Bernhard Holzer, CERN-LHC
Parameter Space for HL-LHC IR8Parameter Space for HL-LHC IR8
*
IP5
IP1IP2
IP8
LEB MeetingLEB Meeting
HL-LHC Parameter Table
Luminosity:
*F * H F = geometric los factor (x-angle)H = hour glass effect
LHC Standard HL-LHC 25ns HL-LHC 50ns
Np 1.15*1011 2.2*1011 3.5*1011
nb 2808 2808 1404
β* 3 m 3 -10 m 3-10 m
εn 3.75 μm 2.5 μm 3.0 μm
σ 18 μm 7.6 μm 8.3 μm
a large variety of beam optics studied & optimised in IP8
bog_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.
IR8 optics, 3m, ATS matched
HL-LHC Luminosity in IR8HL-LHC Luminosity in IR8
LHC_Standard, β*= 3m, ε = 3.75 μrad
€
L = 2*1033
HL-LHC, β*= 3m, Δt = 50ns, ε = 3.0 μrad
€
L =1*1034
HL-LHC, β*= 3m, Δt = 25ns, ε = 2.5 μrad
€
L =1*1034
HL-LHC, β*= 10m, Δt = 25ns, ε = 2.5 μrad
€
L = 3.1*1033
nota bene: values refer to E = 7TeV
The optics foreseen in the HL-LHC concept fot to the expected Luminositybin IR8.
HL- LHC-IR8-”Standard Lumi settings”: envelopes refer to +/- 5 σ crossing angle vert. 100 μrad β* = 3.0 m, εn =3.0 μm, on_LHCb = 1.0 135 μrad hor
hor plane ... dominated by LHCb crossing effect“neg polarity”, sufficient sep. at 2, 3 encounter but cross over due to “wrong” LHCb polarity
Crossing Angles and Loss FactorCrossing Angles and Loss Factor
vert. plane ... guarantees separation from encounter #2.
Crossing Angles and Loss Factor:Crossing Angles and Loss Factor: 3m Optics 3m Optics
HL- LHC-IR8-”Standard Lumi settings”: envelopes refer to +/- 5 σ crossing angle vert. 100 μrad β* = 3.0 m, εn =3.0 μm, on_LHCb = 1.0 135 μrad hor
vert. plane ... guarantees separation from encounter #2.
A vertical crossing angle of 100μrad guarantees sufficient separation at all parasitic encounters =in a range of beam optics between 3 ... 10m.
Crossing Angles and Loss Factor: Crossing Angles and Loss Factor: 10m Optics10m Optics
HL- LHC-IR8-”Standard Lumi settings”: envelopes refer to +/- 5 σ crossing angle vert. 100 μrad β* = 10.0 m, εn =3.5 μm
HL- LHC-IR8-”Standard Lumi settings”crossing angle vert. 100 μrad β* = 3.0 m, εn =3.0 μm, 135 μrad hor
Crossing Angle and Loss FactorsCrossing Angle and Loss Factors
*F * H F
F ≈ 98 %
H ≈ 0.998
Geometric Loss Factor:
Hour Glass Effect
... for nominal LHC parameters
HL- LHC-IR8-”Standard Lumi settings: ”Aperture “after LS2”crossing angle vert. 100 μrad β* = 3.0 m, εn =3.75 μm
on_LHCb = 1.0 135 μrad hor
n1 ok
Crossing Angles and Optics:Crossing Angles and Optics: Aperture Aperture
Velo not includedVelo not included
HL- LHC-IR8-”HL- Lumi settings: ”Aperture “after LS2”crossing angle vert. 100 μrad β* = 10.0 m, εn =3.75 μm
on_LHCb = 1.0 135 μrad hor
n1 oknota bene:10m optics is NOT combined with ATS scheme
Crossing Angles and Optics:Crossing Angles and Optics: Aperture Aperture
Velo not includedVelo not included
AddendumAddendum
LHCb Polarity & Horizontal Crossing AngleLHCb Polarity & Horizontal Crossing Angle
collisions at IP, separation at paras. encounters #2,3collisions after LHCb compensator dipole
collisions at IP, separation at paras. encounters #2,3 via LHCbseparation after paras. encounters #3 via ext. bump
LHC-IR8-Original Design:Combination of internal (LHCb-) angle and external angle
LHCb = “good” (... negative kick on beam 1)LHCb = -1.0 ... -135 μrad b1on_x8 = 0.0 ...........................................on_x8=0.275 ≈ -66μrad
horizontal plane
LHCb Polarity & Horizontal Crossing AngleLHCb Polarity & Horizontal Crossing Angle
collisions at IP, separation at all paras. encounters as the external bump overcompensatesthe effect of the LHCb dipole (nota bene: aperture need !!)
LHC-IR8-Original Design:Combination of internal (LHCb-) angle and external angle
LHCb = “bad” (... positive kick on beam 1)LHCb = +1.0 ... +135 μrad b1on_x8 = +1.0 .. -235μrade
horizontal plane
eff crossing angle = -100μrad
LHCb
LHCb Polarity & Horizontal Crossing AngleLHCb Polarity & Horizontal Crossing Angle
Aperture: β*=3.0m, εn =3.75 μrad
LHCb = “good”
LHCb = “bad”
eff crossing angle = -2.27 mrad
collisions at IP, separation at all paras. encounters
Injection: horizontal crossing-angleInjection: horizontal crossing-angle
LHCb = LHCb = “good”“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
eff crossing angle = +1.93 mrad
Injection: horizontal crossing-angleInjection: horizontal crossing-angle
LHCb = LHCb = “bad”“bad”(... positive kick on beam 1)LHCb = +15.5 ... +2.1mrad b1on_x8 = +1.0 .. -170μrad
horizontal plane
collisions at IP avoided via vert. sep bumpdue to cross over effect separation at all paras. encounters not possible for 25ns operation
Injection: Injection: vertical vertical crossing-anglecrossing-angle
LHCb = LHCb = “bad”“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
crossing angle y’=107μrad emittance εn =2.5closed orbit tolerance 3.0mm
Aperture
Injection: Injection: vertical vertical crossing-anglecrossing-angle
LHCb = LHCb = “bad”“bad”(... positive kick on beam 1)LHCb = +15.5 ... +2.1mrad on_sep8 = +1.0 ... Δx=2.0mmon_x8vi = 0.8 ...... y’ = 125 μrad
default: cor=4mm, en=3.75 optimistic (?): cor=2mm, en=2.5