3/25/2006 KEK LCPACMarc Ross - SLAC

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Results of Beam Instrumentation Studies at ATF

1. Nanometer resolution Beam Position Monitors2. High resolution readout for Ring Beam Position Monitors3. Extraction line laser-based profile monitor (laserwire)4. Fast feedback and feedforward

Cavity Beam Position Monitor RD

• Through use of dipole modes of monolithic (Cu) resonators, cavity BPM’s have far better resolution than striplines or buttons– Effective monopole suppression – Inherent stability– Many practical questions how to realize a large system

(ATF2)

• Intrinsic resolution and systematic offsets much less than 1 um– Excellent resolution allows online calibration process without

interrupting nominal operation

KEK, Tohoku, SLAC, LBNL, LLNL, Cornell, Cambridge, UCL, RHUL, Notre Dame

Goal: Prove viability of cavity BPMs for ILC

– Resolution, systematic errors, calibration process

• 2 sets of triplets installed at ATF– Triplet: residual determines resolution & allows study of

systematic errors– ‘full blown’ mover calibration, including angles

• Excellent ~20 nm resolution from 2004 – (world record)

• Carbon fiber metrology tube (LLNL) mounted in Jan 06– Monitor thermal space frame internal motion

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Two sets of triplets (z ~ 6m):

SLAC/US/UK tripletKEK triplet

Plan to test each individually – then connect (2006)

Present results from both!

3/25/2006 KEK LCPACMarc Ross - SLAC

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Generic Cavity BPM Design: TM11-mode Selective Coupler

• Dipole frequency: 11.424 GHz• Dipole mode: TM11

• Coupling to waveguide: magnetic• Beam x-offset couple to y port

• Sensitivity: 1.6mV/nC/m (1.6109V/C/mm)

• Couple to dipole (TM11) only

• Does not couple to TM01

–Low Q with narrow cavity gap

–May need to damp TM01

–OR, use stainless steel to lower Q

signal

signal

Z. Li

FFTB IP C-band cavity

BPM triplet – this is the

way to test BPM

performance…

T. Shintake - 1998

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• Move one BPM at a time with movers• Extract BPM phase, scale, offset as well as beam motion by linear

regression of BPM reading against mover + all other BPM readings.

Calibration - SLAC

250 pulse sequence

+/-

20

um r

ange

of

mot

ion

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Move BPM in 1 um Steps

SLAC – upstream triplet – 17 nm resolution

resi

dua

l

Development of Cavity BPM - KEK• System

– Three Cavity BPMs developed in KEK– Mover system with an active stabilization using an optical

interferometer– Analog down conversion and phase detection electronics

• Performance– Resolution of the BPM: 17nm– Active mover stabilizes the system better than the resolution

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Downstream triplet – KEK

Recent results:

High resolution readout - Ring Beam Position Monitors

• Goal: Upgrade ATF ring BPM electronics for improved resolution (100nm), stability (1um), calibration (1e-4)– Should allow beam tuning for 1pm-rad vertical emittance– Multi-pass system

• Use existing storage ring technology – fast digital receivers– Notch filter @ 50 Hz– SLS, Fermilab, APS, SPEAR

• Total replacement cost dominated by receiver electronics cost ~400K– Primary effort in designing and testing front end and

infrastructure

KEK, SLAC, Fermilab

7 ‘y’ BPMs: 3 upgraded & 4 original

Stored Beam – 10 minute time scale; ATF lifetime ~ few minutes

Fast ‘jitter’ – slow changes removedVs time for 10 minutes (stored beam)Each point 20 ms accumulation (86500 turns)500 nm rms

EchoTeck

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Legacy – single turn system

Fast ‘jitter’ – slow changes removedvs time for 10 minutes (stored beam)Each point single turn measurement11.6 um rms

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Ring Electronics: Status

• Receiver produced (20 units)– Cal system in design

• Initial commissioning Feb 2006• Second test in June

– Fermilab will join the group, and bring a full crate system for testing

– This is Fermilab’s first direct contribution to ATF

• Partial system remains in use at ATF (8 BPMs)

ATF Laser-wire•Goal: •At ATF, we will aim to measure micron-scale electron spot-sizes with green (532 nm) light.

• Aim at intra-train (fast) scan for 150 ns bunch spacing.

