Overview of
Beam Delivery System
S.Kuroda ( KEK )
•
•
•
•
•
Final Focus Optics
Collimator
Final Doublet
Extraction/Dump
Others
MDI meeting at SLAC 1/6/2005
Final Focus Optics
1. 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
  corrected locally
 GA must be corrected by optics
 2nd order  correction also required
NLC BDS
New TESLA BDS
c=0 Long drift space for dump
[J.Payet, O.Napoly]
Collimator in FFS
OCT tail folding works good
[A.Seryi et al]
Summary of Optics
‘Traditional Optics’
‘Local Correction Optics’
• Easy to understand
• Wide momentum band width
• Tested at FFTB
• Expandability to high energy
• Compact beam line
Recent design tendency is ‘Local Correction Optics’
Collimator
Machine( Detector ) Protection
Background to Detector
SR of Beam Halo at Final Q
Collimation with spoiler+absorber
Energy Collimation
Betatron Collimation
Non-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 section SR by e of (x, p) at distance L
Need iterative collimation for
x+Lp=
2J  L     L 
action variable cut in phase space
2J
L   cos  Lsin  



(Optional use)
(in action-angle var.)
Periodic Optics with = 45° < aperture
emittance measurement
2
2
Performance of Collimator
[A.Drozhdin et al]
Better collimation performance
in NLC/CLIC
(beta+collimation+local correction FF
is better than (+beta)collimation+traditional FF ?
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 machine
much enough time to
detect error
and fire kicker
[TESLA]
Other Issue for Collimator
Spoiler & Absorber
Wake field
Heat load
survivability/life time
Fast emergency extraction
line is necessary
survivable spoiler [A.Seryi]
Muon collimation
Final Doublet
[T.Mihara,O.Napoly 1st ILCWS]
Crossing angle c & L* is the critical parameters for design
Outgoing beam go inside or outside of the bore
Normal Electric Magnet
• Established technology
• Heat loadcooling
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
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 • High gradient
• High gradient
• Power consumption
• Large bore( generally ) • Compact/small bore
• Vibration?
• Adjustability / tunability
 cooling
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
optics
Head-on scheme
Irradiation of septum magnet
No beam diagnostic
after collision is considered
Beam size when no collision
GLC Extraction
Geometry
[K.Kubo]
7mrad crossing
Superconducting final Q is assumed
(out-going particle goes inside of Q )
Diagnostic section is considered.
optics
Transmission and background study
 need more to do
Extraction for 20mrad crossing
[Y.Nosochkov]
2nd focal point in vertical chicane for beam diagnosis
Good transmission for disrupted beam
Others
• Straw-man layout for ILC BDS
[M.Woodley]
11 mrad NLC-style
Big Bends
200 m drifts
IR2
NLC BSY
dump lines
2 mrad
Andrei’s 20 mrad ILC FF (x 4)
Design done except
Pre-IP E-spectrometer
FEXL
Extraction for 2mrad
IR1
20 mrad
IP separation:
150 m (Z), 22 m (X)
Yuri’s ILC 20 mrad dump lines
• Solenoid Field Compensation
Solenoid field at FD
 beam size blow-up
( independent on crossing angle )
LD model,  = 20 mrad
[Y. Nosochkov, A. Seryi]
Anti-solenoid compensation
Total field with and
w/o antisolenoids
LD model,  = 0
With antisolenoids and linear knobs,
y = 0.9%
Anti-solenoids provide
good compensation, and it is
considered as a part of detector
More effective with skew Q