# Presentation: 407871

## Anti-Proton Cooling

- Paul Derwent
- DOE Tevatron Operations Review
- March 21, 2006

## Overview and Goals

- Debuncher:  2 seconds
- Stochastic cooling
- 4-8 GHz
- Liquid He cooled slotted waveguide pickups
- Factor of 10 in longitudinal phase space
- Factor of 7-10 in both transverse phase space dimensions
- ~1.6e8 pbars (~30e10/hr)
- Accumulator:  ~few hours
- Stochastic cooling
- 2-4 GHz stacktail, 2-4 & 4-8 GHz core momentum
- 4-8 GHz transverse slotted waveguide pickups
- Preserve Longitudinal phase space
- Increase particle density by factor of 5000
- Factor of 3-5 in both transverse phase space dimensions

- Recycler:  ~1 day
- Stochastic cooling
- 0.5-1 GHz & 1-2 GHz momentum
- 2-4 GHz transverse
- Electron cooling
- 0.5 A 4.34 MeV beam
- Needs transverse overlap of electron and anti-proton beam
- Longitudinal Emittance ~ 54 eV-sec
- Transverse Emittance ~ 5 π mm mr
- 600e10

**Notes:**
_x0010__x0010_

## Debuncher Cooling

- Transverse Cooling:
- >300 π mm mr
- 1-2e8 per pulse
- Power limited (TWT and kickers)
- Design*:
- 1e8 particles
- Cooling time ~0.7 sec
- Measure:
- ~1e8
- Horizontal:  0.69±0.03 sec
- Vertical:  0.74±0.03 sec
- Factor of 17 in 2 seconds
- Expect factor of 12 for 2e8 (36e10/hr)

- *J. Marriner,. Fermilab Pbar Note 573,
-  http://www-bdnew.fnal.gov/pbar/documents/pbarnotes/pdf_files/PB573.PDF

## Debuncher Cooling

- Momentum Cooling:
- Design:
- Factor of 10 in 2 seconds
- Measure:
- Cooling time 0.32 seconds
- Factor of 13 in 2 seconds
- Asymptotic width defined by gain and intensity
- Ramp gain down through cycle
- Distribution fills the notch
- Heating from other particles

## Debuncher Cooling

- Measure for 1e8 particles:
- Transverse:  Factor of 17 in 2 seconds
- Expect factor of ~12 for 2e8 particles
- Limited by available power
- Add notch filters to B3 & B4 - more power for cooling?
- Optimize gain ramp?
- Longitudinal:  factor of 13 in 2 seconds
- Limited by asymptotic width, not rate
- 2 turn notch filters for half cycle?
- Optimization of mix of transverse and longitudinal (e.g.,
- gate off initially to give transverse a head start?)

## Accumulator Cooling

- Stacktail:  van Der Meer solution:
- Constant Flux:
- Solution:
- Exponential Density Distribution generated by Exponential Gain Distribution
- Max Flux = (W2||*E**d*)/(f0p ln*(F**max**/F**min**))*
- W bandwidth, *F**max** *and *F**min** *frequency range
- f0 beam revolution frequency, p beam momentum
- || phase slip factor
*E**d*  characteristic gain slope

## Accumulator Cooling

- Interplay between stacktail and core:
- Stop constant flux and accumulate!
- Ed changes
- 2-4 GHz core momentum
- Same bandwidth
- Flux goes down
- 4-8 GHz core momentum
- Higher bandwidth
- Sustain flux for longer
- Core `back pressure’ will require transfer to Recycler to sustain flux

## Core 4-8 GHz Momentum Cooling System Bandwidth

- 1 GHz of bandwidth at 7 GHz is ~3x more powerful than 1 GHz of bandwidth at 2.5 GHz
- ln(Fmax/Fmin)
- By replacing the trunk coaxial cable with optical fiber, the 4-8 GHz system will be 5.7x more powerful than the 2-4 GHz system

## Accumulator Cooling

- Measurements of bandwidth and slope:
- 1.2 GHz
- 9.5 MeV
- ~30 mA/hour max
- Change Ed by moving pickup tank ~8 mm, adjust relative gains and phase
- 12 MeV
- ~36 mA/hour max
- Bandwidth upgrade:  4-6 GHz pickups and kickers
- 9 MeV
- ~50 mA/hour max

- 10 Feb 06:  20.12e10 in one hour
- Ed ~ 9.5 MeV
- Gain, bandwidth from core 4-8

## Record Hour

## Accumulator Cooling

- 2003 Plan:
- Implement 4-8 Core momentum cooling
- In Progress:  bandwidth and gain improvements
- Tank Move option (dependent on input flux)
- Probably in next year
- 4-6 GHz bandwidth upgrade (dependent on input flux)
- When flux requires it

## Recycler Cooling

- Stochastic cooling:
- To prepare injected beam for integration into main stash
- Transverse cooling so that e-beam overlaps anti-proton beam
- Goal:  15 π -> 10 π in 25 minutes for 25e10
- ~5 π for shots
- Electron cooling:
- Majority of work in longitudinal space

## Recycler Cooling

- Operational experience with e-cool
- Optimize operational mix between e-cool & stochastic cooling -- learning experience
- Best setup of stochastic cooling?
- Gain gating:
- stash and injected beam separated in time (barrier buckets) with much different characteristics (>300e10 vs 25e10)
- Different gain for stash and injected beam?
- Change momentum system to transverse
- Cool injected beam faster transversely, let e-cool take over?

##  Anti-proton cooling

- Cooling systems effectively handling 20e10/hour
- Measurements show can handle 30e10/hour
- Burden moving from Accumulator to Recycler!
- Working on upgrades (stacktail) and optimization (Debuncher, Recycler) to gain operational margin for >35e10/hour