ILC Beam Delivery System Layout and Lattice Design Deepa Angal-Kalinin ASTeC, Cockcroft Institute...

ILC Beam Delivery System Layout and Lattice Design

Deepa Angal-Kalinin

ASTeC, Cockcroft Institute

Cockcroft Institute SAC23-24th November 2006

http://www.lancs.ac.uk/cockcroft-institute/default.htm

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



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



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



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



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



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



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



ILC BDS Layout Changes

15 - 20 mrad

25 mrad

2 - 7 mrad 25 mrad

First ILC Workshop, KEK, November 2004Working hypothesis




Snowmass, August 2005 to Vancouver, July 2006




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




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



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



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



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.




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




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



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



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




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


ILC Beam Delivery System Layout and Lattice Design Deepa Angal-Kalinin ASTeC, Cockcroft Institute...

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