Development of an advanced neutron guide system at J-PARC

Transcription

Development of an advanced neutron
guide system at J-PARC/MLF BL06
for VIN ROSE
Masahiro Hino
Research Reactor Institute, Kyoto Univ.
(KURRI)
NDS2012, July.9 (2012), Grenoble,
France
NDS2012, July.9-11
(2012), Grenoble, France
KUR（Kyoto University Reactor)@Kumatori
1MW(5MW),Pool type, 50h/week,
BNCT, NAA, NRG, Neutron Optics&SANS
KUR restart after big
earthquake with no big problem
Kumatori
(KURRI)
Tokai
(JRR-3&J-PARC)
France
E3(Ni guide):PGA for BNCT
First neutron guide in Japan(1969~)
B4（SM guide)：NRG
First long neutron SM
guide in the world(1985～)
First CNS(Liquid D2)
in Japan.
(It doesn’t operate now)
CN2:SANS
CN3:Neutron Optics
KUR top view
France
VIN ROSE(Village of Resonance Spin Echo spectrometers)
MIEZE target:
small molecule
dynamics and
magnetic fluctuation,
etc… @flexible sample
environment
NRSE target:
Soft matter(bio-,macromolecules)
dynamics,etc@small
sample with high S/N
（Beam size< 5x5mm2 ）
France
Inelastic scattering spectrometers at J-PARC
+POLANO(BL23)
VIN ROSE is only one S(q,t)
Spectrometer at J-PARC.
MIEZE&NRSE cover
wide time domain
(0.1ps to 100ns)
※50ns is first design target
France
Neutron Spin Echo method
Larmor precession
z
Energy resolution
and beam
monochromatization
independent from
each other!
PNSE   S (Q,  ) cos  d
 I (Q,  )
I (Q,  )  exp   t 
  DQ2
Fourier
Time：
y
B0(+z)
B0(-z)
x
Polarized
neutron
（wide-band)
PNSE
L L0

mv3
:Simple case
D:diffusion constant
F.Mezei、Z.Phys.255 146(1972).
Neutron velocity changes
→ PNSE reduces
France
NRSE（Neutron Resonance Spin Echo) method
Sample
2s
2s L

mv3
Resonance condition:
NSE：Static magnetic field
NRSE：RSF+zero(weak) magnetic field
R.Golub, et al., Phys. Lett. A123 (1987) 43.
France
MIEZE（Modulated IntEnsity by Zero Effort) method

