Beam at the Paul Scherrer Institut

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1 Development of a Nextgeneration High-intensity Muon Beam at the Paul Scherrer Institut FELIX ANTON BERG ON BEHALF OF THE HIMB GROUP MUON PRODUCTION AND BEAM INTERCEPTORS ISTITUTO NAZIONALE DI FISICA NUCLEARE

2 Outline 1 Overview on experimental demands on muon beam properties Conventional muon beam generation The High-intensity Muon Beam project at the Paul Scherrer institut Initial Design Modification of target station High acceptance beam transport system

Muons versatile tools in 2 different fields High energy muon collider Neutrino factories MuSR/ Solid State Physics / Surface Analysis Low energy particle

3 Muons versatile tools in 2 different fields High energy muon collider Neutrino factories MuSR/ Solid State Physics / Surface Analysis Low energy particle physics: Intensity / Precision frontier Tomography Discovery of a big void in Khufu s Pyramid by observation of cosmic-ray muons DOI: /nature24647

4 Experimental demands 3 - Muon Collider studies µ + & µ Especially low emittance High muon flux High laboratory frame lifetime Pulsed structure Design of a 6 TeV Muon Collider DOI: / /11/09/P09003

simulation of the PSI LEM beam line: energy loss and muonium formation in thin foils

5 Experimental demands 4 - Solid state Physiscs / µsr kev - MeV µ + Low emittance Low-High muon flux High Polarization with tunable orientation Pulsed and CW Geant4 simulation of the PSI LEM beam line: energy loss and muonium formation in thin foils and the impact of unmoderated muons on the µsr Spectrometer DOI: / /10/10/P10025

6 Experimental demands 5 - Muon Lifetime Intermediate surface µ + rates Pulsed structure (µs) Detailed report of the MuLan measurement of the positive muon lifetime and determination of the Fermi constant DOI: /PhysRevD

7 Experimental demands 6 - Mu2e conversion µ < 50 MeV/c High muon flux Pulsed structure Backgroud reduction Mu2e Technical Design Report arxiv:

8 Experimental demands 7 - E989 g-2 Magic momentum 3.09 GeV/c High polarization The Muon g 2 experiment at Fermilab DOI: /j.nuclphysbps

9 Experimental demands 8 - Muonic atoms kev MeV µ High muon flux The size of the proton DOI: /nature09250

10 Experimental demands 9 - CLFV MEG II Surface muon 28 MeV/c µ + High muon flux CW beam γ New particle? μ + e + Goal: BR(μ+ e+ γ) < 6 90% CL The design of the MEG II experiment arxiv:

Sensitivity O 10 15 10 16 Research Proposal for

11 Experimental demands 10 - CLFV Mu3e Surface muon 28 MeV/c µ + High muon flux CW beam Final Sensitivity O Research Proposal for an Experiment to Search for the Decay arxiv:

12 Future intensity demands 11 J-PARC H-Line O 10 8 Mu3e II O 10 9 COMET O Mu2e O MuCool Muonium LE-MuSR Muon Collider

13 Ideal Muon Beam 12 Variety of experiments demand for variety of beam conditions Pulsed vs. CW Background / pileup reduction in coincidence measurements Momentum depends on application stopped beams require low momenta ΔR tot a δp p p 3.5 A High Stopping Density µ+ Beam DOI: / X(76) Common demands : High rate (with option of reduction) Small phase space volume

14 Muon beam facilities 13 - Overview Laboratory/Beamline Energy/ Power Present Muon µ + /µ - Rates [Hz] Future estimated µ + /µ - Rate [Hz] PSI (CH) 590 MeV, 1.3 MW DC LEM μ + πe μ + HiMB O(10 10 ) μ + / O(10 8 ) μ - JPARC (JP) 3 GeV, 1MW Pulsed Reached 400kW µ 1MW) MUSE / µ 1MW COMET 8 GeV, 56kW Pulsed µ /2020 FNAL (USA) Mu2e 8GeV, 25kW Pulsed µ /2020 RAON/RISP (KO) 600 MeV, 400kW DC) μ + CSNS (CN) 1.6 GeV, 100kW Pulsed μ + TRIMUF (CA) 500 MeV, 75kW, DC M20/M9B / RAL ISIS (UK) 800 MeV, 160kW, Pulsed / RIKEN RAL RCNP Osaka Univ. (JP) 400 MeV, 400W DC MUSIC 10 6 / /

15 Muon beam generation 14 Proton nucleon interaction : Mainly from pion decays Direct production : e + + e µ + + µ

16 Muon beam generation 14 Proton nucleon interaction : Mainly from pion decays Direct production : e + + e µ + + µ

17 Muon beam generation 14 Proton nucleon interaction : Mainly from pion decays Direct production : e + + e µ + + µ Studies of a Scheme for Low Emittance Muon Beam Production From Positrons on Target DOI: /JACoW-IPAC2017-WEOBA3

