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Pion capture system for PRISM

Pion capture system for PRISM. M. Yoshida Osaka Univ. 2006/11/13 PRISM workshop @ Osaka Univ. PRISM/PRIME project. Phase Rotated Intense Slow Muon source Collect 68MeV/c m -. proton beam. PRIME detector. pion production, capture and transport system. Phase rotator.

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Pion capture system for PRISM

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  1. Pion capture system for PRISM M. Yoshida Osaka Univ. 2006/11/13 PRISM workshop @ Osaka Univ.

  2. PRISM/PRIME project • Phase Rotated Intense Slow Muon source • Collect 68MeV/c m- proton beam PRIME detector pion production, capture and transport system Phase rotator

  3. Capture/Transport solenoid channel • Transport pions and muons in 2T solenoid • Bent towards experimental area • Put radiation shield along proton beam line • Reduce background by wiping out higher energy particles

  4. Target • Resistance against Heat/Shock • Liquid target: high resistance, but need much R&D • Solid target: easy operation, but need to select robust material and need careful design for heat removal • Pion yield • High Z : high pion multiplicity • Low Z : less absorption of low-energy pions • Proton beam • Narrow spot : high collection efficiency • Wide spot : easier to reduce heat shock • To collect low-energy pions in PRISM • Default option: Solid LowZ (Graphite) target with wide-spot proton beam • Alt. option: Solid HighZ (Tungsten) target with narrow-spot proton beam • Need to study availability

  5. Muon yield as a function of target tilt angle • MARS１４+ICOOL • Tungsten target • ６T capture solenoid 1T transport • Number of muons 10m downstream target • Momentum selection : 68MeV/c+-20% • 20% larger yield at 0.2 rad (~10 deg)

  6. 5cm 15cm Simulation setup for heat load study • MARS15(04) • Primary beam • 40GeV • size s=1.0cm • 1014 protons/sec  100W = 6.24MeV/primary p • Magnetic field • uniform 6Tesla • Solenoid inner bore R=15cm • Target • Graphite (1.7g/cm3) • radius=2cm, length=80cm (2x interaction length) • Shield • Tungsten • length 140cm • thickness 25cm – 35cm • Coil • 90%SC (40%NbTi + 60%Cu) + 10%Kapton • density 7.00 g/cm3 • length 140cm • thickness 5cm – 20cm protons

  7. Particle flux Charged hadron flux Neutron flux R (cm) z (cm)

  8. Deposit energy distribution • Al-stabilized SC coil • Density 3.1g/cm3 • Deposit E： 0.5W/kg •  5 MGy/year • Tungsten radiation shield • 20cm thick, 140cm long • Inner bore: 30cm • Outer diameter : 70ｃｍ • Density : 19.3g/cm3 • 8.5 ton • Deposit E ： 70 kW

  9. Heat Load on Coil (target tilt: 10deg) 360Ｗ Al安定化超伝導コイル 620Ｗ Cu安定化超伝導コイル タングステンシールド：110kW

  10. Concepts of pion capture/transport system for PRISM • Capture low-energy pions produced in Graphite target with 6T solenoid field • Low-Z material • to avoid absorption in the target • Collect backward pions from the target • 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 • Injected proton beam is assumed to have 1cm-sigma spot on Target • Collect backward pions • The first trial of conceptual design has been done.

  11. Current Distribution6T2T in 6 steps • 2800kA / (1400mm long x 120mm thick) • 17 A/mm2 • 520kA/(1000mm x 15mm thick) • 35 A/mm2 • 4x104kA / (4x200mm long x 15 mm thick) • 35 A/mm2 • 320kA / (300mm long x 15 mm thick) • 71 A/mm2 • 200kA / (500mm long x 15 mm thick) • 27 A/mm2 • 240kA / (500mm long x 15 mm thick) • 32 A/mm2 • 520kA / (1000mm long x 15mm thick) • 35 A/mm2 17 A/mm2 71 A/mm2 35 A/mm2 35 A/mm2 35 A/mm2 33 A/mm2 27 A/mm2

