Neutron Scattering under Extreme Conditions
at the Spallation Neutron Source
Jamie Molaison
Neutron Scattering Sciences Division
Oak Ridge National Laboratory
International Workshop on Synchrotron High Pressure
Mineral Physics and Materials Science
Argonne National Laboratory - December 6-7, 2007
Neutron Scattering Sciences Division
December 6-7, 2007
Collaboration
•
•
John Parise - Stony Brook University
H.-k. Mao, R. J. Hemley - Carnegie Institution of Washington
• Gene Ice - Oak Ridge National Laboratory
• Darren Locke, Lars Ehm, Dave Martin - Stony Brook University
• Ian Swainson, R. Rogge, L. Cranswick - NRC CNBC Chalk River
December 6-7, 2007
Neutron Scattering Sciences Division
Neutrons and Neutron Sources
• You can work in extreme sample environments (T, P,...) e.g. He
cryostat (Shull & Wollan) and penetrate into dense samples
• Sensitivity to a wide range of properties, both magnetic and
structural
• The magnetic and nuclear cross-sections are comparable, nuclear
cross-sections are similar across the periodic table
98-6242 uc/rfg
December 6-7, 2007
Neutron Scattering Sciences Division
EXAMPLE: Spin Reorientation
in α-Fe2O3
up to 70 kbar at room
temperature – C2 (NRC), WAND
Intensity of (111) peak
drops with increasing
pressure
70 kbar
z
x
Hexagonal structure, vectors
indicate spin directions along
the c–axis above 70 kbar
EOS and transitions
in ice used to deter. P
Remaining
Ice VI
y
Spin vector angle w.r.t c-axis
Ice VII [110] peak
of transformed sample
Ice VI
1600
Ice VI
Intensity
Ice VI
2.18 GPa (545 bar)
1200
2.58 GPa (600 bar)
3.69 GPa (700 bar)
800
4.40 GPa (800 bar)
5.23 GPa (900 bar)
400
5.85 GPa (990 bar)
6.41 GPa (1050 bar)
Ice VII
mag
n
nuc
lear
p
etic
pea
k
eak
s
s
0
30
32
34
36
38
40
42
2 theta (degrees)
Neutron Scattering Sciences Division
December 6-7, 2007
Pressure Ranges and Neutron Scattering
Adapted from
N. W. Ashcroft
E-F School Verenna
Italy 2001
1E28
1E18
Metallic Hydrogen
P at center
of neutron star
P at center
of white-star
7
10
5
10
3
Pressure (Atm)
10
1E8
0.01
high pressure X'll
10 forms
o
P where H2O freezes at 100 C
4
Pressure at greatest
ocean depth
3
10
Atm P at sea level
-1
2
10
10
-3
Vapor P of water
at triple point
-5
Sound at threshold
of pain
-7
Radiation P at Sun
10
1E-12
Chemsitry under pressure
high pressure
(compound/Bio)
1
P cosmic
microwave BG
10
10
1E-32
PIA in ice
1
10
1E-22
P at center of Earth
(~350 GPa)
core-mantle boundary
(100 GPa)
PIA in quartz
5 densification of
10 silica
non-equilibrium P of
hydrogen in intergalactic
space
Existing Pressure
Devices
10
Available at Current
Neutron Sources
1 Atm = 1 bar, 10 kbar = 1 GPa
100 Gpa = 1 Mbar
December 6-7, 2007
Neutron Scattering Sciences Division
SNAP Pressure Cells
Panoramic Design
Paris-Edinburgh (P-E) Design
First Gen
First Gen
Second Gen
Second Gen
Large volume: ~80
mm3
Beijing-Washington
Design
Sample size = 100 µm
(linear) to 1 mm3
Neutron Scattering Sciences Division
Large volume:
40-60 mm3
December 6-7, 2007
SNAP Research — Cell Testing
Pair Distribution
Function
K.W. Chapman, P.J.
Chupas, D. Locke,
J.B. Parise 2006 in
preparation
Densification process glassy water.
Tulk, et al. PRL, 97, 2006
CaSiO3 glass up to 90 kbar,
x-ray data, L. Ehm, D.