2s L
mv3
Nothing between sample and detector！
One spin state at sample position. It is easy,
○ to combine MIEZE with a polarimetry analysis instrument(SANS, NR),
○ to synchronize with the sample environment(i.e. pulse magnetic field and laser).
△ It is, in principle, difficult to measure with high energy resolution
R.Gähler, et al., Physica B180-181 899(1992).
France
The advantage of TOF-MIEZE
 MIEZE signal is scanned every neutron pulse. (MIEZE
measurement can be done with one neutron pulse if neutron flux is strong
It is possible to synchronize with the sample
environment (i.e. pulse magnetic field and laser excitation).
 One spin state at sample position.→ It is easy to combine
MIEZE and the other polarized TOF spectrometers.
enough.)
1.0
1.0
N(R)SE
0.8
CMIEZE
Pz
0.5
0.0
-0.5
-1.0
0.6
0.4
0.2
-1.0
-0.5
0.0
L, cm
0.5
ΔN(Phase shift)
1.0
MIEZE
0.0
0
4
8
12
Elapsed time(μsec)
France
A problem for MIEZE spectroscopy with high resolution
Detector
1  cos 
Id 
2
δLsd=Lsd(1)-Lsd(2)
Lsd(1)
Lsd(2)
1period@λ=0.81nm
0.49mm@1MHz
4.9mm@0.1MHz
2s
 L12  L2 s  Lsd  Lsd 
  2std 
v
Sample
Slit
●
●
polarized
neutron beam
The contrast of MIEZE signal decays without inelastic
scattering, in other words, the decay of signal measures
only path dispersion (δLsd) between sample and detector
France
Correction of Beam Divergence in NRSE
without
sample
with
sample
Correction device like Fresnel coil in NSE is necessary for high resolution
France
The Correction with 2D elliptic mirrors
NRSE condition:
τ=100 ns L(RSF)=2.5m λ＝2nm
RSF(ωe)=0.8MHz
M.Bleuel et al., Neutron Spin Echo Spectroscopy,
Lecture Notes in Physics, (2002).
M.Kitaguchi, et al.,Physica B406(2011)2470.
France
Realized free shape NiC/Ti
replica supermirror sheet
m
(on PET)
1
2
3
4
Reflectivity
1.0
Peeling off technique
has been established!
5
R>0.7
@m=4.6
0.8
0.6
0.4
0.2
0.0
0.2
0.4
0.6 0.8 1.0 1.2
-1
Q(nm NDS2012,
)
July.9 (2012), Grenoble,
France
Yamamura
Group
Soyama
Group
Without
focusing mirror
With focusing mirror
France
Schematic top view of BL06
(↑ BL07 side)
NRSE
Two curved guide
(↓ BL05 side)
Iron beam dump
7.3
12
MIEZE
17
2 beam lines @ BL06
35
22.5
27
31
Z: distance from the source [m]
In biological shutter(z=2.3→7.2m), m=2 straight guide(9x9cm2)
Guide
Length
NRSE
4.7 m curve(a) (z=7.3→12m)
4.8 m curve(b) (z=12.3→17.1m)
5.4 m straight*(c)(z=17.3→22.7m)
MIEZE
4.7 m curve(a)
4.8 m curve(b)
Characteristic
wavelength:λ*
MIEZE:λ*=2.9Å
NRSE:λ*=4.9Å
Radius
140 m
140 m
cross section
30(w) ×48-120(h) mm
15 (w) × 50(h) mm
Mirror
m = 2.5
m = 3.0
Focus
Vertical: (a), (b), (c) :ellipsoidal
―
Horizontal: (c) ellipsoidal NDS2012, July.9 (2012), Grenoble,
France
NRSE
guide
4deg
150deg
45deg
22deg
20deg
35deg
MIEZE
17
22.5
Key is Neutron Optics
35
27
31
Z: distance from the source [m]
Beam size@sample is less than 5x5mm2
a pair of large(>1.2m) elliptical focusing m>3 supermirrors
(to correct the effect of beam divergence)
m>5 polarizing and analyzing mirrors
(to measure wide band wavelength)
In NRSE, neutron guide should be installed between each
devices to transport neutrons with wide divergent angle
France
FY2011 manufactured materials(after bid)
①BL06 mirror holder with iron shielding
Total：1.5M$
②BL06 up stream(12-16m) concrete shielding
③BL06 electric basic infrastructure（main switchboard etc)
④8’ t=3mm silicon wafers for supermirrors
NRSE(7.3-22.7m)
MIEZE(7.3-17.1m)
①
②
France
Up stream part(7.3-12.0m)
NRSE(w=3cm, a=11.8m,b=6cm)
MIEZE(w=1.5cm, h=5cm)
NRSE:
SM(m=3) on
Si(150x140x3mm)
MIEZE:
SM(m=3) on
Si(150x70x3mm)
France
Numerical simulation of BL06 by PHITS
Neutron guide is
covered by iron
block
BL06 area is covered with concrete walls(which is
as thin as possible)
Iron beam dump installed
to biological shielding
area(which is inside 12m
from source)
France
Numerical simulation of
BL06 beam line by PHITS
MIEZE(17.1m):
3.4×108 n/cm2/s/Å(λ= 3.5Å)
NRSE(z=22.7 m):
1.6×108 n/cm2/s/Å(λ= 5.2 Å)
France
NiC/Ti multilayer（10000layers）
Back to 2004
σ=0.55nm
d=2.97nm
R=24%
The TEM picture measured by
P.Schubert and T.Krist@HMI
France
Which model is more realistic?
(a)Rough
(b)Diffuse
σ~0.55nm is much larger than that we expected.
In this case, (b) diffuse surface is more realistic.
If (b) is correct, we don’t be so nervous for substrate and
obtain high reflectivity by increasing number of layer!
France
m=3 NiC/Ti supermirror(650 layers)
Theoretical
layer number
<400 for m=3
(nm)
σ:Debye-Waller
factor
σSi=0.3-0.4nm
M.Hino et al.,
NIMA600(2009)207.
France
Φ200mm
Maximum Sample size is 8”(φ200mm)
Φ200mm
300mm
m=
1
2
3
4
80
60
0.8
0.6
40
0.4
0.2
5Q
NDS2012, July.9 (2012),
0.0 Grenoble,
1
2
3
4
France
Incident angle(degree)
20
0
Flipping ratio
Reflectivity
1.0
7Q
5
Supermirror fabrication & estimation at KURRI
150x140mm
4pices(m=2.5)
150x70mm
8pices(m=3)
Φ480mm
Number of reflection >2
(Ave.～3.9)
Measured reflectivity is
as same as (better than)
ideal curve in PHITS
KUR- CN3 port for
Neutron Optics
France
Summary and next step
 KEK & Kyoto Univ. started to construct BL06 beam line at JPARC for VIN ROSE in FY2011. We will install neutron guide in
next summer and get first beam within FY2013.
 The BL06 beam line has been designed and simulated
numerically by PHITS. The neutron intensity and dose level are
acceptable.
 KURRI group succeeded in fabricating a large-scale supermirror.
 KURRI group started to fabricate all supermirrors for the BL06
neutron guide(total length～29m). I want to improve in-house
technique for our future (facility at Kyoto Univ.).The reflectivity of
all mirrors should be checked more precisely and we choice
good mirrors.
France
THANK YOU!
Collaborators
KURRI: T.Oda,M.Kitaguchi, M.Bleuel, Y.Kawabata,
JAEA: H. Hayashida, N.Achiwa, T. Ebisawa, M.Katagiri,
D.Yamazaki, K.Oikawa, F.Maekawa, M.Ebine,
A.Birumachi, K.Soyama
KEK:
N.L.Yamada,H.Sagehashi,H.Seto,
H.M.Shimizu and NOP collaboration
France

Development of an advanced neutron guide system at J-PARC

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