Dean Karlen University of Victoria & TRIUMF APS NW Section ... · Dean Karlen University of...

Dean KarlenUniversity of Victoria & TRIUMF

APS NW Section Meeting 2005Victoria, Canada

May 13, 2005May 13, 2005 The International Linear Collider / Dean Karlen, UVic & TRIUMFThe International Linear Collider / Dean Karlen, UVic & TRIUMF 22

The International Linear ColliderThe International Linear Collider

Next in the line of Next in the line of ee++ee-- colliderscolliders at the high at the high energy frontier of particle physicsenergy frontier of particle physics

SLAC/SLC

CERN/LEP


year

1980 1990 2000 2010 2020 2030

Cen

tre-o

f-mas

s en

ergy

(GeV

)

100

1000PETRAPEPTRISTANSLCLEP - ILEP - IIILCILC - II

ee++ee−− colliderscolliders at the frontierat the frontier

Z0 threshold

W+W− threshold

tt thresholdHZ0 threshold?

dark matter threshold?


Why Linear?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


““High EnergyHigh Energy”” Particle PhysicsParticle Physics

Increasing the collision energy allows for new Increasing the collision energy allows for new fundamental processes to be observed and probes fundamental processes to be observed and probes matter and space at smaller distance scalesmatter and space at smaller distance scalesThe two main HEP tools in the past 3 decades: proton The two main HEP tools in the past 3 decades: proton colliderscolliders and electron and electron colliderscolliders

protons are more easily accelerated to high energies because protons are more easily accelerated to high energies because they radiate less synchrotron radiation in a circular acceleratothey radiate less synchrotron radiation in a circular acceleratorrelectron interactions are more easily studied because the initiaelectron interactions are more easily studied because the initial l state is simplerstate is simplerboth tools have been essential to advance our knowledge of both tools have been essential to advance our knowledge of fundamental physics:fundamental physics:

discoveries of new phenomenadiscoveries of new phenomenatesting models that account for these phenomenatesting models that account for these phenomena


Interplay of proton and electron Interplay of proton and electron colliderscolliders

proton proton colliderscolliders electron electron colliderscolliders1980’s: SppS• discovery of the Z0, W+, W−

1990’s: LEP/SLC• detailed investigation

of Z0, W+, W− production• indirect influence of top

quark – definitive predictionof its mass

• indirect influence of Higgsboson – mass estimated

2010’s: ILC• detailed study of the Higgs• detailed study of dark matter

2000’s: LHC• discovery of the Higgs boson?• discovery of the dark matter

particle?

1990’s: Tevatron• discovery of the top quark


Linear Collider Physics: ILinear Collider Physics: IThe electromagnetic and weak forces are now known to The electromagnetic and weak forces are now known to arise from a unifying symmetry in naturearise from a unifying symmetry in nature

This was most precisely demonstrated by the LEP/SLC This was most precisely demonstrated by the LEP/SLC experimentsexperiments

The symmetry between the electromagnetic and weak The symmetry between the electromagnetic and weak forces is broken (weak bosons are heavy)forces is broken (weak bosons are heavy)

The Higgs model is an ad hoc component of the Standard Model The Higgs model is an ad hoc component of the Standard Model that describes why the symmetry is brokenthat describes why the symmetry is broken

it seems to work for low energy processes but falls apart at it seems to work for low energy processes but falls apart at high energieshigh energies

the model predicts that a new particle exists (the Higgs the model predicts that a new particle exists (the Higgs boson) with definite propertiesboson) with definite properties

the ILC will be able to make a large variety of precision the ILC will be able to make a large variety of precision measurements that will provide critical data to understand measurements that will provide critical data to understand the real nature of electroweak symmetry breakingthe real nature of electroweak symmetry breaking


The golden processesThe golden processes

At LEP, the golden processes for studying the At LEP, the golden processes for studying the electroweak sector were:electroweak sector were:

At the ILC, the golden processes for At the ILC, the golden processes for studying the Higgs sector are:studying the Higgs sector are:

LEP beam energies were not sufficiently high enough LEP beam energies were not sufficiently high enough for these process to occurfor these process to occur

0Zee →−+ −+−+ → WWee

HZee 0→−+νν→−+ Hee


Higgs production at a LCHiggs production at a LC


Linear Collider Physics: IILinear Collider Physics: II

From astrophysical observations, it appears that From astrophysical observations, it appears that ~25% of the Universe is ~25% of the Universe is ““Dark MatterDark Matter””

neutral, stable, cold (massive), nonneutral, stable, cold (massive), non--baryonicbaryonicnew physics new physics –– a new (conserved) quantum number?a new (conserved) quantum number?production and detection of dark matter particles at production and detection of dark matter particles at future future colliderscolliders would be very exciting!would be very exciting!

