1. Target & Capture for PRISM Koji Yoshimura Institute of Particle and Nuclear Science High Energy Accelerator Research Organization (KEK)

2. NufactJ03 May 16-17, 2003, TMU Contents Targetry for PRISM Solenoid capture Conducting Target Summary

3. NufactJ03 May 16-17, 2003, TMU What’s PRISM PRISM( Phase Rotation Intense Slow Muon source) A dedicated secondary muon beam channel with high intensity (10 11 ~10 12  /s)and narrow energy spread(a few%) for stopped muon experiments Pion Capture FFAG PhaseRotator

4. NufactJ03 May 16-17, 2003, TMU Requirements of the Target for PRISM Pion Momentum ~100 MeV/c backwards capture sheme available! Emittance As low as FFAG acceptance horizontal 10000  vertical 3000  Method Solenoidal Capture Conducting Target

5. NufactJ03 May 16-17, 2003, TMU Solenoidal Capture Capture Maching section Decay section Emittance B field B （ T) R(m) π π

6. NufactJ03 May 16-17, 2003, TMU Simulation Setup Simulation code MARS, GEANT3 12 T field -> 3T 47MeV/c ~ 85 MeV/c Backward 2000  ~ 3000  vertical acceptance proton 12 T 3 T

7. NufactJ03 May 16-17, 2003, TMU 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. NufactJ03 May 16-17, 2003, TMU 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 Design Need precise heat load data Experimental data is necessary! Absorber SC Coil Thickness of Absorber 34 cm, 100W

9. NufactJ03 May 16-17, 2003, TMU 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 10 11 proton/s

10. NufactJ03 May 16-17, 2003, TMU Around ’95

11. NufactJ03 May 16-17, 2003, TMU Target for -Fact in US

12. NufactJ03 May 16-17, 2003, TMU Comparison B12 T6 T Useful aperture R0.050.10 Cryost. IR0.550.65 Coil IR0.650.75 Coil mean R~0.85~0.83 Coil OR1.1~0.9 Coil length~2.0 S/CNb3Sn/NbTiNibTi Stored energy~250 MJ~60 MJ Coil mass~50 Ton10 Ton Cost (Estimate)20 M$7.8 M$

13. NufactJ03 May 16-17, 2003, TMU REALISM Baseline option B=6T Φ =800mm, L=1200 Graphite Target L=2 λ =800mm Still Need R&D ~500 W heat is deposited in SC coil Quench protection Radiation safety

14. NufactJ03 May 16-17, 2003, TMU R&D Plan Cooling Method ~500W Pool boiling Thermo siphon (Using convection) R&D Coil will be constructed this year Half or Quarter size Heating using AC LOSS Or Special heater Engineering Design -> Future Upgade

15. NufactJ03 May 16-17, 2003, TMU 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. NufactJ03 May 16-17, 2003, TMU Basic Priciple (Inside the target) Proton Acceptance

17. NufactJ03 May 16-17, 2003, TMU 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

18. NufactJ03 May 16-17, 2003, TMU 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?

19. NufactJ03 May 16-17, 2003, TMU Mercury Test Loop Mercury 18 litter ~ 250 kg Study mercury flow

20. NufactJ03 May 16-17, 2003, TMU Summary Solenoidal Capture Standard scheme Beam test was successfully performed using the mockup Design parameters will be considered. Realistic R&D Model coil Conducting Target Lot of merits R&D Work has just started! Proof of principle Feasibility test of High current liquid target