Neutrino Factory in Japan: based on FFAG

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1 NuFact2, London, July 1-5, 22 Neutrino Factory in Japan: based on FFAG Yoshiharu Mori (KEK) 1. Introduction 2. Scenario of muon acceleration 3. Neutrino Factory based on FFAG 4. Summary

2 NuFact2, London, July 1-5, 22 Muon Suvival for various accelerating filed 5 MV/m : 3.94 km 2 MV/m : 9.85 km 1 Mv/m : 19.7 km.75 MV/m : 26.3 km.3 GeV/c- 2 GeV/c 1.8 E=5MV/m -> 3.9 km E=.75MV/m -> 26.3 km Muon Survival Conventional Scheme PJK Scenario (USA:study1&2, CERN) Energy (MeV) ---> based on Cooling +Linear accelerators

3 NuFact2, London, July 1-5, 22 Neutrino Factory Scenario Linear accelerator based scenario ( PJK Scenario) *high accel. field gradient :E > 5 MV/m ( L ~ 4 km) High frequency rf (f > 1 MHz) pro : muon survival >85% con : small acceptance ( ε H,V & dp/p) need phase rotation & muon cooling high cost

4 NuFact2, London, July 1-5, 22 Neutrino Factory Scenario Ring accelerator scenario (FFAG Scenario) *low accel. field gradient: E ~.5-1 MV/m # of turns ~ >3 turns (R ~.15 km): pro: low frequency rf ( f~ 5-1 MHz) large acceptance ( ε H,V & dp/p) no-need phase rotation &muon cooling low cost (*depend on scheme) con: muon survival ~5%, however, large acceptance may compensate it. large acceptace & quick acceleration?

5 NuFact2, London, July 1-5, 22 Conceptual Design of Neutrino Factory in Japan Scenario * FFAG accelerator complex for muon acceleration i) large acceptance : ε Ν ~.3mrad, dp/p~.5 h,v ii) no-cooling & no-phase rotation * Proton driver : JHF 5-GeV PS i) beam power : ~MW ii) construction(phase-i) completed in 27

6 B2 FFAG-I.3-1GeV/c 3BTC2 3BTD2 C3 M3 3BTM1 NC1 D1 NM1 ND2 3BTD1 3BTC1 C1 ND1 SM1 1m FFAG-2 1-3GeV/c SM3 FFAG-3 3-1GeV/c M1 D3 M2 C2 MSR 2GeV/c D2 D2 SM2 FFAG-4 1-2GeV/c KD2 KM2 KSM1 KC1 KD1 KM1 Accelerator Scenario - FFAG Option NuFact2, London, July 1-5, 22 target & capture FFAG based neutrino factory proton driver JHF 5-GeV PS p=.3~1gev/c p=1gev/c~3gev/c PRISM µ-e conversion p=3gev/c~1gev/c FFAG cascade p=11gev/c~2(5)gev/c muon storage

7 NuFact2, London, July 1-5,22 Proton Driver FFAG

8 B2 NuFact2, London, July 1-5, 22 Proton Driver Proton driver is JHF 5-GeV PS. injection energy 3 GeV extraction energy 5 GeV (4 I) # of protons 3.3 x1 14 ppp repetition rate.3 Hz (~3.6 sec) ave. beam current beam superperiod 3 harmonic number 9 rf frequency 3BTC2 3BTD2 D3 C3 SM3 ND1 NC1 NM1 1m 15 µa (@slow beam extr.) M3 3BTM1 ND2 3BTD1.6MW(4GeV-phaseI) 3BTC1.75 MW(5GeV-phaseII) D1 SM1 1.68MHz(inj.)-1.73MHz(ext.) C1 M1 C2 M2 SM2 D2 D2 KD2 KM2 KSM1 KD1 KM1 KC1

9 NuFact2, London, July 1-5, 22 Possible Upgrading Path in Future 1) Increase main ring cycle MR cycle 3.64 sec. --> 1.5 sec. Beam Power ~ 2 MW * rf voltage : x2 * maget power supply : FWG no needs to change main parts 2) Increase beam intensity energy injection acceleration extraction time P1 P3 P4 P5 P2 slow beam extraction Beam stacking 4 batches ---> 8 injection Beam Power ~ 4MW * barrier bucket beam stacking : modest space charge Beam losses have to be reduced