One possible explanation arises in a model of One possible explanation arises in a model of particle physics known as particle physics known as ““supersymmetrysupersymmetry””

in this model, all particles have in this model, all particles have supersymmetricsupersymmetricpartners (partners (sparticlessparticles) ) –– the lightest would be stablethe lightest would be stable


Dark Matter at the ILC?Dark Matter at the ILC?

There are strong hints that the dark matter There are strong hints that the dark matter could be produced at the ILCcould be produced at the ILC

SupersymmetricSupersymmetric models generally favour models generally favour sparticlesparticlemasses below ~ 1 masses below ~ 1 TeVTeVThe dark matter density is consistent with a neutral The dark matter density is consistent with a neutral particle having particle having ““weakweak”” strength couplingsstrength couplings

The LHC has the best chance to discover the The LHC has the best chance to discover the supersymmetricsupersymmetric particlesparticles

the signature: a large amount of energy is taken the signature: a large amount of energy is taken away by invisible particlesaway by invisible particleschallenging study at LHC: initial state is not well challenging study at LHC: initial state is not well known, final state involves at least two DM particlesknown, final state involves at least two DM particles

The ILC offers the ability to study them in detailThe ILC offers the ability to study them in detail


Consensus in the HEP communityConsensus in the HEP community

Given the broad range of fundamental physics Given the broad range of fundamental physics questions that it addresses, the HEP community questions that it addresses, the HEP community sees the ILC to be the next step that is needed sees the ILC to be the next step that is needed to advance the fieldto advance the field

over 2700 particle physicists have signed a document over 2700 particle physicists have signed a document supporting the physics potential of the ILCsupporting the physics potential of the ILCthe US DOE places the ILC as the top priority for midthe US DOE places the ILC as the top priority for mid--term new facilities term new facilities committees for future accelerators in Asia and Europe committees for future accelerators in Asia and Europe also put the ILC as their first priorityalso put the ILC as their first priority


Building the ILCBuilding the ILC

Over the past decade, significant effort has gone Over the past decade, significant effort has gone into the necessary R&D to design a linear into the necessary R&D to design a linear collider to reach the required specifications:collider to reach the required specifications:

Energy: 500 Energy: 500 GeVGeV –– 1000 1000 GeVGeVrequires RF cavities with a large accelerating requires RF cavities with a large accelerating gradient (>30 gradient (>30 MeV/mMeV/m))

Luminosity (density of collisions): > 10Luminosity (density of collisions): > 103434 cmcm−−2 2 ss−−11

requires large numbers of electrons (> 10requires large numbers of electrons (> 101010) ) packed into very small bunches (< 500 x 5 nmpacked into very small bunches (< 500 x 5 nm22) ) brought into collision at high rate (> 10brought into collision at high rate (> 1044 ss−−11))


Building the ILCBuilding the ILC

Two complete designs were prepared that met Two complete designs were prepared that met these requirementsthese requirements

the key feature distinguishing them was the nature of the key feature distinguishing them was the nature of the RF accelerating cavities:the RF accelerating cavities:

US + Japan US + Japan –– high frequency, room temperaturehigh frequency, room temperatureGermany Germany –– lower frequency, superconductinglower frequency, superconducting

international technical review found both suitableinternational technical review found both suitable

In 2004, an international committee charged In 2004, an international committee charged with selecting one accelerating technology chose with selecting one accelerating technology chose the superconducting optionthe superconducting option

the worldthe world’’s labs now work toward a single designs labs now work toward a single design


Superconducting accelerator cavitiesSuperconducting accelerator cavities


Possible Tunnel LayoutPossible Tunnel Layout

Need a 30 km tunnel to reach energy goalNeed a 30 km tunnel to reach energy goal


Damping ring R&DDamping ring R&D

ATF facility in Japan hasATF facility in Japan hasdemonstrated necessarydemonstrated necessaryreduction in reduction in emittanceemittance


Linear collider detector conceptsLinear collider detector concepts

LDC

SiD

GLD


Linear collider detector challengesLinear collider detector challenges

Compared to the LHC, the ILC environment is Compared to the LHC, the ILC environment is much less severe, but the performance much less severe, but the performance requirements are much more demanding:requirements are much more demanding:

