1. Overview of Final Focus Optics, Collimeter, Final Doublet and Extraction/Dump
S.Kuroda ( KEK )
Final Focus Optics
Collimeter
Final Doublet
Extraction/Dump
MDI meeting at SLAC 1/6/2005

2. Final Focus Optics
1. Beam size blow-up due to energy spread( chromatic effect )
Ds = x d s
Generally x is large for FF. (x =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” : x corrected locally

3. Traditional Optics TESLA TDR x correction by SX far upstream of IP
Transfer matrix of -I between SXs
h= h’=0 at IP

4. Local Correction Optics
 x corrected locally
 GA must be corrected by optics
 2nd order h correction also required
NLC BDS
New TESLA BDS
qc=0 Long drift space for dump
[J.Payet, O.Napoly]
Collimeter in FFS
OCT tail folding works good
[A.Seryi et al]

5. 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’

6. Collimeter Machine( Detector ) Protection Background to Detector
SR of Beam Halo at Final Q
Collimation with spoiler+absorber
Off-momentum Collimation
Betatron Collimation
Non-linear field in beam line
Simulation is required
for performance check
[TESLA]

7. Off-Momentum Collimation
SR protection
x+Lp = (h+L h’)d< r
Machine protection
High dispersion
& low beta section

8. Betatron Collimation High beta & dispersion free section
Need iterative collimation for
action variable cut in phase space
(Optional use)
Periodic Optics with DY= 45°
emittance measurement
SR by e of (x, p) at distance L
x+Lp=
(in action-angle var.)
< aperture

9. Performance of Collimeter
Better collimation performance
in NLC/CLIC
beta+d collimation
is better than d +beta ?
[A.Drozhdin et al]

10. Other Machine Protection
Magnetic Energy Spoiler(MES)
OCT+skew SX
Large d beam kicked
by OCT horizontally
large Dx in skew SX
x-y coupling & beam blow-up
Fast Extraction Line
Long bunch spacing in
Cold machine
much enough time to
detect error
and fire kicker
[TESLA]

11. Other Issue for Collimeter
Spoiler & Absorber
Wake field
Heat load
survivability/life time
survivable spoiler [A.Seryi]
Muon collimation

12. Normal Electric Magnet
Final Doublet
Crossing angle qc & L* is the critical parameters for design
Outgoing beam go inside or outside of the bore
Normal Electric Magnet
• Established technology
• Heat loadcooling

13. Super-conducting Magnet
• High gradient/Low power consumption
• Large bore radius
( common with outgoing beam )
• Vibration?  He flow in cryostat
LHC
Various type of SC magnets are proposed
Compact SC magnet
Small bore/double aperture
Flat inner tube

14. Permanent Magnet • High gradient w/o power consumption
• Compact/small bore
• Adjustability/tunability
Hybrid
Field compensation mover

15. Summary for Final DoubletEM SC PM
• Established technology
• Power consumption
 cooling
• High gradient
• Large bore
• Vibration?
• Compact/small bore
• Adjustability/tunability

16. Beam Extraction/Dump • Charged beam extraction
Boundary condition by qc and L*
Machine protection by beamstrahlung g
• Dump for beamstrahlung
• Material of the dump for e± & beamstrahlung