Electron Cooling in the Accumulator McGinnis
Electron Cooling in the AccumulatorElectron Cooling in the Accumulator
Dave McGinnis
Electron Cooling in the Accumulator McGinnis
Install Electron Cooling in the Accumulator AP50 Install Electron Cooling in the Accumulator AP50 PitPit
A50 Straight Section was used for the E835 detector Straight section no longer used for anything
• Large pit beneath beam pipe (~4ft below floor level) Counting room no longer used AP50 Drop hatch available
15 meters of straight section between Q1’s Zero dispersion Lattice functions could be modified with Q1,Q2,Q3
settings
Electron Cooling in the Accumulator McGinnis
Install Electron Cooling in the Accumulator AP50 Install Electron Cooling in the Accumulator AP50 PitPit
AP50
Pit
Electron Cooling in the Accumulator McGinnis
Install Electron Cooling in the Accumulator AP50 Install Electron Cooling in the Accumulator AP50 PitPit
Electron Cooling in the Accumulator McGinnis
Accumulator Momentum ApertureAccumulator Momentum Aperture
Accumulator Momentum Aperture measured to be 206 mm at A314 scraper (J. Morgan – 5/19/03)
Electron Cooling in the Accumulator McGinnis
Accumulator Aperture with Electron CoolingAccumulator Aperture with Electron Cooling
Accumulator Aperture would be Divided into 3 Regions 208 mm required for 10-mm-mrad Aperture
Injection Region Beam is injected from the Debuncher every 1.5 seconds The transverse beam size is 5-mm-mrad The momentum spread is 5 MeV The Stacktail Region is shielded from the injection kickers
by shutters
h=21m
Dh=9m
10-mm-mrad
Aperture
(un-normalized)
Electron Cooling in the Accumulator McGinnis
Accumulator Aperture with Electron CoolingAccumulator Aperture with Electron Cooling
Stacktail Region The beam is bunched with RF and decelerated from the injection orbit to the
Stacktail deposition orbit The beam is stochastically stacked with a 4-8 GHz stacktail system and a 4-
8 GHz Core system The Stacktail is shielded from the high density core in the electron cooling
region by means of a shutter in the stochastic cooling pickup region. The beam is transversely cooled from 5 to 1 -mm-mrad with a stacktail
betatron cooling The momentum aperture of the entire stacktail region is 43.5 MeV The stacktail system fills 10 eV-sec (6 MeV) every 55 minutes
h=21m
Dh=9m
10-mm-mrad
Aperture
(un-normalized)
Electron Cooling in the Accumulator McGinnis
Stacktail Performance with an Input Flux of 90x10Stacktail Performance with an Input Flux of 90x101010 pbars/hrpbars/hr
Stacktail Bandwidth
Core Bandwidth
Eds Edc Es+Ebd Ec Fraction
Unstacked
(GHz) (GHz) (MeV) (MeV) (MeV) (MeV) (%) 2-4 4-8 20 5 77.4 9.6 50 2-6 4-8 8 5 48.4 9.6 66 2-6 2-6 8 8 45.2 12.8 55 4-8 4-8 5 5 33.9 9.6 72 0 1 2 3 4 5 6 7 8 9 10
1
10
100
2-4 GHz2-6 GHz2-6 GHz No Core4-8 GHz
Debuncher Energy Spread (MeV)
Stac
king
Int
erva
l (m
inut
es)
0 2 4 6 8 101
10
100
2-4 GHz2-6 GHz2-6 GHz No core4-8 GHz
Debuncher Energy Spread (MeV)
Uns
tack
ed C
urre
nt (
mA
)
0 2 4 6 8 1010
100
1 103
1 104
2-4 GHz2-6 GHz4-8 GHz
Debuncher Energy Spread (MeV)
Pow
er (
Wat
ts)
0 2 4 6 8 1010
100
1 103
1 104
2-4 GHz2-6 GHz4-8 GHz
Debuncher Energy Spread (MeV)
Pow
er (
Wat
ts)
2 3 4 5 6 7 8 9 100
0.2
0.4
0.6
0.8
2-4 GHz2-6 GHz2-6 GHz No Core4-8 GHz
Debuncher Energy Spread (MeV)
Cor
e T
rans
vers
e E
mit
tanc
e (p
i-m
m-m
rad)
Electron Cooling in the Accumulator McGinnis
4-8 GHz High Dispersion Pickups4-8 GHz High Dispersion Pickups
Average Signal to Noise for 100x1010 Particles(3-05-03)
10
100
1000
2 3 4 5 6 7 8
Frequency (GHz)
Sig
nal t
o N
oise
2-4 dp
4-8 dp
Electron Cooling in the Accumulator McGinnis
Accumulator Aperture with Electron CoolingAccumulator Aperture with Electron Cooling
Electron Cooling Region Once 10 eV-sec of the core is filled up:
• The Stacktail is gated off• The shutter to electron cooling is opened• The stochastic core is bunched and decelerated to the
deposition orbit of the electron cooling region• The electron cooling shutter is closed and stochastic
stacking is restarted.• Electron Cooling Rate – 11 eV-Sec/hr (6.8 MeV/hr)
Electron Cooling in the Accumulator McGinnis
AdvantagesAdvantages
Machine circumference 7x smaller than Recycler
No Rapid transfers No beam loss No transverse emittance dilution No longitudinal emittance dilution No waiting for transfer
Electron cooler can be placed closer to ring 8 GeV beam only in Accumulator Shielding requirements much less
Accelerator Performance Vacuum
• Ring Size• Equipment
– Pumping speed– Bakeout system
Aperture No Main Injector ramps to contend with
Electron Cooling in the Accumulator McGinnis
DisadvantagesDisadvantages
Stacktail Betatron cooling Cooling section length
Recycler -> 20 meters Accumulator - > 12 meters
Available longitudinal phase space
Electron Cooling in the Accumulator McGinnis
Things to DoThings to Do
Come up with a physics design for 4-8 GHz Betatron Cooling – Derwent
Verify 4-8 GHz stacktail envelope calculations with detailed Fokker-Plank Simulations – Derwent
Determine how to modify beta functions in A50 Sector – Werkema
Electron Cooling Calculations – Burov Come up with a design of 4-8 GHz Pickups –
Sun,McGinnis Civil Construction Aspects – Harms Schedule – McGinnis, Nagaitsev
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