BPM statushallaweb.jlab.org/experiment/g2p/collaborators/pzhu/... · 2013. 12. 11. · BPM status...
Transcript of 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
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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
another gain setting
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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
another gain setting
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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
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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
BPM BUse 0503 100nA const
BPM BUse 0503 100nA const
BPM BUse 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
BPM BUse 0503 50nA const
BPM BUse 0503 100nA const
BPM BUse 0503 100nA const
BPM BUse 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
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BPM ABPM ABPM B
Use 0503 50nA const
BPM BUse 0503 50nA const
BPM BUse 0503 100nA const
BPM BUse 0503 100nA const
BPM BUse 0503 50nA const
BPM BUse 0503 50nA const
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Target position calculated :0503 50nA const: 11.1696 2.042220510 50nA const: 10.3268 5.796690510 100nA const: 8.64751 5.80262