Dependence of Muon Rate on Geographic Direction

(North, South, East, West)


            The experiment is to determine the rate at which muons are detected as a function of their North/South, East/West direction.  You are to rotate the apparatus in a horizontal plane through an angle of 180° while monitoring coincidences in the 3 detectors.  Realize that the telescope counts muons traveling in either direction, so you are detecting muons traveling in opposite directions at the same time. (How will you determine the direction of travel?)  (Will your results be affected by the Earth’s magnetic field?)



Mount the 3 paddles so that they can detect horizontally traveling muons, and so the paddles can rotate in a horizontal plane.  (How will you keep the distance and position of the paddles consistent?) 

Runs much less than several hours will be rather useless for this experiment, because there aren’t many muons traveling horizontally.  You will need to determine the length of time of the runs that will give you enough data to accurately interpret it.

After performing the first coincidence run you will need to rotate your entire apparatus and do another coincidence run.  Be sure that by the end of your experiment you have rotated the apparatus through 180°.  (Why don’t you need to rotate the apparatus through 360°?)



            Calculate the muon rates (# hits/time) and the uncertainty in the rates.  A way to present your results is to graph the muon rate as a function of the geographic direction, where 0° is North, East is 90° and so on.  Include the error bars for the count rates.

            Were there significant differences associated with the direction?  Were your results what you expected?  What are some variables that could have affected your results?