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“Super Sweet Time Experiment” Alpha Decay’s Cosmic Ray Experiment Extravaganza Luke Salbert Chloe Zhang Lo-Hua Yuan Joe Rosenbaum
So…What Are Cosmic Rays Anyway? • Cosmic rays are subatomic particles that travel through space at high speeds with high energies. • Come from sources within our galaxy and beyond. (The origin of ultrahigh-energy cosmic rays is still uncertain). • Primary cosmic rays are ordinary nuclei that come directly from outer space (approx. 80% are protons; also some neutrons). • Primary cosmic rays collide with particles in earth’s atmosphere and create air showers of secondary cosmic ray particles—the majority of which we detect on earth’s surface being muons.
Purpose • To determine whether the time of day affects the amount of (secondary) cosmic rays sensed by our cosmic ray detector.
Hypothesis • If we measure at different times of the day then the amount of cosmic rays detected will not differ significantly. We hypothesize this because although we know cosmic rays can come from anywhere in the universe, we also know that the sun emits (via solar flares) some of those cosmic particles. However, due to the great distance between the sun and the earth and other factors (such as the earth’s magnetic field, solar wind, the extent of the sun’s contribution, etc), we do not think the amount of cosmic rays we detect will differ significantly based on the rotation of the earth.
Experimental Design • Materials: • Cosmic ray detector • A closed room without windows and at constant temperature • Laptop • Loggerpro/Labpro • Table • Some tape to mark where detector will be placed on table
Procedure • Place the detector in the control room in the center of the table. • Using tape, mark the table where the detector will be placed for all trials. • Check background radiation by placing the detector on its side so that the paddles are perpendicular to the table. • Collect data for 5 minutes at 1 minute intervals. • Reposition the detector so that the paddles are parallel to the table. • Collect data for 10 minutes at 1 minute intervals. • Once again, record background radiation by placing the detector on its side with paddles perpendicular to the table. • Collect data for 5 minutes at 1 minute intervals. • Repeat above steps every 4 hours
Legend for graphs • Trial 1: Wed 6 pm reading • Trial 2: Wed 10 pm reading • Trial 3: Thurs 2 am reading • Trial 4: Thurs 6 am reading • Trial 5: Thurs 10 am reading • Trial 6: Thurs 2 pm reading
Data Cosmic Ray Trials N U M B E R O F C O U N T S Time reading interval
Cosmic Rays Average Counts N U M B E R O F C O U N T S Trial Number
Average Background Radiation N U M B E R o F C O U N T S Trial Number
Cosmic Rays Adjusted(excluding background radiation) NUMBER OF COUNTS Trial Number
Results • Limiting ourselves to addressing only those cosmic rays produced by the sun, if the rotation of the earth did have an effect on the amount of cosmic rays detected, then we would expect to see fluctuations in our data. For instance, a decrease in counts during the night when the cosmic ray detector is farthest away from the sun and an increase in counts during the day when the detector is closer to the sun. • We do see a slight decrease in counts going deeper into the night and a slight increase in counts with the rising of the sun. However, the margins of error associated with each of our average cosmic ray counts are too great for us to reject that there was no difference in the amount of cosmic rays detected at different times of the day. • Furthermore, we see that there were actually more counts detected Wednesday at 6 pm and 10 pm than there were on Thursday afternoon at 2 pm.
Conclusion • Our hypothesis that the amount of cosmic rays we would detect would not differ significantly at different times of the day was shown to be true.
Error Analysis • Only collected data for 20 hours • If time permitted, we could have collected data for more cycles of days • Temperature in control room was not really constant throughout trials. • Very warm Wed 10 pm and Thurs 2 am • Not as warm Thurs 6 am and Thurs 10 am • Thurs 2 pm trial warmer and more humid than 6 am and 10 pm trials on Wed, but not as warm as Wed 10 pm and Thurs 2 am trials. • Weather conditions may have changed during the course of the experiment • We didn’t consider the different angles of the sunlight very explicitly.
Extensions • How would different weather conditions (ex. Air pressure, cloud cover, thunderstorms, snowstorms…) effect the amount of cosmic rays detected? • How would different positions on the earth effect cosmic rays detected? • Does being inside or outside a building effect cosmic rays?