ILC Beam Delivery System Layout and Lattice Design Deepa Angal-Kalinin ASTeC, Cockcroft Institute Cockcroft Institute SAC 23-24 th November 2006
Jan 07, 2016
ILC Beam Delivery System Layout and Lattice Design
Deepa Angal-Kalinin
ASTeC, Cockcroft Institute
Cockcroft Institute SAC23-24th November 2006
CI SAC, 23-24 November 20062
Lattice Design and Simulation Team@CI
ASTeC
Frank Jackson James Jones Stephan Tzenov Deepa Angal-Kalinin
Manchester
Rob Appleby Dragan Toprek Adina Toader
Ph.D. Student Anthony Scarfe
CI SAC, 23-24 November 20063
Background
Before the technology decision for the linear collider (August 2004) – studies were mainly focussed on TESLA design Problems related to head-on extraction Poor collimation performance Local chromaticity final focus system was designed but was not
integrated with rest of the BDS Alternative solutions to head-on : small vertical or small horizontal
crossing angle – collaborations with LAL(Orsay), CEA(Saclay) The team developed understanding of BDS design and requirements,
implemented the required simulation codes in order to contribute to the evolving designs, established good collaborations
After the technology decision Small crossing angle solution and extraction line design required urgently NLC collimation and final focus design was adapted to ILC, performance poor than NLC
CI SAC, 23-24 November 20064
Interaction region - Crossing angle choice
Challenges in both the schemes Large aperture shared magnets or compact magnets No/ marginal/complete reliance on crab crossing Axial/Non-axial field in the solenoid Preserve pre-IP beam or emphasis post-IP beam Reflected backgrounds or pre-IP constraints
Physics prefers head-on with minimum background
Very small 0 – 2 mrad Large 14 – 25 mrad
Shared magnets => coupled design Separate magnets
Incoming and outgoing beams
CI SAC, 23-24 November 20065
2mrad crossing angle extraction line design
CI team took a lead role in developing the 2 mrad extraction line design (part of SLAC-BNL-UK-France Task Force)
Due to higher cost of this line and challenges in magnet design, this crossing angle solution is now an alternative to the baseline with 14 mrad
CI team is working with LAL to optimise the extraction line to minimise the beam losses and magnet apertures
The optimised doublet (Appleby, Bambade, Toprek) at 500 GeV CM show significantly less losses in the IR region
Re-designing the rest of the line –minimum line to start with (Appleby) Comparison of number of hits in VXD for the 2 mrad and 20 mrad (with
DID) showed that the pair background increases for 20 mrad with DID
=> 14 mrad + anti-DID solution, now adapted for the RDR
CI SAC, 23-24 November 20066
Contributions to the ILC : collimation optics
Tools to estimate the collimation depths for different crossing angle geometries
Original Performance
Halo Tracking to FD entrance
New Performance
Collimation depth
Better collimation efficiency
F. Jackson
Optimisations still continuing
CI SAC, 23-24 November 20067
Contributions to the test facilities : ATF2
Tuning procedures and tolerances for the ATF2 Several generic options for tuning of
final-focus beam at IP – Traditional, Rotation Matrix, ‘dumb’
Would like to test these algorithms at ATF2, which will present an ideal opportunity to provide some limited analysis of the viability of these methods.
Aim to increase our contributions with the help of Ph.D. student Anthony Scarfe
Expertise in tuning area, used to define the correction method in the long undulator section
The techniques developed are applicable to any accelerator
Beam sizes before and after tuning 1mrad QD0 Rotation
J. Jones
Relative luminosity vs tuning knob
CI SAC, 23-24 November 20068
Contributions to the test facilities : ESA
Optics design for several experiments at ESA, SLAC (January’06 and April’06 beam tests)
Require small beam sizes in x and y planes for collimator wakefield and BPM experiments
Optics modelling challenges: high dispersion and SR in A-line
Careful emittance and Twiss measurements followed by beam tuning
Achieved goals of y100m and x~200m in separate lattice configurations
vert beam size 83m for collimator wakefield tests
horz beam size 240m for BPM studies
F. Jackson
CI SAC, 23-24 November 20069
ILC BDS Layout Changes
15 - 20 mrad
25 mrad
2 - 7 mrad 25 mrad
First ILC Workshop, KEK, November 2004Working hypothesis
CI SAC, 23-24 November 200610
ILC BDS Layout Changes
Snowmass, August 2005 to Vancouver, July 2006
CI SAC, 23-24 November 200611
ILC BDS Layout Changes
At Vancouver (July 2006), first cost estimates indicated significantly higher costs for 2 mrad line => base line configuration changed to 14/14 from 20/2.
