Transcript Pion capture and transport system for PRISM M. Yoshida Osaka Univ. 2005/8/28 NuFACT06 at UCI.

Pion capture and transport
system for PRISM
M. Yoshida
Osaka Univ.
2005/8/28
NuFACT06 at UCI
PRISM/PRIME project
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Phase Rotated Intense Slow Muon source
Collect 68MeV/c m-
PRIME detector
proton beam
pion production, capture
and transport system
Phase rotator
Concepts of pion capture/transport
system for PRISM
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Capture low-energy pions produced in Graphite
target with 6T solenoid field
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Low-Z material
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Collect backward pions from the target
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Direction of emitted low energy pions is almost isotropic
helps to reduce radiation heating on cold mass (avoid high
energy hadrons)
Tilt target by 10 deg. to implement proton beam pipe
Energy deposit on superconducting coil of capture
solenoid < 100W
Al-stabilized SC coil to reduce cold mass
Transport pions+muons in long 2T solenoid channel
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Bent solenoid channel
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to avoid absorption in the target
Target should be off-site from experimental area
Reduce background by wiping out higher energy particles
The first trial of conceptual design has been done.
Heat load estimation
MARS Simulation
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5cm
Graphite (1.7g/cm3)
radius=2cm
Tungsten shield
Magnetic field
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40GeV
size s=1.0cm
1014 protons/sec
Target
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140cm
MARS15(04)
Primary beam
uniform 6Tesla
Solenoid inner R=15cm
Coil
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Al-stabilized superconducting
Coil
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71%Al + 11%NbTi + 14%Cu +
４%G10-tape
density 3.1 g/cm3
15cm
protons
Heat load on coil
Energy deposit (W )
600
80cm-long graphite target
0cm -5cm
0cm -10cm
0cm -15cm
500
400
Coil: 89 W
Shield: 41 kW
300
200
100
0
20
30
25
Shield thickness (cm )
35
Choose
thickness of shield = 30cm
thickness of coil = 12cm  17 A/mm2
target length = 60cm
Spatial distribution of deposit energy
16
14
deposit (W )
12
0
90
180
270
10
8
6
270
4
2
0
0
0
50
100
z pos (cm )
150
180
90
Geometry of Pion Capture System
magnetic field [Tesla]
300
300
900
600
To transport
solenoid 
500
3600
1400
p-,m- distributions @3m
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0.058 p-+m-/POT @3-meter downstream traget
10cm
15cm
20cm
25cm
Pt
Radius squared (cm2)
Total momentum (GeV/c)
Transport solenoid channel
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Transport pions and muons in 2T
solenoid
Bent towards experimental area
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put radiation shield along proton
beam line
Parameters of transport solenoid
arc radius : 4000 mm
bend angle : 90 deg.
Bs : 2 T
By : 0.05 T
coil inner raduis : 350 mm
(inner wall : 50mm)
coil thickness : 50.0 mm
coil length : 629.0 mm
current : 36.5 A/mm^2
step angle : 10 deg.
4 meters
10 deg.
A. Sato
Transport loss in bent solenoid
Before BS
-: 9056
 -: 21009
total :30065
-7%
After BS
-: 2041
 -: 26089
total :28130
G4BeamLine
Simulation
A. Sato
Summary
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Conceptual design of pion capture solenoid and transport bent
solenoid has been performed for PRISM
Heat load on coils of capture solenoid can be less than 100W
as 40 GeV proton beam injected, assuming 0.6MW beam
power.
Design works for the solenoid magnets are being started in
collaboration with KEK
To improve pion yield
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Reduce beam spot size on target
Field gradient around the target
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acceptance would increase by mirroring forward pions
To fit to FFAG acceptance (H: 40p mm-rad, V:6.5p mm-rad)
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optimize field profile in the capture system to reduce muon
emittance. (keep higher field?)
Horizontal position/direction
distribution at exit of transport solenoid
Smooth curve
bend in 3 steps
Capture
Matching
Bent
Injection Point：s=7m
Post