CLIC Overview Andrea Latina (APC/FNAL) for the CLIC/CTF3 Collaboration June 10, Low Emittance Muon Collider Workshop, FNAL

Outline Introduction –Physics Case –Linear Colliders CLIC –Introduction and main challenges –The two beam accelerator scheme –CLIC technological issues CTF3 – CLIC Test Facility –Recent achievements Summary

High Energy Physics after LHC ICFA: International Commitee for Future Accelerators

Linear Collider e + e - Physics Higgs physics –Tevatron/LHC should discover Higgs (or something else) –LC explores its properties in detail Supersymmetry –LC will complement the LHC particle spectrum Extra spatial dimensions New strong interactions...=> a lot of new territory to discover beyond the standard model Energy can be crucial for discovery “Physics at the CLIC Multi-TeV Linear Collider” CERN “ILC Reference Design Report – Vol.2 – Physics at the ILC”

Linear versus Circular Colliders Storage Rings Acceleration+collision every turn “re-use” RF “re-use” particles  efficient  Synchrotron Radiation Losses Luminosity  Event rate Linear Collider One-pass acceleration+collision RF used only once Particles dumped at each collision  need high acceleration gradient  need small beam sizes at IP ~40 MHz ~10 Hz m2m2 nm 2 n b = bunches/train N = particles per bunch f rep = repetition frequency  x,y = sizes of the beam at IP H D = beam-beam enhancement factor ~10 34 cm -2 s -1

Main Challenges for a LC High E cm : long linac / high gradients nanometer beam sizes at the Interaction Point Small emittance generation and preservation  Stabilization and Final Focusing

1 st challenge: High Gradients Super conducting SW cavities : high efficiency, long pulse, gradient ~35 MV/m, but long filling time Normal conducting cavities : high gradients (with traveling wave structures), high frequency, short filling time, short pulse RF ‘flows’ with group velocity v G along the structure into a load at the structure exit pulsed RF Power source d RF load Main linac

2 nd challenge: interaction point beam sizes (picture from A. Seryi, (values for CLIC, 11/2008 Vertical size is smallest In order to maximize the luminosity we need very small beam sizes at the interaction point and a flat beam ) IP

3 nd challenge: emittance  Key concept in linear colliders: Generation and preservation of very small emittance! Generation of small emittances: synchrotron radiation damping -> damping rings Preservation of small emittances: precision alignment and steering, limitation of collective effects (synchrotron radiation, wake fields) Beam qualityLattice RMS beam size RTMLMain linac Beam Delivery Damping Rings Source

…emittance preservation With severe detrimental factors Intra-Beam Scattering, e - cloud… Wakefield Misalignment : Beam-Based Alignment Stabilization: ground motion, vibrations… Precise instrumentation Beam based corrections and feed-backs for dynamic effects Transport the beam from the damping rings to the IP without significant blow-up in the different subsystems: RTML Ring To Main Linac (RTML) Main Linac BDS Beam Delivery System (BDS) RTMLMain linac Beam Delivery

CLIC: Compact Linear Collider Centre of mass energy3TeV Luminosity (in 1% energy)2x10 34 cm -2 s -1 Repetition rate50 Hz Loaded accelerating gradient100 MV/m Main linac RF frequency12 GHz Overall two-linac length41.7 km Bunch charge4·10 9 Beam pulse length240 ns Average current in pulse1 A Hor./vert. normalized emittance660 / 20 nm rad Hor./vert. IP beam size before pinch45 / ~1 nm Total site length48.25 km Total power consumption400 MW Key parameters: Goals of the study:

CLIC at different energies 3 TeV Stage Linac 1Linac 2 InjectorComplex I.P. 3 km 20.8 km 3 km 48.2 km Linac 1Linac 2 InjectorComplex I.P. 7.0 km 1 TeV Stage 0.5 TeV Stage Linac 1Linac 2 InjectorComplex I.P. 4 km ~14 km 4 km ~20 km

CLIC schematic 3 TeV Drive beam

The CLIC Two-Beam Accelerator main beam 1 A, 156 ns 9 GeV TeV DRIVE BEAM PROBE BEAM

Why a two-beam scheme? Luminosity scales as wall-plug-to-beam efficiency. Need to obtain: high- gradient acceleration and efficient energy transfer. High-frequency RF maximizes the electric field in the RF cavities for a given stored energy. However, standard RF sources scale unfavorably to high frequencies, both in for maximum delivered power and efficiency. A way to overcome such a drawback is to use standard low-frequency RF sources to accelerate the drive beam and then use it to produce RF power at high frequency. The drive beam is therefore used for intermediate energy storage.  Luminosity

Drive Beam Idea Very high gradients possible with NC accelerating structures at high RF frequencies (30 GHz → 12 GHz) Extract required high RF power from an intense e- “drive beam” Generate efficiently long beam pulse and compress it (in power + frequency) Long RF Pulses P 0, 0,  0 Short RF Pulses P A = P 0  N 1  A =  0 / N 2 A = 0  N 3 Electron beam manipulation Power compression Frequency multiplication ‘few’ Klystrons Low frequency High efficiency Accelerating Structures High Frequency – High field Power stored in electron beam Power extracted from beam in resonant structures

Two Beams scheme

CLIC acceleration system

Why 100 MV/m at 12 GHz?

