R&D Status of PRISM-FFAG Akira Sato Osaka University for the - PowerPoint PPT Presentation

R&D Status of PRISM-FFAG Akira Sato Osaka University for the PRISM working group FFAG04 @ KEK Oct 13, 2004

contents • PRISM Overview • Optics design • with unique method • Magnet design • RF R&D • Summary & Issues

super cond. solenoid pi capture Less beam contamination High Intensity long flight length in the FFAG phase rotation large acceptance FFAG Narrow energy spread high power p beam, PRISM Phase Rotated Intense Slow Muon source Search for Lepton Flavor violation 105MeV e- B( μ -N → e-N)<10 -18 low Energy μ - stopped μ experiment intensity : 1011-1012 μ ±/sec beam repetition : 100-1000Hz muon kinetic energy : 20 MeV (=68 MeV/c) kinetic energy spread : ±0.5-1.0 MeV π contamination < 10-18

started in JFY2003. PRISM-FFAG ring construction has PRISM Layout P RODUCTION T ARGET P RIMARY P ROTON P ROTON B EAM D UMP *Solenoid Pion Capture C APTURE M ATCHING S OLENOID *Pion-decay and Transport S ECTION S OLENOID *Phase Rotation FFAG advantages: I NJECTION S YSTEM synchrotron oscillation necessary to do phase rotation large momentum acceptance 5 M necessary to accept large momentum distribution at the FFAG RING beginning to do phase rotation large transverse acceptance RF C AVITY muon beam is broad in space E JECTION S YSTEM

Schedule • JFY2003: RF amp. production • JFY2004: RF cavity construction, FFAG magnet construction • JFY2005: FFAG magnet production (continue) • JFY2006: FFAG magnet construction (completed) • JFY2007: muon acceleration and phase rotation, test cooling?

Optics Design & Beam Dynamics

(68MeV/c +- 20%) PRISM-FFAG requirements • Large acceptance • Ｈ：>20000πmm mrad • Ｖ：>3000πmm mrad • Quick phase rotation (～1μs) & mom. acceptance • Compact magnet • RF field gradient ~200kV/m • ~2MV/turn • scaling FFAG • F/D : variable • k value : variable

Tune study - PoP FFAG -

quasi-3D what’s problem • modeling of the fringing fields Bz(gauss) TOSCA 4000 z=0(cm) • TOSCA : perfect, but takes long time... z=3(cm) TOSCA z=6(cm) 2000 • SAD, MAD ... : need parameters (FINT) z=9(cm) z=12(cm) • need real data or TOSCA 0 • field at position far from mid. plane -2000 10 12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 • can estimated from field data of mid. plane theta(deg) ) • -> doesn't work at high z. to study large aperture FFAGs *model fringing field correctly *calculate field at not only mid. plane but also off mid. plane solution using POISSON -> quasi-realistic 3D magnetic fields

θ How to make quasi-realistic 3D magnetic fields step 1 : field F magnet field D magnet D magnet clump clump r5 calculate magnetic field (B θ ,Bz) ( z, θ ) of each z- θ cross sections (r1-r5). r4 x-axis is considered as θ - axis (approximation). r3 step 2 : r2 convert the field (B θ ,Bz) (ri,z, θ ) to (Bz,B θ ,Br) (ri,z, θ ) by using Maxwell eq. r1 r B z ( z i ) = B y ( z i ) x ( θ ) z B θ ( z i ) = B x ( z i ) Figure 1: Top view of a triplet magnet.   B r ( z i ) = dB z ( Z i − Z i − 1 ) + B r ( Z i − 1 )   dr   ( Z i ) step 3 : to make a fine mesh field map, apply a 2D spline interpolation to the above field D F D map. z MAGNET CYCLE = 3420 x ( θ ) r Figure 2: A magnet model used in POISSON calculation.

quasi-3D Comparison b/w TOSCA and quasi-3D Bz(gauss) Bz(gauss) TOSCA TOSCA quasi-realistic 4000 4000 z=0(cm) z=0(cm) z=3(cm) z=3(cm) z=6(cm) z=6(cm) 2000 2000 z=9(cm) z=9(cm) z=12(cm) z=12(cm) 0 0 -2000 -2000 10 12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 10 12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 theta(deg) theta(deg) 4000 4000 Bt(gauss) Bt(gauss) TOSCA quasi-realistic z=0(cm) z=0(cm) 2000 2000 z=3(cm) z=3(cm) z=6(cm) z=6(cm) z=9(cm) z=9(cm) 0 0 z=12(cm) z=12(cm) -2000 -2000 -4000 -4000 10 12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 10 12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 theta(deg) theta(deg) Br(gauss) Br(gauss) TOSCA quasi-realistic 400 400 z=0(cm) z=0(cm) z=3(cm) z=3(cm) z=6(cm) z=6(cm) z=9(cm) z=9(cm) 200 200 z=12(cm) z=12(cm) 0 0 > 10 hours ! a several min. 10 12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 10 12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 theta(deg) theta(deg)

quasi-3D mag. field 3D tracking by geant3.21 Optics Design parameters : number of cell FD,DFD,FDF k value F/D ratio gap size to study : acceptance (H,V) tune tune shift beam size etc

2D Acceptance Study DFD, N=10, half gap=15cm, w/o field clamps, r0=6.5m for 68MeV/c Horizontal phase spaces are plotted Vertical phase spaces are plotted in in a tune diagram. a tune diagram.

