1Albrecht Wagner

TESLA: a new Tool for Science

Exploring the femtosecond (10-15 s) domain:

- the world after the big bang

- the change of matter on shortest time scales

2Albrecht Wagner

TESLA

On curved paths electrons emit synchrotron radiation.Ä Energy lossÄ Linear accelerators needed to reach highest energies!Ä Highest possible accelerating gradients necessary.

3Albrecht Wagner

The Scientific Case of theLinear Collider

Understanding the Higgs-Mechanism and the masses of elementary particles

Understanding Understanding matter, matter, energyenergy, , spacespace and time.and time.

Are “stings” the fundamental entities?

Connecting quarks and the cosmos

4Albrecht Wagner

The World-wide Consensus on the next LC

A world-wide consensus has formed for a baseline LC project in which positrons collide with electrons at energies up to 500 GeV, with luminosity above 1034 cm-2s-1. The energy should be upgradable to about 1 TeV. Above this firm baseline, several options are envisioned whose priority will depend upon the nature of the discoveries made at the LHC and in the initial LC operation.The LHC and LC will offer mutually supporting views of the new physics world at the TeV scale.

OECD GSF Consultative Group on High-Energy Physics:There should be a significant period of concurrent running of the LHC and the LC, requiring the LC to start operating before 2015.

5Albrecht Wagner

The Standard Model

3 families of particles

3 forces and their particles

The mechanism of mass generation© Scientific American

6Albrecht Wagner

Key Questions of Particle Physics

• What is mass/matter ?

• Can the forces be unified?• Fundamental symmetry of forces and building blocks?• Can quantum physics and general relativity be united?• Do we live in 4 dimensions?• What happened in the very early universe ?• Origin of dark matter

why are carriers of weak force so heavy while the photon is massless?

7Albrecht Wagner

Where do the experimental answers lie?

• At highest energiesHadron Colliders- LHC under construction at CERN

• In precision measurementsElectron-Positron Collider- e.g. TESLA

Physics and experience teach us that we need these different tools to answer the open questions and that they complementeach other

The Path to the Experimental Answers

© Physics Today

8Albrecht Wagner

The Power of e+ e-

Colliderse+

e-

• well defined production process, simple kinematics

• precise knowledge of quantum numbers in initial state

• precise (<%) knowledge of the cross sections

• polarisation of e- and e+ beams possible

• energy and momentum of all partons known

• energy of system can be varied• low background

q q µ µ

9Albrecht Wagner

Test of the SM at the Level of Quantum Fluctuations

Indirect determination ofthe top mass

possible due to

• precision measurements

• known higher orderelectroweak corrections

)ln(,)( 2

W

h

W

t

MM

MM

∝

LEP

10Albrecht Wagner

The Higgs Mechanism andthe Higgs Boson

In the Standard Model the Higgs mechanism is responsible for the generation of mass

• All elementary particles are originally massless• The entire universe is filled by a field• Elementary particles gain their mass through the interaction

with this field• The field gets distorted by the particle -> Mass generation• The field quantum: The Higgs Boson

The Higgs is the last missing element of the Standard Model

11Albrecht Wagner

The Higgs: Key to Understanding Mass

Where is the Higgs?

Mass limits for the Higgs

from precision tests of the SM

114 < m(H) < 206 GeV (95 % CL)

A Linear Collider measures:• mass• quantum numbers• lifetime• couplings= test the mechanism of mass

generation

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Higgs Branching Ratios

Branching ratios measure the Higgs coupling to fermions,

a test of the Higgs mechanism

accuracy a few %

500 fb-1

at 350 GeV

Marco Battaglia

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Unification of particles and forces• Eliminates mathematical problems in

SM• Part of quantum theory of

gravitation

• consequence: many new particlesevery known particle has a supersymmetric partner

• the lightest SUSY particle is stable, possible link to dark matter

Supersymmetry

Fermions(Bosons)

Bosons(Fermions)

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• Unification of quantum-physics and general relativity

• Elementary particles = excitations of an elementary string: 10-33 m

• In how many dimensions do we live?

