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 loadcooling 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