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HL-LHC Optics Configuration vs. Experiment Desiderata. Bernhard Holzer for the WP2, Task2.2 Team B. Dalena , A. Bogomyagkov , R. Appleby, A. Fauss-Golfe , J. Payet , A. Chance’, K. Hock, M. Korostelev , R. deMaria , J. Resta , C. Milardi , L. Thompson, M. Thomas, A. Wolski. - PowerPoint PPT Presentation
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The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
HL-LHC Optics Configuration vs. Experiment Desiderata
Bernhard Holzer for the WP2, Task2.2 Team
B. Dalena, A. Bogomyagkov, R. Appleby, A. Fauss-Golfe, J. Payet, A. Chance’, K. Hock, M. Korostelev, R. deMaria, J. Resta, C. Milardi, L. Thompson, M.
Thomas, A. Wolski
2
HL-LHC Parameter List
Parameter nominal 25ns 50nsNb 1.15E+11 2.20E+11 3.50E+11
nb 2808 2808 1404
Ntot 3.2E+14 6.2E+14 4.9E+14
beamcurrent[A] 0.58 1.12 0.89
x-ingangle[mrad] 300 590 590
beamseparation[σ] 9.9 12.5 11.4
β*[m] 0.55 0.15 0.15
εn[μm] 3.75 2.50 3
εL[eVs] 2.51 2.51 2.51
energyspread 1.20E-04 1.20E-04 1.20E-04
bunchlength[m] 7.50E-02 7.50E-02 7.50E-02
IBShorizontal[h] 80->106 18.5 17.2
IBSlongitudinal[h] 61->60 20.4 16.1
Piwinskiparameter 0.68 3.12 2.85
geom.Reductionfactor'R' 0.83 0.305 0.331
beam-beam/IPwithoutCrabCavity 3.10E-03 3.28E-03 4.72E-03
beam-beam/IPwithCrabcavity 3.75E-03 1.08E-02 1.43E-02
PeakLuminositywithoutleveling[cm-2s-1] 1.0E+34 7.4E+34 8.5E+34
VirtualLuminosity:Lpeak/R[cm-2s-1] 1.2E+34 24E+34 26E+34
Events/crossingwithoutleveling 19->28 210 475
LevelledLuminosity[cm-2s-1] - 5E+34 2.50E+34
Events/crossingwithleveling *19->28 140 140
x-angle
β*ε
L0
ideal luminosity formula
loss factor due to crossing with an angle(pure geometric effect ... but large)
★★★★★★
* R
≈ 0.33
Luminosity & Loss Factor
R * H
Luminosity & Beam Optics
The HL-LHC Lattice & Optic has to establish β* at IP1 & 5 to reach a “virtual luminosity” of
and for the given bunch intensities this means
to small for the IR1 / 5 matching section squeeze starts at neighboring sectors (“ATS”) .
€
ˆ L (25ns) = 24 *1034 cm−2s−1
ˆ L (50ns) = 26*1034 cm−2s−1
€
βx* = β y
* ≈15cm
IP2IP8 IP1
HL-LHC Wish-List of the Experiments
5
present Luminosity HL-max Luminosity HL-leveled Luminosity
IR 1 / 5 0.7*1034 2.4 ... 2.6*1035 2.5 ... 5 *1034
IR 2 6*1030 1 *1033 1 *1031
IR 8 2*1032 1 *1034 1 ... 2 *1033
Establish a set of different beam optics (i.e. β*) that combines the HL-LHC options in IR1,5 with the boundary conditions for IR2, IR8.
set up four baseline opticsbased on assumptions on aperture & magnet technique
170
HL-LHC Wish-List of the Experiments
6
to be discussed ... within WP2 & Experiments
Lmax β* Llev β*
IR1,5 25ns 2.4*1035 0.15 5.0*1034 0.65
50ns 2.6*1035 0.15 2.5*1034 1.35
IR8 1.1*1034 3 1-2*1033 15-30
IR2 1.1*1033 30 1.1*1031 - ? -
HL-LHC Beam Optics... and as latest version: 150mm Triplet Aperture / 140T/m Gradient
Problem & Solution: ATS combines the different LHC Interaction Regions.a large variety of beam optics studied & optimised in IP8 / IP2bog_150_0100_0100_3000_3000.madx β*(IP8) = 3m standard ATS, roundbog_150_0050_0200_3000_3000.madx β*(IP8) = 3m standard ATS, flat_xybog_150_0050_0200hv_3000_3000.madx β*(IP8) = 3m standard ATS, flat_yxbog_150_5500_5500_10000_10000.madx β*(IP8) = 10m ATS_injectionbog_150_0400_0400_0500_0500.madx β*(IP8) = 50cm ATS ions
each optics has to be „implemented“ into the overall LHC lattice & optics.
court. A. Bogomyagkov
the “ATS Squeece Optics (15cm/15cm/10m/10m)
IP3, Standard FoDo Optics IP1, ATS Optics
Find an otpics solution that is feasible for the Luminosity upgrade and guarantees adequate conditions for the ALICS and LHCb experiment at the same time.
