Development of mini-focusing small-angle neutron instruments - - PowerPoint PPT Presentation

Development of mini-focusing small-angle neutron instruments (mfSANS)

Michihiro Furusaka

Graduate School of Engineering, Hokkaido University

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My locations

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Hokkaido University

• Electron linac based

neutron source

Tokai

• J-PARC

spallation neutron source

• JRR-3 Reactor

Tsukuba

• KEK,
• accelerator complex
• KENS has been shutdown

Collaborators

• M. Furusaka, F. Fumiyuki, A. Homma, T. Satoh , Y. Sasaki, Y. Okusawa, N.

Ishikawa

• Y. Kiyanagi, T. Kamiyama, K. Kamada
• Grad. Sch. Eng., Hokkaido Univ.
• M. Sugiyama, T. Satoh, M. Hino
• KUR, Kyoto Univ.
• P. Mikula
• NPI, Czech
• H. Yoshizawa, M. Shibayama, H. Endoh, Y. Kawamura, T. Asami
• ISSP Univ. Tokyo
• H. Takahashi, K. Fujita
• Grad. Sch. Eng., Univ. Tokyo
• K. Hirota, K. Ikeda, Y. Otake
• RIKEN
• S. Ikeda, S. Naito, H. Shimizu, T. Otomo, T. Torikai, T. Ino, S. Satoh, J. Suzuki
• KENS, KEK
• K. Wada, S. Aoki
• National Center of Neuro Psychiatric
• H. Mochiduki, T. Yasuda
• Jyuntendo Univ.
• S. Fujiwara
• JAEA

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I n s t r u m e n t s c i e n t i s t s N e u t r

• n

s c a t t e r i n g M e d i c a l d

• c

t

• r

s D e v i c e d e v e l

• p

m e n t

Most of us know that neutron is a very powerful probe!

4

Large neutron facilities

• Big facilities like
• ILL, Oak Ridge, Munich, NIST, JRR-3, KAERI, ANSTO, ...
• ISIS, Luhan center, PSI, SNS, J-PARC
• Bright future?

5

01

7 reasons not to use neutron

7 reasons not to use neutron

• I have to submit a proposal to get beamtime...
• well, I don't know how to do it...
• Where can I find information...
• I heard it is difficult to obtain beamtime...
• I have to wait for almost 1 year...
• I don't know what kind of information we can get with

neutron...

• I don't know how to analyze data...
• I looked for a book, but they are too difficult to

understand...

• I know how to use laboratory X-ray instrument, but...

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Current situation

This is what we have now...

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Large neutron facilities

• Machine time already oversubscribed
• Not very suitable to train scientists/students
• Difficult to install your own instrument
• limited beamlines
• everyday instruments are out of scope
• Instruments for developing countries (cost, traveling)
• Difficult to test new ideas.

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Huge and expensive SANS instruments

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SANS-U@JRR-3

32m

NIST 30m SANS

• Only 1 instrument

at a guide-end.

• Need a cold

neutron source.

We have difficulties:

• Neutron facilities are expensive and

not always available in developing countries

• Neutron instruments are also expensive
• Maintaining the instruments requires manpower and

budget

• Training young scientists/students are difficult
• We desperately need next generation scientist!

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In case of X-ray

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X-ray

• Laboratory sources are available anywhere
• Proper training methods established
• Variety of books available
• You can ask experienced people around.
• If laboratory source is not appropriate,

you can always use synchrotron radiation

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Solution?

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Solution: Many compact SANS instruments

incident beam Compact SANS units

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But How?

• RFQ accelerator + DTL ≈3-11MeV
• Li or Be target
• Combined with:
• many mfSANS modules,
• mini-reflectometers,
• mini-powder machines??

By the way, how about accelerator-driven laboratory-size neutron-source

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U b i q u i t

• u

s i n s t r u m e n t

How to make compact instruments: Focusing is the key.

Focusing makes instrument compact! compact ≈ low cost

• Cf. Focusing gives us no-gain in intensity!

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Ellipsoidal mirror focusing SANS

• Ellipsoidal mirror
• 1~10 mmø aperture

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F1 F2 Detector Slit Mirror Shielding plate

1mm 10mm

Kamada et al. (Hokkaido Univ.)

Sample Ellipsoidal Mirror

Focusing SANS instrument is Compact!

