LOW BACKGROUND THIN-WALL FLOW COUNTERS FOR MEASURING BETA ACTIVITY OF SOLIDS

Journal Article · Fri Apr 01 04:00:00 EST 1960 · Rev. Sci. Instr.

DOI:https://doi.org/10.1063/1.1716988· OSTI ID:4172022

Lal, D; Schink, D R

The construction and performance of disk-shaped thinwalled flow counters suitable for measuring very small beta activities of solids is described. The circular faces, which serve as the cathode, consist of conducting films. Either a single pear-shaped loop of wire whose plane is parallel to that of the faces, or a group of straight wires stretched across the midplane serves as the anode. The counters are operated in the Geiger region. Samples can be counted against both faces of the counter. Performance data are given for counters having active volumes of 0.2 to 7 cc, and having active areas of 1.8 to 23 cm/sup 2/. Counting efficiencies for natural potassium (mounted on Lucite) vary from 30% to 47%, depending on the relationship of sample area to counter dimensions. Inside a 20- cm steel shield and an anticoincidence ring the background counting rates varied approximately as 1 count/hr/cm/sup 2/ of counting area. Backgrounds as low as 1 count/hr were obtained. The disk geometry permits the use of a smaller metal and anticoincidence shield than is possible with cylindrical geometry. Counters shielded successively with 1.9-cm mercury, 5-cm steel, and 5-cm lead, and operated with a flat multiple-anode anticoincidence counter (15 cm/sup 2/), actually gave lower background than with the 20-cm steel and anticoincidence ring assembly. An integral counter assembly, consisting of ~2-cm diam disk-shaped counter and a diskshaped guard counter (~7-cm diam), was constructed and gave satisfactory results. (auth)

• Research Organization: Scripps Institution of Oceanography, La Jolla, Calif.
• Sponsoring Organization: USDOE
• NSA Number: NSA-14-013907
• OSTI ID: 4172022
• Journal Information: Rev. Sci. Instr., Journal Name: Rev. Sci. Instr. Vol. Vol: 31
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ANODES
BACKGROUND
BETA PARTICLES
CATHODES
COINCIDENCE METHODS
CONFIGURATION
COUNTERS
CYLINDERS
DIAGRAMS
ELECTRIC CONDUCTIVITY
ENGINEERING AND EQUIPMENT
FOILS
IONIZATION CHAMBERS
LEAD
LUCITE
MEASURED VALUES
MERCURY
OPERATION
PERFORMANCE
POLYMERS
POTASSIUM
RADIOACTIVITY
SAMPLING
SHIELDING
SOLIDS
STEELS
VOLUME
WIRES