MOMENT 靶站模拟

1. MOMENT靶站模拟 袁野 20170605 高能物理计算和软件会议@成都

2. 提纲 • Muon产生俘获与MOMENT • MOMENT靶站 • EMuS靶站

3. High intensity muon source is very useful in particle physics and multi-discipline research • Particle physics： • Precise parameters measurement • BSM new physics search • Neutrino Factory/Muon Collider

4. Muon Physics: Worldwide Effort* * Incomplete list of past, present & future muon experiments • Lifetime – Fermi constant • MuLan & FAST at PSI • Decay parameters (r, d, h, Pmx ...) • TWISTat TRIUMF and polarization measurements at PSI • Muon Capture • MuCapat PSI: gP, pseudoscalar coupling • MuSunat PSI: basic EW interaction in 2N system • Lepton Flavor Violation • m->eg – MEGand m3eat PSI • me conversion: Mu2e(FNAL), COMET, DeeMee(JPARC) • Anomalous magnetic moment (g-2) • E821at BNL and Muon g-2at FNAL & JPARC • Search for Electric Dipole Moment • E821at BNL and Muon g-2 at FNAL & JPARC • Lorentz / CPT violation tests • E821at BNL and Muon g-2at FNAL & JPARC • Proton charge radius • Muonic Lamb shift (CREMA), MuSEat PSI • Muonium Spectroscopy • Muonium hyperfine at LAMPF &MuSEUM at JPARC • ... TWIST Mu2e Peter Winter, Review of experimental status on precision muon physics and EDMs, NuFact2016, August 25, 2016

5. Multi-discipline Research：  SR (Spin Rotation, Relaxation and Resonance), widely used in material science, especially because of surface muon is 100% polarizated Running: SS@PSI, SRCMMS@ TRIUMF 、EC Muon Facility@ISIS, RIKEN/RAL Muon Facility、MUSE@J-PARC Proposed: China CSNS、KOREA RAON、JAPAN MuSIC、USA BNL/AGS

6. Proton bunch Target 高强度muon束流的三大技术瓶颈 • 高强度质子束流 当前O（MW），建设中ESS：4MW 10MW？： ADS，目标15MW • 高效率次级粒子的俘获 Traditional way: side capture by horn or solenoid • Muon冷却 MICE Pions Capture

7. 提高muon 流强 R.M. Dzhilkibaev, V.M. Lobashev, Sov.J.Nucl.Phys 49, 384 (1989) Solenoidal B field confines soft pions. Collect their muons. Simulated by G4Beamline

8. NF proposed Capture Solenoid: adiabatically convert the transverse momentum into the longitudinal momentum by tapered magnetic field • Demonstrated by MUSIC PT R  B  R2 = Constant • Improved 1000 times compare with PSI’s result

9.  Decay channel - a 0-free neutrino beam line • Neutrino energy: ~ 300 MeV  baseline = 150 km • Although we loose some statistics due to lower cross section, but we gain by being background free from p0

10. MOMENT Concept • MOMENT: A muon-decay medium baseline neutrino beam facility • MOMENT was launched in 2013 as the third phase of neutrino experiments in China • Neutrino experiments at DayaBay continues data-taking • Jiangmen (JUNO, or DYB-II) has started civil construction • A dedicated machine to measure CP phase, if other experiments (such as LBNF, HyperK) will have not completed the task • As a driving force to attract researchers from China to work on neutrino experiments based on accelerators

11. A concept to exploit high-flux medium-energy muon-decay neutrinos • Using a CW proton linac as the proton driver • Based on the China-ADS linac • 15 MW in beam power • Fluidized target in high-field SC solenoid • Granular tungsten or mercury jet • Collection of pions and muons • Neutrino beam from pure + or - decays • Medium energy (250 MeV) for medium-baseline experiment • From long decay channel instead of decay rings for NF and nuSTORM

12. MOMENT • Big project, R&D needed for everything • Proton driver • High intensity target station • Pion & muon beamline • Detector • ……

13. MOMENT target station 基准设计采用喷射水银靶 存在腐蚀和环境污染 替代靶方案的技术研发的重点

14. Heat load • To reduce the head load in the SC coils and cryostat and radiation dose rate to the SC conductors, an internal shield is needed. Simulation was done by FLUKA • Results show that we need at least 80cm carbonic-tungsten shield at target position

