Tevatron Orbit Stabilization

1. Tevatron Orbit Stabilization Dean Still June 2, 2008

2. Tevatron Orbit Stabilization • History and Purpose for Implementing • Components of the Orbit Stabilization • How well does it work • Summary D. Still - AEM- Tevatron Orbit Stabilization

3. History and Purpose of the Tevatron Orbit Stabilization • Created in Sept of 2005 as a way of countering changes in the orbit during a store. • These changes in the orbit during the store were mainly coming from motion in the CDF and D0 lowbeta quads due to changing environmental conditions of the support structures. • Since then many changes & improvements to these support structures have been made but orbit changes in a store still occur. D. Still - AEM- Tevatron Orbit Stabilization

4. Store 3969 from Feb 17 , 2005 A4Q3 pitch sensor Ver A37 BPM A4Q3 roll sensor CDF Proton Halo Losses Example: Halo Losses as a Result of B0 Lowbeta Quad Motion (2005) Invar rods Replace by support column 11/2004 (Courtesy T. Johnson) New support column sensitive to temp. D. Still - AEM- Tevatron Orbit Stabilization

5. Example: Result of D0 Lowbeta Quad Motion (2007) Test where was injected into Girder that effected orbit Orbit Stabilization D1 air flow 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. D. Still - AEM- Tevatron Orbit Stabilization (Courtesy of T. Johnson)

6. History and Purpose of the Tevatron Orbit Stabilization (2) • In spring 2006 – added an additional component to OS – smooth to reference orbit at Initiate Collisions. • Feb 2008 - CDF had problems with a HVAC breaker – we found had no way to combat losses due to poor lifetime at lbseq25 before Int. collision due to poor orbit. (Lost 2 stores). • March 2008 – Added smooth to reference orbit when the tevatron lands at lbseq 25, Int collision and end of store. D. Still - AEM- Tevatron Orbit Stabilization

7. Tevatron Orbit Stabilization • History and Purpose for Implementing • Components of the Orbit Stabilization • How well does it work • Summary D. Still - AEM- Tevatron Orbit Stabilization

8. 2nd Smooth To Ref at collision Ramp Start of Store 1st Smooth To Ref at lowbeta Squeeze Start Orbit stabilization Types of Orbit Stabilization • There are 2 types of orbit corrections made by OS. • Orbits is smoothed to a reference orbit file one time at lowbeta, at Int collisions and at the end of a store. • Once a store begins, the orbit stabilization starts and corrects the orbit every 30 sec. D. Still - AEM- Tevatron Orbit Stabilization

9. Components of Orbit Stabilization • OS is an automated process. (state driven) • It uses 4 Tevatron dipole correctors. • It takes a reference orbit at beginning of store and then a new orbit every 30 sec. and corrects any error. • It use an SVD to compute solution. Set dipole correctors Orbit Stabilization Process ACNET interface Ref Orbit at start of store States New orbit every 30sec D. Still - AEM- Tevatron Orbit Stabilization

10. CDF Lum Ver Pos E11 HC49 VD11 VB11 HA49 Hor Pos E11 Orbit stabilization counter A typical Store 6130 – May 10, 2008 • Holds hor. & ver position ~ .15 mm over entire store. (use E11 because collimtor location) • Dipole Correctors change ~ HA49 = .1 A HC49 = .1 A VB11 = .7 A VD11 = .3 A D. Still - AEM- Tevatron Orbit Stabilization

11. Typical Smoothing at Lowbeta by OS Store where orbits are starting to deviate but Lowbeta orbit are held close due to OS smoothing. Store with good orbits and errors from reference Lowbeta orbits Ramp orbits Squeeze orbits Operation Limit Desired limit D. Still - AEM- Tevatron Orbit Stabilization

12. Tevatron Orbit Stabilization • History and Purpose for Implementing • Components of the Orbit Stabilization • How well does it work • Summary D. Still - AEM- Tevatron Orbit Stabilization

13. 2008 Estimate of Performance • 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. A Look from Jan 1 to May 10 , 2008 CDF changes Humidity in hall OS corrector VB11 CDF support Column temp CDF HVAC Breaker problem D. Still - AEM- Tevatron Orbit Stabilization

14. 6090 6080 6082 6093 CDF Column Temp VPE11 VB11 corrector How well does it work? • 5 stores over a period as temp of CDF support column changes. • Orbit Stabilization does a great job of holding orbit stabile during the store …but…when there are large deviations no way to feed forward the corrections for next store. Quench store 6083 not orbit related but there are big problems with orbits. (Apr 24 - 28, 2008) D. Still - AEM- Tevatron Orbit Stabilization

15. Resulting Ramp, Squeeze & Lowbeta Orbit Errors Store 6090 after CDF lowbeta quad column temp recovering. Store 6082 orbit errors before CDF collision hall Humidity change. D. Still - AEM- Tevatron Orbit Stabilization

16. Example: OS Compensating for Tripped Corrector Store 6177 May 30, 2008 • During store 6177, Corrector VB12 tripped off and OS compensates for orbit error. • Correction is only applied at B0 where corrector is tripped. • Overall orbit is maintained. CDFLUM B0 Corrector VB11 Compensates orbit VD11 Corrector VB12 tripped off D. Still - AEM- Tevatron Orbit Stabilization

17. Summary • Orbit Management, Orbit Management, Orbit Management! • Orbit stabilization is one key component of many which attempt to manage the Tevatron orbits compensating for errors during a store and providing a reproducible orbits at collisions. • There is no way to combat fast cycling temperature changes and resulting orbits. D. Still - AEM- Tevatron Orbit Stabilization