Status of the AP2 Optics

1
Status of the AP2 Optics

• Keith Gollwitzer
• Antiproton Source Department
• November 19, 2004

2
Purpose Use of AP2

• Transport of pbars from target-lens to Debuncher
• Goal of transporting of 35? mm-mrad (norm. 330?
  mm-mrad) ?P/P of 2.25
• Many secondaries come out of the target and enter
  AP2
• Number of pbars for Run 2 is 1e8 per stacking
  cycle
• 1 of secondaries at the end of AP2 are the
  desired pbars

3
5 Year History of AP2 Optic Models

• Fermilab MAD for Console Application for beam
  line orbit corrections (1999)
• Verification(?) when part of forward proton study
  of complete P1-P2-AP1-AP2 beam line
• Fermilab OptiM offline studies (2001-now)
• Includes apertures and has been compared to older
  survey
• LBNL MAD studies (2003-2004)
• Alignment and chromatic effects on transport
  efficiency
• LBNL AT Accelerator Toolbox (2004)
• Continuation of MAD studies and includes turns in
  Debuncher (in progress)

There have been no lattice meas. to verify these
models
Will not Cover today
4
Current Lattice Functions
Target Station Lens
Down Bend
Left Bend
Injection
5
What to do about Lattice

• Previous slide showed an asymmetric lattice about
  the left bend including large horizontal ?
• This shutdown some rework of powering AP2 quads
• Q724 will be powered (new supply)
• Q725 moved from Q716 buss to own supply
• Q702703 shunts swapped with Q719720
• Q728 shunt swapped with Q732
• Change to new lattice after startup

6
Proposed Lattice Functions
Target Station Lens
Down Bend
Left Bend
Injection
7
Beam Sizes for All of AP2
8
Beam Sizes for Upstream AP2
Perfect Alignment
Dump Shielding
New Beam Stop
9
Beam Sizes for Left Bend of AP2
10
Beam Sizes for Downstream AP2
IBV1 V730
Injection Septum
11
A Look at Tracking

• MARS simulation to generate pbars from 120GeV
  protons striking the target
• Since momentum spectrum is flat, can re-use
  particles by randomizing momentum
• OptiM does the Lithium lens focusing and multiple
  scattering as well as propagation and checking
  against apertures
• Tracking has been used to confirm loss points
  as well as optimize transport efficiency

12
Intensity and Momentum Spread while being tracked
through AP2
MARS simulation of 120GeV protons on target
production of pbar secondaries Tracking by OptiM
Initial beam spread of 15
13
AP2 Chromaticity

• Valeri performed studies a few years ago for Run
  2 Upgrade Plan and a quick look recently
• Originally optimize for current power circuits
  now have plan with minimal changes noted before
• Noticed chromatic effect that appears to decrease
  transport efficiency by 10
• Believe can recover half of the losses(?)
• LBNL is studying and we will in the near future

14
2 pbars
x,y position coming out of Lens, no angle
Big symbols are where the set of different
momenta particles started out of Lens Small
symbols is position distribution coming out of
Injection Septum in Debuncher
15
Chromatic Solution(?)

• Ideal to add sextuple in dispersion regions
• No space
• Alternative is to add sextuple component to
  existing quadruples
• Modeling in progress
• Power each half of quad separately
• Beside sextuple will also have dipole kick
• Will have to rotate quads in horizontal
  dispersion regions

16
Status

• Repository has OptiM August04 lattice
• Need to update apertures
• Need to update circuits
• Change excitation once new lattice is applied
• Compare laser tracker component positioning with
  model once survey data are available
• Verify models with lattice measurements
• New BPM system to be available in the next few
  months