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■ Conventional point collimation ■ Focusing

ℓ D L d

■ Same resolution/intensity

• Angular resolution

≈D/L≈ d/ℓ

• Intensity:

Lens/mirror Sample Sample Detector Detector Virtual Source

I ∝φ ⋅dΩi ⋅ dΣ

dΩ ⋅Vsample ⋅η⋅dΩ f

≈ c

• m

p a c t

Focusing vs. Pinhole

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x qx qx

Focusing in real space Small pinhole

qmax

• qmax

Δqx

x qx x qx qmax

• qmax

Δqx

Focusing in k space

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2θ'=2θ 2θ α'= α α Detector "plane" Sample Focusing beam

ki kf

2θ'

q' ki kf Real space Reciprocal space

Mini-Focusing Small-Angle Neutron Scattering Instrument (mfSANS) @Hokkaido University

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Time-of-flight focusing SANS

45MeV Electron Linac @Hokkaido University

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Electron Linac Pulsed cold neutron source:

• Best for developing

neutron sources & devices

• Flux≈1/10,000 JRR-3@JAEA

Solid methane moderator

Time Averaged Intensity compared

24 1.E+07 1.E+08 1.E+09 1.E+10 1.E+11 1.E+12 1.E+13 1.E+14 1.E+15 1.E+16 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02

E (eV) Time Averaged neutron intensity (n/cm2/s/str/eV)

Port03 coupled JSNS Coupled (cylindrical), simple model JSNS Decoupled H2 (Ed=1eV) JSNS Decoupled H2 (Gd Poison) SNS (2MW) ISIS CH4 (160kW) KENS-CH4 KENS-CH4 KENS-H2O KENS-H2O ILL-Cold ILL-thermal

ILL JSNS KENS CH4 JRR-3 HU CH4 KENS H2O HU H2O Factor 2-3 uncertainties

Ellipsoidal Mirror

• Mirror length：900 mm
• Major axis : 2 m
• Minor axis ：20 mm
• Borated glass
• Ni coating

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Made by JNOP

mfSANS at Hokkaido Univ.

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Detector Ellipsoidal mirror Beam port Data acquisition system Sample

Fe 20nm Powder; Preliminary data

• 1mmφ aperture
• cross sectional plot

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10 5 5 104 0.001 0.01 0.1 1

FWHM~1mm

1.5~2mm in other direction

Bovine thighbone, cross section SANS preliminary analysis

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!"#$%#&' !"#$%#(' !"#$%#)' !"#$%#*' !"#$%#+' !"#$%#!' !"#$%#&! !"#$%#'! !"#$%#!!

!"#$"%&#'! ()*+,-!

./0&/12*3$4/5$)()* ()*-!

I(q)∝q-3 I(q)∝q-2 I(q)∝q-1 mfSANS@H.U. 5mmφ mfSANS@JRR-3 2mmφ、10mmφ

Okusawa et al

Qmin=0.002 ~ 0.003 A-1

mfSANS@JRR-3/JAEA

Monochromatic neutron focusing SANS

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Prototype focusing SANS@JRR-3

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～ 2 . 5 m

Detector Sample Focusing Mirror Ellipsoidal mirror 2.5 Qc supermirror

L：900mm W：≈20mm

mfSANS@JRR-3

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Aperture

Ellipsoidal mirror

• Mirror Parameters
• 2.5 m between focal points
• short radius 20 mm
• ≈1/6 of an arc (66 deg)
• 2.5 Qc supermirror coating

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Direct beam profile

• 2 mmφ aperture
• FWHM ≈2.5 mm

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Ni powder 20nm

• Qmin = 5×10-3 A-1 using 2mmø aperture.

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0.100 0.050 0.020 0.010 0.005 0.002 0.001 0.01 0.1 1 10 100

Direct beam I(q)~q-4 q/A-1 I(q) High-angle detector bank P r e l i m i n a r y d a t a

• 48 Linear position sensitive

detectors at higher angle

• 1/2 inch dia, 600 mm in length
• GE made

wider-angle scattering

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10 Water 散乱関数

1.00 0.50 0.20 0.10 0.05 0.02 Q1 106 105 104 0.001 0.01 IQ

I(q) Water q/A-1 0.05 0.6 P r e l i m i n a r y d a t a

Micro-phase separated block copolymer

36 0.00 0.02 0.04 0.06 0.08 1 104 5 104 0.100 0.050 0.010 0.005 0.001

mfSANS 2mmφ、2hrs SANS-U 4m

Prism λ>λ0 λ=λ0 λ<λ0

S i c r y s t a l R ≈ . 7 m

Strongly bent perfect crystals

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5.8A Crystal Bender

C u r r e n t l y , r e fl e c t i v i t y i s v e r y l

• w

. M a y b e t h e s t a c k i n g

• f

c r y s t a l s i s t h e p r

• b

l e m .

