Target & Collector R&D for PRISM

1. Target & Collector R&D for PRISM Koji YOSHIMURA KEK July 2, 2002 @NuFact’02

2. Contents • Targetry for PRISM • Solenoid capture • Conducting Target • Summary

3. What’s PRISM Pion Capture • PRISM( Phase Rotation Intense Slow Muon source) • A dedicatedsecondarymuon beam channelwithhigh intensity(1012m/s)and • narrow energy spread(a few%) for stopped muon experiments FFAG PhaseRotator Sensitivity ~100 x MECO

4. Requirements of the Target for PRISM • Pion Momentum • ~100 MeV/c • backwardscapture sheme available! • Emittance • As low as FFAG acceptance • horizontal 10000p, vertical 3000p • Method • Solenoidal Capture • Conducting Target

5. Solenoidal Capture • Capture • Maching section • Decay section • Emittance • B field π R(m) B（T) π

6. Simulation Setup • Simulation code • MARS, GEANT3 • 12 T field -> 3T • 47MeV/c ~ 85 MeV/c • Backward • 2000 p ~ 3000 p vertical acceptance 3 T proton 12 T

7. Simulation Results • Target material • W is better than C • B field • Determined by Capture field • Target Radius • Loss due to hit target • Reabsorption • Yield of pion • 0.002~0.006 muon/proton

8. SC Solenoid in High Rad. Env • Thick radiation shield is necessary • Yokoi’s Technote • ~100 W • Radiation shield of 34 cm in thickness is needed • Large bore for absorber • High stored energy • Extremely expensive • ~ 20 M$ for 12 T coil • Design • Need precise heat load data • Experimental data is necessary! SC Coil Absorber 34 cm, 100W Thickness of Absorber

9. Beam experiment with R&D Magnet • Beam test with R&D mag • Direct measurement of heat load by radiation • Study behavior of magnet under heating condition • R&D Magnet • 10 T hybrid SC coil • Cryo cooler • He free • Compact • Y. Kuno, A. Yamamoto • KEK PS • 12 GeV proton • 1011 proton/s

10. Calorimetric Method Q = K DT

11. PRISM R&D Magnet

12. Superconducting Coils

13. Proposed Layout

14. Schedule • 2001.11 Bench test with heater • 2002.3~4 Modification • 2002.5~8 Bench test after mod. Making Coil Mockup • 2002.fall Beam test with Mockup • 2003.fall Beam test with R&D Mag

15. Conducting Target • Confine pions inside the target with troidal field • B. Autin, @Nufact01 • Advantage over Solenoid • Low emittance beam • Linear transport element • No SC solenoid channel • Cheaper! • Cooling condition better?

16. Basic Priciple Acceptance Proton B. Autin et al. (Inside the target)

17. Comparison of target material • Mercury is good candidate • Minimum Power • Easy to cooling • Higher pion yield • Technical Issues • How to cut off electrical circuit? • Container • Shockwave • Cavitation • Thicker wall can be used! • No reabsorption B. Autin et al.

18. Setup for current test • 1st phase • 1000 A DC • 100 J • 2nd phase • 250 KA 2.5ms Pulse (K2K horn PS) • 15 KW • 3rd phase • 1 MW? • Beam test? Y. Yamanoi

19. Summary • Solenoidal Capture • Standard scheme • Beam test will be performed usigng test SC solenoid • Design parameters will be considered. • Conducting Target • Lot of merits • R&D Work has just started! • Proof of principle • Feasibility test of High current liquid target