The Cosmic Effect - An Adventure in the Process of Experimentation and Data Analysis
The Adventure - Overview
This site and its contents serve as an interactive archive of a journey through the process of experimentation and data analysis using the Lawrence Berkeley National Laboratory's Cosmic Ray Detector.
Over the course of multiple experiments, the data collected was used to analyze both the nature of cosmic particles and the nature of the detector itself as a data collecting instrument.
Note: Diagram not to scale.
Note: Although only one area of cosmic particle detection is shown, cosmic particles can be detected regardless of the direction they travel through the scintillators.
Note: The area of detection shown only applies when the detector is running in coincidence mode (see next section).
What is the detector, and how does it work?
Two paddles - called scintillators - are placed parallel to each other. Each scintillator is connected to a photomultiplier. When a cosmic particle passes through a scintillator, it causes a release of a photon, which the photomultiplier detects. This energy is then converted to an electric current that, once amplified by the photomultiplier, is strong enough to be interpreted by the breadboard of the detector (not shown) (Twitty et al, "Guide to Using the Berkeley Lab Cosmic Ray Detector").
For more details, see pages two and three of https://cosmic.lbl.gov/documentation/UsingtheDetector.pdf.
The Detector - Data Collection
The Cosmic Ray Detector may collect data in one of three ways using its two scintillators.
Coincidence Mode: The detector looks for instances that occur in each scintillator within the allowed time frame of 800 nanoseconds. This mode is the most reliable as it reduces the effect of phototube noise (the systemic error caused by the photomultipliers). The detector only records the detection of a cosmic particle if an instance occurred in both scintillators within this time frame (Twitty et al, "Guide to Using the Berkeley Lab Cosmic Ray Detector").
For more details on phototube noise, see page three of https://cosmic.lbl.gov/documentation/UsingtheDetector.pdf.
Upper Single Mode: The detector registers any and all instances that occur in the upper scintillator with no restrictions. This method of detection is susceptible to the systemic error caused by phototube noise (Twitty et al, "Guide to Using the Berkeley Lab Cosmic Ray Detector").
Lower Single Mode: The detector registers any and all instances that occur in the lower scintillator with no restrictions. This method of detection is susceptible to the systemic error caused by phototube noise (Twitty et al, "Guide to Using the Berkeley Lab Cosmic Ray Detector").
Details regarding the Experiments Conducted
Chi Squared per Degrees of Freedom: In the following experiments, the chi squared per degrees of freedom values (a measure of how accurately a trendline represents a data set) were calculated based off of an error definition specific to the form of data collected (counts). Refer to the following page to view how margins of error and the chi squared per degrees of freedom values were calculated.
Heading Definition relative to Detector Orientation: In the experiments conducted, headings were recorded. Since the detector's heading may be defined in multiple ways, refer to the following page to view how it was defined in the following experiments.
The Adventure - Launch!
Begin your adventure to explore the nature of cosmic particles and the workings of a cosmic particle detector with a digital tour of experiments and graphs, or select an experiment from the archive to view!
Conclusion and Acknowledgements
See the Conclusion and Further References page for more information regarding the detector.
Thanks to Howard Matis, Ph.D. for his assistance and guidance regarding the use of the detector and for his generosity in lending the detector itself.
Thanks to Eugene Mizusawa, Ph.D. for designing and organizing The Athenian School's internship program.
Thanks to Glenda Zarbock and Noreen DiMaggio for their assistance in transporting the detector.
About the Author
This website was designed by Radman Zarbock as the final report for his March 2019 internship project. The Athenian School's internship program was started by Eugene Mizusawa, Ph.D. when Radman was a sophomore. Radman participated in the program the first year it was offered, working as the intern of Howard Matis, Ph.D. of Lawrence Berkeley National Laboratory and studying particle physics. He used one of the portable LBNL Cosmic Ray Detectors to conduct experiments and learn firsthand about the nature of cosmic particles. This website acts as both an archive of his work and an interactive database that other passionate learners may use to explore the methods of experimentation and data analysis.
Twitty, Colleen and Howard Matis. "Guide to Using the Berkeley Lab Cosmic Ray Detector." LBNL. Published August 2002. Accessed 29 March 2019. https://cosmic.lbl.gov/documentation/UsingtheDetector.pdf.