The Fermilab Accelerator Complex

1
The Fermilab Accelerator Complex

• Series of presentations
• Overview of FNAL Accelerator Complex
• Antiprotons Stochastic Cooling
• Antiprotons Shots and Shot preparation
• Main Injector Preparing Beam for Pbar and
  Tevatron
• Tevatron From 150 to 980 and collisions
• To increase local knowledge among CDF members of
  what is going on over there in the Main Control
  Room.

2
Intro To Accelerator Physics

• All Classical (Relativistic) EM
• good reference is An Introduction to the Physics
  of High Energy Accelerators by D. Edwards and M.
  Syphers
• Hamiltonian of a charged particle in EM field
• Small angle approximation around CENTRAL ORBIT
• Set of Conjugate variables
• x, x horizontal displacement and angle
• y, y vertical displacement and angle
• E, s energy and longitudinal position
• s bct sometimes use t instead
• Equation of Motion
• C is circumference of accelerator -- Periodicity!
  

3
Intro To Accelerator Physics

• Restoring force k(s) is dependent on location
• Dipoles
• Quadrupoles
• Drifts
• General Solution
• b(s) is solution to a messy 2nd order
  Differential Equation
• Beam size depends on Amplitude of oscillation and
  value of b(s)
• Can change Position by changing angle 90?
  upstreamused for extraction/injection/cooling/IP
  position

4
4 Bumps to Control Position and Angle
5
Beam Size

• Relate the INVARIANT EMITTANCE (phase space area)
  to physical size
• Gaussian Beams
• 95 (Fermi Standard)
• s2 eb / 6p
• Include relativistic contraction (beams gets
  smaller as they are accelerated!)
• At B0 b(s) b(1s2/b2)
• For 20p mm mr beams at IP
• s (20p x10-6 m r 0.35 m / 6pg)1/2 3.5 x
  10-5 m 35 mm
• Convolute p and pbar s 25mm

6
Longitudinal Effects

• Longitudinal Acceleration
• Time Varying Fields to get net acceleration
• Synchronous PHASE and Particle
• Path Length can depend on ENERGY
• Revolution Frequency can depend on ENERGY
• Expressed via Phase Slip Factor h
• gt transition energy
• Accelerating phase needs to change by 180 as
  cross transition

7
Frequency Domain

• Frequency Spectrum
• Time Domain ???(tnT0) at pickup
• Frequency Domainharmonics of revolution
  frequency f0 1/T0
• AccumulatorT01.6 ?sec (1e10 pbar 1 mA)f0
  (core) 628888 Hz
• 127th Harmonic 79 MHz

8
Luminosity Distribution

• Simplifying Assumptions
• Transverse planes have same lattice functions
• p and pbar beams have same emittance
• ep epbar e
• sz v(sp2 spbar2)
• Not simply Gaussian in longitudinal or transverse
  planes
• Transverse size grows with longitudinal position!

9
FNAL Accelerators Proton Chain

• Protons for Collisions
• H- Source
• Plasma Ion Source
• Cockroft-Walton 18 KeV to 750 KeV
• Linac
• 750 KeV to 400 MeV H- ions
• Booster
• 400 MeV H- ions to 8 GeV protons
• Multiple injection into same phase space
• Stripping Foil to convert H- to proton
• RF 37 MHz to 53 MHz
• 84 RF Buckets
• Bunch 1 RF Bucket
• Turn 1 Filling of 84 bunches with H- ions
• 10 turns, 5 bunches -- remaining protons sent
  to Booster abort
• Batch transfer of beam to MI
• 15 Hz cycle (RLC resonant circuit)

10
FNAL AcceleratorsProton Chain

• Main Injector
• 8 GeV protons to 150 GeV protons
• 2 second cycle
• RF 52.8 MHz to 53.1 MHz
• 588 RF Buckets
• 7x Booster Circumference
• 7 Booster batches would fill every bucket
• Coalescing of 5 bunches into 1 bunch at 150 GeV
• Tevatron
• 150 GeV protons to 980 GeV protons
• RF 53.1 MHz (doesnt change much!!!)
• 1113 RF Buckets (18.8 nsec spacing)
• 13.25x Booster Circumference
• 36 transfers from MI
• Injected on Helical orbit, ß 1.7 m
• Low ß squeeze (ß 0.35 m)
• Bring beams to collision

11
FNAL AcceleratorsMaking Pbars

• From protons to pbars
• H- source
• Linac
• Booster
• 9 Turns, 84 buckets
• Goal 5e12 to MI
• Main Injector
• From 8 GeV to 120 GeV
• 1.5 second cycle
• Bunch Rotation
• Extraction to Pbar target
• Goal 4.5e12 on target
• Pbar target and collection
• Ni target
• Lithium Collection Lens
• Transfer Line
• Select 8 GeV pbars, 4 momentum acceptance

12
FNAL AcceleratorsMaking Pbars

• Debuncher
• 8 GeV pbars, 4 momentum spread, 250p mm mr
  emittance
• 90 buckets (note only 84 come in!)
• RF 53.1 MHz (matched to MI at 120 GeV)
• Debunch
• Stochastic cooling in transverse and longitudinal
  planes
• Goal 9e7 pbars per cycle
• Accumulator
• 8 GeV pbars, 0.05 momentum spread, 80p mm mr
  emittance
• 84 Buckets
• RF 52.8 MHz
• RF and stochastic stacking
• gt100e10 pbars
• Goals
• 18.5 pbars/1e6 protons on target
• 20e10 pbars/hour

13
FNAL AcceleratorsPbar Chain

• Pbars to Collisions
• Accumulator
• Select fraction of stack into 4 RF Buckets
• Put 52.8 MHz on top (7 - 11 RF Buckets per group)
• Main Injector
• 8 GeV pbars to 150 GeV pbars
• Coalescing of 7-11 RF buckets into 1 bunch
• Transfer of 4 bunches to Tevatron
• Tevatron
• 150 GeV pbars to 980 GeV pbars
• 9 transfers from MI (4 per transfer -gt 36
  bunches)
• Injected on Helical orbit, ß 1.7 m
• Low ß squeeze (ß 0.35 m)
• Bring beams to collision

14
Coming Attraction

• 14 December 2000
• Antiprotons Stochastic Cooling
• Paul Derwent
• FNAL BD/Pbar