18 Pion production (p + + nucl.) 15 Positive Pions Negative & neutral Pions 290 MeV 600 MeV Double Pion production

19 Muon production 16 μ ± π ± Surface Muons Decay Muons μ + π + π ± μ ± Cloud Muons Proton Beam

target volume completely π + decay in region around target cloud

20 Pion production (p + + nucl.) 17 Depending on Tπ either stopped inside the target or leave the target volume completely π + decay in region around target cloud muons π + captured in secondary beamline decay muons π + stop inside the target and decay surface muons Tπ Pμ

21 Pion production (Geant4) 18 Geant4 pion production cross sections not optimized for low energies HiMB-Modell : Parametrization of cross sections to existing data Accuracy O 10% Θ = 22.5 E = 585 MeV Θ = 90 E = 585 MeV Target Studies for Surface Muon Production DOI: /PhysRevAccelBeams

22 HiMB Model Validation 19 MuE4 surface muon beamline PiE5 surface muon beamline Multipole Channel Separator Extraction dipole Quadrupole Triplets

Muons PRODUCTION, CHARACTERIZATION, AND MONITORING OF

23 Particle production from 20 standard graphite target Beam composition seen by the PiE5 channel acceptance Surface Muons PRODUCTION, CHARACTERIZATION, AND MONITORING OF SURFACE MUON BEAMS FOR CHARGED LEPTON FLAVOR VIOLATION EXPERIMENTS

24 PSI - the world s highest 21 intensity surface µ + beams Proton beam : 590 MeV 50 MHz / 20 ns CW surface muons 2.4 ma or 1.4 MW 2 Production Targets SINQ neutron source µ + /s protons µ + /s

25 The Muon production 22 target E Rotating target (1 Hz) Polycrystalline graphite 40 mm length in beam direction 50 kw proton beam energy deposit 1700 K radiation cooled 30 % loss of protons Delivers world most intense surface muon beams protons

26 The High-intensity Muon 23 Beam (HiMB) project Next-generation experiments demand for several orders of magnitude higher surface µ + flux Two-pronged approach : High-yield surface muon production target High capture efficiency & large-phasespace acceptance transport channel

HiMB @ SINQ 24 Residual proton beam (~1 MW) dumped on SINQ Replace existing quadrupoles with solenoids: Preserve proton beam

27 SINQ 24 Residual proton beam (~1 MW) dumped on SINQ Replace existing quadrupoles with solenoids: Preserve proton beam footprint Capture backward travelling surface muons Extract muons in Dipole fringe field surface µ + ma proton beam current

HiMB @ SINQ 25 Backward travelling pions stopped in beam

phasespace (divergence & source extent) Capture solenoid

moderator tank High radiation level close to target Several

28 SINQ 25 Backward travelling pions stopped in beam window Capturing turned out to be difficult : Large phasespace (divergence & source extent) Capture solenoid aperture needed to be increased, but constrained by moderator tank High radiation level close to target Several iterations with different capturing elements Sought alternative solution EH

conventional production target and high-acceptance

29 Reconsider production 26 target E Simulation with new model showed O surface µ + /s HiMB with conventional production target and high-acceptance solenoidal channel upstream SINQ p π + μ + proton beam π + μ +

30 Change of target material 27 Optimize material choice to increase surface muon rate Relative μ + Yield π + Stop Density μ + Range Relative Target Length n σ π + de dx π + de 1 dx μ + ρ C Z/A C ρ target Z/A target Light elements favoured Material must withstand harsh environment Choice of B 4 C or Be 2 C shows 10 / 14 % gain while preserving density for proton beam

31 Production target 28 geometry Thinning down target width effectively increases the overlap of proton beam and surface muon production layer Maintain material budget seen by proton beam Proton beam centring vs. rates in opposing beamlines Measured for boxlike standard target Transverse surface muon production depth Simulated for boxlike standard target 100 µm

32 Production target 29 geometry Comparison studies of different target geometries Enhancements normalized to standard target Standard Grooved Trapezidal Forked Rotated Slab x 1.0 x 1.1 x 1.4 x 1.5

33 Rotated slab target 30 Thin down target width without comprimising proton beam footprint Muon yield depends on rotation angle

Measurement in forward / backward / sideways direction

34 Rotated slab target 31 - Prototype test Upgrade existing graphite production target E 40 mm 8 slanting angle Measurement in forward / backward / sideways direction Production and implementation feasible Thermal simulation ongoing

Rotated slab target 32 - Prototype test Expect 30-50 %

35 Rotated slab target 32 - Prototype test Expect % enhancement Measurement foreseen in three directions in 2019

36 HiMB PSI 33 Take out existing thin target M

HiMB Project @ PSI 34 New target station

37 HiMB PSI 34 New target station downstream present TgM location ~90 extraction to existing experimental areas Large phase space acceptance solenoidal channel

38 HiMB PSI 35 - New target design Rotated slab target under 5 20 mm effective length for proton beam 150 mm long ~90 extraction (~ +50 %) Probably alternate material (~ +14 %)

HiMB rotated slab target 36 - transverse phase space Phase space @ generation

39 HiMB rotated slab target 36 - transverse phase space Phase generation (10 mm protons) : ε x = π mm mrad ε y = π mm mrad x = 80 mrad / 4.6

40 Baseline Design for the 37 Capture Solenoid Large aperture capture solenoid Close to target Radiation hardness Symmetric layout

41 The HiMB beam line layout - First G4Beamline simulation 38 Large aperture solenoids and dipoles Large number of muons can be transported Almost parallel beam, no focus, no beam diagnostics, no separator

The HiMB beam line layout 39 - Comparison 1.2 10 11 7.

