Liquid scintillation systems

Several papers present reviews of measurement methods or improvements in existing methods. Yamashita et al. (1987) present the description of a portable liquid scintillation system that can be used for thoron (Rn-220) as well as radon (Rn-222) in water samples. Thoron measurements have not been made for houses where radon in water may be a significant source. Such an instrument could be useful in making such determinations as well as in studying geochemical problems as described in this report. A review of measurement methods by Shimo et al. (1987) and of development and calibration of track-etch detectors (Yonehara et al., 1987) are also included. Samuelsson... 

Figure 5. Cross section of a scintillation vial illustrating a system for counting nsI in a liquid scintillation system.

The deposition of polonium on metal wires gives rise to a useful a-source. Tips of metal wires having a length 10 mm and a diameter of 0.2 mm were utilized. They were made of Al, Ni, Pd, Pt or An. Each was immersed in 100 pi of a solution containing °Po (300 Bqml ) for 15 h at 27°. Alpha particle emission was measured using a liquid scintillation system. There was an observed diminution in the a-pulse spectra for all of the wires except Al. This was attributed to the mutual diffusion between the wire metal and °Po. The °Po deposited on the Al wire had a tendency to be eluted with the liquid scintillator. This was attributed to physical absorption on the porous metal oxide layer on the Al wire and °Po. The °Po deposited by the Al wire had a tendency to be eluted with the liquid scintillator. It was possible to prepare a °Po -Al wire as a useful a-source by heating at 120° for 30 minutes. 

Liquid Scintillation Systems, LSS Neutron Counting Systems, NCS Direct-Current Plasma Optical Emission Spectrometry, DCP-OES IR Spectroscopy (e.g. FTIR)... 

Samples for liquid scintillation counting consist of three components viz. (1) the radioactive material, (2) a solvent, usually aromatic, in which the radioactive substances is dissolved or suspended, and (3) one or more organic fluorescent substances. Components (2) and (3) make up the liquid scintillation system. The P particles emitted from the radioactive sample (most of the radioisotopes used in biochemical research are P emitters) interact with the scintillation system, producing small flashes of light or scintillations. The light flashes are detected by a photomultiplier tube (PMT). Electronic pulses from the PMT are amplified and registered by a counting device called a scaler. 

Breakdown in control and stability of the immediate detector environment with regard to cleanliness, temperature level, power supply, and radiation background interferes with reliable radiation detector operation. Electronic components function best at a cool, constant temperature in a dust-free environment. Special low-temperature and power-supply-stability controls are needed to stabilize the response of gamma-ray spectrometers and liquid scintillation systems. 

Three liquid-scintillation systems have been used (i) a 4tt3(LS)-y coincidence system, which employs a hemispherical cell placed above a single phototube fLucas et aJ., 1977),... 

Urinary cAMP was analyzed by mean of cAMP assay kit (Radiochemical Centre Amersham England). Samples were added to a liquid scintillant mixture (Instagel, Packard) and counted in a liquid scintillation system Unilux I Nuclear Chicago C 6850- (Normal range in our laboratory is 1440 - 4500 nmoles/24 hours) (8). 

For beta particles with greater than 0.26 MeV of energy traveling through water, Cerenkov radiation is emitted. This can be counted in a liquid scintillation system and has the advantage of simple preparation. No other particles or photons will be detected. 

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