The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear...
Transcript of The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear...
![Page 1: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/1.jpg)
The Future Linear Collider Project
Dean KarlenUniversity of Victoria & TRIUMF
CAP 2004Winnipeg, June 14, 2004
![Page 2: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/2.jpg)
June 14, 2004 The Future Linear Collider Project 2
What is a linear collider?
• Next in the line of high energy e+e- colliders
SLAC/SLC
CERN/LEP
![Page 3: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/3.jpg)
June 14, 2004 The Future Linear Collider Project 3
e+e- colliders at the frontier
year
1980 1990 2000 2010 2020 2030
Cen
tre-o
f-mas
s en
ergy
(GeV
)
0
100
200
300
400
500
600
PETRAPEPTRISTANSLCLEP - ILEP - IILC
![Page 4: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/4.jpg)
June 14, 2004 The Future Linear Collider Project 4
why linear?
Centre-of-mass Energy (GeV)
0 100 200 300 400 500 600
Circ
umfe
renc
e / L
engt
h (k
m)
0
10
20
30
40
50
60
$
circular colliders
linear colliders
2ER ∝
EL∝
A circular 500 GeVmachine would be170 km around andconsume 45 GW
![Page 5: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/5.jpg)
June 14, 2004 The Future Linear Collider Project 5
Physics of a Linear Collider
• Just as LEP/SLC studied electroweak symmetry to high precision, the LC will study electroweak symmetry breaking to high precision:• LEP/SLC firmly established the electroweak theory
• likewise, LEP/SLC could have shown the Standard Model to be incorrect
• the large variety of measurements would have pointed to the new theory
• The LC will either firmly establish the mechanism of EWSB & mass generation,
• or it will provide critical data to point to the new theory
![Page 6: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/6.jpg)
June 14, 2004 The Future Linear Collider Project 6
Legacy of LEP/SLC/Tevatron:• A large number of
precise measurements testing the SM at the level of quantum fluctuations…
![Page 7: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/7.jpg)
June 14, 2004 The Future Linear Collider Project 7
Higgs appears to be within grasp
• From these precision measurements:mH < 240 GeV@ 95% CL
• Direct searchesat LEP:
mH > 114.4 GeV@ 95% CL
![Page 8: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/8.jpg)
June 14, 2004 The Future Linear Collider Project 8
The golden processes
• At LEP the golden processes for studying the electroweak sector were:
• At the LC the golden processes for studying the Higgs sector are:
• LEP beam energies were not sufficiently high enough for these process to occur
−+−+ → WWee0Zee →−+
HZee 0→−+ νν→−+ Hee
![Page 9: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/9.jpg)
June 14, 2004 The Future Linear Collider Project 9
The golden processes
• Cross section vs. Higgs mass
![Page 10: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/10.jpg)
June 14, 2004 The Future Linear Collider Project 10
Higgs production at a LC
![Page 11: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/11.jpg)
June 14, 2004 The Future Linear Collider Project 11
![Page 12: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/12.jpg)
June 14, 2004 The Future Linear Collider Project 12
Recoil mass Ecm = 350 GeVL = 500 fb−1
XHZee −+−+ µµ→→ 00 bbqqHZee →→−+ 00
with 5C fitδmH ~ 50 MeV
![Page 13: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/13.jpg)
June 14, 2004 The Future Linear Collider Project 13
Higgs couplings
• Branching fractions to fermions & bosons:
• confirm(?) its role in mass generation
• distinguish SM fromSUSY Higgs (?)
![Page 14: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/14.jpg)
June 14, 2004 The Future Linear Collider Project 14
Other Higgs properties
• Confirm (?) fundamental properties:
• spin & parity
• total width
• its couplings to Gauge bosons and to itself• confirm its role in EWSB
)()(
WWHBRWWHTotal
H →→Γ
=Γ
![Page 15: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/15.jpg)
June 14, 2004 The Future Linear Collider Project 15
Other precision measurements
• Fermion pair production• sensitive to Z´, W´, R-parity violation, leptoquarks• sensitivity reaches beyond √s
• for example, LC is sensitive to Z´ if mZ´ < 5 -10 √s
• Top mass measurement: δmtop ≈ 100 MeV• W pair production
• a gain by 2 orders in magnitude in the sensitivity to anomalous couplings in the gauge sector
• Return to the Z0 peak and W W threshold• 30 fb−1 at Z0 peak → 109 Z0 in a few months• with 80% (60%) e− (e+) pol. → δsin2θeff ≈ 0.00001
![Page 16: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/16.jpg)
June 14, 2004 The Future Linear Collider Project 16
mtop (GeV)165 170 175 180 185
sin2θ e
ff
0.2300
0.2305
0.2310
0.2315
0.2320
0.2325
SMMSSMNow+LHC+LC+GIGA Z
Now +LHC +LC +Z0,W+
δMW 30 MeV 15 MeV 15 MeV 6 MeV
δsin2θeff 0.00017 0.00017 0.00017 0.00001
δmt 5 GeV 2 GeV 0.1 GeV 0.1 GeV
68% C.L.
