Absorption of Gamma Rays - Ryerson Department of Physics

N1-4the blocker. Repeat this for multiple layers of lead up to four sheets. Record the thickness ofeach lead sheet using a micrometer.6. Repeat step 5. for copper and aluminum. Note: for each of these materials n 0 will besame as the value recorded in step 3.7. Return the 137 Cs source to your lab demonstrator and sign out a 60 Co source. Repeatsteps 3. and 4. for the 60 Co (i.e. lead only).8. Return the 60 Co source to your lab demonstrator. Remove all the blockers from thedetector cavity and take three one-minute counts for the background radiation.9. Turn down the high voltage to zero and turn off the scaler timer.AnalysisTake the average of each set of three counts per minute. Subtract the background average fromeach average to correct for background radiation. Plot all the results on a single graph page,plotting the natural logarithm of the average counts/min against the absorber thickness incentimetres. Draw the best straight line through the points for each material. The slopes of theselines are the linear absorption coefficients. Look up the densities of the absorbing materials used.Divide each of their linear absorption coefficients by the appropriate density in g/cm 3 . The resultis called the mass absorption coefficient. Compare the results for each absorber and comment.Also compare the results for lead using the different sources and comment.