A new Fankuchen-cut Ge(533)/(733) monochromator with a
120
o take-off angle has recently been installed in BT-1, the
high-resolution powder diffractometer at the NIST Center for Neutron Research..
BT-1 has 32 detectors with 5
o spacing and offers two in-pile
collimation settings (7' and 15') and three monochromator take-off angles (75,
90 and 120 degrees). This allows the instrument configuration to be tailored to
suit the experiment at hand
.
BT-1 routinely operates with a
resolution Δd/d of ≈0.15%, a resolution matched by only one other
instrument in the U.S. However, this resolution can be improved considerably, to
≈0.08%, when needed. Alternately, throughput can be improved through use
of a longer wavelength with slightly relaxed resolution. The new Ge
monochromator allows for higher resolution, improved throughput and operation at
two wavelengths (1.5 and 1.2 Å). The 1.2 Å mode offers accessible
range of reflections to nearly be doubled, with all of the "new data" within the
monochromator's optimal resolution condition. Approximately 63 days/year (25%)
on BT-1 are available to outside users via a rapid-response proposal system.
Access for proprietary measurements is also possible, as well as for
collaborative projects. See http//www.ncnr.nist.gov/xtal for more details on
access.