Life to Death: A Lifetime Study of a Muon

1. Life to Death: A Lifetime Study of a Muon By: Adam Blake, Ben Orkiszewski, Sarah Watzman, Ben Zerhusen AFFILIATED WITH THE UNIVERSITY OF CINCINNATI RESULTS BACKGROUND MATERIALS AND METHODS • COSMIC RAYS • Originate from the sun and deep space • One cosmic ray hits in a square centimeter every second • Often break apart in Earth’s atmosphere and decay into smaller particles in an event called showers MUONS • A muon is just a heavy electron • The half-life of a muon is 1.5 microseconds, which is much too short to observe from the surface of the Earth • Due to its lack of stability, the average lifetime of a muon is only 2.2 microseconds • Time dilation allows us to observe the lifetime of muons rather than the shorter half-life • MATERIALS • 3 home-made scintillator panels • - plastic • - photo multiplier tubes (PMT) • - black electric tape • - toilet paper role • DAQ interface card • Three-tier wooden stand • Computer equipped with HyperTerminal • QuarkNet database • METHOD • Assemble three scintillator panels. • Stack the scintillator panels vertically on the wooden stand roughly 0.5 meters apart. • Connect the cables to the DAQ interface card and the HyperTerminal. • Turn on the HyperTerminal program and run a new study for sixteen days (we ran it December 3, 2007, through December 18, 2007). • A) For December 3, 2007, to December 5, 2007, we used two panels to collect data. • B) For December 6, 2007, to December 18, 2007, we used three panels to collect data. • 5) At the beginning of each day, save the data from the previous day and start a new study. • 6) The HyperTerminal collects the data and the QuarkNet database compiles the data. Our results were lower than the accepted value, disproving our hypothesis. When analyzing the data, we varied the bin value between 5 and 40 and the width of the gate from 1e-5 and 1e-4 seconds. By changing the parameters of the data, we were able to observe lifetime values ranging from .71 microseconds to 1.19 microseconds. The bin number dictates the number of data points used on the graph, so the lower the bin number the fewer the data points used. When less data points are used, the curve fit is more accurate so the lifetime value obtained from this graph will be more accurate as well. Yet if more data points are used, the curve fit will be more precise so the lifetime value obtained will be more precise. Therefore, we considered the lifetime values found using both high and low bin numbers, ranging from 5 to 40. CONCLUSIONS PURPOSE AND HYPOTHESIS The purpose of our experiment was to verify the accepted value of the lifetime of a muon, 2.2 microseconds. We believed the value for the lifetime of a muon which we would obtain from our experiment would be close to the accepted value of the lifetime of a muon, within 0.1 microseconds. Due to the difficulty of obtaining the accepted value for the lifetime of a muon (2.2 microseconds), we analyzed the data by varying the gate width and bin number. Our methods were not as accurate as we had hoped because of the nature of our scintillators: they were thin, preventing the muon from decaying within one single panel. A more efficient system would have used significantly thicker scintillator panels, increasing the chances that the muons would decay within a single panel. Bin Number: 120; Lifetime: 0.718 microseconds Bin Number: 5; Lifetime: 0.936 microseconds