Comparison of background gamma-ray spectra between Los Alamos, New Mexico and Austin, Texas.

Background counts in gamma-ray spectrometry are caused by a variety of sources. Among these are naturally occurring radioactive materials (NORM) in the environment, interactions from cosmic radiation, and contamination within the laboratory. High-purity germanium detectors were used to acquire long background spectra in Los Alamos, NM (elevation ~7,300 feet) and Austin, TX (elevation ~500 feet). This difference in elevation has a sizeable effect on background spectra due to cosmic interactions, such as ( n, n′) and ( n, γ). Los Alamos also has a fairly high NORM concentration in the soil relative to Austin, and this gives way to various spectral interferences. When analyzing nuclear forensics samples, these background sources can have non-trivial effects on detection limits of low-level fission products. By accurately determining the influence that elevation and environment have on background spectra, interferences within various laboratory environments can be more accurately characterized. [ABSTRACT FROM AUTHOR]