Neutron Source Strength Calibrations

The neutron source calibration facility operated by NIST is a world-class calibration laboratory providing neutron source  calibration services for radioisotopic sources with neutron emission rates ranging from5 x 10⁵ to 10¹⁰ s^-1.

Calibrations are performed using the manganous sulfate bath technique in which the emission rate of the source to be calibrated is compared to the emission rate of NBS–1, the national standard Ra–Be photo-neutron source. Neutron source calibrations typically have a relative expanded uncertainty of about 2.5%, depending on the details of the source encapsulation.

The principal customers for this service are commercial vendors of radioisotopic neutron sources, manufacturers of instruments and devices that monitor radiation exposure and dose, secondary calibration laboratories that service the aforementioned radiation monitoring instrumentation, nuclear electric generating stations, nuclear fuel fabrication facilities, US Department of Defense establishments, and government and private research and development laboratories.  In addition to its external customers, the neutron source calibration facility also provides important contributions to other neutron irradiation and calibration services provided by NIST, as well as to intramural research programs in neutron metrology and fundamental neutron physics.

During the period 2009-2010, 8 external vendor neutron sources were calibrated.  In support of these measurements, our own standard neutron sources (NBS–1, BIPM) and the background rates were measured several times.  NIST provides a neutron emission rate calibration service in support of US nuclear programs.