# Presentation: 156389

## Tevatron Progress:Operational, Instabilities, and Diagnostics Update 

- Fermilab Seminar
- April 29, 2003
- Mike Martens -- Operational
- C. Y. Tan -- Instabilities
- Jim Steimel -- Diagnostics

## Luminosity Since June 2002

- 151 HEP stores
- 160 pb-1 to each detector
- Increase in luminosity from 15e30 to 40.5e30
- Run I record of 25.0e30 broken on 7/26/2002
- Run II record of 40.5e30 set on 3/20/2003

- Fermilab Seminar, April 29, 2003

## Goals and Current Performance

- 		Current	FY03
- _Parameter__	__Status__	__Goal__	__  __	__    __	__	__ _
- Typical Luminosity	3.5e31	6.6e31	cm-2sec-1
- Integrated Luminosity	6.0	12.0	pb-1/week
- Protons/bunch	200e9	240e9
- Antiprotons/bunch	22e9	31e9
- Higher intensity  Fundamental physics limitations
- Beam-Beam Effects
- Instabilities
- Beam Halo and Lifetimes
- Understanding/Solving these issues requires ...
- Stable Tevatron Lattice
- Diagnostics
- Study Time

- Fermilab Seminar, April 29, 2003

## Beam Intensities

- _Number of antiprotons _
- Increase factor of 2.5 Oct  March
- from 9e9  22e9 per bunch

- _Number of protons _
- Mostly steady
- in the 200e9 range

- Fermilab Seminar, April 29, 2003

## Tevatron Emittance

- General comments on emittance blow-up from Flying Wire measurement**
- (95%, normalized emittances):
-   < 1 - 2 at proton injection
-   ~ 5 - 6  at pbar injection
-   < (negative) 2 - 3 protons at 150 (scraping)
-   ~ (negative) 0 -3 pbars at 150 (scraping)
-   4 -7 blowup on ramp (prots and pbars)
-   occasional instability, 5 – 50, at 980 Gev

- ** There remains uncertainty of FW emittance measurements.  (See later slides)

- Fermilab Seminar, April 29, 2003

## Reasons for L-progress Since Jun’02 

- “Shot lattice”			       AA	        x 1.40
- Pbar emittance at injection 	Tev/Lines                x 1.20
- Pbar coalescing improvement	      MI         x 1.15
- Shoot from larger stacks                                    x 1.10
- Improved Tev Pbar efficiency                             x 1.10
- More Protons at Low Beta	                                _x 1.10_
- 						total	         x 3.3
- ....plus additional improvements in the Tevatron:
- Tunes/coupling/chromaticities at 150/ramp/LB
- Orbit smoothing
- Longitudinal dampers to stop s blowup
- Transverse dampers improves 150 Gev lifetime
- F11 vacuum

- Fermilab Seminar, April 29, 2003

## Tune/coupling/chromaticity/orbits

- Tune up is essential for consistent operations ...
- Much effort during “Studies Periods” is actually maintenance  (orbit smoothing and tune/coupling/chromaticity adjustments)
- ... and for understanding more complicated physics
- Beam-beam effects, instabilities and dampers, beam lifetimes, beam halo rates, etc. are more difficult to understand when machine parameters drifting.
- Some troubles:
- Tune/coupling drifts at 150 Gev. (Now compensated.)
- Tune/coupling snapback on the ramp. (Now compensated.)
- Chromaticity snapback?  (Was measured. Is OK.)
- Orbit drifts. (Started BPM and smoothing improvements)

- Fermilab Seminar, April 29, 2003

## Tune Drift @ 150 Gev

- M.Martens, J.Annala

- Fermilab Seminar, April 29, 2003

## Tevatron Magnet Alignment

- Measured rolls of dipoles and quads during Jan 2003 shutdown.
- Used “portable tilt-meter” for quick measurements
- Data roughly consistent with vertical dipole corrector strengths
- Dipoles rolled 4 mrad gives ~0.5 mm “scalloped” vert orbit
- Coupling from one quad rolled 4 mrad gives min tune split ~0.0025