15. Granular waterfall target and simulation tools • Granular Dynamics Simulation: • Adopting DEM (Discrete Element Method) • Including calculation of contact forces among particles and solving motion equations. • Accelerating DEM implementation on multi-GPUs • Beam-Target interaction Simulation • Using Monte Carlo particles transport software—Geant4 • Adopting the QGSP_FTFP_INCLXX_HP PhysicsList 与兰州近物所合作研究固体靶方案

16. Discrete element method (DEM) • The Discrete element method (DEM) has been widely accepted as an effective method to solve problems of granular materials in static packing or flows. • Interactions between two particles are given by Hertz-Mindlin model and the normal and tangential forces between two contacted particles are: • Integration of the motion equation is carried out by using Velocity-Verlet scheme:

17. Multi-GPU DEM algorithm Speedup of Tesla M2090 (Fermi) and Tesla K20 (Kepler) Flow chart of multi-GPU DEM algorithm

18. Schematic of a granular waterfall Granular Velocity Distribution Profile of the waterfall with different hopper outlet width 5d 10d 20d

19. Density distributions

20. G4 simulation of pions production with different models Geometry: D1 x L40 cm Tungsten Beam: Proton

21. Geometry: D0.6 x L50m Magnetic field: 15 T in beam-target interaction region, tapers to 4 T when z > 15 m Muons yields: (/proton/GeV) 150 < P (GeV/c) < 450 Collected at z=50 m For different beam energies and target widths

22. Beam energy: 1.5 GeV Muons yields: (/proton) 150 < P (GeV/c) < 450 Collected at z=50 m All momenta • Further work on optimization: • Magnetic field • Beam launch position and direction 150 < P(GeV/c) <450

23. Muon Source • Effective way to produce high intensity muon is hitting target by powerful proton beam, so muon sources are constructed within High intensity proton accelerate facilties. • No muon source and experiment in China by now • p + p → p + n + +

24. Synergy between Neutrino physics & MuSREMuS(Experimental Muon Source) Space reserved by CSNS

25. CSNS: China Spallation Neutron Source First beam on Jul. 2017 EMuS

26. HEPA: High Energy Proton Experimental Area

27. Layout of HEPA Proton beam line

28. Beamline layout of EMuSand operation modes • Beam operation modes (independent): • Neutrino mode • Wide energy spectra • Ref. Pπ=300-500MeV/c • Surface muon mode • Momentum spread: ±5% • Ref. Pμ=29MeV/c • Decay muon mode • Momentum spread: ± 10% • Ref. Pμ =100-200MeV/c

29. 废弃质子束流与muon束流的分离与引出是重大的挑战废弃质子束流与muon束流的分离与引出是重大的挑战

30. Simulation in G4BL Design of proton beam line Y O Z X O Z

31. First CS: 5T, =560mm, L=1000mm TS: =300mm Angle between axis of target and CS: 15deg, for proton extraction Target material: Graphite Capture solenoid: CS Bending section Transfer solenoid:TS 31

32. Coil magnetic field calculation（With Transfer Coil） Target Coils Transfer Coils Yoke Field curve along center axis

33. Vacuum Cryostat Layout of CS and TS—3D Thermal shield Coil support Coil • Large current：about 4000 A • Current lead: • Copper current lead + HTS current lead • Heat leak of cold end: about 1.5 W • Cooling method：Conduction cooling (two-phase helium ，Cryogenic station provide helium）

34. The overall geometry

35. The insulators Thermal insulator Electrical insulator

36. The solenoids Liquid helium Steel wire Insulator Copper stabilizer 热沉积和辐射损伤的精细模拟与 冷却方案验证正在进行中 NbTi wire

37. total surface muons as function of TS aperture for slow and fast tapers (from 5t3 T) total surface muons per second polarization ~ 80-83 % • surface muons • (muons from pions decay at rest) : • μ+ • 27 MeV/c < pμ+< 29.8 MeV/c • pπ+ = 0 MeV/c 2.5% stat. error • total yields > 108 per second • max aperture of 20 cm could be used only for surface muons

38. Compare between EMuS and other muon source

39. 总结 • 高强度质子束流靶站的设计与建造是极为困难的技术挑战 • 通过瀑布型颗粒靶和EMuS项目的预研中国有望在这一领域作出世界领先的贡献 谢谢！