Overview of Beam Delivery System

• Final Focus Optics• Collimator• Final Doublet• Extraction/Dump• Others

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

Collimator in FFSOCT tail folding works good

Summary of Optics

‘Traditional Optics’ ‘Local Correction Optics’

• Easy to understand

• Tested at FFTB

• Wide momentum band width

• Expandability to high energy

• Compact beam line

Recent design tendency is ‘Local Correction Optics’

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

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

[TESLA]

Energy Collimation

SR protection x+Lp = (+L ’)< r

Detector protection Background study

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

2J

L cos Lsin

2J L 2 L2

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

(in action-angle var.)< aperture

Performance of Collimator

Better collimation performance in NLC/CLIC(beta+collimation+local correction FF is better than (+beta)collimation+traditional FF ?

[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 Collimator

Spoiler & Absorber Wake field Heat load survivability/life time

Muon collimationsurvivable spoiler [A.Seryi]

Fast emergency extractionline is necessary

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

[T.Mihara,O.Napoly 1st ILCWS]

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 • Fine tuning for temperature/ rad. Damage

Adjusting for big E change( e.g. Z-pole ) Hybrid Field compensation mover

Summary for Final Doublet

EM SC PM

• Established technology

• Power consumption

cooling

• High gradient

• Large bore( generally )

• Vibration?

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

Beam Extraction/Dump • Charged beam extraction

Boundary condition by c and L* Diagnostic section 1) Energy 2) Polarization …… Chicane for photon separation 2nd focusing point for Laser collision Machine protection by beamstrahlung • Dump for beamstrahlung? • Background( neutron ) study from the extraction/dump ……•

TESLA Extraction

Head-on schemeIrradiation of septum magnetNo beam diagnostic after collision is considered

optics

Beam size when no collision

GLC ExtractionGeometry

optics

7mrad crossingSuperconducting final Q is assumed (out-going particle goes inside of Q )Diagnostic section is considered.

Transmission and background study need more to do

[K.Kubo]

Extraction for 20mrad crossing

2nd focal point in vertical chicane for beam diagnosisGood transmission for disrupted beam

[Y.Nosochkov]

Others• Straw-man layout for ILC BDS

Yuri’s ILC 20 mrad dump lines

IR120 mrad

IR22 mrad

Andrei’s 20 mrad ILC FF (x 4)

NLC BSYdump lines

11 mrad NLC-styleBig Bends

200 m drifts

IP separation:150 m (Z), 22 m (X)

Design done except Pre-IP E-spectrometer FEXL Extraction for 2mrad

[M.Woodley]

• Solenoid Field Compensation

LD model, = 20 mrad

LD model, = 0

Solenoid field at FD beam size blow-up( independent on crossing angle )

With antisolenoids and linear knobs, y = 0.9%

Total field with and w/o antisolenoids

Anti-solenoids provide good compensation, and it is considered as a part of detectorMore effective with skew Q

[Y. Nosochkov, A. Seryi]

Anti-solenoid compensation