|
Instrument Specifications
Available Monochromator
Sample Environment and Ancillary Equipment
Example for a Recent Experiment
Data Analysis Software (PF, IsoDEC)
Publications
How to obtain Beam Time on BT8
The Residual Stress Diffractometer is used for measuring lattice strains and
preferred orientation (texture), for studying residual and applied stress in
engineering materials, and the effect of materials processing on preferred
orientation. Designed for versatility, the heart of the instrument is a
rotating drum that allows - together with three monochromators - to select
wavelengths from 0.08 nm to 0.32 nm. This enables the measurement of d-spacings
anywhere between 0.06 nm up to 0.22 nm at the optimal 2theta=90 deg.. The size of the
sampling volumes used on a regular basis varies from 1 mm3 to 200 mm3.
The double focusing Si-Monochromator has a variable curvature which allows the
optimization of the measurement for intensity (texture), for resolution (peak
broadening) or for Figure of Merit (strain). Beams with minimal or without
higher order contamination can also be produced, either by using the Si(311)
monochromator reflection which has no second order, or by using a pyrolytic
graphite filter. The instrumental background is low and, depending on material,
pathlength and gauge volume, peak to background ratios typically range from 1
(steel, 80 mm path, 125 mm3 gauge volume) to 300 (steel, 8 mm path,
8 mm3 gauge volume). The detector is a position sensitive neutron
detector with an angular opening of approx. 8 deg..
Beam time for BT8 is granted quickly, either through a beam time request
using the IMS system or on an
informal basis by contacting the instrument responsible. Measurements are done
either by the applicant(s) or - on a collaborative basis - by a staff member.
Depending on the extent of the proposal, we are encouraging applicants to
conduct measurements themselves after completing appropriate training and
orientation with full support by the residual stress group. For questions and
beam time requests please contact:
Thomas Gnaupel-Herold, 301-975-5380, tg-h@nist.gov
Last modified 23-May-2012 by website owner: NCNR (attn: Thomas Gnaeupel-Herold) by Thomas Gnaupel-Herold
|