Precise and Fast Timing Network- a first view -

B. JeanneretCTC , December 2009

CLIC_TC,DEC_09,Time_network,BJ 2

Tolerance on Phase and Gradient• Luminosity and understanding/adjustment of the Beam Delivery and of

the Final Focus, DB vs. MB D.Schulte & R.Tomas, PAC09

Not much margin on these. i.e. σ ϕ = 0.2o ΔL/L = -1% σ ϕ = 0.4o ΔL/L = -4%

Overall cycle DB intertrain (or sector to sector)

Many contributions to : intrinsic + measurement errors, two beams , …

On top : MB vs. MB : twice smaller

1fs = 10-15 s

CLIC_TC,DEC_09,Time_network,BJ 3

e+ injector, 2.4 GeV

e- injector2.4 GeV

CLIC 3 TeV

e+ main linace- main linac , 12 GHz, 100 MV/m, 20.85 km

BC2BC2

BC1

e+ DR365m

e- DR365m

booster linac, 9 GeV, 2 GHz or 4 GHz ?

decelerator, 24 sectors of 868 m

IP1

BDS2.75 km

BDS2.75 km

47.9 km

drive beam accelerator2.38 GeV, 1.0 GHz

combiner rings Circumferences delay loop 72.4 m

CR1 144.8 mCR2 434.3 m

CR1CR2

delayloop

326 klystrons33 MW, 139 ms

1 km

CR2delayloop

drive beam accelerator2.38 GeV, 1.0 GHz

326 klystrons33 MW, 139 ms

1 km

CR1

TAR=120m

TAR=120m

245m 245m

83ps

TOL : 45fs

DB

MB

Feed-back box

CLIC_TC,DEC_09,Time_network,BJ 4

Timing and feed-back strategy in the tunnel• To relax on δφ : feed-forward &

back before entering each DECEL

9 GeV MB as a fast clock

Timing line

TA

MB to IP

DB∆t to:injectors DB & MBDamp. RingsMB TADB TAs@50 Hz

BA

Phase from B, Energy jitter δE from A&B,Phase correction for δE

C

D

C&D, Phase error MB/DB , to synchronizethe injector linacs

Open issue: frequency band of δE correction

E

D.Schulte et al,CLIC Note598A.Andersson & J. SladenEPAC06,TUPCH086PAC07,MOPAN066

CLIC_TC,DEC_09,Time_network,BJ 5

Fast & Precise timing network

…

MBTA

DRe-

Pre-DRe-

MBlinac

DRe+

IPEXP

TADBLinac

DLCR1,2

Source

MBLTL

Fbackbox

24 x

9Gev LTL

DECEL

Main Linac2km

50m

1km

500m

?

2km

100m

1km

20km

50mAll this for σt = 15fs

Here σt = 7.5fs to synchronizethe two complex

Here relaxed, tol must be set for full capture and match to damping timeBootLinac

CLIC_TC,DEC_09,Time_network,BJ 6

Long distance Cabling Issues

• Thermal expansion of copper :– dL/L =αΔT= 1.7 10⋅ -5 ΔT

• L = 100m , dL = δz = 5 mum ΔT = δz/α/L = 3 10⋅ -3 K

• XFEL approach– Move to optical fibers, with continuous length

measurement (reflect signal to the emitter)– Lasers and special fibers to produce soliton waves

CLIC_TC,DEC_09,Time_network,BJ 7

Precise timing network• Little (or no) expertise on site as of today.• Complicated optical systems• Expertise exists at XFEL (DESY,PSI)

• Presentations at CLIC09 : WG3 THURSDAY 11h00-12h30

– Long distance Optical Fibers with fs resolutionF. Oemer Ilday / Bilkent Univ. Ankara

– Overview of the Phase Measurement System at SLS/PSIVladimir Arsov / PSI

– Femtosecond optical synchronization system for FLASHMatthias Felber / DESY

CLIC_TC,DEC_09,Time_network,BJ 8

Open Issues• The whole timing network must afford a time resolution

δt = 15fs (7.5 fs for a part) – to be refined

– Which part must be fast, i.e allow for intra-cycle feedback/correction ?

– Which part need be precise only, i.e. allow for inter-cycle

analysis/diagnostics ?

• In-house expertise to be built-up

• In parallel : explore source of errors

– Measurements proper

– Slow movements

– Vibrations (nearby transformers, pulsed kickers, water turbulences, …)