• Bent perfect Si crystal

in fully asymmetric geometry

• Si (111)
• Extremely small bent radius R ≈ 2m
• usually R≈10~20m
• 0.5 t × 120 × 20 mm slabs ×30,
• long wavelength 5.8A
• usually λ≈1~2A

Currently, poor monochromator performance

• Improved monochromator being tested

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neutron mirrors Bent Perfect Si monochromator neutrons

deflector 1Qc~4Qc Beam divergence ±10mrad → +80mrad Pin hole Large Δλ/λ

High Resolution Detectors

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Resistive wire type PMT +ZnS scintillator

• Li (n, α); ZnS(Ag) scintillation
• 3inch, 5inch PMT
• R2486-04
• Good resolution
• <1mm
• convenient system for optical device test.

[ m [ mm [ m [ mm

Hirota, Satoh et al. (RIKEN, KEK, NOP)

Micro-strip Gas counters under development

• He(n, p) reaction
• High reliability
• "Grid lines" between anode

and cathode

• High resolution
• 0.6mm FWHM
• High counting rate:
• 0.2-1MHz in future.
• 10x - 100x

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0.6mm FWHM

• K. Fujita,Takahashi et al. (Tokyo Univ.)

• MSTube：640 mm effective length
• 1.6～3.2 mm position resolution
• 0.2MHz; high count rate

Ultra-long Micro-Strip Gas Counter

640mm

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Local signal Global signal

• K. Fujita, H. Takahashi et al., Univ. Tokyo

Remaining problem: SANS instruments at small-reactors?

1̃5MW?

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• 1 MW TRIGA reactor
• No cold source
• Radial beam port

SANS

Reaktor TRIGA PUSPATI (RTP), Malaysia

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By Megat Harun modified by M.F.

Beamport entrance Coarse Collimator entrance Reactor wall

3 layers of misaligned HOPGs

Shielding wall

d=1.2 cm @sample

83.62o

Be-filter Detector 400 cm

d=15.2 cm d=11 cm d=11 cm

400 cm

d=10 cm

Source = 1.5 x 1012 n/cm2/s

• Q ≈ 0.013 Å-1 - 0.1 Å-1
• Intensity estimation at sample:

1.3x 103 n/cm2/s

• Conversing collimator/loosely focused

beam?

Existing MySANS RTP (Malaysia SANS)

By Megat Harun modified by M.F.

• Possibilities:
• 1. Converging Multi-Holes Collimator, bigger sample
• (≥7 Holes/≥7 Masks)
• Max 1.0 cm; Min 0.6 cm; α = 0.286°
• 2. Loosely focused beam by focusing mirrors.

Detector Sample 40 cm 320cm 480 cm Monochromator shielding Wall 800 cm

Proposal of new SANS Configuration

By Megat Harun modified by M.F.

Inelastic scattering correction

Not so much progress; manpower problem.

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• simulate I(Q) with S(Q,ω) of ideal gas at SWAN

Inelastic Scattering Correction

IS

raw(Q) − IPrOH raw (Q) − IPrOH raw (∞)

( ) βH

[ ]

1 TS (σS )

4 5 6 7

1

2 3 4 5 6 7

10

2

I(Q) /a.u.

0.01

2 3 4 5 6

0.1

2 3 4 5 6

1

2 3

Q / Å

• 1

before correction after correction

βH= ρS(H )/ρPrOH(H )

5 6 7 8 9

1

2 3 4 5 6 7 8 9

10

2

I(Qe) (a.u.)

5 6 7 8

0.1

2 3 4 5 6 7 8

1

2 3 4

Qe / Å -1

• Exp. (PrOH, run# I5_03323)
• Calc. (ideal gas, Meff=2)
• Calc. (ideal gas, Meff=200)

M=2 M=200

incoherent inelastic scattering by H

,

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• M. Misawa, Niigata Univ.; T. Otomo, KENS, KEK

Summary

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Summary

• Large facilities alone are not effective.
• We need complimentary compact instruments and small

sources.

• To educate next generation scientists; to be sustainable!
• To test new ideas
• Focusing instruments are small.
• Pulsed focusing SANS instrument @Hokkaido Univ.
• 4m instrument
• Focusing SANS instrument @JRR-3
• 2.5m instrument
• SANS for low power reactors:
• Conversing collimator/loosely focused beam?

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• A new type of MSGC Detector development
• New Postdoc in Univ. Tokyo.
• Final process: packaging process is now in hand.
• Successfully made and tested at JRR-3
• Inelastic scattering corrections
• Not much progress.

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