42 The HiMB beam line layout 39 - Comparison μ + /s μ + /s MuE4 Hybrid Target E 40 mm μ + /s μ + /s HiMB Initial Design Solenoid 5 20 mm slab Capture efficiency Transmission Overall efficiency MuE4 ~ 6 % ~ 7% ~ 0.4 % HiMB ~ 26 % ~ 40 % ~10 %

43 ToDo 40 Optimization of capturing Optimize final focussing Iterative Beam line optimization and implementation of beam monitoring and particle separator locations with max. transmission Minimize shielding modifications Particle separation Investigate impact on proton beam properties Study extraction angle Determine new target location Disposal of highly radioactive waste Study Mu3e setup phase space acceptance and optimize final focus properties Find solution with current users of Target M

44 HiMB - Outlook 41 HiMB aims at surface muon beam intensities O μ + /s Initial simulations show that such rates are feasible μ + - Beam optics and investigations on proton beam modifications underway HiMB opens the door to interesting physics opportunities for particle physics and materials science using high-intensity and high-brightness muon beams (Mu3e Phase II, Low energy MuSR, Muonium spectroscopy, )

45 HiMB Project at PSI continues in pursuit of the Intensity Frontier! 42 Grazie mille per la vostra attenzione!

46 Backup slides 43

47 Gamma Factory 47 Partially Stripped Ion (PSI) beams Resonant absorption of the laser photons by the PSI beam, followed by a spontaneous atomictransition emissions of secondary photons The initial laser-photon frequency is boosted by a factor of up to 4 γ 2 Direct production of muons (10 12 muons/s) or via positrons (10 12 positrons/s) The Gamma Factory proposal for CERN arxiv.org/abs/

48 Pion stopping distribution 44 for different target types

49 Comparison of transverse 45 emittance e + + e µ + + µ (1 cm 44 GeV e + ) PSI πe5 area (4 cm 590 MeV p + ) PSI HiMB (2cm sin MeV p + ) ε x (mm mrad) βγε x (mm mrad) P (MeV/c)

50 Simulation tools for HiMB 46 TRANSPORT : matrix based phase space propagation TURTLE : matrix based single particle tracking G4Beamline : For final optics (highly non-linear beam line) Beamline optimization with G4BLOPTIMA

51 G4BLOPTIMA 47 G4Beamline Optimization Cross-platform Pythonbased optimization tool for G4Beamline 51

52 G4BLOPTIMA 48 GUI & Online monitoring 52

53 G4BLOPTIMA 49 Output PDF for all optimization parameter saved after each iteration History File with relevant quantities for later analysis

54 G4BL Beammaker 50 Python based beam analysis, manipulation of TURTLE / G4Beamline output and arbitrary phase space generation

Future Muon Beams for 51 Colliders MICE (MUON IONIZATION COOLING EXPERIMENT) : 6D Phase space cooling of Hot muon beams from conventional pion decay beams Intrinsically cold muons from generation

55 Future Muon Beams for 51 Colliders MICE (MUON IONIZATION COOLING EXPERIMENT) : 6D Phase space cooling of Hot muon beams from conventional pion decay beams Intrinsically cold muons from generation Lattice design and expected performance of the Muon Ionization Cooling Experiment demonstration of ionization cooling DOI: /PhysRevAccelBeams Novel proposal for a low emittance muon beam using positron beam on target DOI: /j.nima

Change of target material 52 Optimize material choice to increase surface muon rate Relative μ + Yield π + Stop Density μ + Range Relative Target Length n σ π + de dx π + de 1 dx μ +

56 Change of target material 52 Optimize material choice to increase surface muon rate Relative μ + Yield π + Stop Density μ + Range Relative Target Length n σ π + de dx π + de 1 dx μ + ρ C Z/A C ρ target Z/A target Z 1 3 Z 1 Z 1 Z = 1 Z 2/3 Material must withstand harsh environment Choice of B 4 C or Be 2 C shows 10 / 14 % gain while preserving density for proton beam

57 Surface muon momentum 57

58 Survival probability 52

MuSIC- RCNP at Osaka University

Commissioning of new DC muon beam line, MuSIC- RCNP at Osaka University Dai Tomono Research Center for Nuclear Physics (RCNP), Osaka University On behalf of the MuSIC- RCNP collaboration tomono@rcnp.osaka-