CLIC-UK Programme Status Philip Burrows John Adams Institute Oxford University 1

CLIC-UK programme CI/Manchester: main beam RF, crab cavities CI/Lancaster: crab cavities ASTeC: drive-beam quads + crab cavities JAI/Oxford: beam FB+FF, laserwire, BPMs JAI/RHUL: transverse beam size, cavity BPMs Dundee: longitudinal beam profile monitor 2

Drive beam 3

Drive Beam Quadrupoles (ASTeC) High energy quad – Gradient very high Low energy quad – Very large dynamic range Erik Adli & Daniel Siemaszko High Energy Quad Low Energy Quad

Basic Engineering Concept Steel Non-magnetic support PM Block Steel Pole Norbert Collomb

Measured Field Quality

7 Drive beam phase feed-forward (Oxford) Schulte

8 Drive beam phase feed-forward Skowronski

System concept (CDR) urad kick at each bend - 0.5% energy spread, 1m dispersion -> 5mm rms - beam pipe diameter >> 50mm - 4 kickers at each bend - > 400kW peak power amplifier to each kicker dipole magnet 1m kicker 400kW amp 8m5m 8m NOT TO SCALE 9

CTF3 phase FF prototype 10

11 Phase monitor (Frascati) Signal down-mixer (CERN) Feedback processor + firmware (JAI Oxford) Drive amplifier (JAI Oxford) Kickers (Frascati)  1 mrad kick  1.2 mm path length change  17 degrees at 12 GHz  0.2 degree resolution CTF3 phase FF prototype

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Feedback and instrumentation 16

ATF2/KEK: prototype final focus 17 Goals: 1)37 nm beam spot (65 nm achieved 2013) 2)Beam spot stabilisation at c. 5 nm level

ATF2/KEK: prototype final focus 18 Beam feedback + feed-forward systems Precision cavity + stripline BPMs Beam size diagnostics Beam tuning techniques

19 Aim to stabilise beam in IP region using 2-bunch spill: 1. Upstream FB monitor beam at IP 2. Feed-forward from upstream BPMs  IP kicker 3. Local IP FB using IPBPM signal and IP kicker Beam feedback + feed-forward (Oxford)

Upstream FONT5 System Analogue Front-end BPM processor FPGA-based digital processor Kicker drive amplifier Stripline BPM with mover system Strip-line kicker Beam BPM Resolution < 350nm Dynamic range of the BPM system+/-500μm System Latency<150 ns Amplifier Bandwidth~30 MHz 20

Interaction Point FONT System Analogue Front-end BPM processor FPGA-based digital processor Kicker drive amplifier Strip-line kicker Designed in house 12.5 cm stripline kicker Based on ATF stripline BPMs Beam Cavity BPM 21

ATF2 beam stabilisation results 1.Upstream FB: beam stabilised at IP to ~ 300 nm 2. Feed-forward: beam stabilised at IP to ~ 106 nm 3. IP FB: beam stabilised at IP to ~ 93 nm Getting interesting! (i.e. hard) 22

IP Feedback in CLIC CDR 23

ATF2 beam position monitors (RHUL) IBIC : Beam Instrumentation at ATF2 (S. T. Boogert for ATF collab.) 11/03/201624

CLIC Main beam BPM prototype Low-Q stainless steel cavity Simulation in – Gdfidl – Microwave studio Measurement – RHUL (before) and CERN (after brazing) – Beam CALIFES Dipole cavity – f dipole = GHz – Q L = 274 – Q 0 =450 Reference cavity – f dipole = GHz – Q L = /03/2016 IBIC : Beam Instrumentation at ATF2 (S. T. Boogert for ATF collab.) 25

26 Transverse beam size (JAI)

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Electro-Optical Spectral Decoding (Dundee) Spectral Decoding (EOSD): The Coulomb field temporal profile of the e-bunch is encoded on to a time-wavelength correlated optical probe pulse. The profile is read-out through the spectrum of the probe pulse. Where, Simulations of bunch-induced polarisation change and non-linear interaction

