The Linear Collider:
a UK perspective
Grahame A. Blair
Edinburgh, 8th February 2006
•
•
•
•
•
•
Introduction to the machine
Detectors
UIK activities
Timescales
Some key Physics (time ?)
Summary
www.linearcollider.org
Superconducting Niobium Cavities
Y. Kokoya, GDE Frascati 2005
Generic Linear Collider
Damping Rings
Main Linac (RF)
Beam Delivery System
Particle Sources
< ~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+
Schulte
• Increase in luminosity (×~2)
• Beamstrahlung  Lumi. Spectrum
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
Cross section
(pb)
Mtop=175 GeV
100 fb-1 per
point
Statistical
Precision
~0.05 GeV
0.02%
Etot(GeV)
Martinez et al.
Initial State
e-R
e+L
e-R
e-R
R
R
• W-production suppressed
• s-wave production of charginos ~  sharp threshold
• Specific polarisations for specific couplings (eg SUSY)
http://www.ippp.dur.ac.uk/~gudrid/power/
• s-wave production of selectrons ~  sharp threshold
• Direct production of higgs
Worldwide LC Studies
http://blueox.uoregon.edu/~lc/wwstudy/
http://blueox.uoregon.edu/~lc/alcpg/
http://acfahep.kek.jp/
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/
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 IP
It is possible that 1 IP will become the baseline –
The physics community needs to make its case clear
Adapted from Y. Kokoya, GDE Frascati 2005
SID
Design philosophy
• Aim for SiW calorimeter
with best possible
resolution
• Keep radius small to
make this affordable
• Compensate by high Bfield (5 T) and very
precise tracking (Si)
• Fast timing of Silicon to
suppress background
LDC
Design philosophy
• Fine resolution
calorimeter for particle
flow
• Gaseous tracking for
High tracking efficiency
and redundancy
• Large enough radius
and high enough B-field
(B=4 T) to get required
momentum resolution
GLD
Design philosophy
• Large radius for
particle-flow
optimisation
• Gaseous tracking for
High tracking efficiency
and redundancy
• Fine grained
scintillator-tungsten
calorimeter
• Moderate B-field (3 T)
Energy Flow in Jets
Some processes where WW and ZZ need to
be separated without beam constraints.
Requires ΔE/E~30%/E
E 30 %

E
E
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/RHUL
Cockroft: 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
Full simulations
Backgrounds
~3km
Optimisation
Precision Diagnostics
• Energy
• Polarisation
• Luminosity
2 mrad Optics Design
SLAC-BNL-UK-France
Task Group
O.Napoly, 1997
QF1
pocket coil quad : C. Spencer
 Final Focus and extraction line optimized simultaneously
 Quadrupoles and sextupoles in the FD optimized to
 cancel FF chromaticity
 focus the extracted beam
D. Angal-Kalinin
BDSIM
Beamlines are built
of modular
accelerator
components
Full simulation
of em showers
All secondaries
tracked
Screenshot of an IR Design in BDSIM
BDS: Muon Trajectories
Concrete tunnel 2m radius
BDS
View from top
Multi-Seed Luminosity Studies
with the ILC Simulation Model
LUMI Feedback
Optimisation (Position +
Angle)
350 GeV CME
25
 = 1.6747  0.067286
20
15
3
x 10
34
5
0
1.5
1.55
1.6
1.65
1.7
1.75
-2 -1
34
Luminosity / cm s  10
18
500 GeV CME
1.8
1.85
 = 2.8788  0.075445
16
Luminosity / cm-2s-1
10
2
ANG + IP Fast
Feedback
1
14
12
0
10
8
0
100
200
300
Bunch #
400
500
600
6
4
2
0
2.7
2.75
2.8
2.85
2.9
2.95
-2 -1
34
Luminosity / cm s  10
3
3.05
G. White
FONT3 installation on ATF
beamline
BPM processor board
FEATHER
kicker
Amplifier/FB board
ATF beamline installation
June 05
37
P. Burrows
Bunch-Bunch Interaction Simulations
TESLA
parameters
PINIT=1.0
low Q
parameters
PINIT=1.0
Before interaction
During interaction
After interaction