• String theories predict new particles: Supersymmetry

• SUSY scale expected to be close by --> Threshold of a new era

From Particles to Strings

A Linear Collider can measure supersymmetric particles:• masses• quantum numbers• lifetimes• decaysif they exist

15Albrecht Wagner

Extra Dimensions

Emission of gravitons into extra dimensions

+ emission of γ or a jet

measurement of cross sections at different energies allows to determine number of extra dimensions

(500 fb-1 at 500 GeV,

1000 fb-1 at 800 GeV)

cross section for anomalous single photon production

Energy

δ = # of extra dimensions

e+e- -> γG

16Albrecht Wagner

e+e- Colliders:The Challenges

The challenges:

Luminosity: high charge density (1010), > 10,000 bunches/s

very small vertical emittance (damping rings, linac)

tiny beam size (5*500 nm) (final focus)

Energy: high accelerating gradient (> 25 MV/m, 500 - 1000 GeV)

To meet these challenges: A lot of R&D on LC’s world-wide

For E > 200GeV need tobuild linear colliders

Proof ofprinciple:

SLC

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From SLC to TESLA

SLC TESLA

Energy Ecm 100 500 (→ ~1000) GeV Beam Power 0.04 ~10 MWSpot size IP 500 (~50§) ~5 nm Luminosity 3⋅10-4 3 1034 cm-2 s-1

SLC

FFTB

TESLA

500 nm

50 nm

5 nm

1000 nm

Main challenges:

• Luminosity

• Energy

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TESLA X-FEL:a revolutionary photon source

The excellent beam properties in the superconducting TESLA-LINAC allow to use the SASE (Self Amplifying SpontaneousEmission) principle

Brillance:gain ~ 109 compared to existing facilitiesPhoton beam:• X-rays at 0.1 nm• Full coherence

(Laser)• Pulse length < 100 fs

(time scale of chemical reactions)

• Energy tuneable

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How to build an X-FEL?

Self Amplified Spontaneous Emission (Kondratenko, Saldin 1980)

requires small emittance electron beam

• Spont. Emission

• for certain wave lenghts, fulfilling a resonance condition

lasing

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Properties of the X-ray Laser

• Wavelength of atomic dimensions> 0.1 nm

• Highest brilliance~ 109 times that of sources of the 3. generation

• Very short pulselength100 fs

• Tunable in wavelength • Coherence

Synchrotron radiation power P of an incoherent electron distribution: P ~ Ne

Radiation from a point charge (bunch length < λ radiation): P ~ Ne

2

Gain: ~ Ne = 10 9 ...10 10

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Science with the X-FEL

Movies of chemical reactions

Main fields of research with the XMain fields of research with the X--FEL:FEL:• atomic, molecular and cluster phenomena, plasma physics• non-linear processes and quantum optics• condensed matter physics and materials science• ultra-fast chemistry and life-sciences Plasma physics

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Structural Biology (1)

Today: imaging of bio-molecular assemblies with atomic resolution require crystallisation

Classical diffraction from crystal Ribosome Crystals

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Structural Biology (2)

Tomorrow:

imaging of non-crystaline bio-molecular assemblies with atomic resolution

and on time scales of chemical reactions (femto seconds)

Diffraction from single molecule

Solution:

X-FEL

Lysosyme

24Albrecht Wagner

The Story of SC Cavities

Development of Gradients in superconducting RF cavities

0

5

10

15

20

25

30

35

40

45

1980 1985 1990 1995 2000 2005

Year

Gra

die

nt

(MV

/m)

World Average

CEBAF

TESLA

TESLA

TESLA el.polish

SC RF structures for accelerators were developed in many countries

To meet the challenge of high gradients needed for high energy Linear Colliders the TESLA collaboration has attracted ~ all the world expertise in SC, thus leading to major progress

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The TESLA Collaboration

• The TESLA Collaboration was set up in 1992

- at present 51 Institutes in 12 countries

Original Goals:

Obtain accelerating gradients of at least 25 MV/m (theoretical limit approx. 50 MV/m)Realise a 30 km long Linear Collider with a centre of mass energy of 500 GeV.

