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

nn oscillation _

free neutron

L =ψ Mψ

ψ = n n ⎛ ⎝ ⎜ ⎞ ⎠ ⎟

M = E0 c 2δm c 2δm E0 ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ n1,2 = 1 2 n ± n

( )

m1,2 = mn ± δm

I(t) = I(0)sin2 c 2δm  t

τ nn ,free > 8.6 ×107s (CL = 90%)

neutron source detector (conversion target)

(4.8±0.2)π (200-250MeV)

0.95 0.05

N T nn oscillation measurement _

neutron source detector (conversion target)

simple flight path

Ω~10µsr

neutron source detector (conversion target)

additional acceptance with focusing optics 

Ω~10 msr Ω~10µsr

Date(2013/08/02) by(H.M.Shimizu) Title(Neutron Mirror Optics) Conf(Snowmass 2013) At(Minneapolis) page

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Neutron Reflection

n

U : 有効ポテンシャル

U= m bN 2πh

2

n

mn: neutron mass b: scattering length N: atom number density

Fermi potential φc(Ni)/λ=1.7 mrad/Å v⊥(Ni)=7 m/s

Date(2013/08/02) by(H.M.Shimizu) Title(Neutron Mirror Optics) Conf(Snowmass 2013) At(Minneapolis) page

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Multilayer Mirror (Monochromatic)

φc(Ni)/λ=1.7 mrad/Å v⊥(Ni)=7 m/s

exp(-k⊥2Rrms2) non-uniformity and roughness decreases the reflectivity

Date(2013/08/02) by(H.M.Shimizu) Title(Neutron Mirror Optics) Conf(Snowmass 2013) At(Minneapolis) page

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Supermirror

φc(Ni)/λ=1.7 mrad/Å v⊥(Ni)=7 m/s m =φc/φc(Ni)=vc(Ni)/vc

exp(-k⊥2Rrms2) non-uniformity and roughness decreases the reflectivity

m=4-7 Supermirrors

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

supermirrors m≤7

30mm 30mm

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

wide-band multilayer (quasi-monochromatic) reflectors m≤10

 z ~4m L~200m point source, no gravity, monochromatic

critical velocity of total reflection of natural Ni We need multilayer mirror to go beyond m~1.

v z m

neutron source detector (conversion target)

 v z ~4m L~200m finite-size source, no gravity, monochromatic z m

neutron source detector (conversion target)

 v z ~4m L~200m finite-size source, gravity, monochromatic z m

neutron source detector (conversion target)

FOM Distribution

 v z ~4m finite-size source, gravity, polychromatic

0.001 0.01 0.1 1 10 100 1000 0.001 0.0001 109 1010 1011 1012 1013 1014 moderator intensity [n cm-2 s-2 sr-2 eV-2 MW-1 ] neutron energy [eV]

neutron source detector (conversion target) Source Spectrum

T m(z) z m

v z m(z)

neutron source detector (conversion target)

T(z)

FOM Distribution

z m nn with horizontal path and ellipsoid supermirror optics _

commercially available

detector (conversion target) neutron source 200m z=1.5–40m / m=6

z m

(J-PARC source spectrum)

present baseline design

commercially available

detector (conversion target) neutron source 200m z=1.5–40m / m=6

z m

(J-PARC source spectrum)

present baseline design (scaled image)

commercially available

~100 times acceptance ~100 times acceptance

detector (conversion target) neutron source 200m z=6.5–40m / m=6

z m

(J-PARC source spectrum)

z=1.5–6.5m / m=6–10

further acceptance with super high-m mirrors

commercially available accessible

~100 times acceptance ~100 times acceptance

visualization of the acceptance of horizontal flight path

accessible commercially available

z>0.1m cos>0.9

visualization of the acceptance of veritical flight path

accessible commercially available

z>0.1m cos>0.9

~1000 times acceptance ~1000 times acceptance

required mirror accuracy

displacement Δx pointing error Δ ~LΔ LΔ << detector radius ~ 1m Δx << detector radius ~ 1m

required mirror accuracy

slope error (along mirror-axis) (LΔ)PV << detector radius ~ 1m Δ (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 multilayer deposited on thick substrates replica mirror to be glued on backing plates

• r

assembly of segmented mirrors

azimuthal mosaic segmentation is not appropriate

requires both precise machining and polishing of substrates requires relatively less precise machining requires replica fabrication technique

slope error should be controlled below mrad accuracy

0.1m2/batch 2 batch/day (m=3) 0.2 m2/day/fab.machine Ion Beam Sputter @ Kyoto Univ. Research Reactor Inst.

production of super high-m multilayer mirrors

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.)

3 production units and 2 R&D units DC Magnetron Sputter Ni-alloy deposition is currently under study.

(Ux-lab. Nagoya Univ.)

X-ray telescope fabrication skills (replica multilayers)

Hokkaido Univ., Faculty of Engineering Kyoto Univ., Faculty of Science RIKEN, Innovation Center KEK, J-PARC

Tokyo Nagoya Osaka Sapporo Sendai Fukuoka

Honshu Island Hokkaido Island Shikoku Island Kyushu Island

Kyoto

electron 45MeV proton 3.5MeV proton 7MeV proton 400MeV (3GeV)

for R&D, education for education for engineering and industrial applications for special sources (medical use and UCN) Nagoya Univ., Faculty of Science

(proton 2.8MeV)

Summary

• ptics enhances experimental sensitivity to nnbar oscillation

adjusting multilayer mirror fabrication skills (in Japan) for mass production

currently man-power limited

• ptimization, assembly design, alignment strategy,

mass production of mirrors, ...