ILC GDE
14mrad
14mrad
CI SAC, 23-24 November 200612
ILC BDS Layout Changes
Valencia, November 2006
CCR will be submitted this week by the BDS area leaders
1 IR; two complementary push-pull detectors discussed with detector concepts and WWS
14 mrad
ILC GDE
CI SAC, 23-24 November 200613
Present activities and Objectives
Contributing to several critical decisions on the ILC Interaction Region(s)
The BDS lattice design for the new baseline configuration Risks vs performance Push-pull task force Optimisations and tuning studies Layout details : CFS (shafts/caverns, IR halls) Surface assembly for the detectors Muon walls
Contributing to the RDR costing and writing Optimisations for 2 mrad and modified head-on extraction line
designs : cost effective, with input from magnet designers studying the minimum layout design for these options without
downstream diagnostics
CI SAC, 23-24 November 200614
Future Plan : Beam Line Integration
Continue lattice optimisations for better performance, include realistic beam and machine errors
ATF2 skew/emittance LW, final focus, tuning, tail folding tests Large crossing angle issues Beam Line Integration :Major involvement of CCLRC’s engineering
expertise Lattice design and simulations Collimation design Vacuum design
Other CI major activities viz; crab system and beam dumps integrate naturally with this proposal
Depends on the outcome of LC-ABD2 funding request
Background & wake fields : main concern
CI SAC, 23-24 November 200615
Future Plan : Collimation Design
BDS and extraction lines include ~20 different types of collimators Most critical ones are with the adjustable gaps <mm and long tapers CI is a leading contributor (with CCLRC, Birmingham and SLAC) on
critical collimator issues: wakefields, survivability ESA and simulations (C. Beard’s talk)
Future programme builds on this and will prototype ILC collimators for:
• optimal mitigation of wakefields and component damage (and its detection);
• overall engineering design: tolerances, alignment, movable jaws, cooling, machine protection.
Depends on the outcome of LC-ABD2 funding request
CI SAC, 23-24 November 200616
Future Plan : Vacuum Design
• BDS has complex vacuum design :• Spoilers with fraction of millimetres openings to beam pipe
radius of 200mm in the extraction lines• Synchrotron radiation at 250-500 GeV is significant
• No experimental photon/electron desorption data exists at such energies
• The interaction region geometry is most complex• Backgrounds in the detector are critical• Push-pull detectors will need special engineering solutions• Real vacuum chamber design (material and detailed designs)
to estimate the wakes• Manufacturing and alignment tolerances - stringent• MPS issues
Depends on the outcome of LC-ABD2 funding request
CI SAC, 23-24 November 200617
ILC BDS : Collimation, crab system, beam dumps
Layout & lattice design has a close link with the other tasks lead by the CI Collimation : Carl Beard Crab system : Peter McIntosh Beam dumps: Rob Appleby
Next two talks
ILC GDE
CI SAC, 23-24 November 200618
The ILC beam dumps
ILC beam dumps and collimators are challenging - high power (18MW @1TeV CM) and short energy deposition showers
No experience with such beam dumps. Designs have been scaled from low power beam dumps
More simulation and prototypes required Using CCLRC’s expertise in high power targets (ISIS, T2K), a
programme lead by CI (Appleby) and CCLRC (Densham) has been initiated. Definition of UK beam dumps programme, consisting of physics
(CI) and engineering (CCLRC) UK contribution to dumps and collimator costing Physics simulation studies
CI SAC, 23-24 November 200619
Future plans : Beam Dumps
The CI (Appleby) will lead physics simulation of dumps and collimators throughout the ILC
Energy depositions Shielding and activation of water dump baseline and collimators
Costing and engineering expertise (CCLRC+CI) Study of only viable alternative to main dump: the Noble gas dumps
(Will seek new funding). Crucial if unknown show-stopper for water dump and alternative needed. Site dependent
Depends on the outcome of LC-ABD2 funding request
CI SAC, 23-24 November 200620
Summary
The CI team has developed a skill base for optics and simulations has made significant contributions to the ILC baseline
and is contributing to the Reference Design Report is very well integrated with the global design effort intends to take a bigger role during the technical
design phase with CCLRC’s engineering expertise
Most of the proposed work depends upon the outcome of LC-ABD2 funding proposal submitted to PPARC