10 NuFact2, London, July 1-5,22 Target & Capture FFAG

11 NuFact2, London, July 1-5, 22 How large acceptqance is needed? Muon & pion yield with fixed trans. acceptance assumed acceptance: ε n (1%)=.3πm.rad dp/p = +- 5% proton driver : JHF 5GeV MR (.75MW) peak yield.3 muons/proton pµ =.4~1.5GeV/c P center (GeV/c) P center (GeV/c) X max (mm) X max (mm) π + µ + Yield(π + µ + /1proton P center (GeV/c) 1.5 π µ Yield(π - µ - /1proton P center (GeV/c) X max (mm) X max (mm)

12 Accelerator Scenario - FFAG Option NuFact2, London, July 1-5, 22 Direct Acceleration by Low Frequency RF No Phase Rotation, No Cooling ev.sec Yield/1proton π + +µ + Yield/1proton π - +µ R:8cm R:6cm R:4cm X max (mm).1.5 p/p=+-5%@3mev/c X max (mm) Longitudinal phase space A n =.3πm.rad ~.3muons / proton JHF 5-GeV Proton Driver

13 NuFact2, London, July 1-5,22 FFAG accelerators FFAG

14 NuFact2, London, July 1-5, 22 FFAG Accelerator idea --> 5 s (Ohkawa, Symon,Kolomenski) proton acceleration --> PoP FFAG (KEK),2 1) fixed magnetic field 2) AG focusing 3) synchrotron osc. * large acceptance (trans. & long.) * quick acceleration PoP FFAG synchrotron

15 NuFact2, London, July 1-5, 22 FFAG Parameters momentum(gev/c).3~1 1~3 3~1 1~2 number of sector k number average radius(m) max. B field(t) tune drift length(m) BF length(m) BD length(m) orbit excursion(m) transition γ

16 NuFact2, London, July 1-5, 22 FFAG 1-2 GeV r 2m # of sector 12 B field 6.T

17 1-2GeV FFAG, singlet FODO new version NuFact2, London, July 1-5, 22 k=28, N=2

18 NuFact2, London, July 1-5, 22 Aperture of FFAG: Is it large with large k? larger ring --> large k --> large non-linear field? x OD ρf Ψ r ρd θd θf OF r 1 θ βf βd α = 1 k+1 : momentum compaction factor O Dynamic aperture depends mostly on phase advance/cell!

19 r'(mrad) NuFact2, London, July 1-5, 22 Dynamic Aperture of FFAG ring (.3-1GeV/c) 2 1 normal conducting version Horizontal Acceptance (N=32,k-value=4) phase advance / cell ~ 9 degrees -1 A H ~ >1πmm.mrad -2 r=226mm.3gev/c r(mm) energy gain:6mev/turn

20 Momentum Compaction & Longitudinal Motion Scaling FFAG Magnetic field configuration: Br B r r (, θ) = F( θ hln ) r r Momentum compaction factor: α k NuFact2, London, July 1-5, 22 C C p = α p Orbit length relations: p2 C( p C p 2) ( 1) 1 = p 1 α = 1 + k k * Higher orders such as α 1, α 2, = in scaling FFAG. No higher orders in momentum compaction!

21 NuFact2, London, July 1-5, 22 Scaling FFAG 1 Momentum compaction factor : α = & No higher orders. 1 + k ----> No bucket distortion even at large momentum spread. cf. FFAG Muon Accelerator Momentum [ev] 2.4e+1 2.2e+1 2e+1 Initial Phase=.6[pi radian] Final Momentum 1-2GeV ev =.7MeV/m 1.8e+1 1.6e+1 1 turn 1.4e+1 5 turn 1.2e+1 1e+1 Initial Momentum 8e+9 6e Phase [pi radian]

22 Longitudinal motions in the FFAG rings NuFact2, London, July 1-5, 22.3 ~ 1 GeV/c 1 ~3 GeV /c. 5.5 dp/p dp/p phase[rad] phase[rad] 3 ~ 1 GeV /c 1 ~2 GeV /c.5.5 dp/p dp/p phase[rad] phase[rad]

23 NuFact2, London, July 1-5, 22 Beam tracking -3D 1-2 GeV ring 15 injection after acceleration 6 injection after acceleration 1 4 r' (mrad) 5-5 hor. z' (mrad.) 2-2 ver r (mm) z (mm) Energy (GeV) TURN 4 TURN 12 TURN long. ε T =.3πm.rad, N εl =5eV.sec N magnet: multi-pole model rf freq.=7mhz, ev =.7MeV/m phase (deg.)

