Philip Burrows ATF 15/03/05

FONT Group Progress + Plans 2005

Philip Burrows, Christine Clarke,

Glenn Christian, Hamid Dabiri Khah,

Stephen Molloy, Glen White

(Queen Mary, University of London)

Alexander Kalinin (Daresbury Lab.)

Colin Perry (Oxford)

Doug McCormick, Marc Ross (SLAC)

Philip Burrows ATF 15/03/05

General Strategy

• March 2005:Commission final version of superfast processor + jitter

monitor

• June 2005:FONT3 closed-loop feedback tests with new amplifier

• During 2005: Develop prototype for FONT4 digital feedback system for ILC bunch spacing

• December 2005: First commissioning studies with prototype digital system

• March 2006: Possible first feedback tests with digital system + 3 ILC bunches

Philip Burrows ATF 15/03/05

FONT3 experiment outline

Adjustable-gap kicker

BPM ML11X

Feedback

SuperfastBPM processor

Superfastamplifier

BPM ML12X

BPM ML13X

Aim:

TOTAL latency

< 20 ns

Philip Burrows ATF 15/03/05

FONT3: ATF beamline configuration

kicker BPMML11X

Philip Burrows ATF 15/03/05

FONT3 beam requirements

• 20-bunch train (56 ns)essential in order to see action of delay loop

• Uniform charge within train (better than +- 10%)essential since no time for charge normalisation

• Flat bunch-bunch vertical position profile within traindesirable

• Small bunch-bunch vertical position jitter within train (few microns)essential

• Small train-train vertical jitter (c. ten microns)essential to avoid amplifier saturation (c. 50 microns)

Philip Burrows ATF 15/03/05

FONT3 jitter monitor

• Aim to measure bunch-bunch

jitter at micron level

• First tests June 2004:

bunches resolved, but position

resolution > 10 microns

(common-mode rejection issues)

• Improved processors tested

December 2004 (BPMs 8, 10, 13)

+ 2 BPMs in ring + March 2005

Philip Burrows ATF 15/03/05

y position jitter correlation: extraction line - ring(FONT shift December 2004: 40 sequential 20-bunch trains)

Offers possibilityfor jitter correctionby feed forwardfrom ring to extraction line

ATF2 demandsmicron-levelposition stabilityat entrance tofinal focus

Philip Burrows ATF 15/03/05

Jitter Monitor

Tuesday shift – 8/9 March 2005 (single bunch)– Measured delays between sum and difference

signals using new synchronisation circuit, for BPMs 26 and 27 in ring and BPMs 8 and 13 in extraction.

– BPM26 delay = -208 ps– BPM27 delay = 90 ps– BPM8 delay = 430 ps– BPM13 delay = -384 ps

Philip Burrows ATF 15/03/05

Calibration measurement for BPM26&27– BPM 26 – 1.6877– BPM 27 – 1.3381

Calibration for BPMs 26 + 27

Philip Burrows ATF 15/03/05

Friday shift – 12 Mar

Multibunch mode– 3 BPMs in Extraction line – BPMS 8,10,13– Synchronisation data for BPM10– Calibration data for all three BPMs

Single Bunch mode– Exchanged BPM 10 in extraction line for

BPM26 in ring– Took data to study correlation between jitter in

ring and extraction line.

Philip Burrows ATF 15/03/05

Multi-Bunch Calibration

-6 -5.5 -5 -4.5 -4 -3.5 -3 -2.5

x 10-4

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

-1.6 -1.5 -1.4 -1.3 -1.2 -1.1 -1 -0.9 -0.8 -0.7 -0.6

x 10-3

-1

-0.5

0

0.5

1

1.5

-3.2 -3 -2.8 -2.6 -2.4 -2.2 -2 -1.8 -1.6 -1.4

x 10-3

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

ML8X

ML10X

ML13X

1712±111 V/m

2374±24 V/m

2104±20 V/m

Philip Burrows ATF 15/03/05

Multi-Bunch Resolution

•Residuals from fitted position at ML10X based on ML8X and ML13X for 100 consecutive pulses (at 0.7 Hz).

•Estimate of jitter at ML10X -> 3.1 um.

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

x 10-5

0

5

10

15

20

25

30

35

Residual / m

Resolution = 5.7 +/- 1.9 um