The Spallation Neutron Source

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The Spallation Neutron Source
A Powerful Tool for Materials Research
Thomas Mason Associate Laboratory Director for
the SNS Oak Ridge National Laboratory October
18, 2004 ICFA Bensheim, Germany
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Structure determines properties

• 3 forms of Carbon - very different materials

Graphite
Diamond
Buckyballs
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Tools for studying the structure and dynamics of
materials

• Imaging Probes
• Optical microscopes (not anywhere near atom
  level)
• Electron microscopes (nearly atom level)
• Scanning microscopes (atom level)
• Scattering Probes
• Photons (light) x-rays
• Electrons
• Neutrons
• Other
• Nuclear Magnetic Resonance (also known as MRI)
• Computer modeling

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Neutrons and Neutron Sources

• The application of slow neutron scattering to the
  study of condensed matter had its birth in the
  work of Wollan and Shull (1948) on neutron powder
  diffraction
• The neutron is a weakly interacting,
  non-perturbing probe with simple, well-understood
  coupling to atoms and spins
• The scattering experiment tells you about the
  sample not the probe

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Neutrons and Neutron Sources

• You can easily work in extreme sample
  environments H,T,P,...) e.g.4He cryostat (Shull
  Wollan) and penetrate into dense samples
• The magnetic and nuclear cross-sections are
  comparable, nuclear cross-sections are similar
  across the periodic table
• Sensitivity to a wide a range of properties, both
  magnetic and structural

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How do we produce neutrons?

• Fission
• chain reaction
• continuous flow
• 1 neutron/fission
• Spallation
• no chain reaction
• pulsed operation
• 30 neutrons/proton

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Development of Neutron Science Facilities
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Scientific justification for SNS

• Neutrons provide unique insight into materials at
  the atomic level
• see light atoms in biomaterials and polymers
• study magnetic properties and atomic motion
• measure stress in engineering components
• State-of-the-art neutron source has been an
  urgent priority for 15 years
• The SNS will be world leading and help restore
  U.S. leadership
• Total Project Cost 1.4 B
• Scheduled completion June 2006
• www.sns.gov

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SNS will be a USER facility

• User input into the SNS instrument suite
• Experimental Facilities Advisory Committee
  Workshops
• Support (technical, scientific, logistical) for
  users carrying out experiments
• Peer reviewed proposal system
• 1000-2000 users per year from academia,
  government, and industry
• Flexible instrument strategy that supports both
  general user access and dedicated access for
  expert instrument teams that contribute to
  construction and operation of instruments
• 5000 hours per year of user operations with high
  reliability (gt90 with gt95 as ultimate goal)

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SNS - Guiding Principles

• SNS will provide high availability, high
  reliability operation of the worlds most
  powerful pulsed neutron source
• It will operate as a User Facility to support
  peer reviewed research on a Best-in-Class suite
  of instruments
• Research conducted at SNS will be at the
  forefront of biology, chemistry, physics,
  materials science and engineering
• SNS will have the capability to advance the state
  of the art in spallation neutron source
  technology. This includes
• RD in accelerators, target, and instruments to
  keep SNS at the forefront
• Planned enhancement of SNS performance through
  upgrades of the complex and ongoing instrument
  development as part of the normal operating life
  of the facility

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The Spallation Neutron Source

• The SNS construction project will conclude in
  2006
• At 1.4 MW it will be 8x ISIS, the worlds
  leading pulsed spallation source
• The peak neutron flux will be 20-100x ILL
• SNS will be the worlds leading facility for
  neutron scattering
• It will be a short drive from HFIR, a reactor
  source with a flux comparable to the ILL

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Conventional Facilities
CLO South Side (June 04)

• CLO nearing completion
• Target Building working to end of Feb completion
• Initiated planning (and implementation) for
  transition from AE/CM
• Providing for continuing installation work and
  (small) construction activities with a transition
  steering group

Target Building (May 04)
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Accelerator Accomplishments

• Commissioning of DTL 1 3 done on schedule.
• ARR for DTL1-6 and CCL 1-3 closed out September
  7.
• Commissioning of DTL1-6 and CCL 1-3 ongoing.
• Installed 12 production HVCMs on the site to
  support commissioning/testing. 11 are
  operational, some of them at high Pave .
• All klystrons are installed in the gallery.
  DTL/CCL ready. 24 SCL ready.
• 13 cryomodules in the tunnel, rest March 05.
• CHL commissioning through 4.5 K cold box done.
  Feedthrough issue on 2K cold box resolved.
• One MB cryomodule tested at high gradient and
  full pulse length at 4.5K.
• Ring diagnostics on track, with little
  interfering delays.

