Future Lepton Collider 1 Barry Barish Czech Technical University 15-Nov-11 The Future of Accelerator Based Particle Physics 15-Nov-11 Czech Technical University

Path to higher energy  Collider History: Energy constantly increasing with time o Hadron Collider at the energy frontier o Lepton Collider for precision physics  Consensus to build Linear Collider with E cm > 500 GeV to complement LHC physics 15-Nov-11 Czech Technical University Future Lepton Collider 2

15-Nov-11 Czech Technical University Future Lepton Collider 33 Three Generations: Complementarity Discovery Of Charm Particles and 3.1 GeV Burt Richter Nobel Prize SPEAR at SLAC First generation

15-Nov-11 Czech Technical University Future Lepton Collider 44 Rich History of Discovery DESY PETRA Collider Second generation

Future Lepton Collider 55 Precision Measurements CERN’s LEP Collider set the stage for Terascale physics Reveal the origin of quark and lepton mass Produce dark matter in the laboratory Test exotic theories of space and time Third generation 15-Nov-11 Czech Technical University

Future Lepton Collider 66 SPEAR PETRA LEP ENERGY YEAR TeV ILC (or CLIC) GeV Fourth generation? Three Generations of Successful e + e - Colliders The Energy Frontier

15-Nov-11 Czech Technical University Future Lepton Collider 77 The next big accelerator: a lepton collider? Terascale science and how a lepton collider will complement the LHC? Electron-Positron: Why linear? What technology to employ? An option with muons? Designing the ILC -- a new paradigm in international collaboration. A thumbnail description of the ILC Reference Design and Cost? Present program and plans

15-Nov-11 Czech Technical University Future Lepton Collider 88 Exploring the Terascale The Tools The LHC –It will lead the way and has large reach –Quark-quark, quark-gluon and gluon-gluon collisions at TeV –Broadband initial state The ILC –A second view with high precision –Electron-positron collisions with fixed energies, adjustable between 0.1 and 1.0 TeV –Well defined initial state Together, these are our tools for the Terascale

15-Nov-11 Czech Technical University Future Lepton Collider 99 Why e + e - Collisions? Elementary particles Well-defined –energy –angular momentum Uses full COM energy Produces particles democratically Can mostly fully reconstruct events

15-Nov-11 Czech Technical University Future Lepton Collider 10 Comparison: ILC and LHC ILC LHC Beam Particle : Electron x Positron Proton x Proton CMS Energy : 0.5 – 1 TeV 14 TeV Luminosity Goal : 2 x /cm 2 /sec 1 x10 34 /cm 2 /sec Accelerator Type : Linear Circular Storage Rings Technology : Supercond. RF Supercond. Magnet

15-Nov-11 Czech Technical University Future Lepton Collider 11 LHC ILC e + e –  Z H Z  e + e –, H  b … Higgs event Simulation Comparison

15-Nov-11 Czech Technical University Future Lepton Collider 12 Higgs Signal with LHC  Rare decay channel: BR~10 -3  Projected signal and background after data cuts to optimize signal to background  Background large: S/B  1:20, but can estimate from non signal areas CMS

15-Nov-11 Czech Technical University Future Lepton Collider 13 Precision Higgs physics  Model-independent Studies mass absolute branching ratios total width spin top Yukawa coupling self coupling  Precision Measurements Garcia-Abia et al

15-Nov-11 Czech Technical University Future Lepton Collider 14 Higgs Coupling-mass relation Remember - the Higgs is a Different! It is a zero spin particle that fills the vacuum It couples to mass; masses and decay rates are related

15-Nov-11 Czech Technical University Future Lepton Collider 15 The linear collider will measure the spin of any Higgs it can produce by measuring the energy dependence from threshold ILC: Is it really the Higgs ? Measure the quantum numbers. The Higgs must have spin zero !