- Fermilab Seminar, April 29, 2003

## Beam-beam Interaction As Major Factor

* **Pbar transfer efficiency strongly depends on N_p, helix separation, orbits, tunes, coupling, chromaticity and beam emittances at injection** *
* **Summary of progress with beam-beam since March 2002:*
_*	*__*Mar’02 *  *__*	*__*Oct’02 ***__*	*__*Jan’03 ****__*	*_
*Protons/bunch**	**140e9**	**170e9**	**180e9*
*Pbar loss at 150 GeV**	**20%**	**9%**	**4%*
*Pbar loss on ramp**	**14%**	**8%**	**12%*
*Pbar loss in squeeze**	**22%**	**5%**	**3%*
*Tev efficiency Inj****low beta**	**54%**	**75%**	**75%*
*Efficiency AA****low beta **	**32%**	**60%**	**62%*
**  average in stores #1120-1128**	**	****  average in stores #1832-1845*
**** average in stores #2114-2153 (9 stores)*

- Fermilab Seminar, April 29, 2003

## Tevatron Efficiencies

**proton**
**injections**

**pbar**
**injections**

**ramp**

**Open helix**

**poor lifetimes**

******10% bunched**
**beam loss in ramp**
**and squeeze**

- Fermilab Seminar, April 29, 2003

## Beam-beam Effects: Pbar Only

**8% loss on ramp – DC beam (depends on MI tuneup)**

- Fermilab Seminar, April 29, 2003

## Lifetime Issues at 150 Gev

- Poor Pbar lifetime at 150 Gev
- Depends on emittances, Np, , and bunch number
- Lifetime ~ 0.5-1.0 hrs =>  ~3 hours
- Original injection helix has been modified, separation increased and optimized to fit tight C0 aperture (“new-new helix”)
- Replace lambertsons @ C0 – gain 25 mm vertically
- Poor proton lifetime on helix
- depends on chromaticity
- Instability prevented lower chromaticity (now 8)
- Dampers now allow us to lower chromaticity
- Lifetime   ~2 hours => ~ 3-4 hours (on a good day)

- Fermilab Seminar, April 29, 2003

## Lifetime and Chromaticity at 150 Gev

-  Lower chromaticity is better for lifetime
-  Instabilities appear  < 3-4
-  Run with H = 8, V=8 to avoid instabilities
-  Dampers allow us to lower chromaticity and improve lifetime

- Measured loss rates as function of chromaticity
- (with protons on the pbar helix)

- Fermilab Seminar, April 29, 2003

## Beam-beam @ Injection Vs Emittance

- M.Martens

- Fermilab Seminar, April 29, 2003

## Attacking the Beam-beam Effects

- Smaller emittances from AA  (“AA shot lattice” )
-  Reduced injection errors
- Beam Line Tuner
- Better control of orbits / tunes / coupling
- Tunes up the ramp
- Tune and coupling drift at 150 Gev
- Orbit smoothing
-  Larger injection helix
- C0 Lambertson replacement
- New Separator settings

- Fermilab Seminar, April 29, 2003

## Helix Improvement

- Current helix

- Proposed helix

- Distance from B0

- Distance from B0

- Diagonal separation S

- Aperture limitation at C0

- Increasing proton/pbar helix separation
-  Replace C0 Lambertson with MI magnets
-  Increase vertical aperture at C0 from ~15mm -> 40 mm (but only ~30% larger helix due to other aperture limitations.)
-  Modify helix to increase min separation, Smin, from 5.5 to 6.6

- Fermilab Seminar, April 29, 2003

## January 2003 Shutdown

- C0 Lambertson Replacement
- Increases aperture at C0
- Leads to increased proton/antiproton helical orbit separation.
- Schottky monitor
- Measure chromaticity non-destructively
- Measure tunes of individual bunches
- CDF Shielding
- Add steel around low beta quads.
- Should reduce backgrounds in muon chambers by factor of 5.
- New TEL electron gun.
- Gaussian shaped emittance of electron beam
- Alignment Work

- Fermilab Seminar, April 29, 2003

## Tevatron Projects in FY’03 

- Priority

- Fermilab Seminar, April 29, 2003

## Tevatron Projects in FY’03 (Cont’d)

- Priority

- Fermilab Seminar, April 29, 2003