The FAIR Antiproton Target
B. Franzke, V. Gostishchev,
K. Knie, U. Kopf, P. Sievers, M. Steck
• Production Target
• Magnetic Horn (Collector Lens)
• CR and RESR
• Radiation Protection
_
Creation of antiprotons (p or pbar)
m = E / c²
mp = mpbar  1 GeV / c²
p
p, > 6 GeV
p at rest
m = E / c²
p
p
pbar
_
Creation of antiprotons (p or pbar)
0.00007
120 GeV (Fermilab)
90 GeV (SIS300)
d(p_bar/p)/dp (arb. units)
0.00006
70 GeV
50 GeV
29 GeV (SIS100)
0.00005
20 GeV
10 GeV
0.00004
0.00003
0.00002
0.00001
0
0
2
4
6
8
10
12
14
16
p [GeV/c]
p = 3.82 GeV / c, E = 3 GeV, Bρ = 13 Tm
18
20
FAIR / CERN / FNAL pbar Sources
CERN (AC+AA)
FNAL
E(p), E(pbar)
25 GeV, 2.7 GeV
120 GeV, 8 GeV
acceptance
200 p mm mrad
 30 p mm mrad
protons / pulse
1 - 2 × 1013
≥ 5 × 1012
pulse length
5 bunches in 400 ns single bunch 1.6 µs
cycle time
4.8 s
1.5 s
FAIR / CERN / FNAL pbar Sources
FAIR
CERN (AC+AA)
FNAL
E(p), E(pbar)
29 GeV, 3 GeV
25 GeV, 2.7 GeV
120 GeV, 8 GeV
acceptance
240 p mm mrad
200 p mm mrad
 30 p mm mrad
protons / pulse
≥ 2 × 1013
1 - 2 × 1013
≥ 5 × 1012
pulse length
single bunch (50 ns) 5 bunches in 400 ns single bunch 1.6 µs
cycle time
10 s
4.8 s
1.5 s
Increases the pbar yield by  50 %
cycle time 10 s (cooling time in the CR)
overall pbar yield: 5 × 10-6 pbar/p (based on CERN data) → 1 × 107 pbar/s
FAIR Collector ring will be operated at h = 1, CERN ring was operated at h = 6
Time needed for stochastic cooling in CR (AC), upgrade possible
y / cm
pbar Distribution After the Target
Ep = 29 GeV
z / cm
ppbar = 3.82 GeV/c ± 3%
From ~ 2.5 × 10-4 pbar / (p cm target) ~ 5 × 10-6 (or 2 %) are "collectable"
R.P. Duperray et al., Phys. Rev. D 68, 094017 (2003)
MARS Simulation of the pbar Yields
150
p = 3.82 GeV/c
Dp/p = ± 3%
100
x' [mrad]
50
0
-50
-40
-30
-20
-10
0
10
20
30
40
-50
-100
after target
acceptance of separator
-150
x [mm]
50
Collecting pbars: Magnetic Horn
B  1/r
primary beam does not hit the horn
reaction
products
Collecting pbars: Magnetic Horn
target
beamCERN
axis ACOL
magnetic
fieldI =
area
Horn,
400 kA
Collecting pbars: Magnetic Horn
MARS Simulation of the pbar Yields
150
p = 3.82 GeV/c
Dp/p = ± 3%
100
x' [mrad]
50
yield =
0
-50
-40
-30
-20
0
-10
10
20
30
40
-50
-100
after target
after horn
acceptance of separator
-150
x [mm]
50
pbars in the ellipse
primary protons
4.2E-05
4.2E-05
4.0E-05
4.0E-05
3.8E-05
3.8E-05
3.6E-05
3.6E-05
3.4E-05
3.4E-05
3.2E-05
3.2E-05
3.0E-05
3.0E-05
2.8E-05
2.8E-05
2.6E-05
2.6E-05
yield [pbar/p]
yield [pbar/p]
MARS Simulation of the pbar Yields
2.4E-05
2.2E-05
2.0E-05
1.8E-05
1.6E-05
2.4E-05
2.2E-05
2.0E-05
1.8E-05
1.6E-05
1.4E-05
1.4E-05
1.2E-05
1.2E-05
1.0E-05
1.0E-05
8.0E-06
after target, dp/p<3%, theta<80mrad
8.0E-06
6.0E-06
after target, dp/p<3%, theta<80mrad
6.0E-06
4.0E-06
4.0E-06
Ir, d=3, rms=0.1
2.0E-06
Ni d=3, rms=0.62
2.0E-06
0.0E+00
4
6
8
10
12
14
target length [cm]
16
18
20
0.0E+00
4
6
8
10
12
14
target length [cm]
16
18
20
Temperature Increase in the Target
Fluka simulation
10000
2.2E-05
29 GeV/c, r = 1 mm (s)
13
0.10
