Tevatron Orbit Stabilization

Tevatron Orbit Tevatron Orbit StabilizationStabilization

Dean StillDean Still

June 2, 2008June 2, 2008

D. Still - AEM- Tevatron Orbit Stabilization

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• History and Purpose for History and Purpose for ImplementingImplementing

• Components of the Orbit Components of the Orbit StabilizationStabilization

• How well does it workHow well does it work• SummarySummary


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History and Purpose of the History and Purpose of the Tevatron Orbit StabilizationTevatron Orbit Stabilization• Created in Sept of 2005 as a way of Created in Sept of 2005 as a way of

countering changes in the orbit during a countering changes in the orbit during a store.store.

• These changes in the orbit during the store These changes in the orbit during the store were mainly coming from motion in the CDF were mainly coming from motion in the CDF and D0 lowbeta quads due to changing and D0 lowbeta quads due to changing environmental conditions of the support environmental conditions of the support structures.structures.

• Since then many changes & improvements to Since then many changes & improvements to these support structures have been made but these support structures have been made but orbit changes in a store still occur.orbit changes in a store still occur.


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Example: Halo Losses as a Example: Halo Losses as a Result of B0 Lowbeta Quad Result of B0 Lowbeta Quad

Motion (2005)Motion (2005)

CDF Proton Halo Losses

Ver A37 BPM

A4Q3 pitch sensor

A4Q3 roll sensor

Store 3969 from Feb 17 , 2005

Invar rods Replace by support column 11/2004 (Courtesy T. Johnson)

New support column sensitive to temp.


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Example: Result of D0 Example: Result of D0 Lowbeta Quad Motion Lowbeta Quad Motion

(2007)(2007)

(Courtesy of T. Johnson)

In Aug 2007 found that air pressure differences between D0 collison hall and Tev tunnel caused small changes to Lowbeta quads and orbits. Air flow between Tev Tunnel

And D0 collision Hall.

Test where was injected into Girder that effected orbit

D1 air flow

Orbit Stabilization


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History and Purpose of the History and Purpose of the Tevatron Orbit Stabilization Tevatron Orbit Stabilization

(2)(2)• In spring 2006 – added an additional In spring 2006 – added an additional component to OS – smooth to reference orbit component to OS – smooth to reference orbit at Initiate Collisions.at Initiate Collisions.

• Feb 2008 - CDF had problems with a HVAC Feb 2008 - CDF had problems with a HVAC breaker – we found had no way to combat breaker – we found had no way to combat losses due to poor lifetime at lbseq25 before losses due to poor lifetime at lbseq25 before Int. collision due to poor orbit. (Lost 2 stores).Int. collision due to poor orbit. (Lost 2 stores).

• March 2008 – Added smooth to reference orbit March 2008 – Added smooth to reference orbit when the tevatron lands at lbseq 25, Int when the tevatron lands at lbseq 25, Int collision and end of store. collision and end of store.


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Types of Orbit Types of Orbit StabilizationStabilization

Ramp

Squeeze

Start ofStore

1st Smooth To Ref at lowbeta

2nd Smooth To Ref at collision

Start Orbitstabilization

There are 2 types of orbit corrections made by OS.

1)Orbits is smoothed to a reference orbit file one time at lowbeta, at Int collisions and at the end of a store.

1)Once a store begins, the orbit stabilization starts and corrects the orbit every 30 sec.


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Components of Orbit Components of Orbit StabilizationStabilization

• OS is an automated process. (state OS is an automated process. (state driven)driven)

• It uses 4 Tevatron dipole correctors.It uses 4 Tevatron dipole correctors.• It takes a reference orbit at beginning It takes a reference orbit at beginning

of store and then a new orbit every 30 of store and then a new orbit every 30 sec. and corrects any error.sec. and corrects any error.

• It use an SVD to compute solution.It use an SVD to compute solution.

Orbit Stabilization

ProcessRef Orbit at start of store

New orbit every 30secStates

ACNET interface

Set dipole correctors


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A typical Store 6130 – May A typical Store 6130 – May 10, 200810, 2008

• Holds hor. & ver Holds hor. & ver position ~ .15 position ~ .15 mm over entire mm over entire store. store. (use E11 because (use E11 because collimtor location)collimtor location)

• Dipole Correctors Dipole Correctors change ~change ~

HA49 = .1 AHA49 = .1 A HC49 = .1 AHC49 = .1 A

VB11 = .7 AVB11 = .7 A VD11 = .3 AVD11 = .3 A

Hor Pos E11

Ver Pos E11CDF Lum

Orbit stabilization counter

HC49

VD11

HA49

VB11


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Typical Smoothing at Typical Smoothing at Lowbeta by OSLowbeta by OS

Store with good orbits and errors from reference Store where orbits are starting to deviate butLowbeta orbit are held close due to OS smoothing.

Ramp orbits

Squeeze orbits

Lowbetaorbits

Desired limit

Operation Limit


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2008 Estimate of 2008 Estimate of PerformancePerformance

CDF supportColumn temp

A Look from Jan 1 to May 10 , 2008

A Look from Jan 1 to May 10 , 2008

CDF HVACBreaker problem

CDF changesHumidity in hall

OS corrector VB11

•2 highlighted regions caused serious problems with orbits.

•This is the period which implemented OS smoothing at lowbeta and end of store in addition to just after collisions.

•Feb 11 – March 4 period saw 4 lost stores to quenches due to changing orbits.


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How well does it work?How well does it work?• 5 stores over a 5 stores over a

period as temp of period as temp of CDF support column CDF support column changes.changes.

• Orbit Stabilization Orbit Stabilization does a great job of does a great job of holding orbit stabile holding orbit stabile during the store …during the store …butbut…when there are …when there are large deviations no large deviations no way to feed forward way to feed forward the corrections for the corrections for next store.next store.

6080 6082 6090 6093CDF Column Temp

VB11corrector

VPE11

Quench store 6083 not orbit related but there are big problems with orbits. (Apr 24 - 28, 2008)


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Resulting Ramp, Squeeze & Resulting Ramp, Squeeze & Lowbeta Orbit ErrorsLowbeta Orbit Errors

Store 6082 orbit errors before CDF collision hall Humidity change.

Store 6090 after CDF lowbeta quad column temp recovering.


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Example: OS Compensating for Example: OS Compensating for Tripped CorrectorTripped Corrector

• During store During store 6177, Corrector 6177, Corrector VB12 tripped off VB12 tripped off and OS and OS compensates for compensates for orbit error.orbit error.

• Correction is only Correction is only applied at B0 applied at B0 where corrector where corrector is tripped.is tripped.

• Overall orbit is Overall orbit is maintained.maintained.

Store 6177 May 30, 2008

Corrector VB12 tripped off

B0 Corrector VB11Compensates orbit

CDFLUM

VD11


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SummarySummary• Orbit Management, Orbit Management, Orbit Orbit Management, Orbit Management, Orbit

Management!Management!

• Orbit stabilization is one key component of Orbit stabilization is one key component of many which attempt to manage the Tevatron many which attempt to manage the Tevatron orbits compensating for errors during a store orbits compensating for errors during a store and providing a reproducible orbits at collisions.and providing a reproducible orbits at collisions.

• There is no way to combat fast cycling There is no way to combat fast cycling temperature changes and resulting orbits.temperature changes and resulting orbits.

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Tevatron Orbit Stabilization