Overview of Beam Delivery System

1
Overview of Beam Delivery System
S.Kuroda ( KEK )

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

MDI meeting at SLAC 1/6/2005
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Final Focus Optics
1. Beam size blow-up due to energy spread(
chromatic effect )
?? ????? Generally ? is large for FF.
(? 103104, 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
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Traditional Optics
TESLA TDR ? correction by SX
far upstream of IP Transfer matrix of -I
between SXs ? ?0 at IP
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Local Correction Optics
? ? corrected locally ? GA must be corrected by
optics ? 2nd order ? correction also required
NLC BDS
New TESLA BDS
?c0 ?Long drift space for dump
J.Payet, O.Napoly
Collimator in FFS ?OCT tail folding works good
A.Seryi et al
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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
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Collimator
Machine( Detector ) Protection Background to
Detector SR of Beam Halo at Final Q
Collimation with spoilerabsorber Energy
Collimation Betatron Collimation Non-linear
field in beam line ?Simulation is required
for performance check
TESLA
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Energy Collimation
SR protection xLp (?L ?)??lt r Detector
protection ? Background study
High dispersion low beta section
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Betatron Collimation
High beta dispersion free section Need
iterative collimation for action variable cut
in phase space (Optional use) Periodic
Optics with ?? 45 ?emittance measurement
SR by e? of (x, p) at distance L xLp
(in action-angle var.) lt aperture
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Performance of Collimator
A.Drozhdin et al
Better collimation performance
in NLC/CLIC ?(beta??collimationlocal
correction FF is better than
(?beta)collimationtraditional FF ?
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Other Machine Protection
Magnetic Energy Spoiler(MES) OCTskew 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
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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
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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
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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?
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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
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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
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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
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TESLA Extraction
optics
Head-on scheme Irradiation of septum magnet No
beam diagnostic after collision is considered
Beam size when no collision
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GLC Extraction
K.Kubo
Geometry
7mrad crossing Superconducting final Q is
assumed (out-going particle goes inside of Q
) Diagnostic section is considered. Transmission
and background study ? need more to
do
optics
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Extraction for 20mrad crossing
Y.Nosochkov
2nd focal point in vertical chicane for beam
diagnosis Good transmission for disrupted beam
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Others
Straw-man layout for ILC BDS
M.Woodley
Design done except Pre-IP E-spectrometer
FEXL Extraction for 2mrad
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Solenoid Field Compensation
Y. Nosochkov, A. Seryi
Solenoid field at FD ? beam size
blow-up ( independent on crossing angle )
Anti-solenoid compensation
Anti-solenoids provide good compensation, and
it is considered as a part of detector More
effective with skew Q