Muon Facility at J-PARC Proton Driver Efficiency WS 29/Feb/2016 Naritoshi Kawamura MUSE (Muon Science Establishment) J-PARC/KEK

J-PARC J-PARC consists of 3 accelerators (Linac, RCS, MR) and 3 experimental facilities (MLF, Hadron, Neutrino).

Muon Facilities in the world ISIS (pulse) J-PARC (pulse) TRIUMF (CW) PSI (CW) Country Japan U.K. Switzerland Facility J-PARC MUSE RAL ISIS PSI proton energy [GeV] 3.0 0.8 0.59 proton intensity [MW] 1.0 (Goal) 0.16 1.3 m+ [/s] (surface) 3108 (U line) 6105 3107 m- [/s] 1107 7104 2107 CW / Pulse Pulse (25Hz) Pulse (50Hz) CW 50 GeV Synchrotron (0.75 MW) 3 GeV Synchrotron (25 Hz, 1MW) Materials and Life Science Experimental Facility （Muon & Neutron) Linac (181MeV  400 MeV) Pulsed muon beam don't need to mind about the pileup. No limit for proton beam intensity, but a highly segmented spectrometer is needed for mSR.

Materials and Life Science Facility RCS (3GeV333mA) MLF Muon target Spallation neutron target Exp. Hall #1 Exp. Hall #2 Exp. Hall #1 Exp. Hall #2 High rad. area is isolated from the experimental halls Beam transport tunnel

Materials and Life Science Facility H S Exp. Hall #1 H 40m Muon production target S Neutron spectrometers U D U Neutron spallation target D 30m Exp. Hall #2

Exp. hall #2 (West wing) U D U line: ultra slow muon The world strongest muon beam is provided to generate ultra slow muon (USM). USM microscopy opens a new research field of muon science. U D U line D line: decay muon Momentum tunable (<120 MeV/c) m+ and m- beam meets a variety of users’ programs. Constraction phase #1 D line

Kicker and septum was installed to provide muon beam both D1 and D2. D-line mSR spectrometer in D1 Kicker magnet to D1 to D2 D1 D1 D2 Kicker and septum was installed to provide muon beam both D1 and D2. D2 Kicker Off =double pulse Kicker On =single pulse World record!

20 times higher than D-line U-line SC curved solenoid NC large aperture capture solenoid 3GeV proton SC focusing solenoid w/ Wien filters SC curved solenoid 6.4107/s @ 212 kW was observed in 2012. 20 times higher than D-line All beamline magnets are axial focusing Simultaneous extraction of m+ and m- beam The world strongest pulsed muon: 3108 m+/s, 1107 m-/s

Generation of ultra slow muons 106 USM/s by 100 mJ/pulse 122-nm light

Exp. hall #1 (East wing) H S S line: surface muon Surface muons are provided to many experimental areas simultaneously. H S Extension of H-line for g-2/EDM exp. H line: fundamental physics Higher intensity tunable (<120MeV/c) m+ and m- beams are provided. H line S line

S-line S1 S2 S3 S4 Double-pulsed Structure 40ms 25Hz Port 2 S3 S1 S4 Kicker S2 Kicker S line is dedicated to mSR studies, and provides muon beam to 4 experimental areas simultaneously. At present, S1 area is completed.

H-line H-line: A beam line for fundamental physics studies to search new physics beyond the SM.

Optics for H line +B -B 3GeV proton Capture solenoid (HS1) 30 MeV/c mono-chromatic beam calc. performed by a MC-code (G4beamline) Large aperture short solenoids do not allow us to use transfer matrix calculation which use near axis assumption. Bending magnet (HB1) ↑beam transport tunnel Gate valve (HGV1) Kicker magnets and/or wien filers are installable +B Transport solenoid (HS2 and HS3) -B Septum or bending magnet (HB2) Experimental area #1 Conceptual design was proposed by J. Doornbos, TRIUMF. Experimental area #2 and #3

High rad. area around the target 4 secondary beamlines can be extracted. D line: under common use, open for users U line: under commissioning S line: under commissioning H line: only frontend magnets exist H S D 3GeV proton U H line Snapshot of maintenance floor 2.4-m high from the beamline D line Muon target P S line U line M2 tunnel (beam transport tunnel)

Design concept of high rad. magnet plug radiation shield radiation-hard coil level adjust spacer seamless piping at beam line level halo monitors Utility connection at FL+4m level (maintenance floor) phthalic paint or Ni-plate

Muon production target 1/3 ISIS neutron target Beam envelope QN2 f70mm Beam loss QN3 QN4 The 2-cm graphite target causes a 5% (50 kW) beam loss mainly at target and scrapers. Another 5% loss is reserved for the second muon target to be installed in M1. The effect of radiation and the related things was well-studied for designing M2 devices. >150W QN1 Target & Scrapers Neutron target 5% loss Transport efficiency

Fixed target Isotropic Graphite IG-430U (Toyo Tanso) Diameter: 70mm Thickness: 20mm P-Beam diameter; 16 mm (2s) 4kW heat @ 1MW proton beam 70 mm 20 mm The 1st fixed target was used for 5 years since the 1st beam without replacement. Duration of acc. operation: 15000 hours Proton beam stop due to muon target: 3 hours (Water flow Low) ⇒ stable Stainless steel pipe (Water) Copper frame Hot Iso-static Press method

Life time of muon target The limit of target use will be 1 DPA. Target deformation is 1%. DPA is expected to reach at 1 DPA after ½ ~ 1 year irradiation under 1MW. Target replacement work consumes much money, time and human resources. Development of the rotating target Beam profile: uniform in p-space DPA Heat generation Test of the radiation damage on graphite at PSI.

Rotating target Referring to PSI, rotating target is adopted to distribute the radiation damage in graphite to a wider area. Proton beam Current fixed target Rotating target 330 mm The lifetime of graphite becomes long enough. The lifetime of bearing determines the total one. Solid lubricant in bearing: Silver coating with MoS2 is selected in PSI's target. Tungsten disulfide at MUSE. Expected lifetime: 10 years Proton beam

Efficient muon facility What is efficient muon beamline? Large number of muons per proton. Efficiency = muon production yield  capture and transmission efficiency 2  1015 proton/s (=1 MW)  5% is used. 107-108 muons/s in each 4 beam lines 10-6 m/p may be a conventional value. New target material (SiC…) High capture and transmission efficiency by placing the solenoid just beside the target Geometrical constraint Þ new target station

Summary In MUSE, 4 beamlines are extracted, and they can answer a variety of users’ requests. Typical value of 10-6 m/p is achieved. To improve this, new target station is needed. However, from a different standpoint point Efficient facility: number of experiments to be conducted in a unit time is important. Furthermore, requested beam conditions by users have a variety, i.e. m+, m-, momentum... For the next generation facility, we have to consider what is efficient facility.