Sandia's nuclear radiation standards include alpha and beta sources, gamma ionization chambers used in conjunction with a gamma source range, steady-state and pulsed neutron sources, and a certified tritiated methane gas bottle. These primary sources, which are calibrated by NIST, are used on a low-scatter range to certify survey meters and to verify dosimeter response. Customer lead probes or other detectors and dosimeters are certified by comparison with the standard using a laboratory neutron generator as the source.
Certification is in terms of total neutrons produced at the source target.
A bottle of tritiated methane gas whose activity has been certified is used to set the response of tritium monitors. The primary sources are used to certify similar sources that are used, in turn, to calibrate survey instruments. An internal gas proportional counter is used for calibration of the thin sources. Results are expressed in terms of emission into 2 pi rather than as absolute decay rates because the counter does not distinguish between direct and back-scattered particles. Chambers are used to standardize the dose from a Cs-137source range.