PART V: Experimental Procedure

You will be given a sheet (PART VI) for recording your laboratory data and a piece of semi-log graph paper on which you can draw your graphs. Your T.A. will show you how to make the measurements. The procedure is as follows:

 

  1. Turn on the counter.

  2. Place the silver in the drum.

  3. Count the background for several 10-second intervals to get a rough idea of the rate.

  4. Count and record the background rate for four 100-second intervals.

  5. Remove the silver from the drum and place it near the counter. Begin timing (t = 0) as soon as you have the silver near the counter. Count decays for 30 ten-second intervals, taking readings during 1.5 second display intervals. Record each reading on the data sheet.

  6. Replace the silver in the drum.

  7. Repeat steps 4 to 6 four more times to obtain a total of five sets of readings.

  8. Calculate and record the total number of counts for each time interval on the data sheet.

  9. Calculate and record the average background for a 50 second interval from all of your background measurements. Subtract the background from the data and plot the result on the semi-log plot. Start the time axis at Interval 1 and continue for thirty intervals. Determine the range of the vertical (radioactivity) axis from the lowest and highest counts you measured. Label the axes of the graph.

  10. Draw a best fit curve through your data points. The curve should be straight at both early and late times.

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