cm round optics Need to evaluate impact of imperfections!
15/15 Optics 4D/5 slices BB
10.6 s end of leveling
Collimators
Intensity scan
Optics 15 cm round
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
DA in s (2.5 mm)
Nominal
US2
1.9
2.26
2736
15/15 10
466
16.3
5.06
2.2
2.5
490
19.8
Need to evaluate impact of imperfections!
First estimates are positive

21. 15 cm round optics 6D BB 6 D requires a bit more, Energy scaling also!
11.9 s end of leveling
Collimators
DA in s (2.5 mm)
Intensity scan
Optics 15 cm round
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
Nominal
6 D requires a bit more, Energy scaling also!

22. 15 cm round optics 15/15 Optics 590 mrad
Need to understand deep at 2.2 e11 ppb
Is it real? Simulations on-going !
Need also Imperfections!

23. 30/7.5 Beam-beam interactions only
30/7.5 Optics 4D/5 slices BB
12.5 s end of leveling
Collimators
Intensity scan
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
Nominal
This case at 7 TeV at 6.5 TeV you need 0.5 sigma more (440 mrad)

24. Beam-beam interactions only
30/7.5 Optics 6D Hirata
12.5 s end of leveling
Collimators
Nominal
Intensity scan
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
Needs still some understanding! Tune scan on-going and FMA
6D beam-beam needs more separation!
This case at 7 TeV at 6.5 TeV you need 0.5 sigma more (440 mrad)

25. Beam-beam interactions only!
30/7.5 Optics 2.2 e11 ppb
Collimators
Intensity scan
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
Need to clarify the 4D and 6D differences!
FMA studies on-going!
Imperfections have strong impact needs to be evaluated!

26. 30/7.5 Optics 540 mrad 15cmOptics 590 mrad
Results are new, need check!
Tune scan could help understanding
15cmOptics 590 mrad

27. Tune scan Tune scan shows possible improvement of DA for higher tunes
30/7.5 Optics 2.2 e11 ppb
Tune scan
Optics cm
IP1&IP5 with crossing angle
NO crab cavities
IP8 off
Maximum 32 long-range/IP
Tune scan shows possible improvement of DA for higher tunes

28. Flat 30/7.5 Intensity scans All scenarios are at the limit!
Here no margin!
16.5 s first encounter for 4D simulations
18 s first encounter for 6D simulations
NEEDS studies to understand this effect
NEEDS tune scan (on-going)
Leveling in Sep plane (Larger beta in sep plane) could IMPROVE?
Constant ratio of betas leveling?

29. BB Long range wire compensation
IP1 & IP5 Head-on
15 cm round Optics HL-LHC
590 mrad crossing angle
FMA and footprints tool in Sixtrack!
Need official release to make them available to everyone
IP1 & IP5 Head-on + LR

30. BB Long range wire compensation
1 Wire next to TCT IP5
1 Wire next to TCL IP1
200 A rematch2
200 A rematch3
200 A
200 A rematch1
338 A
A wire exist in Sixtrack by Bela Erdelyi and Tanaji Sen (Benchmarked versus F. Zimmermann)
Testing On-going preliminary results showed
Need wire implemented in MADX for matching tune shift!
Need MADX to Sixtrack convertion!

31. Summary
Several results for BB only! Sorry some are still analyzed! Need to collect results faster!
Preliminary results need a decision in what to define as DA minimum to define crossing angles!
For flat options larger separations seems needed but not obvious to give one separation!Tunes, optics and intensity change picture
Imperfections are important for low beta optics, needs some studies!
Leveling with separation plane should improve things! Relax separation in crossing plane by larger beta in sep plane?
Pacman families not yet studied, on-going!
No intermediate optics to check impact of constant ratio leveling
Past studies suggest tune scan could improve, very little for optic
Leveling scenario optics fundamental to study a case
Wire studies are possible, need implementations in MADX!
Still many things to be checked i.e. 4D versus 6D, Lifetrack vs Sixtrack for flat, B2 implementation etc.

32. FMA and footprints 40/20 323 mrad 1.3 e11 ppb 1.98 mm

33. 1.38e mm 40/20
296mrad
390mrad

34. 1.8mm 40/20
296mrad
390mrad