The Linear Collider: a UK perspective

• Introduction to the machine• Detectors• UIK activities• Timescales• Some key Physics (time ?)• Summary

Grahame A. BlairEdinburgh, 8th February 2006

www.linearcollider.org

Superconducting Niobium Cavities

Y. Kokoya, GDE Frascati 2005

Generic Linear Collider

Damping Rings

Particle Sources

Main Linac (RF)Beam Delivery System

< ~20 km > < ~4 km >

DR Circumf. Baseline: 6km

Damping Process

Y. Kokoya, GDE Frascati 2005

A Possible Layout

• Approximately follow earth’s curvature• Upgrade path to ~1 TeV

LC for Physics Purposes:

• e+e- collisions with √s tuneable 0.5 – O(1) TeV• e-e- mode.• Polarisation: e- 80% (L/R); e+ 60% (?).• Possibility to run at √s ~ 90 – 160 GeV (“GigaZ”)• Luminosity 3-6.1034 cm-2 s-1 specific

analyses can assume up to about 1 ab-1

Also possible/important; Compton scattering to

produce or e

Bunch Interactions

e+ e-

• Increase in luminosity (×~2)

• Beamstrahlung Lumi. Spectrum

Schulte

Luminosity Spectrum

• sharp peak• approx same as ISR (tuned) – few % in tail for 0.5-1 TeV machines

TESLA TDR

Precision Measurement of the Top Mass

Precision measurement of fundamental particle properties

The top quark is the heaviest: most sensitive to new physics

Etot(GeV)

Cross section (pb)

Statistical Precision ~0.05 GeV0.02%

Mtop=175 GeV100 fb-1 per

point

Martinez et al.

Initial State

e-R e+

L• W-production suppressed• s-wave production of charginos ~ sharp threshold• Specific polarisations for specific couplings (eg SUSY)

e-R e-

R• s-wave production of selectrons ~ sharp threshold

R R• Direct production of higgs

http://www.ippp.dur.ac.uk/~gudrid/power/

Worldwide LC Studies

http://blueox.uoregon.edu/~lc/wwstudy/

http://acfahep.kek.jp/

http://blueox.uoregon.edu/~lc/alcpg/

Worldwide studies (2)

http://www.desy.de/conferences/ecfa-lc-study.html

http://clicphysics.web.cern.ch/CLICphysics/

The Detectors

http://physics.uoregon.edu/~ lc/wwstudy/concepts/

Adapted from Y. Kokoya, GDE Frascati 2005

Number of IPs• 2 IPs + 2 detectors is the baseline.

• The cost of 2nd IP (beamline + exp.hall) corresponds to the energy 14-19% of 500GeV (change of tunnel cost not included).

Caveats: Total cost estimation from 3 regions agree well but the cost of individual components scatter in wide ranges.

• This means 405-430 GeV LC with 2IP is comparable in cost

with 500GeV LC with 1 IPIt is possible that 1 IP will become the baseline –The physics community needs to make its case clear

Design philosophy• Aim for SiW calorimeterwith best possible resolution• Keep radius small to make this affordable• Compensate by high B-field (5 T) and very precise tracking (Si)• Fast timing of Silicon to suppress background

SID

Design philosophy• Fine resolution calorimeter for particleflow• Gaseous tracking forHigh tracking efficiency and redundancy• Large enough radiusand high enough B-field(B=4 T) to get requiredmomentum resolution

LDC

Design philosophy• Large radius for particle-flow optimisation• Gaseous tracking forHigh tracking efficiency and redundancy• Fine grained scintillator-tungsten calorimeter• Moderate B-field (3 T)

GLD

Energy Flow in JetsSome processes where WW and ZZ need to be separated without beam constraints.

Requires ΔE/E~30%/E

EE

E %30

EE

E %30

S. Worm, LCUK meeting, Oct 05

Particle/Machine Physics

• The LC will be a very challenging machine• Particle physicists are taking part in

machine studies• Beam diagnostics and control• Background estimates• Design studies• The particle physics programme now goes

beyond “what comes out of the IP”.