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Challenges for TESLA

• Material propertiesmoderate Nb purity, low Residual Resistance Ratio (RRR), low thermal conductivity, quenches at moderate fields

• Cavity treatments and cleannesshigh pressure rinsing and clean room assembly

• Microphonicsmechanical vibrations in low beta structures

• Multipactoring (MP)MP has been the major limit for HEPL and electron linacs to

1984 • Quenches/Thermal breakdown

because of low RRR and poor purity • Field Emission

General limit before TESLA because of poor cleaningprocedures and material

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Preparation of TESLA Cavities

9-cell, 1.3 GHz, TESLA cavity

The steps:

Scan of Nb sheets -> inclusionsIndustrial production:

Deep-drawing of half-cells Chemical preparation of weldingElectron beam welding

Heat treatment (8000)-> stress anneal

Heat treatment (14000)-> increase thermal conductivity

Chemical etchingHigh pressure rinsing

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The Cryo-Module

The layout of one cryo-module – the basic building block of the linear accelerator

One input coupler per cavity

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Assembly of TESLA Modules: Impressions

Machine cost distribution

Main LINAC Modules

Main LINAC RF System

Civil Engineering

Infrastructure

X FELIncrementals

Damping Rings

HEP Beam Delivery

AuxiliarySystems

Injection Systems

1131

587 546

336241 215

124 101 97

Million Euroe- Beam lines

e- Damping Ring

High energy physics detector &Xray Free Electron Laser laboratory

e+ Main LINAC

Electron sources e+ Source

X FEL Switchyard

Beam dumps

DESY site Westerhorn

TESLA schematic view

Auxiliary halls

~ 33 km

e+ Damping Ring

e+ Deliverye- Main LINAC I PDelivery e-

e+ Beam linePreLinac

Systems Overview

There are more systems to the accelerator than just the cryo-modules ..

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The TESLA Test Facility

Tasks:

Test of all components

Operation for > 15 000 h

Base for costing

Conclusion:

The technical readiness has been demonstrated

Construction of a prototype accelerator:

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0 2 4 6 8 10 12 1410-12

10-11

1x10-10

1x10-9

1x10-8

1x10-7

1x10-6

1x10-5

1x10-4

E = Esh

exp(z/Lg)

Wsh

~ 1-2 W

TTF FEL saturation September 10, 2001λ = 98.1 nmL

g = 0.68 m

Esat

= 90 µJ

E [

J]

z [m]

Properties of the Laser

Level ofspontaneousemission

All measured properties of the laser agree with the theoretical predictions, e.g. saturation (gain: 10*10^6)by far the most brilliant VUV light source world-wide

@ 100 nm

104 105 106 1070

10

20

30

40

∆E/E = 0.7 %

Single FEL pulse

Inte

nsity

[arb

. uni

ts]

Wavelength [nm]

Simulation

simulation

single FEL pulse

∆E/E = 0.7%

Power: 226 +- 50 MW observed @ 100 nm200 expected @ 70 nm

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Tunability and Coherence

2/1 E∝λ àTransverse coherence

Also seen in opening angle ofradiation at saturation

Slit distance: 3 mm

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Interaction of Intense Radiation (100 nm) with Matter

Measurement of

• multi-photon processes

• cross sections

• life time of intermediate states

• Coulomb explosion

as function of intensity

First Experiments at TTF

Increasing intensity

VUV-Laser

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First Results

0 100 200 300 400 500 600 700 800

0,0

0,2

0,4

single shot

average size of clustersN=300

7+6+

8+

5+

4+

Xe++

Xe3+

Xe+

inte

nsity

[arb

. uni

ts]

time of flight [ns]

(Th.Möller et al.)