15-Nov-11 Czech Technical University Future Lepton Collider 16 What can we learn from the Higgs? Precision measurements of Higgs coupling Higgs Coupling strength is proportional to Mass

15-Nov-11 Czech Technical University Future Lepton Collider 17 e + e - : Studying the Higgs determine the underlying model SM 2HDM/MSSM Yamashita et al Zivkovic et al

15-Nov-11 Czech Technical University Future Lepton Collider 18 - Measure quantum numbers - Is it MSSM, NMSSM, …? - How is it broken? ILC can answer these questions! -tunable energy -polarized beams Supersymmetry at ILC e + e - production crosssections

15-Nov-11 Czech Technical University Future Lepton Collider 19 ILC Supersymmetry Two methods to obtain absolute sparticle masses: In the continuumKinematic Threshold: Minimum and maximum determines masses of primary slepton and secondary neutralino/chargino Determine SUSY parameters without model assumptions Martyn Freitas

15-Nov-11 Czech Technical University Future Lepton Collider 20 The abundance of the LSP as dark matter can be precisely calculated, if the mass and particle species are given. ILC can precisely measure the mass and the coupling of the LSP The Dark Matter density in the universe and in our Galaxy can be calculated. The most attractive candidate for the dark matter is the lightest SUSY particle Dark Matter Candidates LSP

15-Nov-11 Czech Technical University Future Lepton Collider 21 New space-time dimensions can be mapped by studying the emission of gravitons into the extra dimensions, together with a photon or jets emitted into the normal dimensions. Linear collider Direct production from extra dimensions ?

15-Nov-11 Czech Technical University Future Lepton Collider 22 Possible TeV Scale Lepton Colliders ILC < 1 TeV Technically possible ~ QUAD POWER EXTRACTION STRUCTURE BPM ACCELERATING STRUCTURES CLIC < 3 TeV Feasibility? Longer timescale Main beam – 1 A, 200 ns from 9 GeV to 1.5 TeV Drive beam - 95 A, 300 ns from 2.4 GeV to 240 MeV Muon Collider < 4 TeV FEASIBILITY?? Much longer timescale Much R&D Needed Neutrino Factory R&D + bunch merging much more cooling etc ILC CLIC Muon Collider

15-Nov-11 Czech Technical University Future Lepton Collider 23 ILC Baseline Design Gev e+ e- Linear Collider Energy 250 Gev x 250 Gev Length km # of RF units 560 # of cryomodules1680 # of 9-cell cavities Detectors push-pull 2e34 peak luminosity 5 Hz rep rate, > 6000 bunches per cycle IP spots sizes:  x 350 – 620 nm;  y 3.5 – 9.0 nm

15-Nov-11 Czech Technical University Future Lepton Collider 24 RDR Design Parameters Max. Center-of-mass energy500GeV Peak Luminosity~2x /cm 2 s Beam Current9.0mA Repetition rate5Hz Average accelerating gradient31.5MV/m Beam pulse length0.95ms Total Site Length31km Total AC Power Consumption~230MW

Future Lepton Collider 25  E ~ (E 4 /m 4 R) Linear implies single pass cost Energy Circular Collider Linear Collider R Synchrotron Radiation R ~ 200 GeV < 5 nm vertical Low emittance (high brightness) machine optics Contain emittance growth Squeeze the beam as small as possible at collision point 15-Nov-11 Czech Technical University

Future Lepton Collider 26 ILC – Underlying Technology Room temperature copper structures OR Superconducting RF cavities

15-Nov-11 Czech Technical University Future Lepton Collider 27 SCRF Technology Recommendation The recommendation of ITRP was presented to ILCSC & ICFA on August 19, 2004 in a joint meeting in Beijing. This recommendation is made with the understanding that we are recommending a technology, not a design. We expect the final design to be developed by a team drawn from the combined warm and cold linear collider communities, taking full advantage of the experience and expertise of both (from the Executive Summary). This led to the formation of the Global Design Effort (GDE) ICFA unanimously endorsed the ITRP’s recommendation on August 20, 2004 Strong international interest in developing SCRF technology

15-Nov-11 Czech Technical University Future Lepton Collider 28 GDE -- Designing a Linear Collider Superconducting RF Main Linac

Traveling wave structures NC standing wave structures would have high Ohmic losses => traveling wave structures RF ‘flows’ with group velocity v G along the structure into a load at the structure exit Condition for acceleration: Δφ=d·ω/c (Δφ cell phase difference) Shorter fill time T fill =  1/v G dz - order <100 ns compared to ~ms for SC RF pulsed RF Power source d RF load particles “surf” the electromagnetic wave 15-Nov-11 Czech Technical University Future Lepton Collider 29