UK funding for accelerator science for particle physics 2004 - 2007

UK funding agency, PPARC, secured from Govt. £11M for ‘accelerator science’ for particle physics, spend period April 04 – March 07

Called for bids from universities and national labs; large consortia were explicitly encouraged

LC-Beam Delivery £9.1M + 1.5M CCLRC UKNF £1.9M 2 university-based accelerator institutes: John Adams: Oxford/RHULCockroft: Liverpool, Manchester, Lancaster, NW dev. agency.

Funding period ends in 2007; new bid will be finalised in July 2006.

LC-ABD Collaboration

• Bristol • Birmingham • Cambridge• Dundee • Durham • Lancaster• Liverpool • Manchester • Oxford • QMUL• RHUL• University College, London • Daresbury and Rutherford-Appleton Labs;

41 post-doctoral physicists (faculty, staff, research associates) + technical staff + graduate students

UK Interests:Beam Delivery System

Beam Delivery System

~3km

Full simulations

BackgroundsOptimisationPrecision Diagnostics• Energy• Polarisation• Luminosity

Final Focus and extraction line optimized simultaneously Quadrupoles and sextupoles in the FD optimized to

cancel FF chromaticity focus the extracted beam

SLAC-BNL-UK-France Task Group

QF1

pocket coil quad : C. Spencer

O.Napoly, 1997

2 mrad Optics Design

D. Angal-Kalinin

BDSIMBeamlines are builtof modular accelerator components

Full simulationof em showers

All secondariestracked

Screenshot of an IR Design in BDSIM

BDS: Muon Trajectories

BDS

Concrete tunnel 2m radius

View from top

Multi-Seed Luminosity Studies with the ILC Simulation Model

1.5 1.55 1.6 1.65 1.7 1.75 1.8 1.850

5

10

15

20

25

Luminosity / cm-2 s-1 1034

= 1.6747 0.067286

2.7 2.75 2.8 2.85 2.9 2.95 3 3.050

2

4

6

8

10

12

14

16

18

Luminosity / cm-2 s-1 1034

= 2.8788 0.075445

350 GeV CME

500 GeV CME

0 100 200 300 400 500 6000

1

2

3x 10

34

Bunch #

Lu

min

os

ity

/ c

m-2

s-1

ANG + IP Fast Feedback

LUMI Feedback Optimisation (Position +

Angle)

G. White

37

FONT3 installation on ATF beamline

BPM processor board

Amplifier/FB board

FEATHERkicker

ATF beamline installation June 05

P. Burrows

Bunch-Bunch Interaction Simulations

Before interaction During interaction After interaction

TESLA parameters

low Q parameters

PINIT=1.0

PINIT=1.0

Laser-wire: Principle

Laserwire - PETRA+ UCL

11.2.05

System recently upgraded

ATF-LW Vacuum Chamber

Built atOxfordDO +Workshop

VacuumTestedAt DL

Superconducting Helical Undulator

Superconducting bifilar helix

First (20 period) prototype constructed (RAL)

Design field 0.8 T

Period 14 mm

Magnet bore 4 mm

Winding bore 6 mm

Winding section 4 4 mm2

Overall current density 1000 A/mm2

Peak field (not on-axis) 1.8 T

Cut-away showing winding geometry

Parameters

Wakefields

θChange in beamline aperture

• Wake-fields from the head of the bunch can disturb the tail• Wake-fields from earlier bunches can disturb later ones• (such effects can also be useful – eg. Smith-Purcell radiation)

Wakefield box

ESA z ~ 300m – ILC nominaly ~ 100mm (Frank/Deepa design)

Magnet mover, y range = mm, precision = 1m

1500mm

N. Watson

Slot Side view Beam view

1

=324mrad

r=2.0mm

2

324mrad

r=1.4mm

3

324mrad

r=1.4mm

4

=/2rad

r=4.0mm

h=38 mm

38

mm

L=1000 mm

7mm

r=1/2 gap

As per last set in Sector 2, commissioningAs per last set in Sector 2, commissioning

Extend last set, smaller r, resistive WF in CuExtend last set, smaller r, resistive WF in Cu

cf. same r, taperedcf. same r, tapered

Lattice design + Simulation8%

Beam Transport + Backgrounds

9%

Laser-wire15%

Longitudinal Profile7%

Polarisation1%

LiCAS15%

FONT+ BPM Spectrometry17%

Polarised Positron Undulator

8%

Crab Cavity13%

Collimation5%

Training+ General2%

Overview of LC Projects

Essentially independent of Linac-technology

The GDE Plan and Schedule

2005 2006 2007 2008 2009 2010

Global Design Effort Project

globally coordinated

Baseline configuration

Reference Design

ILC R&D Program

Technical Design

FALC

Siting

International Mgmt

expression of interestsample sites

regionial coord

ICFA / ILCSC

Funding

Hosting

Machine Summary

• The ILC is now being defined.• The Baseline is under “Configuration Control”• Global Design Effort is in place, with a very

active programme aiming at a Reference Design Report at end of 2006.

