Neutron Mirror Optics and participation of Japan H.M.Shimizu Dept. - PowerPoint PPT Presentation

Neutron Mirror Optics and participation of Japan H.M.Shimizu Dept. Phys., Nagoya University hirohiko.shimizu@nagoya-u.jp

_ ΔB=-2 ΔL=0 free neutron nn oscillation τ nn ,free > 8.6 × 10 7 s (CL = 90%) L = ψ M ψ n 1,2 = 1 ( ) m 1,2 = m n ± δ m n ± n 2 ⎛ ⎞ ψ = n ⎛ ⎞ c 2 δ m E 0 M = ⎜ ⎟ ⎜ ⎟ I ( t ) = I (0)sin 2 c 2 δ m n c 2 δ m ⎝ ⎠ E 0 ⎝ ⎠ t 

_ (4.8±0.2)π (200-250MeV) 0.95 0.05 nn oscillation measurement detector neutron source (conversion target) T N

simple flight path detector neutron source (conversion target) Ω ~10µsr

additional acceptance with focusing optics detector neutron source (conversion target) Ω ~10µsr  Ω ~10 msr

Date(2013/08/02) by(H.M.Shimizu) Title(Neutron Mirror Optics) φ c (Ni)/λ=1.7 mrad/Å N: atom number density b: scattering length m n : neutron mass n 2 2πh bN m U= U : 有効ポテンシャル Neutron Reflection 6 page Conf(Snowmass 2013) At(Minneapolis) v ⊥ (Ni)=7 m/s Fermi potential n

Date(2013/08/02) by(H.M.Shimizu) Title(Neutron Mirror Optics) Conf(Snowmass 2013) At(Minneapolis) page 7 Multilayer Mirror (Monochromatic) φ c (Ni)/λ=1.7 mrad/Å v ⊥ (Ni)=7 m/s non-uniformity and roughness decreases the reflectivity exp(-k ⊥ 2 R rms2 )

Date(2013/08/02) by(H.M.Shimizu) Title(Neutron Mirror Optics) Conf(Snowmass 2013) At(Minneapolis) page 8 Supermirror φ c (Ni)/λ=1.7 mrad/Å v ⊥ (Ni)=7 m/s m =φ c /φ c (Ni)=v c (Ni)/v c non-uniformity and roughness decreases the reflectivity exp(-k ⊥ 2 R rms2 )

m=4-7 Supermirrors Supermirror: commercially available up to m=7 (v ⊥ =50m/s) supermirrors m ≤ 7 http://www.swissneutronics.ch/

wide-band multilayer (quasi-monochromatic) reflectors m ≤ 10 m=10 NiC/Ti wide-band quadruple-stack multilayer 30mm 30mm 85060 bilayers in total = 4 × (10336+10929 bilayers) quadruple-stack of double-sided multilayer mirrors

point source, no gravity, monochromatic detector neutron source (conversion target) v ~4 m  z L~200 m m critical velocity of total reflection of natural Ni We need multilayer mirror to go beyond m~1. z

finite-size source, no gravity, monochromatic detector neutron source (conversion target) v ~4 m  z L~200 m m z

finite-size source, gravity, monochromatic detector neutron source (conversion target) v ~4 m  z L~200 m m z

finite-size source, gravity, polychromatic detector neutron source (conversion target) T v ~4 m  m ( z ) z FOM Distribution moderator intensity [n cm -2 s -2 sr -2 eV -2 MW -1 ] m Source Spectrum 10 14 10 13 10 12 10 11 10 10 10 9 z 0.0001 0.001 0.01 0.1 1 10 100 1000 0.001 neutron energy [eV]

_ nn with horizontal path and ellipsoid supermirror optics neutron source detector (conversion target) v T ( z ) z m ( z ) m FOM Distribution commercially available z

present baseline design 200m detector (conversion target) m z=1.5–40m / m=6 commercially available neutron source z (J-PARC source spectrum)

present baseline design (scaled image) 200m detector (conversion target) m z=1.5–40m / m=6 ~100 times acceptance ~100 times acceptance commercially available neutron source z (J-PARC source spectrum)

further acceptance with super high-m mirrors 200m detector (conversion target) z=1.5–6.5m / m=6–10 m z=6.5–40m / m=6 ~100 times acceptance accessible ~100 times acceptance commercially available neutron source z (J-PARC source spectrum)

visualization of the acceptance of horizontal flight path z>0.1m cos  >0.9 accessible commercially available

visualization of the acceptance of veritical flight path z>0.1m cos  >0.9 accessible ~1000 times acceptance commercially available ~1000 times acceptance

required mirror accuracy displacement Δ x Δ x << detector radius ~ 1m pointing error L Δ  << detector radius ~ 1m ~L Δ  Δ 

required mirror accuracy slope error (along mirror-axis) Δ  (L Δ  ) PV << detector radius ~ 1m ( Δ  ) PV < 1/200 = 5 mrad path length = 200m ( Δ  ) PV < 1/1000 = 1 mrad path length = 1000m

required mirror accuracy limitation to the azimuthal mosaic segmentation   < 1/200 = 5 mrad path length = 200m  < 1/1000 = 1 mrad path length = 1000m

assembly of segmented mirrors azimuthal mosaic segmentation is not appropriate slope error should be controlled below mrad accuracy assembly of replica mirror to be glued on backing plates requires both precise machining and polishing of substrates or multilayer deposited on thick substrates requires relatively less precise machining requires replica fabrication technique

production of super high-m multilayer mirrors Ion Beam Sputter @ Kyoto Univ. Research Reactor Inst. 0.1m 2 /batch 2 batch/day (m=3) 0.2 m 2 /day/fab.machine Ion Beam Sputter @ Japan Atomic Energy Agency (RF Magnetron Sputter for Quicker Mass Production)

self-sustaining substrateless mirror (replica mirror) no substrate (radiation hardness expected)

X-ray telescope fabrication skills (replica multilayers) (Ux-lab. Nagoya Univ.)

X-ray telescope fabrication skills (replica multilayers) (Ux-lab. Nagoya Univ.) 3 production units and 2 R&D units DC Magnetron Sputter Ni-alloy deposition is currently under study.

Hokkaido Univ., Faculty of Engineering Kyoto Univ., Faculty of Science (proton 2.8MeV) Nagoya Univ., Faculty of Science for special sources (medical use and UCN) for engineering and industrial applications for education for R&D, education proton 400MeV (3GeV) proton 7MeV proton 3.5MeV electron 45MeV RIKEN, Innovation Center KEK, J-PARC Summary optics enhances experimental sensitivity to nnbar oscillation optimization, assembly design, alignment strategy, mass production of mirrors, ... adjusting multilayer mirror fabrication skills (in Japan) for mass production currently man-power limited Hokkaido Island Sapporo Sendai Honshu Island Tokyo Nagoya Kyoto Osaka Shikoku Island Fukuoka Kyushu Island