![Page 17: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/17.jpg)
June 14, 2004 The Future Linear Collider Project 17
Consensus of our leaders
• (2000-2002) ACFA, ECFA, HEPAP:• The next large accelerator-based project of particle
physics should be a linear collider• (Late 2003) US DOE Office of Science:
• Future Facilities Plan: LC is first priority mid-term new facility for all US Office of Science
• (Jan. 2004) ACFA, ECFA, HEPAP:• The chairs reaffirmed their community’s priorities
for a 500 GeV linear collider operated in parallel with the LHC
![Page 18: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/18.jpg)
June 14, 2004 The Future Linear Collider Project 18
Consensus amongst ourselves
• (Paris announcement): “Over 2600 physicists from around the world have signed a document supporting a high-energy electron-positron linear collider as the next major experimental facility for frontier particle physics research.”
• “Understanding Matter, Energy, Space and Time: the Case for the Linear Collider”• http://sbhep1.physics.sunysb.edu/~grannis/lc_consensus.html
![Page 19: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/19.jpg)
June 14, 2004 The Future Linear Collider Project 19
Linear collider technology
• Two design concepts for a linear collider:• TESLA: led by DESY (Germany)
• lower frequency (1.3 GHz) superconducting cavities• Initially: Ecm= 500 GeV L = 3×1034 cm-2 s-1
• Later: Ecm= 800 GeV L = 5×1034 cm-2 s-1
• Lower wakefields, looser tolerances, higher luminosity
• NLC/GLC: led by SLAC & KEK (US & Japan)• higher frequency (11.4 and 5.7 GHz) warm cavities• Initially: Ecm= 500 GeV L = 2×1034 cm-2 s-1
• Later: Ecm= 1 – 1.5 TeV L = 4×1034 cm-2 s-1
• highest gradients
![Page 20: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/20.jpg)
NLC
SLC
LEP
TESLA
![Page 21: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/21.jpg)
June 14, 2004 The Future Linear Collider Project 21
Accelerator structures
• The heart of the linear collider:
TESLANLC
![Page 22: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/22.jpg)
June 14, 2004 The Future Linear Collider Project 22
Accelerator physics challenges
• technical challenges for a linear collider:• high gradients
• TESLA: TTF has performed according to design gradient• higher gradient cavities now routinely constructed
• NLC: gradients achieved in NLCTA, but damage observed• redesign completed, problem solved
• low emittance• damping ring test facility (ATF at KEK) successful
• small beam spot size (high luminosity)• final focus test facility shows required demagnification
![Page 23: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/23.jpg)
June 14, 2004 The Future Linear Collider Project 23
Beam spot sizes:
• SLC (500 nm)
• FFTB (50 nm)
• TESLA/NLC (2-5 nm)
![Page 24: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/24.jpg)
June 14, 2004 The Future Linear Collider Project 24
Vibration control system
• The small vertical beam sizes (few nm) necessitate an accurate vibration control system for the linear collider magnets near the interaction point.
• Tom Mattison (UBC) is studying the feasibility of a 10 m baseline laser interferometer to monitor and control the vibration of heavy objects at the nanometer scale
![Page 25: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/25.jpg)
June 14, 2004 The Future Linear Collider Project 25
Linear collider detector concepts
![Page 26: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/26.jpg)
June 14, 2004 The Future Linear Collider Project 26
Linear collider detector challenges
• Compared to LHC, the LC environment is much less severe, but the performance requirements are much more demanding:
• Vertexing: σ ~ 5 µm ⊕ 10 µm/(p sin3/2 θ)• 1/5 rbeampipe, 1/30 pixel area, 1/30 thickness c.f. LHC
• Tracking: σ(1/pt) ~ 5 ×10-5 GeV-1
• 1/10 of LHC. 1/6 material in tracking volume
• Jet energy: σE ~ 0.3 √E• 1/200 granularity of calorimeter c.f. LHC
![Page 27: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/27.jpg)
June 14, 2004 The Future Linear Collider Project 27
Linear collider detector challenges
• Example: Higgs recoil mass
σ(1/pt) ~ 5 ×10-5 GeV-1
is necessary!