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Installation Klystron Gallery

• RF systems for Front End, Drift Tube Linac, and
  Coupled Cavity Linac fully installed
• Superconducting Linac RF Systems well underway
• Integrated test of a medium beta cryomodule in
  the linac tunnel

30 sc klystrons out of 81 installed
CCL 1 installed
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DTL / CCL 1-3 Commissioning

• Finished commissioning of DTL 1-3. Had beam after
  only 36 hours and 100 transmission within 2
  days.
• Started beam for DTL/CCL1-3 on Sept. 7. 100
  transmission after setting all correctors to 0.

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Target Monolith Installation
Core Vessel and Shielding
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Target Service Bay Installation

• Much of the XFD installation to date has been
  under the target building construction contract
• We are transitioning to the time and materials
  model for the work to prepare for contract close
  out Feb 05

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Instruments

• 16 instruments approved
• Excellent progress with funding
• DOE including 75 M SING Project, foreign, NSF
• Working to enhance instrument technology

• International
• engagement and
• interest in the
• instrument suite
• Continuing
• engagement with
• scientific community

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SNS Reflectometers
Magnetism vertical sample
Rminlt 510-10 Qmax 1.5 Å-1 (Liquids)
7 Å-1 (Magnetism) dmin 7 Å 50-100 NIST NG-1
Liquids horizontal sample
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Simulated Detector Count Rates(10-8 10-10
reflectivity range)
10 Å SiO2 on Si Sample size 25 mm x 25 mm
Scattering Angle ? 20 deg. Resolution ??/?
10 ??/? 10
Marked region can be measured within 8 minutes
! ( gt100 counts per TOF channel)
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Diffraction

• Nanoscale Ordered Materials Diffractometer (NOMAD)

• Highest flux a short wavelengths is crucial for
  studies of local disorder in complex materials

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High Pressure Cells Limit Sample Volume

• Pressure cell of the type to be employed on SNAP
  (Spallation Neutrons and Pressure) beamline

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Example Deformation and Damage

• VULCAN Is a Compound Instrument Designed to
  Tackle Engineering Problems

• Mechanism of deformation and damage in realistic
  fatigue cycles
• Assuming a cycling machine at a frequency of 3000
  6000 rpm (50 to 100Hz), and requiring
  Bragg-peaks to be recorded on the same time
  scale, a gain factor of 30 to 50 is needed as
  compared to the best existing instrument
• SNS Provides a factor of 17 with Power Upgrade
  we are there
• VULCAN instrument realizes the gain!
• Comparable benefits across the instrument suite

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SNS SANS

• Extended Q-Range 0.001-12 Å-1
• Moderate resolution
• Performance 3-5 x D22 (ILL) HFIR, 30-100 x
  ISIS

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SANS Science

• (a) Self-assembled arrays of nanoparticles show
  order on two distinct length scales giving rise
  to
• (b) information at both high and low Q in the
  diffraction patterns.

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Q-Resolution Diagram for Elastic Instruments
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Inelastic Scattering is Almost Always Intensity
(sample size) Limited

• Phonon density of states of ZrW2O8

• Acoustic magnons in Fe3O4

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HPTS Chopper Backscattering Spectrometers
Dynamics
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Status of SNS Instruments
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Status of Other Approved IDT Instruments
NSE Neutron Spin Echo Spectrometer (BL
15) Dynamics on mesoscopic scales, particularly
for biomolecules, polymers, and other soft matter
systems Michael Monkenbusch (Juelich) Michael
Ohl (Juelich) Dieter Richter (Juelich) Catja
Pappas (HMI)
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Status of Other Approved IDT Instruments contd
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Q-? Diagram for Inelastic Instruments
adapted from Neutron Scattering Instrumentation
for a High-Powered Spallation Source R. Hjelm,
et al., LA0-UR 97-1272
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SNS 20-year plan

• SNS will evolve along the path envisaged in the
  Russell Panel specifications
• In 20 years, it should be operating 45
  best-in-class instruments with two differently
  optimized target stations and a beam powerof 34
  MW
• Ultimate target performanceis probably the
  biggest unknown in projecting maximum power
  obtainable at SNS
• The Power Upgrade and Long Wavelength Target
  Station should follow a sequence that meshes with
  deployment of the initial capability and national
  needs

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DOE Office of Science20-Year Facilities Plan
The SNS Upgrades are the next major BES projects
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Summary

• The Spallation Neutron Source, through a
  combination of improved neutron intensity and
  state of the art instrumentation will provide
  qualitatively new capabilities for studies of the
  structure and dynamics of materials
• The traditional strengths of neutrons scattering
  will be extended to allow studies of smaller
  samples, faster processes, higher resolution, and
  more complex materials in more exotic sample
  environments
• New applications of neutron scattering will
  become possible with the 20-200X gains compared
  to present capability