LSC Analysis

There are several models of liquid scintillation counters in use at KUMC.  If you have never used this instrument and would like to learn how, please contact EHS for instructions.

Liquid Scintillation Counter (LSC) Theory of Operation:  In general, an LSC is detecting beta particles.  This is done indirectly.  When radioactive materials are placed in a vial containing liquid scintillation fluid, the emitted beta particles interact with the fluid to produce photons of light.  The photons of light are then multiplied and counted by the LSC.  The intensity of the light produced is proportional to the initial energy of the beta particle.

Each LSC is a little bit different; please consult the EHS Office, the Operating Manual, or other users if you need assistance performing this type of analysis.  Some things common to all LSC's are the following:

  1. Liquid scintillation counters have a very good counting efficiency for beta emitters -- on the order of 60 to 100% if an optimum geometry is chosen.
  2. Contamination on the outside of your sample vials can contaminate the inside of your LSC -- always make sure your samples are clean before placing them into the sample holders.
  3. Efficiency of detection can be adversely affected by anything that could block or change the light output:    
    • Don't block the light by writing on the vial. 
    • Don't fold the swipe so that the "dirty" surface is folded inside the swipe.
    • Try not to introduce any chemicals into the scintillation fluid.  This can result in false positive readings.
    • Bubbles in the fluid can lower the count by blocking the light output; allow the bubbles to settle out before analyzing the sample.   

Liquid Scintillation Counter

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