Short Introduction to CLIC and CTF3, Technologies for Future Linear - - PowerPoint PPT Presentation

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Short Introduction to CLIC and CTF3, Technologies for Future Linear - - PowerPoint PPT Presentation

Mar 15, 2024 256 likes •514 views

Short Introduction to CLIC and CTF3, Technologies for Future Linear Colliders Explanation of the Basic Principles and Goals Visit to the CTF3 Installation Roger Ruber The CRT: Our Home Accelerator = + F e ( v B E ) = F m a

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Short Introduction to CLIC and CTF3, Technologies for Future Linear Colliders

Explanation of the Basic Principles and Goals Visit to the CTF3 Installation Roger Ruber

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2 Roger Ruber - CLIC/CTF3 Visit - Introduction

The CRT: Our Home Accelerator

a F E B v F m e = + × = ) (

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3 Roger Ruber - CLIC/CTF3 Visit - Introduction

Collider History

  • hadron collider at the frontier of physics

– huge QCD background – not all nucleon energy available in collision

  • lepton collider for precision physics

– well defined CM energy – polarization possible

  • LHC starting up

– energy constantly increasing – consensus for next machine Ecm ≥0.5 TeV for e+e-

p p e+ e-

[top quark] [W±, Z boson] [gluon] [Nν=3] [charm quark, τ lepton]

“Livingstone” plot (adapted from W. Panofsky)

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4 Roger Ruber - CLIC/CTF3 Visit - Introduction

Hadron collision Lepton collision

p p e+ e-

Simulation of HIGGS production e+ e– → Z H Z → e+ e–, H → b b

Hadrons versus Leptons: Typical Event Patterns

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5 Roger Ruber - CLIC/CTF3 Visit - Introduction

Circular versus Linear Collider

Circular Collider many magnets, few cavities, stored beam higher energy → stronger magnetic field → higher synchrotron radiation losses (∝E4/R) Linear Collider few magnets, many cavities, single pass beam higher energy → higher accelerating gradient higher luminosity → higher beam power (high bunch repetition)

source main linac N S N S

accelerating cavities

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6 Roger Ruber - CLIC/CTF3 Visit - Introduction

Cost of Circular & Linear Accelerators

Circular Collider

  • ΔE ~ (E4/m4R)
  • cost ~ aR + b ΔE
  • optimization: R~E2 → cost ~ cE2

Linear Collider

  • E ~ L
  • cost ~ aL

cost energy

Circular Collider Linear Collider

200 GeV e-

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7 Roger Ruber - CLIC/CTF3 Visit - Introduction

e+ Linac Interaction Point with Detector e- Linac e+ source e- source RF power Source RF power Source

Linear Collider R&D Challenges:

  • 1. high accelerating gradient
  • 2. efficient power production

accelerating cavities accelerating cavities

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8 Roger Ruber - CLIC/CTF3 Visit - Introduction

Acceleration of Charged Particles

  • Lorenz (EM) force most practical
  • increasing particle energy
  • to gain 1 MeV energy requires a 1 MV field

Direct-voltage acceleration used in

  • TV tube: 20~40 kV
  • X-ray tube: ~100 kV
  • tandem van de Graaff: up to ~25 MV

) ( E B v F + × = e

eU d e E = ⋅ = Δ

∫

r E

+

  • e-

+

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9 Roger Ruber - CLIC/CTF3 Visit - Introduction

Higher Integrated Field: Modulation with Drift Tubes

  • shields particle while field direction is reversed
  • length adapted to particle velocity & RF frequency

electric field Courtesy

  • E. Jensen
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10 Roger Ruber - CLIC/CTF3 Visit - Introduction

Static or Modulated Fields (RF) DC acceleration not always possible:

  • keep beam tube at ground potential
  • circular machine:

→ use oscillatory waveform

= ⋅

∫

s E d

Proton Ekin β = v/c 50 MeV 0.314 1.4 GeV 0.916 25 GeV 0.999 3 PS 450 GeV 0.999 998 SPS 7 TeV 0.999 999 991 LHC

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11 Roger Ruber - CLIC/CTF3 Visit - Introduction

Surfing: or How to Accelerate Particles

DC Accelerator RF Accelerator

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12 Roger Ruber - CLIC/CTF3 Visit - Introduction

Cavity Type Acceleration Configuration

  • time-varying electro-magnetic field:

– magnetic field encircles beam – accelerating gap fed with RF voltage

  • cell length must be proportional to

– particle velocity – frequency

  • magnetic field tracks particles’ energy to keep equilibrium orbit

unchanged B E

∫∫ ∫

⋅ ∂ ∂ − = ⋅ A t B s E r r r r d d

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13 Roger Ruber - CLIC/CTF3 Visit - Introduction