HL-LHC Optics in IR2
IP2
HL-LHC optics: injection to proton collisions
IR8b*=10 m
IR1b*=5.5 m
IR2b*=10 m
IR4 IR5b*=5.5 m
IR6
IR8b*=3 m
IR1b*=0.4 m
IR2b*=10 m
IR4 IR5b*=0.4 m
IR6
IR8b*=3 m
IR1b*=0.15 m
IR2b*=10 m
IR4 IR5b*=0.15 m
IR6
Injection optics
Transition topre-squeeze optics
ATS tocollision optics
250 - 300 fb-1 per year
find a smooth transition without (too many) hysteresis problems
5.5m injection optics
40cm pre-squeeze optics
15cm ATS optics
HL-LHC Optics in IR1, 5
Standard low-beta-Squeeze
ATS-Squeeze
HL-LHC Optics in IR1, 5
Optics Transition via ATS is “smooth by definition”.
Optics Transition Injection – Pre-Squeeze needs TLC optimisation
court. M. Korostelev
* F
Lattice, Loss Factor & Crab Cavities
F
Optimse the lattice (i.e. quad positions) to gain crab effectiveness.
Study of additional quadrupoles at Q5 / Q6 / Q7 ...
Q4 / Q5 / Q6 in triplet configuration & add. Q7 ... allows for much larger βs at the Crab Cavities
add. Quad at Q5: no big change
additional k-strength needed at Q7
Lattice Optimisation for Crab Cavitiescourt. B. Dalena
14
space needed for crab cavity installation enhanced β function needed for crab cavity effectivenessre-shuffling the matching quads, strengthening Q7(170T/m, 15cm Otpics)
Lattice & Crab Cavities
increase the beta function at the location of the crab cavities
CRAB side and beamHL-LHC baseline [MV]
Best optimization [MV]
Horizontal L5 Beam 1 11.8 8.0
Horizontal R5 Beam 1 13.4 8.2
Horizontal L5 Beam 2 13.4 8.2
Horizontal R5 Beam 2 11.8 8.0
court. B. Dalena et al
Lattice & Crab Cavities
Standard Bump for Crossing angle & beam separation closes at Q5 ... and leads to (varying) orbit offsets at the crab cavity location.-> bump closure by strong dipole magnet at D2.-> Alternative: transverse cavity positioning feedback following the beam orbits
court. R. DeMaria
16
Crossing Angles & Apertures
2
00
( )s
sβ ββ
Increasing β-function in the mini-beta drift leads to large crossing angles ... to avoid parasitic bunch encounters.
*
s s
β0
crossing angle bump for the case:β=15 cm, ε=3.0μm, +/- 10σ
crossing angle bump for the case:β=15 cm, ε=3.0μm, +/- 10σwith location of parasitic 25ns encounters
Aperture need determined by optics, emittance, orbit tolerances, crossing angleWORK IN PROGRES, LEB-MeetingsM.Gallilee
Crossing Angles & Apertures IR1 & 5
eff crossing angle = -2.27 mrad
collisions at IP, separation at all paras. encounters
Special Problem: 25ns at IR8Injection: horizontal crossing-angle
LHCb = “good”(... negative kick on beam 1)LHCb = -15.5 ... -2.1mrad b1on_x8 = +1.0 .. -170μrad
separation at IP via vert. 2mm sep bump
horizontal plane vertical plane
Injection: vertical crossing-angle
LHCb = “bad”(... positive kick on beam 1)LHCb = +15.5 ... +2.1mrad on_sep8 = +1.0 ... Δx=2.0mmon_x8vi = 0.8 ...... y’ = 125 μrad
optimisation of crossing angle (keep it SMALL) y’=107μrad emittance (keep it SMALL) εn =2.5closed orbit tolerance (keep it SMALL) 3.0mm
collisions at IP avoided via hor. sep bumpseparation ok at paras. encounters 2...4
avoids crossing at IP and paras. encounters 1,2,3
separates the beams from paras. encounters 4
horizontal plane vertical plane
20
Open Questions
• Which baseline optics to choose ... hardware R&D will tell
• Follow up of magnet development
• Do we need a 1km Optics ??
• Finally ... the leveling Problem:
β* leveling in IP 1 & 5 ...but then a synchronous β* leveling in IR2 & IR8 will be DIFFICULT
IP2
21
Open Questions
Finally ... the leveling Problem:
β* leveling via crab cavity voltage (i.e. crossing angle)
changing the crossingangle reduces the luminositybut does NOT reduce the density of vertices inside the “luminous region”.
β* leveling via closed Orbit Bumps-> special magnets needed (orbit in Crab Cavities)-> beam beam problem ? 20 vertices
2 vertices