ABSOLUTE ACTIVITY MEASUREMENTS

Journal Article · Tue Oct 01 04:00:00 EDT 1963 · Atomwirtschaft (West Germany) Changed to ATW, Atomwirtsch., Atomtech.

OSTI ID:4144837

Ramthun, H

Absolute measurement of activity and preparation of standard activities of radioisotopes in common use are discussed. The introduction of the 4 pi - counter represented an essential step forward in the technique of these measurements. These counters are equally suitable for use with alpha and beta emitters. The radiation absorption is kept as low as possible by a special technique of preparing the samples. Thin aluminum rings having low radiation absorption serve as specimen carriers, with a plastic foil about 0.0001 mm thick stretched across the central opening. A droplet of the radioactive solution to be measured is introduced on to the center of the foil, weighed and the liquid evaporated. In the main, differential gas counters are used for the absolute measurement of low energy particle emitters such as H/sup 3/ and C/sup 14/. In this case the radioisotope concerned is mixed, in the form of a gaseous compound, with the counting gas so that no absorption correction is involved. There is no need to know the absorption correction in activity measurements by the coincidence method. This is applicable if at least two particles are simultaneously emitted for each nuclear disintegration. Beta-gamma coincidence counting is the most frequently used. In the case of large source strengihs microcalorimetric methods may be used to measure activity. Here the total radiation, or a known fraction of it, is absorbed in the calorimeter wall and is ultimately converted into heat. The thermal power can be determined with accuracy by comparison with the Joule heating produced by an electric current. Powers as low as 10/sup -7/ w can be measured in the differential calorimeter. (auth)

• Research Organization: Physikalisch-Technische Bundesanstalt, Brunswick
• NSA Number: NSA-18-002101
• OSTI ID: 4144837
• Journal Information: Atomwirtschaft (West Germany) Changed to ATW, Atomwirtsch., Atomtech., Journal Name: Atomwirtschaft (West Germany) Changed to ATW, Atomwirtsch., Atomtech. Vol. Vol: 8; ISSN ATWSA
• Country of Publication: Country unknown/Code not available
• Language: German

Related Subjects

ABSORPTION
ALPHA PARTICLES
ALUMINUM
BEARINGS
BETA PARTICLES
CALORIMETERS
CARBON 14
COINCIDENCE METHODS
CONVERSION
COUNTERS
CURRENTS
EVAPORATION
FOILS
GAMMA RADIATION
ISOTOPE TECHNOLOGY
MEASURED VALUES
POLYMERS
PREPARATION
RADIOACTIVITY
RADIOISOTOPES
SOLUTIONS
STANDARDS
THERMAL RADIATION
TRITIUM