VertexingVertexing: : σσipip ~ 5 ~ 5 μμm m ⊕⊕ 10 10 μμm/(p sinm/(p sin3/23/2 θθ))1/5 1/5 rrbeampipebeampipe, 1/30 pixel area, 1/30 thickness c.f. LHC, 1/30 pixel area, 1/30 thickness c.f. LHC

Tracking: Tracking: σσ(1/p(1/ptt) ~ 5 ) ~ 5 ××1010--55 GeVGeV--111/10 of LHC. 1/6 material in tracking volume1/10 of LHC. 1/6 material in tracking volume

CalorimetryCalorimetry: : σσEE ~ 0.3 ~ 0.3 √√EE1/200 granularity of calorimeter c.f. LHC1/200 granularity of calorimeter c.f. LHC


Vertex detectorVertex detector

Precise Precise SiSi pixel detectors near the collision point pixel detectors near the collision point to detect the displaced vertex of particles coming to detect the displaced vertex of particles coming from the decay of a particle with a very short lifetime from the decay of a particle with a very short lifetime (less than 10(less than 10−−1212 s)s)

examples: charm, bottom quarks, examples: charm, bottom quarks, tautau leptonsleptons


Tracking detectorTracking detector


Tracking challengeTracking challenge

Example: Higgs recoil massExample: Higgs recoil mass

σ(1/pt) ~ 5 ×10-5 GeV-1is necessary!


Tracking technologyTracking technology

Two technologies considered: Two technologies considered: SiSi (few precise (few precise measuring layers) or gas (continuous) measuring layers) or gas (continuous) Gas tracker: Time projection chamberGas tracker: Time projection chamber

to achieve resolution goal requires an advance to achieve resolution goal requires an advance in TPC technologyin TPC technologysee talk by see talk by GabeGabeRosenbaum thisRosenbaum thisafternoon (B2)afternoon (B2)


CalorimeterCalorimeter


Jet Energy Resolution RequirementsJet Energy Resolution Requirements

Goal: distinguish W and Z when they decay into quarksGoal: distinguish W and Z when they decay into quarksrequires excellent jet energy resolution, requires excellent jet energy resolution, σσEE ~ 30% ~ 30% √√EE

, νννν ZZeeWWee →→ −+−+example:

E%30E%60


Calorimeter technologyCalorimeter technology

To reach resolution goal requires narrow To reach resolution goal requires narrow showers and fine segmentation: showers and fine segmentation: SiSi + W + W

Iron Tungsten


Bringing the ILC into realityBringing the ILC into reality

An international structure has been set up to An international structure has been set up to complete the global design of the ILCcomplete the global design of the ILC

Leader of the Global Design Effort: Barry Leader of the Global Design Effort: Barry BarishBarish

ILCSC

GlobalDesignEffort

Asia Regional Team

N. American Regional Team

EuropeanRegional Team

Participating Labsand Universities




ILC timescaleILC timescale2005:2005:

GDE put togetherGDE put togetherDetector concept groups in formationDetector concept groups in formation

2006:2006:GDE to prepare the ILC Conceptual DesignGDE to prepare the ILC Conceptual DesignDetector concept groups to prepare outlinesDetector concept groups to prepare outlines

2007/8:2007/8:GDE to complete the ILC Technical DesignGDE to complete the ILC Technical DesignDetector concepts complete Conceptual DesignsDetector concepts complete Conceptual Designs

2008/9:2008/9:Site selection, government approvals, begin constructionSite selection, government approvals, begin constructionDetector collaborations formDetector collaborations form

2015?:2015?:earliest start of experimental programearliest start of experimental program


SummarySummary

The physics case for a Linear Collider is very The physics case for a Linear Collider is very compellingcompelling

The technologies for the machine and the The technologies for the machine and the experiments are in handexperiments are in hand

The international HEP community is solidly The international HEP community is solidly behind the project and is working together to behind the project and is working together to bring it to reality!bring it to reality!

For more information see:For more information see:www.linearcollider.orgwww.linearcollider.org www.linearcollider.cawww.linearcollider.ca

The International Linear Collidere+e- colliders at the frontierWhy Linear?“High Energy” Particle PhysicsInterplay of proton and electron collidersLinear Collider Physics: IThe golden processesHiggs production at a LCLinear Collider Physics: IIDark Matter at the ILC?Consensus in the HEP communityBuilding the ILCBuilding the ILCSuperconducting accelerator cavitiesPossible Tunnel LayoutDamping ring R&DLinear collider detector conceptsLinear collider detector challengesVertex detectorTracking detectorTracking challengeTracking technologyCalorimeterJet Energy Resolution RequirementsCalorimeter technologyBringing the ILC into realityILC timescaleSummary

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