![Page 28: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/28.jpg)
June 14, 2004 The Future Linear Collider Project 28
Vertex detector
• charm tagging (light Higgs, W) is a challenge• prime motivator for bringing in vertex detector as
close as possible• leading candidate: CCDs (success at SLD)
![Page 29: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/29.jpg)
June 14, 2004 The Future Linear Collider Project 29
Central tracker
![Page 30: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/30.jpg)
June 14, 2004 The Future Linear Collider Project 30
Central tracking designs
• Leading candidate: Time projection chamber
![Page 31: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/31.jpg)
June 14, 2004 The Future Linear Collider Project 31
TPC readout technology choices
• Gas Electron Multiplier (GEM)• negligible E x B distortions: improved resolution• narrower and faster signals: improved 2 particle
separation• reduced ion
feedback
30 cm drift2mm × 7 mm pads
![Page 32: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/32.jpg)
June 14, 2004 The Future Linear Collider Project 32
Magnetic field tests
TRIUMF
DESY
B=0T B=0.9T B=2.5T B=4.5T
![Page 33: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/33.jpg)
June 14, 2004 The Future Linear Collider Project 33
Transverse resolution
• For fields above 1.5 T achieve 100 µmtra
nsve
rse
reso
lutio
n (m
m)
drift time (50 ns bins) 300 mm30 mm
B = 0
B = 0.9 T
B = 1.5 T
![Page 34: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/34.jpg)
June 14, 2004 The Future Linear Collider Project 34
Calorimeter concepts
![Page 35: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/35.jpg)
June 14, 2004 The Future Linear Collider Project 35
Jet Energy Resolution Requirements
• Goal: distinguish W and Z in their hadronic modes• requires: jet energy resolution,
, νννν ZZeeWWee →→ −+−+
EE %30≈σexample:
E%60 E%30
![Page 36: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/36.jpg)
June 14, 2004 The Future Linear Collider Project 36
Moliere radius (Iron vs. Tungsten)
Iron
Tungsten(many images courtesy H.Videau)
![Page 37: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/37.jpg)
June 14, 2004 The Future Linear Collider Project 37
Status of Linear Collider Planning
• A global review of accelerator technologies (2003) concluded that both LC technologies are feasible
• ICFA has set up process to move forward:• Technology recommendation panel to report before
end of 2004• Global design effort to begin once report released• Full detector costings to be prepared next year
LoIs/CDRs to follow in 2007• Site selection possibly as early as 2008,
construction begins before end of decade• First beams possibly by 2015
![Page 38: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/38.jpg)
June 14, 2004 The Future Linear Collider Project 38
Victoria Linear Collider Workshop
• Part of a series of N. American regional meetings held twice a year
• Sign up! www.linearcollider.ca/victoria04• Over 100 registered so far…• Thanks to our sponsors: TRIUMF, IPP, UVic,
NSERC
![Page 39: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/39.jpg)
June 14, 2004 The Future Linear Collider Project 39
TRIUMF bid to host Central Team
• Canada is neutral territory, Vancouver well situated geographically• ILCSC asking labs for EOIs to host 15 – 30
accelerator physicists over the next 4 years• would add expertise and
recognition to TRIUMF• EOI in preparation,
due July 1
ILCSC
CentralDesignTeam
Asia Regional Team
N. American Regional Team
EuropeanRegional Team
Participating Labsand Universities
Participating Labsand Universities
Participating Labsand Universities
![Page 40: The Future Linear Collider Project - University of Victoria...June 14, 2004 The Future Linear Collider Project 3 e+e-colliders at the frontier year 1980 1990 2000 2010 2020 2030 Centr](https://reader033.fdocuments.net/reader033/viewer/2022060522/605106b9135fea2fac2713cb/html5/thumbnails/40.jpg)
June 14, 2004 The Future Linear Collider Project 40
Summary• The physics case for a Linear Collider is very strong• The technology for the machine and experiments is in
hand…• Movement towards a single global proposal and
experimental collaborations• Canada may be playing an important role in the
accelerator design
• To follow the developments, visit:
http://www.linearcollider.ca