Bernhard Holzer, CERN-LHC

Parameter Space for HL-LHC IR8Parameter Space for HL-LHC IR8

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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