THERMAL NEUTRON INSTRUMENTATION

The thermal neutron instruments at the NCNR are housed in the confinement building.

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They include

• BT1 - high resolution powder diffractometer*
• BT4 - filter analyzer spectrometer*
• BT2 - neutron imaging facility
• BT7 - double-focusing triple-axis spectrometer
• BT9 - conventional triple-axis spectrometer
• BT5 - ultra-small angle neutron scattering (USANS) diffractometer*
• BT8 - residual stress diffractometer
• NGO-MACS: Ultra High Efficiency Cold Neutron Spectrometer (under construction)
• facilities for neutron activation analysis

*accessible through user proposals. These and the other instruments are also available for collaborative projects with NIST staff.

A project to modernize the older neutron scattering instruments in the confinement building will be implemented over the next few years. Improvements will be made with regard to safety and flexibility of operation, involving the installation of new monochromator drums which will provide both a safer working environment and an improved signal to noise ratio. Beam apertures will be remotely adjustable, and neutron-sensitive video cameras will be used for sample positioning and alignment. The filter analyzer option on BT4 will be supplanted by a dedicated filter-analyzer instrument, in which the solid angle subtended by the detectors, and hence the useful signal, will be increased by more than an order of magnitude. The greater sensitivity should produce many new possibilities in spectroscopy in the 10-100 meV range, with resolutions of 1-2 meV. The refurbished triple-axis spectrometers will allow the routine use of double- (i.e., both vertically- and horizontally-) focusing monochromator and analyzer assemblies, which can enhance signal by an order of magnitude in many types of experiments.

Thermal neutrons are employed at the NCNR for a wide variety of applications other than neutron scattering, such as maintaining radiation and dosimetry standards, development of radiation detectors, and neutron activation analysis studies for the Food and Drug Administration, the Federal Bureau of Investigation, and a number of other government agencies, industries, and universities.

Last modified 01-February-2008