Standing Wave Pillbox Cavity

electric field (@ 0o) magnetic field (@ 90o)

TM010-mode (only 1/8 shown)

Courtesy E. Jensen

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14 Roger Ruber - CLIC/CTF3 Visit - Introduction

CERN PS 19 MHz Cavity (prototype 1966)

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15 Roger Ruber - CLIC/CTF3 Visit - Introduction

Standing Wave Cavity

  • long pulse time
  • frequency <3 GHz
  • typical 2~5 MV/m
  • superconducting

up to ~30 MV/m

  • ions & electrons,

all energies l=βλ/2

  • 1
  • 0 . 5
0 . 5 1 2 0 4 0 6 0 8 0 1 0 0 1 2 0

z

Electric field (at time t0) Beam

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16 Roger Ruber - CLIC/CTF3 Visit - Introduction

  • short pulses
  • high frequency

>3 GHz

  • typical

10~20 MV/m

  • CLIC:

– 12 GHz – 240 ns – 100 MV/m

  • electrons β~1

(v~c)

Travelling Wave Structure

RF power source electric field

d

particle bunch RF load

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17 Roger Ruber - CLIC/CTF3 Visit - Introduction

e+ Linac Interaction Point with Detector e- Linac e+ source e- source RF power Source RF power Source

Linear Collider R&D Challenges:

  • 1. high accelerating gradient
  • 2. efficient power production

accelerating cavities accelerating cavities

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18 Roger Ruber - CLIC/CTF3 Visit - Introduction

Klystron RF Power Amplifier

  • velocity modulation (RFin)
  • f electron bunch

→ microwave amplifier

  • output power (RFout)

1 MW continuous 150 MW pulsed

  • 0.1 – 300 GHz range

5 – 10% bandwidth

  • expensive

(40-60% efficiency) and high maintenance cost

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19 Roger Ruber - CLIC/CTF3 Visit - Introduction

CLIC Two-beam Power Distribution Scheme

  • high power drive beam

like the modulated klystron beam

  • power extraction in a

deceleration structure (PETS)

  • high power, high frequency
  • sub-harmonic frequency
  • f main beam
  • compress energy density:

“transformer” function

drive beam main beam

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20 Roger Ruber - CLIC/CTF3 Visit - Introduction

Drive Beam Accelerator efficient acceleration in fully loaded linac Power Extraction Drive Beam Decelerator Sector Combiner Ring x 3 Combiner Ring x 4 pulse compression & frequency multiplication pulse compression & frequency multiplication Delay Loop x 2 gap creation, pulse compression & frequency multiplication

RF Transverse Deflectors

Recombination to Increase Peak Power & Frequency

140 µs train length - 24 x 24 sub-pulses - 4.2 A 2.4 GeV - 60 cm between bunches 240 ns 24 pulses – 100 A – 2.5 cm between bunches 240 ns 5.8 µs

Drive beam time structure - initial Drive beam time structure - final

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21 Roger Ruber - CLIC/CTF3 Visit - Introduction

Drive Beam Generation Scheme

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22 Roger Ruber - CLIC/CTF3 Visit - Introduction

e+ Linac Interaction Point with Detector e- Linac e+ source e- source RF power Source RF power Source

Linear Collider R&D Challenges:

  • 1. high accelerating gradient
  • 2. efficient power production
  • 3. build a working accelerator

accelerating cavities accelerating cavities

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23 Roger Ruber - CLIC/CTF3 Visit - Introduction

CLIC: Compact Linear Collider

Main Linac C.M. Energy 3 TeV Peak luminosity 2x1034 cm-2s-1 Beam Rep. rate 50 Hz Pulse time duration 156 ns Average field gradient 100 MV/m # accelerating cavities 2 x 71,548

Φ4.5m tunnel

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24 Roger Ruber - CLIC/CTF3 Visit - Introduction

CTF3 Test Facility

  • demonstration drive beam generation
  • evaluate beam stability & losses in deceleration
  • develop power production & accelerating structures

X 5 Combiner Ring 84 m X 2 Delay loop 42 m Drive Beam Injector 180 MeV Probe Beam Injector Two-Beam Test-stand Drive Beam Accelerator 30 A - 150 MeV 140 ns 30 GHz High Gradient Test stand

CLEX

Decelerator Test Beam Line Drive beam stability bench marking CLIC sub-unit Drive beam generation scheme