Transcript No Slide Title

A “neutron microscope” for nano-scale motion in new materials
Collin Broholm, Johns Hopkins University, DMR 0116585
MACS will open a new window on atomic scale structure and dynamics at the early stages of materials
development. Located at the NIST center for neutron research, the instrument employs a bold new
configuration to probe minute crystals and man-made nano-structures.
20 channel detection system
Sample position
Aperture
Attenuator
Monitor
Shielding
Focusing supermirror
Helium
Cold neutron source
Cooled filters
Shutter
20 ft
Variable Aperture
Radial Collimators
Focusing monochromator
on translation stage
Maximizing neutron flux on small “hot” samples
Collin Broholm, Johns Hopkins University, DMR 0116585
High flux on small samples is achieved through a neutron focusing “Bragg lens”. The device reflects and
concentrates neutrons from an area of 221 square inches to the sample. The flux will exceed that of
conventional instrumentation by more than an order of magnitude.
357 pieces of graphite are accurately
positioned to form a Bragg lens for
exploring the nano-world. It was built at
Johns Hopkins University by engineers
with previous expertise in optics for
astronomy
The PI inspects the MACS incident beam line at the NIST Center for neutron
research. Buried within shielding is the neutron focusing Bragg lens, which
moves along the reactor beam to select different neutron energies. The circular
region where the PI stands will accommodate an adjustable super-mirror guide
that further concentrates reflected neutrons on the sample.
Engineering by P. Brand, M. English, R.Hammond, P. Hundertmark, J. LaRock, J. Moyer, J. Orndorff, D. Pierce, T. Pike, G. Scharfstein, S. Smee, et al.
Window on the nano-world: A multi-channel neutron detector
Collin Broholm, Johns Hopkins University, DMR 0116585
×20
The centerpiece in each
channel is a vertically
focusing double crystal
analyzer system
actuated by a single
motor.
20 channels operate
simultaneously to
detect an order of
magnitude more
neutrons than
conventional
instrumentation.
Engineering by C. Brocker, Z. Huang, P. Hundertmark, N. Maliszewskyj, T. Pike et al.
Neutron scattering
showing quasi-particle
decay in a quantum
spin liquid (Stone et al
Science (2006))