24 Beam Injection NuFact2, London, July 1-5, 22 Y(m) cf. 1GeV ring : ε n =.3πm.rad, dp/p=+-5% kicker magnet : 1.5kG, septum magnet : 1.5T X(m) septum(4kgauss) 2m injection beam kicker(1.3kgauss) 2m -.15 Horizontal phase dp/p= dp/p= /3/ circulating bean emittance : 1π mm mrad space for septum(max: 1cm) dp/p= -.5 dp/p=.75mev/m K=5 r=13cm

25 NuFact2, London, July 1-5, 22 Beam Extraction-1 Septum 2 Initial kicker # kicker 1# X(m).1 Kicker R(m) Kicker θr(radian) θr(radian) θr(radian) θr(radian) 25 θr(radian) Y(m) cf. 1 GeV ring R(m) R(m).2 Septum next(kicker 1) R(m) R(m)

26 NuFact2, London, July 1-5, 22 Beam Extraction-2 cf. 1-2GeV ring Y(m) extracted beam θ R (radian) septum X(m) R(m)

27 NuFact2, London, July 1-5,22 Cooling in FFAG FFAG

28 NuFact2, London, July 1-5, 22 Cooling in FFAG FFAG based Neutrino Factory does not need Muon Cooling. But, some cooling may help the cost reduction. Ring Cooling in the FFAG first(.3-1gev/c) ring *1atm H 2 gas or Liq. hydrogen target in the ring *only for transverse cooling H. Schonauer(CERN) cf. E=.3~1GeV/c ev =1MeV/m β~1.5m

29 Muon Cooling in FFAG ring(.3-1gev/c) NuFact2, London, July 1-5, H2 Gas in.3-1 GeV/c FFAG epsn/epsn 1 N/N cf. E=.3~1GeV/c ev =1MeV/m f rf =5MHz emittance survival β~1.5m.2 Emittnace cooled ~ 5% MeV Energy Large enough for maget cost reduction!

30 NuFact2, London, July 1-5,22 Hardware R&D FFAG

31 NuFact School, London, June 24-28,22 15-MeV proton FFAG accelerator Prototype for various applications: # Madical application : Cancer therapy # Muon phase rotation : PRISM project 15MeV FFAG main parameters No. of sectors 12 Field index(k -value) 7.5 Energy 12MeV - 15MeV Repetition rate 25Hz Max. Magnetic field Focus-mag.: 1.63 Tesla Defocus-mag.:.13 Tesla Closed orbit radius 4.4m -5.3m Betatron tune Horizontal : 3.8 Vertical : 2.2 rf frequency MHz

32 15-MeV proton FFAG accelerator NuFact School, London, June 24-28,22 5m

33 NuFact School, London, June 24-28,22 Yoke-free magnet of triplet sector FFAG X35. Y15. X4. Y1. Z25. Y5. X45. Z2. Z15. X5. Z1. Y-5. X55. Z5. Y-1. X6. Z. Y /Jan/1 21:27:48 Page 44 OPERA-3d Pre-processor 2.69

34 Magnet of 15-MeV proton FFAG NuFact School, London, June 24-28,22

35 Hardware R&D NuFact2, London, July 1-5, 22 1) Low freq. & high gradient RF system :1MV/m, 5-1MHz a)sy2 ferrite cavity b)ceramic gap cavity US-Japan collaboration c)air gap cavity 1 11 SY2 Emax~6.4MV/m ø9m 6.5MHz Emax~6.5MV/m ø6m 6.5MHz Ekp=4.8MV/m Qf µ 1 1 Emax~13MV/m ø4.4m 6.5MHz Emax~12MV/m ø4m 6.5MHz Brf[mT].9MΩ/m ø.6m bore.5mω/m ø.6m bore.4mω/m ø.6m bore a) b) c) rf power : total peak power ~75MW (air gap cavity) ave. rf power ~1MW.45MΩ/m ø.6m bore

36 NuFact2, London, July 1-5, 22 Hardware R&D rf amplifier & power supply: 1kW anode dissipation tetrode --> ~1MW in burst mode operation anode power supply depends on ave. rf power. in total: 75 x 1kw anode diss. tetrode 1MW anode power supply