• The final spot-size measurable at ILC will have implications for the length and layout of the BDS diagnostics section. • The ATF/ATF2 results will be crucial to determine the technical boundaries.

pulsed laser-wire location

BESSY, DESY, Oxford, Royal Holloway, UCL, CCLRC, KEK, Kyoto, SLAC

ATF-LW Vacuum Chamber

Built atOxfordDO +Workshop

VacuumTestedAt DL

ATF Laser-wire

Vacuum chamber built in Oxford and Installed in ATF extractionLine in December 2006.

Laser lighttransported toIP, but nocollisions yet seen; probablya detector issue.

New run plannedFor April 06.

Designingdiagnosticsinsertionat Oxford

LW Practical Considerations

f1 geometry is challenging• Limitations from power• Limitations from angle• Surface optical quality• Alignment tolerance

f1 Lens design is challenging• Limitations from power• Limitations from ghost images• Alignment tolerance• Lens currently under construction

Canidate f/1 Lens Designs

Aspheric doublet

N. Delerue et al.Spheric triplet

ZEMAX course held at JAI in January 2006.

Expertise and possibilities are expanding

Vacuum window

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Laserwire Plans

• Data run in Spring 2006• More runs 06/07; lots of systematics to understand (eg beam jitter,

BPM integration …)• Integrate solid wire scanner into vac. vessel design• Iteration on lens design.• Provide statement to GDE on technical feasibility of reliable micron-

scale LW

Up to Apr 07

Beyond Apr 07 (subject to new funding)

• Play a major role in ATF2 LW system.• Develop fast scanning• Multiple IP’s, laser system, light transport.• Investigate running with UV light.• Collaborate on “Shintake” type systems. ATF2

Feedback On Nanosecond Timescales (3)

Adjustable-gap kicker

BPM ML11X

Feedback

SuperfastBPM processor

Superfastamplifier

BPM ML12X

BPM ML13X

Aim:

TOTAL latency

< 20 ns

Oxford, DESY, CCLRC, KEK, Tokyo Metropolitan, SLAC

ATF extraction line beam direction

FONT3: latency budget

• Time of flight kicker – BPM: 4ns• Signal return time BPM – kicker: 6ns• Irreducible latency: 10ns

• BPM processor: 5ns• Amplifier + FB: 5ns• Electronics latency: 10ns

• Total latency budget: 20ns

• Will allow 56/20 = 2.8 periods during an ATF multi-bunch train

FONT3: BPM processor tests (single-bunch, December 2004 beam tests)

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FONT3: Results (June 3 2005):Delay-loop feedback w. latency 23 ns

56ns bunchtrain

FB on

FB + delay loop on23ns

200um

FONT1,2,3: Summary

67 ns

54 ns

23 nsEven fast enough for CLIC intra-train FB!May also be used at ILC

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• ATF/(ATF2): 1.3 GeV beam, 3 bunches with spacing c. 150ns

• FONT4 (2005-6):• modified FONT3 BPM front-end signal processor • digital FB system• modified FONT2 solid-state amplifier: 300ns long o/p pulse• FEATHER adjustable-gap kicker

• Aiming for first demonstration of FB w. ILC-like bunches: • total latency 140ns (electronics + signal propagation)• stabilisation of 3rd bunch at um level

• First component tests at ATF December 2005/April 2006

FONT4: Prototype Digital Feedback System for ILC IP

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FPGA

DAC

DAC

ADC

ADC

ADC

ADC

Differential To

singleAIN4

AIN3

AIN2

AIN1

AOUT1

AOUT2RAM

Clock circuit

JTAGcircuit

USBcircuit

UARTcircuit

IN Power Jack & switch

5v 2.5v ? v3.3v

JTAG connector

Serial connector

USBconnector

Flash/EEPROM

Clk IN

Differential To

single

Differential To

single

Differential To

single

FONT4: Digital FB Processor Module (Dabiri Khah)

Latency goal 100ns

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1. FONT4 prototype ILC digital FB system

Dec 05: modified analogue BPM processor tests

Apr 06: test of digital FB board

Jun 06: closed-loop FB system test with 3-bunch train

2. Ring -> extraction-line feed-forward

Dec 05: jitter correlations + transfer matrix studies

2006: design + tests of feed-forward system

3. FONT5 prototype ILC digital FB system

2007: algorithm development + tests w. 20-bunch train

FONT plans for ATF/ATF2

ILC ring extraction

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Instrumentation Studies at ATF – 2006

• 20 nm resolution cavity BPM demonstrated– Link 2 systems (2006)

• 500 nm resolution ring BPM system demonstrated– Offsets & drifts (2006)– pm-radian emittance (2006)

• 1 um laserwire scans (2006)• Fast feedback demonstrated (23ns)

– ILC parameters (2006)