Vertical w/ zero h amp w/ small v amp Horizontal w/ zero v amp Horizontal 2D -> 4D acceptance what is the 4D acceptance? ../rz/ffag_n10_g17_tr620-fm.base.rz ur(mrad) ur(mrad) uz(mrad) 500 500 50 0 0 0 -500 -500 -50 -900 -300 300 900 -900 -300 300 900 -180 -60 60 180 r(mm) r(mm) z(mm) acceptable condition : turn more than 6

N=10 N=8 4D acceptance

5cm 10cm 15cm 20cm Acceptance dependence on gap size of magnets DFD, N=10, w/o field clamps, r0=6.5m for 68MeV/c

5m PRISM-FFAG N=10 k=5(4.6-5.2) +,--./$01 F/D(BL)= 6 r0=6.5m for 68MeV/c 23456 789:$01 half gap = 17cm mag. size 110cm @ F center Triplet !"#)* !"#&'( θ F=2.2deg ;<6 789:$01 θ D=1.1deg !"#$% tune h : 2.71 v : 1.52

Magnet Design

Feature of PRISM-FFAG Magnet scaling radial sector Conventional type. Have larger circumference ratio. triplet (DFD) F/D ratio is variable. Ds have field crump effects to realize the large packing factor. the lattice functions has mirror symmetry at the center of a straight section. large aperture important for achieve a high intensity muon beam. thin Magnets have small opening angle. so FFAG has long straight sections to install RF cavities as mach as possible trim coils k value is variable. Therefore, not only vertical tune and also horizontal tune are tuneable. C-shaped

Parameters of PRISM-Magnet r0 650 cm Number of Cell 10 F/D ratio 4~8 k value 4.4~5.2 BL integral 8.6 T· m/half cell @ r=r0 Aperture Horizontal 100 cm Vertical 30 cm

r z θ Field clamp top view 1.10° D 2.00° 4.40° F 969.9 1345.1 2.00° D ° 2022.4 0 1 . 1 R 6500 Field clamp

r θ z cross section at the center of F magnet 1290 No anisotropic inter pole

Main coil Trim coil D D F coils Z-60.0 Z-40.0 Z-20.0 X560.0 X580.0 X600.0 X620.0 X640.0 Y X660.0 X680.0 X700.0 X720.0 X740.0 Z20.0 Z40.0 Z60.0 11/Oct/2004 22: OPERA- Pre-processor 8

Cross section of Trim coils Effect of the flat trim coils /export/home/arimoto/tosca/0409/10/tr575-fm.op3 2000 0 z=0cm z=0cm B F L 1800 B F L z=5cm -5000 z=5cm 1600 z=10cm z=10cm -10000 z=15cm z=15cm B z_F L (Gauss*cm) 1400 B z_D L (Gauss*cm) -15000 1200 1000 -20000 800 -25000 600 -30000 400 -35000 200 -40000 0 580 600 620 640 660 680 700 720 580 600 620 640 660 680 700 720 7 7 6.5 6.5 6 6 K+1 k+1 K+1 5.5 5.5 5 5 k+1 4.5 4.5 4 4 580 600 620 640 660 680 700 720 580 600 620 640 660 680 700 720 r (cm) r (cm)

Field calc. by TOSCA 8 F 7.5 D (trim coil off) 7 6.5 6 k+1 5.5 5 4000 r=600 cm 4.5 r=620 cm 4 r=640 cm r=660 cm 3000 3.5 r=680 cm r=700 cm 3 B z (Gauss) 580 600 620 640 660 680 700 720 z=0 2000 r (cm) 1000 7 6.8 F/D ratio =| BLF /BLD | 0 Center of F magnet 6.6 Center of D magnet 6.4 -1000 0 1 2 3 4 5 6 7 8 9 10 6.2 ! (Deg.) F/D 6 5.8 5.6 5.4 5.2 5 580 600 620 640 660 680 700 720 r (cm)

Parameters of PRISM-FFAG Magnet • Total Mass of yoke: 14 t / cell • F Main coil : 78000 A*T / coil (F/D=4) • D Main coil : 26000 A*T / coil (F/D=4) • F trim coil : 1200 A/coil • D trim coil : 500 A/coil • Electric Power for F Main coil : 740 kW/Ring • Electric Power for D Main coil : 441 kW/Ring

FFAG Acceptance 4D Acceptance： 1G (mm mrad)2 6500π mm mrad Vertical Acceptance 40000π mm mrad Horizontal Acceptance ../rz/ffag_n10_g17_tr620-fm.4da.0.0680.rz (mrad) (mrad) 140 uz(mm) ur(mm) 90 50 200 4D Acc.=1035.5M(mm.mrad) 2 80 120 175 40 70 150 100 60 125 30 80 50 100 40 60 20 75 30 40 50 10 20 25 20 10 0 0 0 0 -100 0 100 -400 -200 0 200 z(mrad) (mm) r(mrad) (mm) Vertical Horizontal

zero chromaticity ../rz/ffag_n10_g17_tr620-fm.base.rz ../rz/ffag_n10_g17_tr620-fm.base.rz 3.5 tune vertical tune vertical tune 2 3 1.8 2.5 1.6 2 1.4 1.5 1.2 1 1 0.8 0.5 50 60 70 80 90 2.6 2.8 3 momentum(MeV/c) horizontal tune horizontal tune

RF R&D

� High field gradient RF Proton Synchrotron RF System SATUNE 250 MIMAS CERN PSB PRISM Cavity 200 CERN PS Field Gradient (kV/m) AGS J-PARC MA Cavities 150 ISIS (High Duty) KEK BSTR 100 KEK PS Ferrite Cavities J-PARC 50GeV MR 50 J-PARC 3GeV RCS 50GeV MR Upgrade 0 KEK-HGC 0 2 4 6 8 10 12 PRISM Frequency (MHz)