Accelerating structures

Best Result so far..

Power Extraction Transfer Structures - PETS

CLIC Accelerating Module

Getting the Luminosity (>2 x10 34 cm -2 s -1 )

Low emittance generation Many other issues besides intra-beam scattering : fast-ion instability and e-cloud (being mitigated using different coating for the vacuum chamber, tests at CESR-TA summer 2009), wiggler design..

Damping Ring Emittances

Rings to Main Linac RTML includes: BC1 stage: bunch length from 5 mm to 1.5 mm at 2.4 GeV Booster linac from 2.4 to 9 GeV Transfer line and turnaround loops BC2 stage: from 1.5 mm to 44 microm => max 5 nm vertical emittance growth is allowed First partcle tracking through the complete system 20 km booster

Emittance Preservation in the Main Linac Vertical emittance growth bugdet is 10 nm

Emittance Preservation in the ML Example for cavity misalignment Cavities misaligned -  y = 100 μm rms -  y’ = 100 μrad rms - no quadrupole misalignments Final cavity position distribution -  y = 85 μm rms Alignment method 1. one-to-one correction 2. structure alignment 3. repeat from 1. three times

Static Imperfections in the ML

Beam Delivery System Optics design for the 3 TeV option (alternative design for 0.5 TeV exists)

Interaction Region

Final Focus QD0 Stabilization QD0 must be stabilized to 0.15 nm for frequencies above 4 Hz

Active Stabilization Studies 0.13 nm have been reached in laboratory, the challenge remains to prove 0.15 nm within the detector B. Bolzon, L. Brunetti, N. Geffroy and A. Jeremie

Conceptual Design Report (CDR) - end 2010 The CLIC CDR should address the critical points: Accelerating structures at 100 MV/m Power Extraction and Transfer Structures (PETS) Generation of the 100 A drive beam with 12 GHz bunch frequency meeting the phase, energy and intensity stability tolerances Main beam low emittances Stabilization of main quads. to 1nm and FD quads to 0.15nm (freqs>4 Hz) Machine protection issues => Test facilities at CERN: CTF3 / CLEX

CTF3: Drive Beam Test-Bench Drive beam

CLIC R&D issues: CTF3/CLEX CTF3 is a small scale version of the CLIC drive beam complex: Provide the RF power to test the CLIC accelerating structures and components Full beam-loading accelerator operation Electron beam pulse compression and frequency multiplication Safe and stable beam deceleration and power extraction High power two beam acceleration scheme

Current Status of CTF3

39EPAC 2008 CLIC / CTF3 G.Geschonke, CERN CLEX building Jan 2008 September 2006 June 2006 June 2008 Probe Beam linac June 2008 Two Beam Test Stand (University Uppsala) Equipment installed (except TBL), Beam foreseen from June 2008

CTF3: full beam loading

Delay Loop

Combiner Rings

CTF3: x 4 combination in CR

CTF3: Power Extraction and Recirculation The first 12 GHz PETS was tested with BEAM in November and December last year Recirculation of the output field was used, to produce more power from the 5A CTF3 current 30 MW of RF power were generated (plot shows 25 MW) RF signal was reproduced using BPM intensity signal  PETS shows excellent behaviour and agreed with design performance  This also means that the this is a very good test-bench to test PETS in two-beam acceleration

Summary Excellent progress towards the CLIC CDR (2010) Technical program is on track but lots of work still to be done. Challenging work and tight schedule! LHC results

The CTF3 – CLIC world wide collaboration 46EPAC 2008 CLIC / CTF3 G.Geschonke, CERN Helsinki Institute of Physics (Finland) IAP (Russia) IAP NASU (Ukraine) Instituto de Fisica Corpuscular (Spain) INFN / LNF (Italy) J.Adams Institute, (UK) JINR (Russia) Oslo University (Norway) PSI (Switzerland), Polytech. University of Catalonia (Spain) RRCAT-Indore (India) Royal Holloway, Univ. London, (UK) SLAC (USA) Uppsala University (Sweden) Ankara University (Turkey) BINP (Russia) CERN CIEMAT (Spain) Cockcroft Institute (UK) Gazi Universities (Turkey) IRFU/Saclay (France) JLAB (USA) Karlsruhe University (Germany) KEK (Japan) LAL/Orsay (France) LAPP/ESIA (France) NCP (Pakistan) North-West. Univ. Illinois (USA) 28 institutes involving 18 funding agencies from 16 countries