# Presentation: 004596

## Why Beam Studies

- Last Week’s CDF Meeting
- 14-21 April:  Consistent good stores > 3.5e31
- 22-23 April:  Tev studies
- Nigel asked why? (more specifically why now?)
- Beam studies in general
- Specific things done last week

## Why studies in general?

- Maintenance:
- Keep the machine in a good operational state
- Think quiet time calibrations....
- Optimize for current conditions
- Takes time as changes at both 150 and 980 have to be matched to ramp and squeeze conditions - have to take beam all the way through the cycle on both proton and pbar helices
- Known state for future studies work
- Improvements
- Spend time working on current known problems and limitations
- e.g., adjust orbit to make use of C0 aperture
- Though have made use of C0 Lambertson removal to lower chromaticities and increase proton intensities (lowered the machine impedance and hence raised instability thresholds)

## Why Studies in general?

- Run II Upgrades Lehman Review, July 2003
- Two Fronts: ~$14M M&S
- x3 in Pbar stacking rate
- Slip Stacking	Target Station	Acceptance
- Stacktail cooling	Electron Cooling	Recycler integration
- Tevatron improvements to handle 3x pbar current
- Active Beam-Beam compensation	Increased Separation
- Does not include possible new magnet construction
- 6.6 T magnets -> shorter so more space for separators?
- Paper models won’t cut it...
- Current Performance limited by beam-beam interactions
- 150 GeV lifetime
- Pbar emittance blowup at injection
- Need measurements to justify expenditures
- Dedicated time more efficient for these measurements

## Why orbit smoothing?

- _Motivation for smoothing_

**Orbit drifts **
** ****~0.5 mm/week**

**Tune changes **
** ****of ~0.001**

**Emittance blowup **
**Poor lifetime**

**Orbit drifts **
**~1.0 mm**

**Aperture **
**problems**

**Losses **
**and quenches**

## Goal for orbit smoothing

-  in the center of the magnets.
-  in the center of aperture at tight spots.
-  at the correct location for injection and abort.
-  at a good location for experiments.

- Develop a **“Standard Smoothing Procedure”** that
-  keeps the orbits stable.
-  is done consistently.
-  can be done relatively quickly.

- Ongoing since last summer -- had reached stable state this spring

## Some History of Orbit Smoothing

- _In August 2002._
- Found erratic orbits and corrector settings.
- Overhauled the orbits  corrector setting.
- Developed a “standard smooth procedure”

- Corrector strengths fluctuating
- by 50 amps during the squeeze.

## More History of Orbit Smoothing

- Then things got “mucked up” due to:
-  A “non-standard smooth” (and a software change.)
-  ~0.5 mm orbit drifts from an unnoticed C:B0QT3 trim quad error.
-  ~0.5 mm orbit changes from unnoticed TEL magnetic corrector trips.
-  Some backwards BPMs.
-  Possible “stale orbit data” ??

-  Orbits were not where we wanted.
-  Correctors running near their 50 amp limit.
-  Standard smoothing procedure no longer worked.

## Smoothing on 4/22/2003
Reduced current in correctors.
Reduced slew rates in correctors.
Kept (or tried to keep) positions in straight sections the same.
Put orbits in center of magnets in the arcs.
Lowered A0 abort block by 3 mm.

Had to retune the Tev. (Tunes changed by 0.01)
Should be able to perform a “standard smooth.”

Came out with good stores ... 3-3.5e31 initial luminosity

- Reduced current in correctors.
- Reduced slew rates in correctors.
- Kept (or tried to keep) positions in straight sections the same.
- Put orbits in center of magnets in the arcs.
- Lowered A0 abort block by 3 mm.
- Had to retune the Tev. (Tunes changed by 0.01)
- Should be able to perform a “standard smooth.”
- Came out with good stores ... 3-3.5e31 initial luminosity

- 22-23 April work