  12. Current Distribution6T2T in 2 steps • 2750kA / (1400mm long x 120mm thick) • 16 A/mm2 • 680kA / (1000mm long x 15 mm thick) • 45 A/mm2 • 100kA / (450mm long x 15 mm thick) • 15 A/mm2 • 620kA / (650mm long x 15 mm thick) • 64 A/mm2 • 200kA / (500mm long x 15 mm thick) • 27 A/mm2 • 520kA / (1000mm long x 15mm thick) • 35 A/mm2 64 A/mm2 16 A/mm2 15 A/mm2 45 A/mm2 35 A/mm2 27 A/mm2

  13. Geometry of Pion Capture System 100 300 600 1200 1400 1000 600 300 1340 To transport solenoid  1220 300 600 700 1000 520A/mm 383A/mm 1964A/mm 520A/mm 1133A/mm 100 magnetic field [Tesla]

  14. Heat load estimationMARS Simulation 140cm • MARS15(04) • Primary beam • 40GeV • size s=1.0cm • 1014 protons/sec • Target • Graphite (1.7g/cm3) • radius=2cm • Magnetic field • uniform 6Tesla • Solenoid inner R=15cm • Coil • Al-stabilized superconducting Coil • 71%Al + 11%NbTi + 14%Cu + ４%G10-tape • density 3.1 g/cm3 5cm Tungsten shield 15cm protons

  15. Heat load on coil Coil: 89 W Shield: 41 kW 80cm-long graphite target • Choose • thickness of shield = 30cm • thickness of coil = 12cm  17 A/mm2 • target length = 60cm

  16. 270 0 180 90 Spatial distribution of deposit energy

  17. Radius distribution at 3m 6T2T 6T1T • Larger radius distribution than 30cm in the case 6T1T • Smaller transport solenoid can be adopted in 6T2T 10cm 15cm 20cm 25cm

  18. High field capture z=160cm s=8.1cm Large area of 6T field can affect on pion emittance? y (cm) z=230cm s=8.1cm Target y (cm) z=300cm s=8.8cm

  19. Field peak positionLarger shield bore (30cm50cm) Target • Pions are collimated at the radiation shield  need larger bore • The magnetic mirror can increase pion yields by 30%, but downstream part of capture solenoid has much larger energy deposit bore50cm bore30cm

  20. Yields (R<30cm@z=300cm) and Heat Load as a function of shield inner bore • Shield inner bore should be larger than 40cm (Shield thickness = 25cm) • Heat Load for 40cm bore = 108W 2006/10/18 M. Yoshida, PRISM Solenoid

  21. Momentum, Radial distribution @20m downstream target Pmu<80MeV/c Nmu=0.069 /POT Pmu<80MeV/c : 23% Nmu=0.043 /POT Pmu<80MeV/c : 30% Pm (GeV/c) R2 (cm2)

  22. Edep: 77W • Yield: 0.070/POT • Edep: 76W • Yield: 0.088/POT • Edep: 96W • Yield: 0.106/POT • Edep: 106W • Yield: 0.091/POT • Edep: 97W • Yield: 0.104 /POT 2006/10/18 M. Yoshida, PRISM Solenoid

  23. Geometry of capture solenoid system 100 300 600 1200 1400 1000 600 1340 To transport solenoid  1220 600 700 700 300 500 1000 200 520A/mm 383A/mm 1964A/mm 520A/mm 1133A/mm magnetic field [Tesla]

  24. Parameters • Proton beam • 30 GeV, 15 microA • Parallel beam, 1-cm spot (gaussian sigma) at the target • Production target • Graphite, Length: 60 cm, Diameter: 4 cm • Al-stabilized Superconducting coil • Radiation shield • Tungsten, Inner bore = 30 cm diameter • Heat Load on 6T coil = 64W • Muon yield after 2-Tesla straight transport solenoid • 0.069 m /POT, R<30cm@20m • 6.5x1012 muons / sec • Muon yield after momentum selection, Pmu<80MeV/c • 0.016 m /POT, R<30cm@20m • 1.5x1012 muons / sec • Need to estimate realistic stopping efficiency

  25. Shield in Matching section R • Muon yield decreases by 7% when shield in matching section increases from 1cm to 10cm • Shield of 5cm thick is enough? • Need to study energy deposit in coils of the section 2006/10/18 M. Yoshida, PRISM Solenoid

  26. MECO Production Solenoid 2.5T 5T 50 cm 140 cm 554 cm 63W in Coil 16kW in Shield

  27. PRISM Solenoid for low-power proton beam (8GeV-1) 100 900 550 1150 550 1000 600 To transport solenoid  600 1100 600 1300 700 300 900 800 200 520 A/mm 390 A/mm 2167 A/mm 650 A/mm 910 A/mm magnetic field [Tesla]

