1. Understanding mass transport in fuel cells using neutron imaging
Dr. David L. Jacobson
National Institute of Standards and Technology
100 Bureau Drive - Stop 8461
Bldg 235, Rm B185
Gaithersburg, MD
Phone: (301)
Fax: (301)

2. Overview Who are we and what is our mission Radiography
Neutron Radiography
NIST fuel cell role
NIST Center for Neutron Research
Fuel cell testing infrastructure
Future goals and direction
Access to the NIST facilities

3. Radiography
Roentgen Hand (1898) formed using xrays

4. Radiography Contrast is due to attenuation of radiation
Scattering density of material can be extracted
N - density of sample atoms per cm3
I0 - incident neutrons per second per cm2
 - neutron cross section in ~ cm2
Sample t

5. Radiography
Neutrons are the able to see hydrogen through heavy elements
Comparison of the relative size of the x-ray and thermal neutron scattering cross section s for various elements.
x-ray cross section H D C O Al Si Fe
neutron cross section

6. Image Geometry
Images are formed

7. What an image is
CCD images each pixel is a count value proportional to the light from the scintillator.
The transmission image below each pixel is a color or grayscaled value proportional to the fraction of neutrons that make it through the sample. i j

8. Neutron Camera CCD chip Lens Neutron beam Mirror Light tight box
Pinhole collimator
Fuel cell
neutron to light converter
Picture of the detector and sample holder assembly
Computer

9. Neutron Imaging Facility

10. Neutron Image Quality Images are formed as shadows
Edges will be blurred by various effects
CCD camera and lens
Neutron to