• UK is involved in two detector projects and an exciting range of accelerator R&D.

• The next round of accelerator-related bids are due for this summer.

a great time to get involved.

ILC Physics:

Higgs Production

For Mh~120 GeV, 500 fb-1, √s=350 GeV

80,000 Higgs

TESLA TDR

Higgs Spin

Threshold excitationcurve

determine spin

20 fb-1 per pointTESLA TDR

Higgs Mass

mh=120 GeV mh=150 GeV

qqbbhZ 0 qqWWhZ 0

500 fb-1 at √s=350 GeV

TESLA TDR

Higgs Recoil Mass

h Z

+

-

Etot= 2 Ebeam

Ptot = 0

500 fb-1, √s=350 GeV

TESLA TDR

Higgs Mass PrecisionMh(GeV) Channel Mh (MeV)

120 llqq 70

120 qqbb 50

120 combined 40

150 ll recoil 90

150 qq WW 130

150 combined 70

180 ll recoil 100

180 qq WW 150

180 combined 80

500 fb-1, √s=350 GeV

Higgs Branching Ratios

h→ BR/BR

bb 0.024

cc 0.083

gg 0.055

ττ 0.050

For mh=120 GeV

Battaglia

Higgs Potential

4322

4

1hvhhvV

λ/λ=0.22 (statistical) for mh=120 GeVRequires 1000 fb-1

Muehleittner et al.

Supersymmetry

Supersymmetry

• Need to discover the SUSY partners

• Every SM has a superpartner

• Spins of SM/SUSY partner differ by ½

• Identical gauge quantum numbers

• Identical couplings

To prove existence of SUSY:

Needs accurate measurements of

Mass spectra, cross-sections, BRs,

Angular distributions, polarisation

SUSY Reference PointsWork with Sugra SPS1a:M1/2=250 GeV M0=100 GeVA0=-100 GeV sign()=+ tan=10

Higgs gauginos sleptons squarks

√s=500 GeV

√s=1TeV

Mass Measurements

Threshold scanschargino ~ slepton ~ 3

55.05.181 m

01

0111 LRee

100 fb-1

Martyn et al.

Endpoint Measurements

√s=400 GeVL=200 fb-1

Both sparticle masses

Martyn

e-e- running

Freitas, Miller, Zerwas

Feng, Peskin

Including width effects

m~50 MeV for 4 fb-1

Luminosity Budget

• Several running modes required.• Input will already exist from LHC

Grannis et al.

Model-Independent Extrapolation

,...),,( kjii gmPfQ

P

Renormalisation Group Eqns

•Measure complete spectrum•Extract soft SUSY parameters at EW scale•Input measured masses, couplings into RGEs•Extrapolate model independently to high scales

Extrapolation: gauginoMi

-1

GeVPorod, Zerwas, GB

Mi2

Q (GeV)

Extrapolations mass terms

mSUGRAstructurereconstructed

Fine structure?

GigaZ• The LC can also provide high luminosity running at the Z-pole and at W-threshold• Approximately 100 fb-1 per year• Needs specific linac bypass design

TESLA TDR

Concrete example - point B’ of “updated benchmark” points:

mSUGRA w/ tan = 10, sgn()=+1, m0=57, m1/2=250, A0=0

Trodden, Birkedal LCWS04 (Adapted)

WMAP

LC

LHC

Cosmologylinks

Physics Summary

• The linear collider will provide high precision measurements at high energy: Masses, chiral couplings, branching ratios…

• Together with LHC data, LC allows model-independent extrapolations to very high energy scales.

• Exciting overlap with LHC analyses complementary searches, constraints in cascades… see G.W talk

• Links to cosmology• Long term programme from O(1) TeV, GigaZ, ,

multi TeV.• An exciting time ahead!