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The Spallation Neutron Source


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Title: The Spallation Neutron Source

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
Structure determines properties
  • 3 forms of Carbon - very different materials

Tools for studying the structure and dynamics of
  • Imaging Probes
  • Optical microscopes (not anywhere near atom
  • 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


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
  • 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

98-6244 uc/rfg

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

98-6242 uc/rfg
How do we produce neutrons?
  • Fission
  • chain reaction
  • continuous flow
  • 1 neutron/fission
  • Spallation
  • no chain reaction
  • pulsed operation
  • 30 neutrons/proton

Development of Neutron Science Facilities
97-3924E uc/djr
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

SNS will be a USER facility
  • User input into the SNS instrument suite
  • Experimental Facilities Advisory Committee
  • 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)

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

The Spallation Neutron Source
  • The SNS construction project will conclude in
  • 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

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)
Accelerator Accomplishments
  • Commissioning of DTL 1 3 done on schedule.
  • ARR for DTL1-6 and CCL 1-3 closed out September
  • 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.

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

Target Monolith Installation
Core Vessel and Shielding
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

  • 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

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
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)
  • Nanoscale Ordered Materials Diffractometer (NOMAD)
  • Highest flux a short wavelengths is crucial for
    studies of local disorder in complex materials

High Pressure Cells Limit Sample Volume
  • Pressure cell of the type to be employed on SNAP
    (Spallation Neutrons and Pressure) beamline

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

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

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

Q-Resolution Diagram for Elastic Instruments
Inelastic Scattering is Almost Always Intensity
(sample size) Limited
  • Phonon density of states of ZrW2O8
  • Acoustic magnons in Fe3O4

HPTS Chopper Backscattering Spectrometers
Status of SNS Instruments
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)
Status of Other Approved IDT Instruments contd
Q-? Diagram for Inelastic Instruments
adapted from Neutron Scattering Instrumentation
for a High-Powered Spallation Source R. Hjelm,
et al., LA0-UR 97-1272
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
  • 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

DOE Office of Science20-Year Facilities Plan
The SNS Upgrades are the next major BES projects
  • 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
  • New applications of neutron scattering will
    become possible with the 20-200X gains compared
    to present capability