tevatron bpm system upgrade technical update
DESCRIPTION
Tevatron BPM System Upgrade Technical Update. Bob Webber Run II Luminosity Upgrade Review February 2004. Key Specifications (Protons): Measurement Range: 15mm Absolute Position Accuracy: < 1.0 mm Long Term Position Stability: < 0.02 mm - PowerPoint PPT PresentationTRANSCRIPT
Tevatron BPM System UpgradeTevatron BPM System UpgradeTechnical UpdateTechnical Update
Bob WebberRun II Luminosity Upgrade Review
February 2004
BPM Technical Update - DoE Run II Review - February 2004 - Webber 2
BPM Accuracy/Resolution SpecsBPM Accuracy/Resolution Specs
This is Table 2 from Requirements document. Table gives the most stringent requirements on the system; for certain types of operation these requirements are relaxed. Note: resolutions are
stated as 3 sigma.
Key Specifications (Protons):Measurement Range: 15mmAbsolute Position Accuracy: < 1.0 mmLong Term Position Stability: < 0.02 mmBest Orbit Position Resolution: < 0.02mm (0.3 sec averaging)Position Linearity: < 1.5%Relative Position Accuracy: < 5%Intensity Stability: < 2%Key Specifications (Pbars)_:Measurement Range: 15mmAbsolute Position Accuracy: < 1.0 mmLong Term Position Stability: < 0.02 mmBest Orbit Position Resolution: < 0.05mm (0.3 sec averaging)Position Linearity: < 1.5%Relative Position Accuracy: < 5%Intensity Stability: < 2%
BPM Technical Update - DoE Run II Review - February 2004 - Webber 3
Block Diagram Cartoon of Signal PathBlock Diagram Cartoon of Signal Path
Note that proton and pbar signal paths from same half of BPM are directly connected together by the stripline --- reflections from one will feed directly into the signal of the other
attenuator 53MHz BPF Eight
Channel
VME
Digital
Receiver
Proton Inside
attenuator 53MHz BPF
attenuator 53MHz BPFProton Outside
Pbar Outside
attenuator 53MHz BPF
Pbar Inside
VME
CPU
ACNET
Diagnostic
and Calibrate
Signals
BPM Technical Update - DoE Run II Review - February 2004 - Webber 4
Demonstrated Beam MeasurementsDemonstrated Beam Measurements
Recycler-type BPM front-end is set up for development and tests in TeV House A1
Connects to both Proton and Pbar signals of one horizontal BPM and one vertical BPM
Interfaced to ACNET with small subset of ultimate required functionality
Closed orbit and turn-by-turn measurement performance have been demonstrated
In use to assess narrowband frequency domain p/pbar signal de-convolution
Will soon demonstrate “wide” time separation of Protons and Pbars (utilize isolated bunches at the ends of the otherwise over-lapping 12-bunch trains); ~50 rather than ~5 nsec timing
BPM Technical Update - DoE Run II Review - February 2004 - Webber 5
Proton Positions in Load of Store #3172: Proton Positions in Load of Store #3172: OldOld vs vs New New
Old: rms error ~140 um for uncoalesced beam, ~70 um for coalesced beam, and 0.6 mm “step” between the two
New: rms error ~25 um for uncoalesced beam, <9 um for coalesced beam, no “step” between the two
BPM Technical Update - DoE Run II Review - February 2004 - Webber 6
Closed Orbit Resolution During Proton LoadingClosed Orbit Resolution During Proton Loading
Green: Vertical Position @ 100 microns/div showing ~10 micron resolution and orbit changes due to leakage fields in ramping injection Lambertson magnet
Red: Beam Intensity showing proton bunches loadingYellow: Time in Supercycle
BPM Technical Update - DoE Run II Review - February 2004 - Webber 7
Upper Limit of Closed Orbit ResolutionUpper Limit of Closed Orbit Resolution
Average of standard deviations for twelve five-minute intervals
First one-hour interval Second one-hour interval
0.0085 ± 0.00061 mm
0.0090 ± 0.00072 mm
Two one-hour periods of 1 KHz bandwidth proton position measurement data, 17 hours apart, in store #3148. (data-logged at
1 Hz) 50 microns / vertical division
Demonstrates upper limit resolution of 9 microns rms in 1 Khz (any real beam motion not excluded) to meet spec of 7 micron 1 sigma
in ~10Hz
BPM Technical Update - DoE Run II Review - February 2004 - Webber 8
Injection Turn-By-Turn --- Un-coalesced ProtonsInjection Turn-By-Turn --- Un-coalesced Protons
0 200 400 600 800 10002.5
2.25
2
1.75
1.5
va14_pos n
n
0 200 400 600 800 10001
1.5
2
2.5
3
ha15_pos n
n
0.5 0.550
0.02
0.04
fftv14p m
1fm
0.5 0.550
0.02
0.04
ffth15p m
1fm
Vertical A14 Horizontal A15
