The objective of this practical course is to provide students with hands-on experience in Nuclear Instrumentation. You will learn to operate the Geiger-Muller (G.M.) Counter, handle radioactive sources safely, and analyze the interaction of radiation with matter.
Before performing any experiment, the Operating Voltage of the G.M. counter must be determined. This is done by plotting the Counting Rate vs. Applied Voltage.
Radioactive radiation from a point source spreads out equally in all directions. This experiment verifies that the intensity (I) of radiation is inversely proportional to the square of the distance (d) from the source.
Procedure: Record the counts for a fixed duration at varying distances. Plotting 1/√(Counts) vs. d should yield a straight line.
Gamma rays are attenuated as they pass through materials like lead or iron. The reduction in intensity follows an exponential law.
Where I0 is the initial intensity, x is the thickness of the absorber, and μ is the Linear Absorption Coefficient.
Unlike gamma rays, beta particles have a finite range. This experiment determines the Mass Absorption Coefficient and the range of beta particles in Aluminum (Al) foils. It helps in understanding the energy of the beta source.
The Dead Time is the short interval of time after a count is recorded during which the counter is "incapable" of responding to another radiation particle.
Radioactive decay is a random process. This experiment involves taking a large number of readings for a source with a long half-life to verify the Poisson Distribution or Gaussian Distribution of the counts.
Tip: Always check the Slope of the Plateau. A good G.M. tube should have a plateau slope of less than 5% per 100V. If the slope is too steep, the tube may be near the end of its life.