37 NuFact2, London, July 1-5, 22 Hardware R&D Superconducting Magnet for FFAG X-4. X-3. Y4. Y3. Y2. Z-3. Z-4. UNITS Length :cm Flux density :gauss Magnetic field :oerste Scalar potential:oerste Vector potential:gauss- Conductivity :S cm -1 Current density :A cm -2 Power :W Force :N Energy :J Electric field :V cm -1 X-2. Y1. X-1. Z-2. Z-1. Z1. X1. Z2. X2. Y-1. Z3. X3. Z4. X4. Y-2. Y-3. PROBLEM DATA cor_a-1.toscab TOSCA analysis (nl) Magnetostatics Case No elements nodes Shape funct. fields Nodal coil fields LOCAL COORDS. Xlocal =. Ylocal =. Zlocal =. Theta =. Phi =. Psi =. Y-4. 24/Feb/1 12:45:51 Pag OPERA-3 Post-processor 2.611

38 NuFact2, London, July 1-5, 22 Magnetic field configuration of SC magnet By_r1_ By_r15_ By_r2_ By_r25_ By_r3_ By_r35_ By_r4_ By_r45_ By_r5_ By_th_ fit : y = e-9 r^5.41 By field [T] By field [T] theta [Deg] θ direction radius [cm] radial direction

39 FFAG-Magnet design B=6T for 1-2GeV ring NuFact2, London, July 1-5, 22 Magnetic field for FFAG: B= B r r k B kb = B + x + r kk ( 1) B 2 2! r x kk ( 1)( k 2) B + 3 3! r 2 x 3 + K Dipole Quadrupole Sextupole Octupole 55 coils arrangement : yoke (iron) 4 O S Q O S O 15 4 D Q O S S O Q D machine center radius [cm] O S O Q S O

40 2D Magnetic Field Calculation (1) NuFact2, London, July 1-5, 22 Design target : r 2 [mm] B 4.5 [T] k 28 Filed components : B Di. B Quad. 4.5 [T] 6.3 [T/m] B Sext [T/m 2 ] B Oct. 2.4 [T/m 3 ] result : Calculated coil currents I Di [ATurn] ( [A/mm 2 ] ) I Quad [ATurn] ( [A/mm 2 ] ) I Sext [ATurn] ( [A/mm 2 ] ) I Oct [ATurn] ( [A/mm 2 ] ) magnetic field [T] r radius [m] 2.5

41 2D Magnetic Field Calculation (2) NuFact2, London, July 1-5, 22 Analysis : By [T] run66 fitting range:-21.5 ~ 21.5 [cm] : chi^2 = Y = *X *X^ *X^3 By [T] run66 fitting range:-21.5 ~ 21.5 [cm] : chi^2 = Y = *r^ x [m] r/r (r=2m) 1.2 polynomial fitting B Di [T] B Quad [T/m] B Sext [T/m 2 ] B Oct [T/m 3 ] r^k fitting B [T] k

42 B2 NuFact2, London, July 1-5, 22 Neutrino Factory in Japan - FFAG Scenario FFAG based neutrino factory FFAG-2 1-3GeV/c FFAG-I.3-1GeV/c C3 ND1 SM3 D3 M2 C2 3BTC2 M3 NC1 NM1 ND2 1m KD2 KM2 KSM1 3BTD2 3BTM1 3BTD1 KD1 3BTC1 MSR 2GeV/c KM1 KC1 SM2 D1 FFAG-3 3-1GeV/c D2 D2 SM1 C1 M1 FFAG-4 1-2GeV/c

43 NuFact2, London, July 1-5, 22 Parameters FFAG no phase rotation,no cooling proton driver 5GeV(1-4MW) Accelerator FFAG-(PRISM).3-1GeV FFAG GeV FFAG GeV FFAG GeV storage ring C~8m Intensity phase 1 3x1 2 muon/y(1mw) phase 2 1.2x1 21 muon/y(4mw) Linac USA:study1 proton driver 5GeV(1-4MW) phase rotation 8MeV/c cooling 1m acceleration linac 2GeV FFAG 2-11GeV RCL 11-2(5)GeV storage ring C~1m Intensity phase muon/y (1MW ) phase 2 4x1 2 muon/y (4MW ) (*USA Study2 ~5 times)

44 NuFact2, London, July 1-5, 22 Summary FFAG based neutrino factory : feasible R&D 1)optimization FFAG lattice (inj. ext. ) hybrid rf (low & high freq.) 2)beam simulation (trans. & long.) 3)hardware: rf cavity, sc-magnet etc.

Neutrino Factory in Japan: based on FFAG

Neutrino Factory in Japan: based on FFAG Yoshiharu Mori (KEK) 1. Introduction 2. Scenario of muon acceleration 3. Neutrino Factory based on FFAG 4. Summary Introduction What is Neutrino Factory? High-intensity