# Presentation: 751816

## Accumulator Ramp Development Progress Report

- Why are we doing this
- Progress so far
- Does it work?
- Impact on Shot Setup
- Remaining work

- S. Werkema

- June 13, 2002

## Why are we doing this?

- Accumulator horizontal emittance is significantly greater than what was measured in Run I.

- S. Werkema

- June 13, 2002

## Why are we doing this?

- Horizontal emittance growth rate is very large

*f**rev* (core orbit)

- S. Werkema

- June 13, 2002

## Why are we doing this?

- In the upgrade from the Accumulator TeV I Lattice to the Run II lattice, horizontal IBS emittance growth was inadvertently increased by over a factor of two.
****Unstack from a lattice that is less amenable to IBS.

- D. McGinnis
- Calculation

- S. Werkema

- June 13, 2002

## Why are we doing this?

- Comparison of old (stacking) and new (shot) lattice

- D. McGinnis
- Calculation

- S. Werkema

- June 13, 2002

## Accumulator Lattice Parameters

|  | Stacking Lattice | Shot Lattice | Run Ib |
| --- | --- | --- | --- |
|  (core orbit) | 0.0097 | 0.0251 | 0.0230 |
| B (Gauss) | 16,714.4  | 16,723.9 | 16,742.0 |
| frev (core orbit) | 628,887 Hz | 628,940 Hz | 628,955 Hz |
| frev (extr. orbit) | 628,765 Hz | 628,724 Hz | 628,725 Hz |

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Summary of Studies:

| Week | Dates | Number of Shifts | Description |
| --- | --- | --- | --- |
| 1 | 4/9 – 4/10 | 3 | p’s on central orbit |
| 2 | 4/17 – 4/18 | 2 | p’s on central orbit |
| 3 | 5/14 – 5/15 | 2 | Ramp to shot lattice.
Multipole corrections
Poor vertical aperture |
| 4 | 5/21 – 5/22 | 4 | Added dipole trims ramps
MI beam not centered in extraction channel |
| 5 | 529 – 5/30 | 3 | Added A:IB Ramp |

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Initial Attempt (1st two weeks)
- Central Orbit
- Crude Software tools (2 hour ramp time)

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Ramp development Shifts
- Better software (Bill Marsh – P170)
- Ramp time now 45 sec.
- Ramp Plotting
- Easily add new devices

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Basic Ramp Development Procedure:
- Initial conditions: beam is unbunched on the core orbit.
- At each primary point do the following:
- Correct tunes
- Correct horizontal and vertical orbit
- Measure revolution frequency and set LLRF frequency devices
- Linearize ramps to adjacent primary points
- At bottom of ramp adjust multipole correctors to get good tunes across the momentum aperture.
- Match extraction beamline (AP3) to shot lattice

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Multipole Correction – Initial tunes vs. *p*/*p*

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Multipole Correction – Final tunes vs. *p*/*p*

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Tunes vs. *p*/*p* – Stacking vs. Shot Lattice

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Shot Lattice Accumulator Extraction Channel

- S. Werkema

- June 13, 2002

## Ramp Development Progress

- Potential Problems:
- Extraction orbit: low horizontal tune/ large horizontal chromaticity
- Large coupling on the extraction orbit
- Beamline match to new lattice
- Match to MIRF
- Smaller bucket area
- Different RF frequency

- S. Werkema

- June 13, 2002

## Does it Work?

- Success = Smaller emittances (from Accumulator core to MI 8GeV)
- Evidence of success observed so far:
- Smaller equilibrium emittances on the core orbit
- ~50% improvement in the beam lifetime
- Smaller emittance observed on beamline SEMs

- S. Werkema

- June 13, 2002

## Does it Work?

- Store 1387, May 31, 2002 (364)

- S. Werkema

- June 13, 2002

## Does it Work?

- Emittance measurements during 5/31/2002 shots:

*J. Morgan*
*Analysis*

- S. Werkema

- June 13, 2002

## Impact on Shot Setup

- Basic Shot Setup Procedure:
- Stop Stacking
- Cool beam into core
- Turn off core cooling
- Ramp to new lattice
- Adjust core cooling delays and turn on cooling
- ~Normal unstacking procedure
- Dump remaining stack!?

- S. Werkema

- June 13, 2002

## Remaining Work

- Revisit beamline matching
- Correct coupling on shot lattice extraction orbit
- Attempt to raise the horizontal tune on the shot lattice  extraction orbit
- Tune-up match to MIRF
- Incorporate procedure into shot setup sequencer
***Develop ramp from shot lattice to stacking lattice***

- S. Werkema

- June 13, 2002