NanoBPM SignalsNanoBPM Signals

Second Mini-Workshop on Nano Project at ATFSecond Mini-Workshop on Nano Project at ATFDecember 11-12, 2004December 11-12, 2004

Toyoko OrimotoToyoko OrimotoYury KolomenskyYury Kolomensky

Lawrence Berkeley Laboratory &Lawrence Berkeley Laboratory &University of California, BerkeleyUniversity of California, Berkeley

in collaboration within collaboration withSLAC, LLNL, UCL SLAC, LLNL, UCL

NanoBPM Signals – Toyoko Orimoto

IntroductionIntroduction

• Waveform fit

• Strip charts for online monitoring

• Offline analysis to determine calibration

• Study of correlations from fits

Nano BPM Nano BPM ProjectProject@ ATF@ ATF

NanoBPM Signals – Toyoko Orimoto

BPM Strip ChartsBPM Strip Charts

NanoBPM Signals – Toyoko Orimoto

BPM Strip ChartsBPM Strip Charts

• Strip charts display position, tilt, and phase from fits

BPM 1

BPM 2

BPM 3

• Raw waveforms & residuals from fits

• Display other statistics: amplitude, frequency, decay time, etc.

• Can also replay offline and change calibrations, etc.

• Online monitoring to steer BPMs

NanoBPM Signals – Toyoko Orimoto

Fit Residuals – “Fish Plots”Fit Residuals – “Fish Plots”• Residuals from fit to waveform – our fit is not correct.

• Change to double fit (see S. Smith’s talk)

NanoBPM Signals – Toyoko Orimoto

Beam Position & Tilt CalibrationBeam Position & Tilt Calibration

movers move cavity in 50 m position steps

(500 rad for tilt calibration)

event

Q

Similar procedure to calibrate tilt

event

I

Q

I

IQ Phase tan-

1(slope)

Slope = position scale

Slope = tilt scale

NanoBPM Signals – Toyoko Orimoto

Calibration CheckCalibration Check

As a cross-check, waveforms were re-fitted with the calibration constants produced using the steps previously outlined.

If calibration constants were good, then Q → position and I → tilt.

So we expect I vs Q plots to be flat and tilt vs event to be flat (in the case of position calibration)…

Q vs. I

NanoBPM Signals – Toyoko Orimoto

““Bow-tie” CorrelationBow-tie” Correlation

• See a “bow-tie” effect in position vs tilt after calibration

• Further away from position, larger spread in tilt

• Avoid such effects by working at smaller amplitudes for calibration for now…

• Also will try to get reference cavity frequency closer to the other BPM frequencies

Position vs Tilt

NanoBPM Signals – Toyoko Orimoto

Frequency & Position CorrelationFrequency & Position Correlation

• Frequency dependence on sign of position

• Difference ~ 0.05 MHz• Such sensitivity occurs

with small amplitude

BPM1 Y Freq vs event

BPM1 Y Amplitude vs event

BPM1 Y Q vs event

NanoBPM Signals – Toyoko Orimoto

Frequency & Position CorrelationFrequency & Position Correlation

… Study this by looking at data with beam centered in different quadrants of the BPMs

Y1 Q

Y1

Fre

quen

cy

See S. Smith’s talk

NanoBPM Signals – Toyoko Orimoto

Position & Tilt CorrelationsPosition & Tilt CorrelationsCorrelation matrix: Dec 02 data

• Correlations from fits computed

X Pos Y Pos X Tilt Y Tilt Ref

BPM 1, 2, 3

X P

os

Y P

os

X T

ilt

Y T

ilt

Ref

Red: high correlation

Green: no correlation

Blue: anti-correlation

• Use this as a debugging tool:

• Sign error in X2 calibration

• Intensity correlated to X2 tilt – problem with the fitting

NanoBPM Signals – Toyoko Orimoto

Position & Tilt CorrelationsPosition & Tilt Correlations

X Pos Y Pos X Tilt Y Tilt Ref

BPM 1, 2, 3

X P

os

Y P

os

X T

ilt

Y T

ilt

Ref • Red: high correlation

• Green: no correlation• Blue: anti-correlation

• Similar to July 2003 data

• Y tilt anti-correlated with X position

• Tilts should be more correlated

Correlation matrix: Dec 07 data

NanoBPM Signals – Toyoko Orimoto

ConclusionsConclusions

• Continue to analyze data offline

• Improve fitting algorithm

• Improve calibration technique

• Study correlations in further detail