Cosmic Ray Detector Experiments LBNL 2017

Purpose –This experiment gave hands-on experience collecting & interpreting data from muon detectors. These detectors were supplied by Howard Matis of LBL.  Students had had no previous experience with the detectors.

Methods –Before working with the detectors, students viewed a video about special relativity & muon decay on their own.  The two hour formal session started with a 30 min power point presentation on what cosmic rays are and how we detect them.  Then, students were shown a high voltage gas detector.  Followed by a discussion, students were trained on how to use the detectors.  There were 9 groups comprised of 4 students and 1 teacher.  Each group had its own detector.  Each group designed a brief experiment.  These experiments ranged from tilting the detectors to get a different count to shielding experiments using different floors in a building. The experiment that most groups did was going to different levels of the building to see if the counts change due to shielding.    

Results -  Each group recorded their data and presented their findings informally. Because of time constraints, there was no formally written data shared with the entire group. Some groups did mention specific numbers of muon counts.  There was a discussion covering the causes of the difference in counts. Their counts in the upper floors of the building were more than the lower floors.

There was also a discussion on why the two detectors had different counts which lead to an explanation which covered the role voltage plays in the sensitivity of the paddles.  Too high of a voltage gives a runaway count, too low of a voltage gives no count. 

Meaning & future investigations - Cosmic rays have played a large role in the development of Particle Physics.  The muon as well as antimatter were first detected by cosmic ray investigations.  Students had also had a presentation on Cosmic Rays & the ICE Cube experiment. This activity gave the students a first-hand experience in understanding & working with particles and helped them make connections with larger research experiments. Further investigations could include continuing to study the different shielding materials, different elevations of detection, & the effects of magnetic fields on the detector as well as the earth’s magnetic field.  

Participating Teachers:

Participating Students