Laser-wire: Principle
Laserwire - PETRA
+ UCL
11.2.05
System recently upgraded
ATF-LW Vacuum Chamber
Built at
Oxford
DO +
Workshop
Vacuum
Tested
At DL
Superconducting Helical
Undulator
Superconducting bifilar helix
First (20 period) prototype constructed (RAL)
Parameters
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
Wakefields
Change in beamline aperture
θ
• 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
sz ~ 300m – ILC nominal
sy ~ 100mm (Frank/Deepa design)
Magnet mover, y range = 1.4mm, precision = 1m
N. Watson
1
Side view
Beam view
a
r=1/2 gap
As per last set in Sector 2, commissioning
h=38 mm
a=324mrad
r=1.4mm
2
Extend last set, smaller r, resistive WF in Cu
3
a=324mrad
r=2.0mm
38 mm
Slot
a=324mrad
r=1.4mm
L=1000 mm
4
cf. same r, tapered
a=p/2rad
r=4.0mm
7mm
Overview of LC Projects
Collimation Training+ General
Lattice design + Simulation
2%
5%
8%
Crab Cavity
13%
Beam Transport +
Backgrounds
9%
Polarised Positron
Undulator
8%
Laser-wire
15%
FONT+ BPM Spectrometry
17%
Longitudinal Profile
7%
LiCAS
15%
Polarisation
1%
Essentially independent of Linac-technology
The GDE Plan and Schedule
2005
2006
2007
2008
2009
2010
Global Design Effort
Project
Baseline configuration
Reference Design
Funding
Technical Design
regionial coord
globally coordinated
sample sites
ICFA / ILCSC
expression ofSiting
interest
FALC
ILC R&D Program
Hosting
International Mgmt
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
excitation
curve
 determine
spin
20
fb-1
per point
TESLA TDR
Higgs Mass
mh=120 GeV
hZ  bb qq
0
TESLA TDR
mh=150 GeV


hZ  W W qq
0
500 fb-1 at √s=350 GeV
Higgs Recoil Mass +
h
Etot= 2 Ebeam
Ptot = 0
500 fb-1, √s=350 GeV
TESLA TDR
Z
-
Higgs Mass Precision
Mh(GeV)
120
120
120
150
150
150
180
180
180
Channel
llqq
qqbb
combined
ll recoil
qq WW
combined
ll recoil
qq WW
combined
Mh (MeV)
70
50
40
90
130
70
100
150
80
500 fb-1, √s=350 GeV
Higgs Branching Ratios
For mh=120 GeV
h→
bb
cc
gg
ττ
BR/BR
0.024
0.083
0.055
0.050
Battaglia
Higgs Potential
1 4
V = v h  vh  h
4
2
2
3
λ/λ=0.22 (statistical) for mh=120 GeV
Requires 1000 fb-1
Muehleittner et al.
Supersymmetry
Supersymmetry
To prove existence of SUSY:
• 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
Needs accurate measurements of
Mass spectra, cross-sections, BRs,
Angular distributions, polarisation
SUSY Reference Points
Work with Sugra SPS1a:
M1/2=250 GeV
M0=100 GeV
A0=-100 GeV
sign()=+
tan=10
√s=1TeV
√s=500 GeV
Higgs
gauginos
sleptons
squarks
Mass Measurements
Threshold scans
chargino ~ 
slepton ~ 3
eR eL  1 1     10 10
100 fb-1
m  = 181.5  0.55
Martyn et al.
Endpoint Measurements
√s=400 GeV
L=200 fb-1
 Both
sparticle masses
Martyn
e-e- running
Including width effects
m~50 MeV for 4 fb-1
Freitas, Miller, Zerwas
Feng, Peskin
Luminosity Budget
• Several running modes required.
• Input will already exist from LHC
Grannis et al.
Model-Independent Extrapolation
Renormalisation Group Eqns
Pi
= f ( Pi , m j , g k ,...)
Q
•Measure complete spectrum
•Extract soft SUSY parameters at EW scale
•Input measured masses, couplings into RGEs
•Extrapolate model independently to high scales
Extrapolation: gaugino
Mi-1
GeV
Porod, Zerwas, GB
Extrapolations mass terms
Mi2
mSUGRA
structure
reconstructed
Fine structure?
Q (GeV)
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
LHC
Cosmology
links
WMAP
LC
Trodden, Birkedal
LCWS04 (Adapted)
Physics Summary
• The linear collider will provide high precision
measurements at high energy: Masses, chiral
couplings, branching ratios…
• Together with LHC data, LC allows modelindependent 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!