Determination of low-level radioactivity in environmental samples by gamma spectroscopy at Argonne National Laboratory

Conference · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6880237

Streets, W E; Heinrich, R R; Lamoureux, L L

We currently have six Ge/Ge(Li) detectors that are being used for gamma counting of environmental samples (three with horizontal geometry, three with vertical geometry). The detectors were calibrated for close-geometry efficiency by counting standards in a set configuration (a height of 6.4 cm in a 4-oz. wide-mouthed Naglene bottle) immediately adjacent to the cryostat face. This configuration was chosen so that the standards would be symmetrical to the centers of both the horizontal and vertical detectors. Two solid standards were prepared by adding a known amount of Standard Reference Material NBL No. 6-A (Pitchblende) and NBL No. 7-A (Monazite Sand) to a blanked soil and mixing. Homogeneity of the standards was checked by counting each standard at each quadrant (on a horizontal detector). The final mixtures showed less than 1% deviation between the high and low quadrant counts. Two liquid secondary standards were prepared from stock solutions of /sup 137/Cs, /sup 131/I, and /sup 110m/Ag, which has been characterized as point sources using several detector efficiency curves. These efficiencies were determined using point source standards from the National Bureau of Standards (NBS) and International Atomic Energy Agency (IAEA). All standards had activity levels that allowed less than 1% counting statistics to be obtained on the major peaks (i.e., those with stronger branching ratio) within two hours. Analysis of the resulting data yield smooth efficiency curves for each of the six detectors. Although the standard compositions varied, solid and liquid, the densities were all approx. =1.0 g/cm/sup 3/. 3 refs.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6880237
• Report Number(s): CONF-8810112-8; ON: DE89003964
• Resource Relation: Conference: 34. annual conference on bioassay, analytical and environmental radiochemistry, Las Vegas, NV, USA, 17 Oct 1988; Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
FIELD TESTS
STANDARDS
GAMMA SOURCES
LOW LEVEL COUNTERS
ANL
DETECTION
LI-DRIFTED GE DETECTORS
MONITORING
GE SEMICONDUCTOR DETECTORS
LI-DRIFTED DETECTORS
MEASURING INSTRUMENTS
NATIONAL ORGANIZATIONS
RADIATION DETECTORS
RADIATION SOURCES
SEMICONDUCTOR DETECTORS
TESTING
US AEC
US DOE
US ERDA
US ORGANIZATIONS
510300* - Environment
Terrestrial- Radioactive Materials Monitoring & Transport- (-1989)