Locke, et al.
rhombohedral ↔ orthorhombic ↔ tetragonal ↔ cubic
250
8
Xe Hydrate, in situ measurement
200
3.5 GPa
Q(S(Q)-1)
6
150
2.6 GPa
4
2.0 GPa
2
N. C. Hyatt (Sheffield),
J. A. Hriljac (Birmingham), et al.
2.5
5.0
7.5
10.0
Q (angstroms^-1)
12.5
Atomic Form Factor
100
50
1.7 GPa
0
0.0
I(Q)
BaTiO3
0
15.0
0
5
10
15
20
Q (angstroms^-1)
Studies of guest cluster geometry
in high pressure clathrate hydrates
December 6-7, 2007
Neutron Scattering Sciences Division
The Spallation Neutron Source
•
•
•
SNS construction finished in 2006, $ 1.4 billion construction cost
Full power = 1.4 MW. SNS is now producing neutrons at
approximately ISIS power levels, plans to increase power.
It is a short drive to HFIR, a reactor source with a flux comparable to the
ILL
December 6-7, 2007
Neutron Scattering Sciences Division
Target Building and Instrument Layout
Beam Line 11A
Powder
Diffractometer
Beam Line 7
Engineering
Diffractometer
(VULCAN)
Beam Line 12
Single Crystal
Diffractometer
(TOPAZ)
Beam Line 4B
Liquids
Reflectometer
Beam Line 4A
Magnetism
Reflectometer
Beam Line 17
Chopper
Spectrometer
(SEQUOIA)
Beam Line 3
High Pressure
Diffractometer
(SNAP)
Beam Line 18
Chopper
Spectrometer
(ARCS)
Beam Line 2
Backscattering
Spectrometer
Proton Beam
December 6-7, 2007
Neutron Scattering Sciences Division
SNAP Overview and Status
Support labs
& mezzanine
Beam Stop
Shutter & Core
Vessel Insert
Stacked
Shielding
Enclosure Ceiling
& Hatch
Instrument
Enclosure
Choppers &
Supports
Sample
Position &
Detectors
Flight Tube
Assembly
P-I-P Shielding
December 6-7, 2007
Neutron Scattering Sciences Division
View at the Sample Position
December 6-7, 2007
Neutron Scattering Sciences Division
Instrument Enclosure
December 6-7, 2007
Neutron Scattering Sciences Division
Instrument Components in the Field
December 6-7, 2007
Neutron Scattering Sciences Division
Focusing Mirrors: The KB Concept
Two curved neutron super mirrors
- One focusing vertically
- One focusing horizontally
December 6-7, 2007
Neutron Scattering Sciences Division
Bending is Practical Option for SNAP Mirrors
•
Monolithic figuring
– ~$400K not in SNAP budget
•
bending
moments
mirror
bending
moments
Differential deposition
– Not right scale for neutron
mirrors (too thick)
•
Bending
– Widely used-cost effective
bending
moments
bending
moments
mirror
leaf
spring
December 6-7, 2007
Neutron Scattering Sciences Division
Micro beams for high pressure neutron scattering
Doubly Focused
Prototype micro-focusing mirrors
NRU reactor at CRL (NRC)
Measured spot size ~ 110 x 110 µm
70000
Signal saturated at 65535
60000
50000
40000
30000
20000
10000
0
555
560
565
570
575
580
585
590
595
600
605
Tulk, Ice, Locke, Xu, Parise, et al. (2004), ORNL, NRC,
Stony Brook and Carnegie Institution.
December 6-7, 2007
Neutron Scattering Sciences Division
Measuring the Spot Size
109 microns in the Horizontal
111 microns in the Vertical
December 6-7, 2007
Neutron Scattering Sciences Division
Microdiffraction from Free-standing Crystal
• 300 x 300 x 700 µm irregular forsterite (Mg2SiO4) single crystal
• Rotated 360o in 20o steps about Φ
Avg. peak int./scatt. vol.
(counts/µm3)
• Focused run gave 701 reflections, unfocused gave 368 (196 common)
focused beam
unfocused beam
rotation angle (degrees)
December 6-7, 2007
Neutron Scattering Sciences Division
Pressure cells coupled with mirrors at CNBC-Chalk River
Looks very much like an x-ray
hutch at a synchrotron facility
- utilize sample alignment
- utilize sample HT-LT
environment techniques
December 6-7, 2007
Neutron Scattering Sciences Division
Microdiffraction from pressurized sample
• 200 x 500 µm FeO single crystal in panoramic cell at ~7 GPa
700 µm
90 µm
beam
sample
200 µm
sample
December 6-7, 2007
Neutron Scattering Sciences Division
Advanced K-B Mirrors for SNAP
• Nested geometry can be farther from sample
• Theoretical increase of ~2.5 in flux vs. standard K-B geometry
December 6-7, 2007
Neutron Scattering Sciences Division
THANK YOU!
December 6-7, 2007
Neutron Scattering Sciences Division