vertical axis units are millimeters in all plots
vertical tune horizontal tune
BPM Technical Update - DoE Run II Review - February 2004 - Webber 9
Turn-by-Turn Long After Injection Single Coalesced Turn-by-Turn Long After Injection Single Coalesced Bunch Bunch
0 200 400 600 800 10002.5
2.38
2.25
2.13
2
va14_pos n
n
0 200 400 600 800 10001
1.5
2
2.5
3
ha15_pos n
n
Vertical A14 Horizontal A15
0.5 0.550
0.02fftv14p m
1fm
0.5 0.550
0.005ffth15p m
1fm
vertical axis units
are millimeters in all plots
Horizontal transverse motion due to persistent synchrotron oscillation
BPM Technical Update - DoE Run II Review - February 2004 - Webber 10
Upper Limits on TBT Resolution --- Vertical A14Upper Limits on TBT Resolution --- Vertical A14
If remove betatron and synchrotron motion by zeroing 17 frequency line amplitudes around betatron frequencies and one at synchrotron frequency, leaving untouched 494 of the original 512 frequencies, TBT resolution is found to be 15 microns
0 500 1000
2.4
2.2
2
va14_pos n
n0 1 10
42 10
40
0.02fftv14p m
fm
Standard deviation of raw data is 34 microns
0 500 1000
2.4
2.2
2
vcooln
n0 1 10
42 10
40
0.02fftv14p m
fm
BPM Technical Update - DoE Run II Review - February 2004 - Webber 11
Same Coalesced Proton Bunch Given Big Vertical Same Coalesced Proton Bunch Given Big Vertical KickKick
Vertical A14 Horizontal A15
0 200 400 600 800 10006
4
2
0
2
va14_pos n
n
0 200 400 600 800 10001
1.5
2
2.5
3
ha15_pos n
n
0.5 0.550
0.5
1
fftv14p m
1fm
0.5 0.550
0.1ffth15p m
1fm
vertical tune horizontal tune vertical tune
BPM Technical Update - DoE Run II Review - February 2004 - Webber 12
Antiproton MeasurementsAntiproton Measurements
Present ratio of proton to antiproton intensities combined with directivity of stripline pick-up produces residual proton signals at the antiproton port about 50% the amplitude of antiproton signals
When antiproton intensities increase they will begin to “contaminate” the proton signals also
We opt to not pursue p/pbar separation by precise timing
Typical signal from pbar end of BPM for present bunch intensities
80 nsec/tic
Pbar bunchsignal Undesired Proton
bunch signal
BPM Technical Update - DoE Run II Review - February 2004 - Webber 13
Antiproton “Plan A”Antiproton “Plan A”
Model BPM as an 8-port network at processing frequency Measure network transfer functions with beam, e.g. ratio of proton
signal on pbar end to proton signal on proton end Measure signals then correct according to pre-determined transfer
function before computing positions Measurements in process to determine achievable accuracy
LinearSystemBPM
UpperProton
UpperPbar
LowerProton
LowerPbar
P Upper In
P Lower In
Pbar Upper In
P UpperScope
In Refl
In Refl
InRefl
InRefl
Pbar UpperScope
P LowerScope
Pbar LowerScope
1
2 7 8
3
4
56
BPM Technical Update - DoE Run II Review - February 2004 - Webber 14
0 5 106
1 105
1.5 105
2 105
0
1
2
protons zz t( )
pbars zz t cptcog( )
t
VA14 Collision
0 5 106
1 105
1.5 105
2 105
0
1
2
protons zz t( )
pbars zz t cptcog( )
t
VA25 Collision
0 5 106
1 105
1.5 105
2 105
0
1
2
protons zz t( )
pbars zz t inj0cog( )
t
VA14 Injection
0 5 106
1 105
1.5 105
2 105
0
1
2
protons zz t( )
pbars zz t inj0cog( )
t
VA25 Injection
Separate p/pbar signals with relaxed timing requiring precision and maintenance of ~50 nsec rather than ~5 nsec
Observe only “isolated” proton or antiproton bunches at ends of 12-bunch trains
No pbar bunches observable One pbar bunch observable
Five bunches observable Two bunches observable
Antiproton “Plan B”Antiproton “Plan B”
BPM Technical Update - DoE Run II Review - February 2004 - Webber 15
Coverage of Ring in Antiproton “Plan B”Coverage of Ring in Antiproton “Plan B”
0 1000 2000 3000 4000 5000 6000 70000
50
100
21
clearz
bpm1
z
After 1st pbar injection nclr 123
0 1000 2000 3000 4000 5000 6000 70000
200
400
21
clearz
bpm1
z
After 4th pbar injection nclr 177
0 1000 2000 3000 4000 5000 6000 70000
200
400
21
clearz
bpm1
z
During acceleration nclr 235
0 1000 2000 3000 4000 5000 6000 70000
200
400
21
clearz
bpm1
z
After 7th pbar injection nclr 226
0 1000 2000 3000 4000 5000 6000 70000
200
400
21
clearz
bpm1
z
At collision nclr 224 Locations with at least one clear pbar bunch (at least 400 nsec from nearest proton bunch) at various times in cycle
x axis is feet around ring from B0, each point is BPM location
y axis is clearance >21 is “clear”