Antiproton Source Apertures

1
Antiproton Source Apertures

• Steve Werkema
• DOE Tevatron Operations Review
• March 22, 2006

2
Outline

• Overview of Activities since March 2005
• AP2 line
• Debuncher
• D-A line
• Accumulator
• Work remaining for each of the above
• Conclusions
• Note that a Goal admittance of 35? mm-mrad means
  accepting a beam emittance of 330? mm-mrad

3
AP2 Line

• Accomplishments and Work Remaining

4
AP2 Beamline

• AP2 Accomplishments
• BPM DAQ Upgrade (completed in June 2005)
• Orbit control
• Lattice measurements
• Observation correction of short and long term
  beam motion trends
• Four new dipole correctors have been installed
• Implemented automatic orbit correction during
  stacking
• Much of the line has been steered to quad centers
• Conducted an obstruction search with a borescope
• No obstructions found

5
AP2 BPM Upgrade

• BPM DAQ upgrade installation completed in June
  2005
• Debuncher injection kicker noise problem solved
  by installing inline high pass filters and
  amplification of the signal at the source.
• These amplifiers are being replaced by low noise
  amplifiers during the present shutdown
• BPM output is sent to the control system on every
  beam pulse. The data is available as ACNET
  devices allows easy readout by client software
  and other users.
• AP2 BPM positions and intensities are routinely
  data logged.
• Software providing for the display, storage, and
  analysis of AP2 BPM data has been written and is
  in operational use.
• RMS fluctuation in the readout of the AP2 BPMs
  varies from 100 µm to 500 µm (average is 200 µm).
• Good enough for orbit correction, but compromises
  lattice measurements
• Should be improved with the installation of low
  noise pre-amps

6
AP2 BPM Upgrade

• AP2 BPM difference orbit during reverse proton
  studies
• RMS is shown in green
• We expect the installation of new low noise
  preamps will reduce the readout fluctuations to
  100 200 µm.

7
AP2 Beamline Automatic steering

• Data log display of four BPMs at the downstream
  end of the AP2 line from 10/1/05 to 1/16/06.
• Introduction of automatic steering (a.k.a.
  Oscillation Overthruster) in the 120 GeV and AP2
  lines significantly reduced variations in the AP2
  beam trajectory.

8
AP2 Beamline

• Work Remaining
• Replace AP2 beam stop (i.e. eliminate 2 vacuum
  windows and 12 feet of spoiled vacuum)
• to be completed this shutdown
• Steer upstream end of the beamline (including Li
  Lens)
• Match lattice to the Debuncher

9
Debuncher

• Accomplishments and Work Remaining

10
Debuncher

• Debuncher Accomplishments
• Completed installation and commissioning of all
  moveable quad stands. We dont plan to install
  any more!
• Installed and commissioned a ramped Debuncher
  EXtraction (DEX) bump.
• Lattice modified to decrease b-functions at
  limiting apertures.
• Eliminates the need to widen the aperture of the
  band 4 stochastic cooling arrays
• Substantial beam study time to steer the closed
  orbit to quad centers and work on the aperture
• Found and removed two aperture restrictions
  horizontal and vertical schottkys
• Net Result
• 25 increase in Deb Admittance in past year
• Ax 32.6 p mm-mrad, Ay 34.6 p mm-mrad
• 32 increase in AP2 Debuncher admittance
• Ax 33.3 p mm-mrad, Ay 31.2 p mm-mrad

11
Debuncher Finding Limiting Apertures

• Debuncher Running Wave application
• A pair of trim dipoles are used to generate a
  closed orbit oscillation that is scanned in phase
  so that the maxima and minima move over the
  entire length of the Debuncher.

Beam loss monitors are used to resolve the
19-fold ambiguity in the location of the orbit
extrema.
12
Debuncher

• Work remaining
• Debuncher extraction kicker aperture upgrade
• Improves horizontal aperture for Dp/p gt 0
• Motorize Debuncher extraction kicker stand
• Motorized girder will be installed this shutdown
• 53 MHz upgrade to Debuncher BPMs
• Allows orbit monitoring and correction during
  stacking
• Possible further adjustments to the lattice
• Quad shunts are being configured for this during
  the present shutdown
• Correct horizontal orbit in the arcs
• We skipped this on the first pass because it will
  change the energy

13
D-A Line
14
D-A Line

• Accomplishments
• Aligned orbit to quad centers
• Implemented injection error correction for proton
  injection into the Debuncher andp injection into
  the Accumulator
• Investigated matching to the Accumulator Þ D-A
  line appears to be matched to the Accumulator

15
D-A Line

• Limiting apertures are the Accumulator injection
  septa (10 p mm-mrad)
• Beam from Debuncher is cooled transversely to lt 3
  p during each stacking cycle

• Conclusions
• Maximum transfer efficiency achieved with cycle
  times gt 2.0 sec
• Beam bigger than 2 3 p could be scraping upon
  injection into the Accumulator

16
Accumulator

• Accomplishments and Work Remaining

17
Accumulator

• Accomplishments
• Spent 4½ shifts of beam study time to improve the
  Accumulator aperture.
• Identified an aperture restriction quadrupole
  pickup
• Quad pickup has been removed
• Scanned all moveable devices

18
Accumulator Admittance
Date Injection Central Core
8/25/1999 H V 8.3 p 9.6 p 10.0 p 9.4 p 8.2 p 7.7 p
2/15/2006 Start of studies H V 6.3 p 7.4 p
2/17/2006 End of studies H V 6.3 p 9.2 p 7.0 p 7.9 p 6.6 p 6.6 p
Improvement Horizontal 11, Vertical
7 Apertures remain substantially smaller than
they were in 1999.
19
Accumulator

• Coupling on extraction and central orbits

20
Accumulator

• Work remaining
• Correct central orbit to quad centers and
  re-center moveable devices
• Correct coupling on the injection orbit
• Look carefully at acceptance of Accumulator
  injection channel

21
Conclusions

• The Perfect Storm
• The confluence of major Tevatron disasters Þ
  copious beam study time the upgrades installed
  so far new instrumentation a significant
  (30) improvement in the AP2 and Debuncher
  acceptance.
• We are now within 10 of our Run II upgrades
  admittance goals.
• Several important tasks remain, indicating a
  good likelihood of even further improvement
• Lattice improvements in the AP2 line and
  Debuncher
• New AP2 beam stop
• Debuncher extraction kicker upgrade
• Debuncher BPM 53 MHz upgrade
• Accumulator orbit correction
• Completion of the Lithium Lens upgrade (summer
  06)