CLIC (Compact Linear Collider) 15-Nov-11 Czech Technical University Future Lepton Collider 30 QUAD POWER EXTRACTION STRUCTURE BPM ACCELERATING STRUCTURES Drive beam - 95 A, 300 ns from 2.4 GeV to 240 MeV Main beam – 1 A, 200 ns from 9 GeV to 1.5 TeV Room Temperature RF

CLIC – in a nutshell Compact Linear Collider e+/e- collider for up to 3 TeV Luminosity 6·10 34 cm -2 s -1 (3 TeV) Normal conducting RF accelerating structures Gradient 100 MV/m RF frequency 12 GHz Two beam acceleration principle for cost minimisation and efficiency Many common points with ILC, similar elements, but different parameters 15-Nov-11 Czech Technical University Future Lepton Collider 31

Test results Accelerating structure developments Structures built from discs Each cell damped by 4 radial WGs terminated by SiC RF loads Higher order modes (HOM) enter WG Long-range wakefields efficiently damped 15-Nov-11 Czech Technical University Future Lepton Collider 32

CLIC: Why 100 MV/m and 12 GHz ? Optimisation - figure of merit: –Luminosity per linac input power Structure limits: –RF breakdown – scaling (E surf <260MV/m, P/Cτ 1/3 limited) –RF pulse heating (ΔT<56°K) Beam dynamics: –emittance preservation – wake fields –Luminosity, bunch population, bunch spacing –efficiency – total power take into account cost model after > 60 * 10 6 structures: 100 MV/m 12 GHz chosen, previously 150 MV/m, 30 GHz A.Grudiev 15-Nov-11 Czech Technical University Future Lepton Collider 33

Muon Collider  A muon collider is an attractive multi-TeV lepton collider option, because muons do not radiate as readily as electrons (m  / m e ~ 207): - COMPACT Fits on laboratory site - MULTI-PASS ACCELERATION Cost Effective operation & construction - MULTIPASS COLLISIONS IN A RING (~1000 turns) Relaxed emittance requirements & hence relaxed tolerances - NARROW ENERGY SPREAD Precision scans, kinematic constraints - TWO DETECTORS (2 IPs) -  T bunch ~ 10  s … (e.g. 4 TeV collider) Lots of time for readout Backgrounds don’t pile up - (m  /m e ) 2 = ~40000 Enhanced s-channel rates for Higgs-like particles A 4 TeV Muon Collider would fit on the Fermilab Site Nov-11 Czech Technical University Future Lepton Collider

Challenges Muons are produced as tertiary particles. To make enough of them requires a MW scale proton source & target facility. Muons decay  everything must be done fast and we must deal with the decay electrons (& neutrinos for CM energies above ~3 TeV). Muons are born within a large phase-space. For a Muon Collider, it must be cooled by O(10 6 ) before they decay  New cooling technique (ionization cooling) must be demonstrated, and it requires components with demanding performance After cooling, beams still have relatively large emittance Nov-11 Czech Technical University Future Lepton Collider

MUON COLLIDER SCHEMATIC Proton source: Example: upgraded PROJECT X (4 MW, 2±1 ns long bunches) muons per year that fit within the acceptance of an accelerator:   N =6000  m  //N =25 mm √s = 3 TeV Circumference = 4.5km L = 3×10 34 cm -2 s -1  /bunch = 2x10 12  (p)/p = 0.1%   N = 25  m,  //N =70 mm  * = 5mm Rep Rate = 12Hz Nov-11 Czech Technical University Future Lepton Collider

Muon Collider cf. Neutrino Factory NEUTRINO FACTORY MUON COLLIDER In present MC baseline design, Front End is same as for NF (although the optimal initial coolers might ultimately be different) Nov-11 Czech Technical University Future Lepton Collider

Muon Collider: Ionization Cooling  TRANSVERSE COOLING: Muons lose energy by in material (dE/dx). Re- accelerate in longitudinal direction  reduce transverse emittance. Coulomb scattering heats beam  low Z absorber.  LONGITUDINAL COOLING: Mix transverse & longitudinal degrees of freedom during cooling. Can be done in helical solenoids.  FINAL COOLING: To get the smallest achievable transverse emittance, over- cool the longitudinal emittance, and then reduce transverse emittance letting the longitudinal phase space grow. ε t,, N (m ) Liq. H 2 RF High Field (HTS) Solenoids 38 More detail about options in R. Palmer’s talk 15-Nov-11 Czech Technical University Future Lepton Collider

