Experiment 1 Hints

This page contains hints and suggestions for running Experiment 1 -- Measuring the zenith angle distribution for incident muons.

Last update: 10 October 2003

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  • If you have never operated this apparatus before, set it up in your home or in a corner of your classroom where it can run undisturbed for a day or more while you become familiar with its assembly and operation.

  • To get a good angular distribution, be prepared to operate the detector at several different orientations, including 0-degrees (pointed straight up vertically), 90-degrees (pointed toward the horizon), and as many intermediate angles as possible. Depending on your situation, consider the following angle sets: (0, 30, 60, 90 degrees) or (0, 15, 30, 45, 60, 75, 90 degrees).

  • Aligning the protractor accurately can be done as follows:
    1. Set up the telescope on a level floor and make sure the protractor is mounted securely on the front of the telescope stand just behind the wing nut.
    2. Using a foot of ordinary sewing thread (or equivalent), make a 1-inch loop in one end and slip that over the wing nut holding the telescope's rotating arm. Now tie a small weight to the dangling end of the thread (a small nut will do). The thread should be dangling in front of the protractor.
    3. Orient the telescope horizontally by using a ruler to measure the distance from the floor to the bottom of the plywood scintillator/photomultiplier support. When both measurements are equal, you have achieved an accurate horizontal orientation.
    4. Rotate the protractor until the string passes along the 90-degree mark. Voila! You have now calibrated the protractor position and you have a method for accurately reading the angle of the telescope.

  • Statistics is an important aspect of "counting experiments" such as this one. The more counts you get, the smaller the fractional error will be. Consider taking data at each angle overnight. You can take a reading during class, adjust the angle and start collecting the data for the next point in about one minute. By the end of the week, you will have a good sample of data to analyze.

  • There are several handy Windows applications that can help with this experiment:
  • Excalibur 32-bit calculator by David Bernazzani, freeware, (http://www.geocities.com/dbergis/freeware.htm, or search on Google) - this is an RPN calculator that includes a full range of scientific functions and hexadecimal to decimal conversions (useful for converting the 4-digit hex scaler on the logic board)
  • MultiTrack Stopwatch by Morimoto Shouji, freeware edition, (http://www2.neweb.ne.jp/wd/morimoto/en/) - this is a 10-channel stopwatch and is useful for timing the data periods of the experiment (although if you run overnight to collect data, reading the wall clock for start and stop times is sufficiently accurate - if you read it carefully).
  • Excel, OpenOffice or some other spreadsheet can also be of use for recording the data, performing the data analysis and even plotting the results.


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