P: Polarizer H: Half wave plate Q: Quarter wave plate : Mirror with actuators : Finger camera Grating Laser: Wavelength: 780 nm Duration: 100 fs Repetition: MHz Pulse energy: 2.7 nJ Crystal: Thickness: 1mm Separation: 5-10 mm Photo-injector Accelerating structureDiagnostic section Beam direction 10 Actuators 3 Rotation motors 6Finger cameras 7 Plane mirrors 2 Polarizers 2 Wave plates 1 Lens 1 Fibre head In CLEX 1 Laser 1 ICCD Camera 1 Motor stage 10 Plane mirrors 3 Gratings 3 Lenses 1 Fibre head In Lab Gated iCCD Camera Intensifier size 25 mm Number of Pixels 1280 x 1024 Pixel Size 6.7 um x 6.7 um Scan Area 8.6mm x 6.9mm Scaling Rates (magnification) 1: 2.17 CCD Temperature (by air) -12 o C Full Well Capacity (Image pixel well depth) 25,000e - Readout Noise 7…8e A/D convertor 12 bit A/D conversion factor (Sensitivity) 5 e - /count Average Dark Charge (Equivalent Background Illuminance) <0.1 e - /pixel sec Readout Time (Full frame) 8 fps Min gating time 3 ns QE ~25% Implementation of the EO monitor at CALIFES

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Crab cavity (Lancaster, ASTeC) 34

Objectives: Calculate wakefield effects for CLIC beams and analyze alignment tolerances. Optimize crab cavity damping structures. Design and fabricate a crab cavity appropriate for high gradient testing at CERN Feasibility studies and associated measurements for the Crab RF distribution system.

Full structure (with coupling and damping) magEz at GHz

CLIC Prototype 1 - UK manufactured Test by measuring S-parameters at each port then combining to get the dual port F-parameters. Cavities have not been tuned yet. The 1 st CLIC crab cavity prototype has been manufactured by Shakespeare Engineering in the UK. Tolerance and surface roughness on single parts have been measured and are acceptable. Structure is planned to be tested at SLAC in the near future.

Prototype 2 – CERN/VDL Built Size Number of cells12 Total length (mm) Active length (mm) The structure being built for high gradient test at CERN has only a single feed as it will not see beam. Cavity is being machined at VDL along with main linac structure to allow comparison of gradients.

Revised Crab Synchronisation Scheme 48MW 200ns pulsed GHz Klystron repetition 50Hz Vector modulation Control Phase Shifter 12 GHz Oscillator Main beam outward pick up From oscillator Phase shifter trombone (High power joint has been tested at SLAC) Magic Tee Waveguide path length phase and amplitude measurement and control 4kW 5  s pulsed 11.8 GHz Klystron repetition 5kHz LLRF Phase shifter trombone LLRF Cavity coupler 0dB or -40dB Expansion joint Single moded copper plated Invar waveguide losses over 35m ~ 3dB -30 dB coupler Forward power main pulse 12 MW Reflected power main pulse ~ 600 W Reflected power main pulse ~ 500 W Waveguide from high power Klystron to magic tee can be over moded Expansion joint RF path length is continuously measured and adjusted

Board Development and CW tests Front end electronics to enable phase to be measure during the short pulses to an accuracy of 2 milli-degrees has been prototyped and dedicated boards are being developed. PLL controller MCU 10.7 GHz VCO Digital phase detector DBMs Power Meters Wilkinson splitter Inputs 400 ns span: RMS: 1.8 mdeg Pk-Pk: 8.5 mdeg 90 s span: Drift rate : 8.7 mdeg/10s Total drift: 80 mdeg

Main linac structure studies (Manchester) Alternative designs including wakefield suppression of HOMs 41

Convex ellipticity Single undamped cell Iris radius=4.0 mm CLIC_DDS_E Elliptical Design –E Fields Circular Square b a

Summary CLIC-UK has delivered significant contributions Discussing next phase aimed at tackling issues in preparation for project implementation plan: Phase feed-forward prototype (CTF3) Nanometer beam stabilisation (ATF2) Beam Delivery System + MDI design Beam instrumentation + diagnostics systems Suggestions to look at dipole magnet design Crab cavity Klystron design 43