Liquid+Scintillation+Counting

Liquid scintillation counting is a method of measuring radioactivity. It was discovered by Samuel Curran in 1944 during his work with the Manhattan Project. This method uses a solution in a glass tube. The device is two sensors positioned on either side to measure flashes of UV light given off by electrons in flour molecules falling back to ground state.



This image shows the basic principles and system for scintillation counting. Two sensors pick up the light being emitted. The coincidence gate filters the data, and it is counted overall to get the data.

__**HOW DOES IT WORK**__

The sample to be tested is dissolved in a solvent with fluors. The sample will give off beta particles. These lose all of their kinetic energy rapidly. The energy is taken up by the solvent making the electrons excited. When the energy is passed to a fluor its electrons become excited, but when the energy passes the electrons fall back into ground state and release a photon. This UV light is then counted to get the scintillation value for how much radioactive material is in the sample.


 * __SETUP__**

The desired sample is dissolved in a solvent with the flours. This new solution will be placed in a clear tube. The probes that sense light be be located on either side and begin to monitor flashes of light given off by the electrons. A coincidence gate is used for a purpose close to how it sounds. It filters out potential background, or coincidental and not electron related, light that could affect the counting process.


 * __USES__**

This technique is often used in conjunction with others. However, on its own it is still very useful in a physical science setting. The technique can be used to test for radioactive chemical in water supplies. As an example a 2008 study looked at uranium content in surface water and ground water utilized by humans to determine if it could be used as an alternative test ( S. Antoniou, A. Tsiali, and I. Pashalidis, 2008). However in cell biology it can be used to test for results. By marking a molecule with a radioactive tag it is possible to measure the presence of it in a liquid scintillation tube, This can help determine if an end product is present of not. Researchers have used this technique for examining extraction of drugs from blood cells and plasma (Altun and Abdel-Rehim, 2008) as an example of biological, even cell biological usage.

__**References**__

Altun, Z., & Abdel-Rehim, M. (2008). Study of the factors affecting the performance of microextraction by packed sorbent (MEPS) using liquid scintillation counter and liquid chromatography- tandem mass spectrometry. //Analytica Chimica Acta//, 630(2), 116-123.

Antoniou, S., Tsiaili, A., & Pashalidis, I. (2008). Alpha radiometry of uranium in surface and ground waters by liquid scintillation counting after separation of the radionuclide bycation exchange. Radiation Measurements, 43(7), 1294-1298.

Hebrew University of Jerusalem. (2009). The Beta-counter. http://departments.agri.huji.ac.il/zabam/beta.html.