  28. Parameters (8GeV-1) • Proton beam • 8 GeV, 15 microA • Parallel beam, 1-cm spot (gaussian sigma) at the target • Production target • Graphite, Length: 60 cm, Diameter: 4 cm • Al-stabilized Superconducting coil • Radiation shield • Tungsten, Inner bore = 30 cm diameter • Heat Load on 6T coil = 72 W • Muon yield after 2-Tesla straight transport solenoid • 0.033 m /POT, R<30cm@20m • 3.1x1012 muons / sec • Muon yield after momentum selection, Pmu<80MeV/c • 0.0082 m /POT, R<30cm@20m • 0.77x1012 muons / sec • Need to estimate realistic stopping efficiency Pm (GeV/c) R2 (cm2)

  29. Summary • 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 / 30 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 • Reduce beam spot size on target • Field gradient around the target • acceptance would increase by mirroring forward pions • To fit to FFAG acceptance (H: 40p mm-rad, V:6.5p mm-rad) • optimize field profile in the capture system to reduce muon emittance. (keep higher field?)

  30. Vertical extraction Y Z

  31. Prompt Dose and Energy Deposition around PRISM target 105 mSv/hr at 1012 incident protons / sec

  32. PRISM Solenoid for low-power proton beam (8GeV-2) 100 900 550 1150 550 1000 600 To transport solenoid  1100 600 1300 700 700 300 500 900 200 520 A/mm 390 A/mm 2056 A/mm 650 A/mm 910 A/mm magnetic field [Tesla]

  33. Parameters (8GeV-2) • Proton beam • 8 GeV, 15 microA • Parallel beam, 1-cm spot (gaussian sigma) at the target • Production target • Graphite, Length: 60 cm, Diameter: 4 cm • Al-stabilized Superconducting coil • Radiation shield • Tungsten, Inner bore = 30 cm diameter • Heat Load on 6T coil = 137 W • Muon yield after 2-Tesla straight transport solenoid • 0.026 m /POT, R<30cm@20m • 2.4x1012 muons / sec • Muon yield after momentum selection, Pmu<80MeV/c • 0.0066 m /POT, R<30cm@20m • 0.62x1012 muons / sec • Need to estimate realistic stopping efficiency Pm (GeV/c) R2 (cm2)

  34. PRISM Solenoid for low-power proton beam (8GeV-3) 100 1400 550 850 700 1000 600 To transport solenoid  1100 600 1300 700 660 300 500 800 200 520 A/mm 390 A/mm 1857 A/mm 572 A/mm 910 A/mm magnetic field [Tesla]

  35. Parameters (8GeV-3) • Proton beam • 8 GeV, 15 microA • Parallel beam, 1-cm spot (gaussian sigma) at the target • Production target • Graphite, Length: 60 cm, Diameter: 4 cm • Al-stabilized Superconducting coil • Radiation shield • Tungsten, Inner bore = 30 cm diameter • Heat Load on 6T coil = 107 W • Muon yield after 2-Tesla straight transport solenoid • 0.022 m /POT, R<30cm@20m • 2.1x1012 muons / sec • Muon yield after momentum selection, Pmu<80MeV/c • 0.0060 m /POT, R<30cm@20m • 0.56x1012 muons / sec • Need to estimate realistic stopping efficiency Pm (GeV/c) R2 (cm2)

  36. 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. Parameters of transport solenoid A. Sato

  37. Summary • 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 • Reduce beam spot size on target • Field gradient around the target • acceptance would increase by mirroring forward pions • To fit to FFAG acceptance (H: 40p mm-rad, V:6.5p mm-rad) • optimize field profile in the capture system to reduce muon emittance. (keep higher field?)

  38. Horizontal position/direction distribution at exit of transport solenoid bend in 3 steps Smooth curve

  39. Capture Matching Bent Post Injection Point：s=7m

  40. muon momentum @15m (GeV) parent pion momentum @3m (GeV) Muon high energy tail • High momentum muons above 75MeV/c could generate background electron by DecayInFlight • No need to keep pions > 160MeV 2006/10/18 M. Yoshida, PRISM Solenoid

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