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Background: From Wikipedia, the free encyclopedia
Liquid scintillation counting is a standard
laboratory method in the life-sciences for measuring radiation from beta-emitting nuclides. Scintillating materials are also used
in differently constructed "counters" in many other fields.
Samples are dissolved or suspended in a "cocktail" containing an
aromatic solvent (historically benzene or toluene, but more recently less hazardous solvents have come into favour) and small amounts
of other additives known as fluors. Beta particles emitted from the sample transfer energy to the solvent molecules, which in turn
transfer their energy to the fluors; the excited fluor molecules dissipate the energy by emitting light. In this way, each beta emission
(ideally) results in a pulse of light. Scintillation cocktails often contain additives that shift the wavelength of the emitted light
to make it more easily detected.
The samples are placed in small transparent or translucent (often glass or plastic) vials that
are loaded into an instrument known as a liquid scintillation counter. The counter has two photomultiplier tubes connected in a coincidence
circuit. The coincidence circuit assures that genuine light pulses, which reach both photomultiplier tubes, are counted, while spurious
pulses (due to line noise, for example), which would only affect one of the tubes, are ignored.
Liquid Scintillation Counter
Counting
efficiencies under ideal conditions range from about 30% for tritium (a low-energy beta emitter) to nearly 100% for phosphorus-32,
a high-energy beta emitter. Some chemical compounds (notably chlorine compounds) and highly colored samples can interfere with the
counting process. This interference, known as "quenching", can be overcome through data correction or through careful sample preparation.
High-energy
beta emitters such as P-32 can also be counted in a scintillation counter without the cocktail. This technique, known as Cherenkov
counting, relies on the Cherenkov radiation being detected directly by the photomultiplier tubes. Cherenkov counting in this experimental
context is normally used for quick rough measurements, since it is more liable to variation caused by the geometry of the sample.
Principles
and Applications of Liquid Scintillation Counting
Principles and Applications of. Liquid Scintillation Counting. A P. RIMER FOR. O.
RIENTATION. ¨C National Diagnostics Laboratory Staff. Principles ...
www.ehs.psu.edu/radprot/LSC_Theory2.pdf
Use and Preparation
of Quench Curves in Liquid Scintillation Counting
protocol. For other LSC¡¯s (1600,1900, 2100, 2200 and 2300) ..... correction in a
liquid scintillation counter. In Peng, C.T., Horrocks, ...
www.ehs.psu.edu/radprot/Packard_quench_curves_calibration.pdf
Liquid
scintillation counting - Wikipedia, the free encyclopedia
Liquid scintillation counting is a standard laboratory method in the life-sciences
for measuring radiation from beta-emitting nuclides. ...
en.wikipedia.org/wiki/Liquid_scintillation_counting
LIQUID SCINTILLATION
COUNTING
LIQUID SCINTILLATION COUNTING. Liquid scintillation counting is an analytical technique which is defined by the incorporation
of the ...
www.uwm.edu/Dept/EHSRM/RAD/HANDOUT.pdf
In the early 1950's, the first attempts were made
to detect 14C by the Liquid Scintillation (LS) counting method. In the 1940's, Broser and Kallman (1947) ...
www.c14dating.com/lsc.html
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Available Liquid Scintillation Resources (from PerkinElmer)