WELLOG ENERGY LEVELS
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Many naturally occurring radioactive elements generate gamma rays. The gamma rays have energy levels measured in millions of electron volts abbreviated Mev or Thousands (Kilo) electron volts abbreviated Kev. A typical scintillation detector produces pulses having pulse heights that are proportional to the incident gamma ray energy levels.
Each radioactive element has a characteristic energy level.
Uranium 234 has an energy level of .093 Mev.
Bismuth 214 has an energy levels of .61 Mev, .77 Mev, 1.12 Mev, 1.76 Mev, 2.2Mev, and 2.4 Mev.
Potassium 40 has an energy level of 1.46 Mev. And no other peaks above this energy level.
Thorium has energy levels at 1.61 Mev, 2.20 Mev – the predominant energy level is at 2.62 Mev.
Note the uranium series has no peaks above 2.42 Mev.
PULSE HEIGHT ANALYSIS:
Due to the characteristic energy levels sown above, it is apparent that with the use of instrumentation that is capable of discrimination based on pulse height, that specific elements can be detected apart from others. Pulse height analysis is performed using electronic circuitry that measures the pulse height of incoming gamma rays and counts those that fit within a certain window. A pulse height window is established by setting the lower and upper limits for the desired energy levels. Pulses that occur within the set limits qualify and are counted. Gamma ray spectrometers perform this function using hundreds of energy channels. The result is a spectrum of gamma ray energies and a display of the quantity of each radioactive element that occurs within the boundaries of each channel.