overview of final focus optics, collimeter, final doublet and extraction/dump

Overview of Final Focus Optics, Collimeter, Final Doublet and E

xtraction/Dump

• Final Focus Optics• Collimeter• Final Doublet• Extraction/Dump

S.Kuroda ( KEK )

MDI meeting at SLAC 1/6/2005

Final Focus Optics1. Beam size blow-up due to energy spread( chromatic effect ) Generally is large for FF. ( =103~104, mainly from final Q)2. Chromaticity correction introducing SX.3. SX also introduces geometric aberration(GA). Need another SX and special optics for the GA cancellation

Two Cancellation Scheme “Traditional” :GA cancelled by -I optics between SXs “Local Correction” : corrected locally

Traditional Optics

TESLA TDR

correction by SX far upstream of IP Transfer matrix of -I between SXs = ’=0 at IP

Local Correction Optics

[J.Payet, O.Napoly]

NLC BDS

[A.Seryi et al]

New TESLA BDS

corrected locallyGA must be corrected by optics 2nd order correction also required

c=0 Long drift space for dump

Collimeter in FFSOCT tail folding works good

Summary of Optics

‘Traditional Optics’ ‘Local Correction Optics’

• Comprehensive

• Tested at FFTB

• Wide momentum band width

• Expandability to high energy

• Compact beam line

Recent design tendency is ‘Local Correction Optics’

CollimeterMachine( Detector ) ProtectionBackground to Detector SR of Beam Halo at Final Q

Collimation with spoiler+absorber Off-momentum Collimation Betatron CollimationNon-linear field in beam line Simulation is required for performance check

[TESLA]

Off-Momentum Collimation

SR protection x+Lp = (+L ’)< r

Machine protection

High dispersion & low beta section

Betatron Collimation

High beta & dispersion free sectionNeed iterative collimation for action variable cut in phase space(Optional use) Periodic Optics with = 45° emittance measurement

2Jβ

−Lα +β( )cosθ+Lsinθ( )≤2J −Lα +β( )

2+L2( )

β

SR by e of (x, p) at distance L x+Lp=

(in action-angle var.)< aperture

Performance of Collimeter

Better collimation performance in NLC/CLICbeta+ collimation is better than +beta ?

[A.Drozhdin et al]

Other Machine Protection Magnetic Energy Spoiler(MES) OCT+skew SX Large beam kicked by OCT horizontally large x in skew SX x-y coupling & beam blow-up

Fast Extraction Line Long bunch spacing in Cold machinemuch enough time to detect error and fire kicker

[TESLA]

Other Issue for Collimeter

Spoiler & Absorber Wake field Heat load survivability/life time

Muon collimationsurvivable spoiler [A.Seryi]

Final Doublet

Normal Electric Magnet• Established technology• Heat loadcooling

Crossing angle c & L* is the critical parameters for designOutgoing beam go inside or outside of the bore

Super-conducting Magnet• High gradient/Low power consumption• Large bore radius ( common with outgoing beam )• Vibration? He flow in cryostat

Various type of SC magnets are proposed

LHC

Small bore/double aperture

Compact SC magnet

Flat inner tube

Permanent Magnet

• High gradient w/o power consumption • Compact/small bore • Adjustability/tunability

Hybrid Field compensation mover

Summary for Final Doublet

EM SC PM

• Established technology

• Power consumption

cooling

• High gradient

• Large bore

• Vibration?

• High gradient • Compact/small bore • Adjustability/tunabilit

y

Beam Extraction/Dump

• Charged beam extraction Boundary condition by c and L* Machine protection by beamstrahlung • Dump for beamstrahlung • Material of the dump for e± & beamstrahlung