Muon Beam Spectro- meter Cooling section Spectro- meter MICE – upstream beamline - Tests short cooling section, in muon beam, measuring the muons before & after the cooling section. one at a time. - Learn about cost, complexity, & engineering issues associated with cooling channels. -Vary RF, solenoid & absorber parameters & demonstrate ability to simulate response of muons Muon Ionization Cooling Experiment (MICE) Nov-11 Czech Technical University Future Lepton Collider

Muon Collider Detectors  Unique to a Muon Collider are detector backgrounds from muon decay.  For TeV muon decays, the electron decay angles are O(10) mradians. Electrons typically stay inside beampipe for few meters. Hence decay electrons born within a few meters of the IP are benign.  Shielding strategy: sweep the electrons born further than ~6m from the IP into ~6m of shielding 40 Map of background particle densities in detector 15-Nov-11 Czech Technical University Future Lepton Collider

International Linear Collider ILC 15-Nov-11 Czech Technical University Future Lepton Collider 41

15-Nov-11 Czech Technical University Future Lepton Collider 42 ILC --- Deep Underground

15-Nov-11 Czech Technical University Future Lepton Collider 43 LHC --- Superconducting Magnet

15-Nov-11 Czech Technical University Future Lepton Collider 44 ILC - Superconducting RF Cryomodule

15-Nov-11 Czech Technical University Future Lepton Collider 45 Global Design Effort 45 Major R&D Goals for Technical Design Accelerator Design and Integration (AD&I) Studies of possible cost reduction designs and strategies for consideration in a re-baseline in 2010 SCRF High Gradient R&D - globally coordinated program to demonstrate gradient by 2010 with 50%yield; ATF-2 at KEK Demonstrate Fast Kicker performance and Final Focus Design Electron Cloud Mitigation – (CesrTA) Electron Cloud tests at Cornell to establish mitigation and verify one damping ring is sufficient.

15-Nov-11 Czech Technical University Future Lepton Collider 46 Proposed Design changes for TDR RDRSB2009 Single Tunnel for main linac Move positron source to end of linac *** Reduce number of bunches factor of two (lower power) ** Reduce size of damping rings (3.2km) Integrate central region Single stage bunch compressor

15-Nov-11 Czech Technical University Future Lepton Collider 47 The ILC SCRF Cavity - Achieve high gradient (35MV/m); develop multiple vendors; make cost effective, etc - Focus is on high gradient; production yields; cryogenic losses; radiation; system performance

Global Plan for ILC Gradient R&D 14-Nov-11 PAC - Prague Global Design Effort 48 New baseline gradient: Vertical acceptance: 35 MV/m average, allowing ±20% spread (28-42 MV/m) Operational: 31.5 MV/m average, allowing ±20% spread (25-38 MV/m)

14-Nov-11 PAC - Prague Global Design Effort 49 Cavity Gradient Milestone Achieved 2010 Milestone TDR Goal Toward TDR goal Field emission; mechanical polishing Other progress

15-Nov-11 Czech Technical University Future Lepton Collider 50

15-Nov-11 Czech Technical University Future Lepton Collider 51 Test Facilities: FLASH SCRF accelerator tests

15-Nov-11 Czech Technical University Future Lepton Collider 52

Example Experimental Results Flat gradient solution achieved –4.5 mA beam Characterisation of solution by scanning beam current –model benchmarking Beam Current (mA) Gradient change over 400us (%) Gradient Tilts vs Beam Current (ACC7) Intended working point ~2.5% 15-Nov-11 Czech Technical University Future Lepton Collider 53

FLASH: Stability 15 consecutive studies shifts (120hrs), and with no downtime Time to restore 400us bunch- trains after beam-off studies: ~10mins Energy stability with beam loading over periods of hours: ~0.02% Individual cavity “tilts” equally stable Energy stability over 3hrs with 4.5mA ~0.02% pk-pk 9 Feb Nov-11 Czech Technical University Future Lepton Collider 54

