Abstract

The objective of this study was to determine if there was any correlation between time of day or night and muon flux, with a particular focus on the effects of the day-night cycle on muon flux. The study was done by analyzing graphs generated when a flux study was run for the dates of July 11, July 25, and July 27 2010 UTC time, or from 1800 military time to 1800 military time  on July 10-11, 24-25, and 26-27 2010 for local time at Garland High School, where the data was collected. The data showed a slight and generally constant increase in the flux for the muons in the typical daylight period, which is generally from about 0700 military time  to 2000 military time. This seems to indicate a slight increase in muon generation in daylight hours and therefore some sort of correlation between daylight and increased muon generation.

Introduction

The purpose of this lab is to determine the relationship between the local time (independent variable) and the number of cosmic rays being detected, or the flux (dependent variable). Flux, the events per meter² in 60 seconds in this case, is thought to be lesser in the night than in the day because the sun is a major source of cosmic rays (which are typically protons) and the heliosphere prevents many interstellar cosmic rays from entering the solar system and entering the Earth’s atmosphere.

Procedures

1.) gather data which was collected over 24 hour periods of time, with data which is compared being from the same location--in this case, from Garland High School at Garland, Texas for July 11,25, and 27 2010 UTC.

2.) run a flux study on the data, in this case with bin size of 3600 and create a graph of the flux vs time

3.) analyze the graph, converting the time values to local time for the location of data collection, and looking for trends which might indicate correlation between time of day and muon flux

Results

The data showed a small but generally constant increase in muon generation during daylight hours when compared to night hours. This suggests that daylight increases muon generation. The dip in muon generation during daylight in the July 10-11 data, however, indicates that other factors might cause muon generation, though it still seems that daylight generally increases generation of muons. 

Discussions & Conclusions

The hypothesis stated that fewer muons would be detected during night, because of a fewer numbers of sun rays directly hitting the earth. This, when combined with the shielding effect of the heliosphere from galactic cosmic rays, supposedly would be able to reduce the amound of cosmic rays hitting the earth, which would reduce the number of muons detected on the surface of the earth.  

  This experiment seems to support this hypothesis, showing generally a slightly higher generation of muons in the daylight hours of 0700 to 1800. However, the data might not be totally consistent with the hypothesis, as some uncontrollable factors, such as solar flares and other possibly random events. The sudden drop in muon detection on the July 11 graph, for example, indicates some random event which reduced the generation or the detection of the muons.

  The uncontrollability of the atmosphere and galactic energy discharges makes it nearly impossible to find conclusive results for this lab with the available materials, and thus renders the results slightly ambiguous.

Extensions:

Testing over consecutive 24 hour periods could have better represented the data analyzed in this experiment, as a sinusoidal curve would have resulted if our hypothesis were indeed correct.

Bibliography

* Flux Study plots and data. Retrieved from http://www18.i2u2.org/elab/cosmic/analysis-flux/ on 13 December 2010.

**Weather data. Retrieved from http://www.wunderground.com/history/ on 11 December 2010.