Liquid Scintillation Counting

Learning Goals

• Understand the theory behind Liquid Scintillation detection.
• Understand how the detection equipment of the Liquid Scintillation works.

PART 1

Introduction

Basically, the liquid scintillation process is the conversion of the energy of a radioactive decay event into photons of light in a liquid. Photomultipliers (PM-tubes) detect the emission of light and convert the light pulse into an electrical signal. The intensity of the light pulse (number of photons emitted) is proportional to the energy of the radioactive decay event. Further, the size (height) of the electrical pulse is proportional to the intensity of the light and, accordingly, also proportional to the energy of the decay event.

The electrical pulse can be handled in an electronic system, which measures its height and stores the events in an intensity-energy array, a so-called multichannel analyzer (MCA) system. Thus, an energy spectrum can be recorded of the decaying radionuclide.