IpXe = 12.1 eVEphot= 12.8 eV

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VUV-FEL User Facility at TTF II

RF commissioning in 2003,

start of FEL operation in 2004

TTF 1

TTF 2

experimental hall

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The Decision of the BMBF

The decisions of the German Ministry for Education and Research concerning TESLA was published on 5 February 2003:

DESY in Hamburg will receive the X-FEL as European project

Germany is prepared to carry half of the 673 MEuro investment cost.

Today no German site for the TESLA linear collider will be put forward. This decision is connected to plans to operate this project within a world-wide collaborationDESY will continue its research work on TESLA in the existing international framework, to facilitate German participation in afuture global project

38Albrecht Wagner

Next Steps for the X-FEL

• Site and some of the technical parameters for XFEL Laboratory are currently reconsidered.

• Formation of European Working Groups under way.

Aim for decision on construction in 2005!

39Albrecht Wagner

Consequences of the Decision for the Linear Collider

Given the decision of the German government the community will now take a path used for other international projects (e.g. ITER): • unite first behind one project with all its aspects, including the technology choice, in 2004 and then • approach all possible governments in parallel in order to trigger the decision process and site selection (2006/2007)Next R&D activities:• Test as many 9-cell cavities as possible, with full power for as long as possible at their highest gradient (35 MV/m). • In order to prepare the construction of the X-FEL, DESY and its partners will focus on issues related to the mass production of all components. This will lead within one to two years to further improvements of the technical design and a better cost evaluation.

40Albrecht Wagner

The Path beyond 25 MV/m

Improvement of cavity surfaces by electropolishing (EP)

First electro-polished single cell cavities

BCP Surface (1µm roughness)

BCP Surface (1µm roughness)

0.5 mm

EP Surface (0.1µm roughness)

0.5 mm

Gradients of 40 MV/m at Q values above 1010 are now reliably achieved in single cells at KEK, DESY/CERN and TJNAF. At DESY EP infrastructure for 9-cell cavities has been commissioned with single cell cavities. 9-cell cavities will follow soon.

41Albrecht Wagner

Cavity Performance

Cavity with all its ancillaries (1/8th of a TESLA cryomodule) under full power

TESLA LC: ready to reach 800 GeV (although beam tests still missing)

42Albrecht Wagner

TESLA Energy Strategy

TESLA luminosity vs. cm-energy, baseline & upgrade

0

1

2

3

4

5

6

7

300 400 500 600 700 800 900

E_cm / GeV

L /

10^

34 c

m^

-2 s

^-1

no add. cost

RF & cryo upgrade

Assuming that cavities will reach 35 MV/m:

TDR (March 2001)

Base line design for 500 GeV, upgrade possibility outlined

• initially operate at an energy of about 500 GeV, to explore the Higgs and related phenomena, and then • increasing the energy to 800-1,000 GeV, to more fully explore the TeV energy scale.

43Albrecht Wagner

Other Projects referencing to the TESLA technology

• High Energy Physics– TESLA– Neutrino Factories and Muon Colliders– Kaon Beam Separation at FNAL– New TEVATRON Injector

• Nuclear Physics– RIA – EURISOL– CEBAF Upgrade

• High Power Proton Linacs for Spallation– SNS, Joint-Project, Korea, ESS– ADS for Waste Transmutation

• New Generation Light Sources– Recirculating Linacs (Energy Recovery)– SASE FELs

200 MHz for Neutrinos

SNS

44Albrecht Wagner

Summary

• Very successful development of the superconducting accelerating technology in international partnership

• The activities of the TESLA collaboration have influenced significantly many other accelerator projects

• The European X-FEL laboratory will provide a revolutionary photon source based on the TESLA technology

• Strong world enthusiasm for a LC, aiming at technology decision in 2004

• New ways of international collaboration (Global Accelerator Network) as the basis for future projects