BPM statushallaweb.jlab.org/experiment/g2p/collaborators/pzhu/... · 2013. 12. 11. · BPM status...

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BPM status

12.11 2013

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Calibration method

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Signal for each antenna :

ϕ=ϕ0 Ir 2−ρ

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r 2+ρ2−2rρcos(θ−θ0)

θ= π4

3π

4−3π

4−π4

angle for 4antennas

I : Beam current

r : BPM vacuum chamber radius(17.3mm)

ρ: radial position of beamθ0: angle position of beam

Assume:Infinite chamber Antenna small enough

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The old method:

When signal large enough, the current and gain change(g+ g stable) will not affect resultThat's why autogain mode works before

Autogain mode:Fix g+ g, let gain auto change with current

● The BPM receiver have linear region● The diff/sum method also have nonlinearity

issue when raster is big

ADC received signal:(g is gain setting for receiver,in receiver's linear region)

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Improvement method:

1st step: rewrite diff/sum:

pedestalValue readout in ADC

Gain factor

Function compare with raw signal received in antenna,that is:

In receiver's linear response region:

Combine with:

Position dependent

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Harp scan step in 5/3:

timeline

Pulsed beam5uAHarp scan

CW beam100nATake run

CW beam75nATake run

CW beam50nATake run

CW beam25nATake run

1 harp scan period, assume position stable during this period

Change position

...

current

Raw ADC data

Get b(offset) from fit

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2nd step: For nonlinearity of diff/sum methood

Temp data

Temp dataFrom

More than 3 groups data

Absolute beam position from harp

Calibration constant

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Use 50nA constant Use 100nA constant

Use 50nA constant Use 100nA constant

BPM B

BPM A 0.65,0.79 0.70,0.90

1.04,0.55 1.22,0.70

Use the method before to compare the calculated value with diffent calibration constant

0.06,0.69 1.08,0.91

4.00,0.97 0.30,0.84

If didn't minus offset:

Test run: an 75nA run

If minus correct pedestal and offset,Constant could be use both 50nA and 100nA

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The subtracted pedestal use the closest one for same gain

Noise test after exp

Auto gain,Forget that

BPM B added carbon cover

First four chan: ALast four chan: B

Pedestal changing for the same gain setting

Best bpm situation BPM A period:4.11 ~ 5.18BPM B period: 5.3~5.18

line type: stepsprePoint: data

10BPM A period:4.11 ~ 5.18BPM B period: 4.11 ~ 4.25

Second best bpm situation

another gain setting

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Abnormal point,Forget thatCode bug

Noise test after exp

Calibration run

Production run

BPM A period:3.31~4.10BPM B period:3.31~4.10

Worse bpm situation


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Production run

Calibration run

Noise test after expBPM A period:3.29~3.31BPM B period:3.29~3.31

Worse bpm situation


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backup

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Digital PartAnalog Part

New BPM Receiver

LNA

X+XY+Y

MultiplyMixer

LocalOscillator

1497MHz

1452MHz

Filter IF Amp45MHz ADC

CICFilter

IIRFilter

sinθsinϕ=12

cos (θ−ϕ)−12

cos (θ+ϕ)

Harmonic samplingSample Rate:36MSPS

∣R∣=√ I 2+Q2

φ= tan−1(QI

)

CORDIC

Noise limitexclude outof band signal

∫ dt ddt

BW=175Hz

Calculate |R| and φ

Cascaded integratorcomb filter

Infinite impulse response filter

We can not see fast raster signal

Div>n

DAC

DAQ0~10V

M15

X+

X−

Y +

Y−

Epics

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BPM period: 5.3~5.18

1 2 3 43.3gev 5t2.2gev 5tstraight 2.2gev 5t

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BPM ABPM ABPM B

Use 0503 50nA const

BPM BUse 0503 50nA const





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Target position calculated :0503 50nA const: 13.6 2.20510 50nA const: 5.0 1.30510 100nA const: 3.5 1.5

2Hz filter Without filter

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BPM ABPM ABPM B

Use 0503 50nA const






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BPM ABPM ABPM B

Use 0503 50nA const






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BPM statushallaweb.jlab.org/experiment/g2p/collaborators/pzhu/... · 2013. 12. 11. · BPM status...

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