15-Nov-11 Czech Technical University Future Lepton Collider 55 Test Facilities: ATF-2 large international collaboration

ATF2 Goals: A. Achievement of 37nm beam size A1) Demonstration of a new compact final focus system; –proposed by P.Raimondi and A.Seryi in 2000, A2) Maintenance of the small beam size –(several hours at the FFTB/SLAC) B. Control of the beam position B1) Demonstration of beam orbit stabilization with nano- meter precision at IP. –(The beam jitter at FFTB/SLAC was about 40nm.) B2) Establishment of beam jitter controlling technique at nano-meter level with ILC-like beam 15-Nov-11 Czech Technical University Future Lepton Collider 56

15-Nov-11 Czech Technical University Future Lepton Collider 57 ATF2 – Beam size/stability and kicker tests IPShintake Monitor Final Doublet

58 15-Nov-11 Czech Technical University Future Lepton Collider

ATF / ATF2 After Earthquake? 15-Nov-11 Czech Technical University Future Lepton Collider 59 See first reports in ILC Newsline 17-March-11 Articles by Toshiaki Tauchi and Rika Takahashi

15-Nov-11 Czech Technical University Future Lepton Collider 60 Test Facilities: Cesr-TA eCloud broad accelerator applications

15-Nov-11 Czech Technical University Future Lepton Collider 61 Mitigating Electron Cloud Simulations – electrodes; coating and/or grooving vacuum pipe Demonstration at CESR critical tests eCloud R&D

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15-Nov-11 Czech Technical University Future Lepton Collider 63 CesrTA - Wiggler Observations IWLC CERN, Geneva, Switzerland 0.002” radius Electrode  best performance

15-Nov-11 Czech Technical University Future Lepton Collider 64 Field Region Baseline Mitigation Recommendation Alternatives for Further Investigation Drift*TiN CoatingSolenoid WindingsNEG Coating DipoleGrooves with TiN Coating Antechambers for power loads and photoelectron control R&D into the use of clearing electrodes. Quadrup ole* TiN Coating R&D into the use of clearing electrodes or grooves with TiN coating WigglerClearing Electrodes Antechambers for power loads and photoelectron control Grooves with TiN Coating Proposed ILC Mitigation Scheme

15-Nov-11 Czech Technical University Future Lepton Collider 65 Interaction Region (old location) Break point for push-pull disconnect Provide reliable collisions of 5nm-small beams, with acceptable level of background, and be able to rapidly and efficiently exchange ~10kT detectors in a push-pull operation several times per year

15-Nov-11 Czech Technical University Future Lepton Collider 66 Push – Pull Detector Concept Vibration stability will be one of the major criteria in eventual selection of a motion system design Both detectors without platformsBoth detectors with platforms

15-Nov-11 Czech Technical University Future Lepton Collider 67 Detector Concepts Report

15-Nov-11 Czech Technical University Future Lepton Collider 68 Detector Performance Goals

15-Nov-11 Czech Technical University Future Lepton Collider 69 Detector Performance Goals

15-Nov-11 Czech Technical University Future Lepton Collider 70 Detector Performance Goals ILC detector performance requirements and comparison to the LHC detectors: ○ Inner vertex layer ~ 3-6 times closer to IP ○ Vertex pixel size ~ 30 times smaller ○ Vertex detector layer ~ 30 times thinner Impact param resolution Δd = 5 [μm] + 10 [μm] / (p[GeV] sin 3/2θ) ○ Material in the tracker ~ 30 times less ○ Track momentum resolution ~ 10 times better Momentum resolution Δp / p 2 = 5 x [GeV -1 ] central region Δp / p 2 = 3 x [GeV -1 ] forward region ○ Granularity of EM calorimeter ~ 200 times better Jet energy resolution ΔE jet / E jet = 0.3 /√E jet Forward Hermeticity down to θ = 5-10 [mrad]

Future Lepton Collider 71 Final Reflections The energy frontier continues to be the primary tool to explore the central issues in particle physics The LHC at CERN will open the 1 TeV energy scale and we anticipate exciting new discoveries A companion lepton collider will be the logical next step, but such a machine has technical challenges and needs significant R&D and design now LHC results will inform the final design and even whether a higher energy options is needed, If so, this may also be possible, but on a longer time scale. 15-Nov-11 Czech Technical University