Tevatron BPM System Upgrade Technical Update Bob Webber Run II Luminosity Upgrade Review February...

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%


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


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


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


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


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


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


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


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


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


Same Coalesced Proton Bunch Given Big Vertical Same Coalesced Proton Bunch Given Big Vertical KickKick


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


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


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


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”


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”

Tevatron BPM System Upgrade Technical Update Bob Webber Run II Luminosity Upgrade Review February...

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