(dE/dm)max [GeV/(prim g)]
melting of Ir
-1.35
D T = 2100 K × w
melting of Ni
Ir
Cu/Ni
2.0E-05
Ir
Cu
Ni
yield [pbar/p]
Maximum Temperature increase D T [K]
2×10 protons per pulse
Gaussian beam profile
melting of Cu
1000
0.08
1.8E-05
1.6E-05
0.06
1.4E-05
0.04
1.2E-05
0.02
1.0E-05
0.00
8.0E-06
0
1
2
3
4
5
6
z [cm]
6.0E-06
-1.68
D T = 360 K × w
-1.68
D T = 310 K × w
c
Ir d=3, rms=0.62
Ni/Cu,
2.0E-06
Ir, d=4.5, rms=1
cCu = 385 J kg-1 K-1
0.0E+00
100
0
0.5
1
1.5
beam width (s ) [mm]
2
2.5
= 130 J kg-1 K-1
4.0E-06
4
6
cNi8 = 440
K-1
10
12J kg-1
14
16
target length [cm]
18
20
CR: Bunch Rotation and
Stochastic Pre-Cooling
bunch
rotation
DE/E =
±3%
50 ns
E
t
adiabatic
debunching
± 0.75 %
stochastic
cooling
± 0.5 %
± 0.1 %
RESR: Antiproton Accumulation
Cross section throught the vacuum chamber at the momentum pick-up
stochastic cooling
for stack core
stack core
stack tail
Antiproton Accumulation
partial aperture
injection kicker
stochastic cooling
for stack core
acceleration by HF
(not in resonance with stack)
stack core
stack tail
160 mm (p/p = 0.8 %)
injected beam
from CR
Antiproton Accumulation
stochastic cooling
for stack core
stack core
stochastic cooling
for beam deposit
(high amplification)
stack tail
160 mm (p/p = 0.8 %)
Antiproton Accumulation
stochastic cooling
for stack core
stack core
stack tail
160 mm (p/p = 0.8 %)
Antiproton Accumulation
deceleration by HF
stack core
160 mm (p/p = 0.8 %)
Antiproton Accumulation
extraction kicker
stack core
160 mm (p/p = 0.8 %)
FAIR / CERN / FNAL pbar Sources
FAIR
CERN (AC+AA)
FNAL
E(p), E(pbar)
29 GeV, 3 GeV
25 GeV, 2.7 GeV
120 GeV, 8 GeV
acceptance
240 p mm mrad
200 p mm mrad
 30 p mm mrad
protons / pulse
≥ 2 × 1013
1 - 2 × 1013
≥ 5 × 1012
pulse length
single bunch (50 ns) 5 bunches in 400 ns single bunch 1.6 µs
cycle time
10 s
4.8 s
1.5 s
Increases the pbar yield by  50 %
cycle time 10 s (cooling time in the CR)
-6 pbar/p (based on CERN data) → 2
overall pbar yield: 1
5 × 10-5
1 × 107 pbar/s
FAIR Collector ring will be operated at h = 1, CERN ring was operated at h = 6
Time needed for stochastic cooling in CR (AC), upgrade possible
Target Station
Target Exchange (target on air!)
Target Station
Dose rates around the pbar target
Fluka input, top view
air
concrete
graphite
iron
vacuum
Super
NESR
target
from SIS 100
CR
RESR
Equivalent dose rates during operation
Equivalent Dose rate [Sv/h],
2 × 1013 protons per pulse, 0.1 Hz
Induced Activity after Shut-Down
airplane
at 12000 m
Induced Activity after Shut-Down
vertical section 4 m downstream of target
air
concrete iron
Summary
• Yield (target / horn / separator):
11 cm Ni-target, copy of CERN horn
~ 2 × 10-5 pbar per primary proton (4 × 107 pbar / s)
• Yield (out of RESR):
~ 1 × 10-5 pbar per primary proton (2 × 107 pbar / s)
• No significant increase of this number can be expected with another
type of collector like a Li-lens.
• time averaged, less than 1 kW is deposited in the target
higher repetition rate should be no problem
• Radiation protection: no principal problems up to now