Cosmic Ray Detector Experiments LBL 2015

Teacher                        High School

Purpose –The purpose of this experiment was for students to have hands on experience collecting & interpreting data from muon detectors. All students have had no previous experience using detectors. These detectors were supplied by Howard Matis of LBL.

Methods – After learning how to operate the detector, each of the 4 teams composed of 10 students, 2 teachers & a detector, choose one of the following investigations to determine the rate of flux of muon counts tilting the detector between 0 and 90 degrees from the horizontal.

There was a 5minute experiment of the paddles orientated horizontally, a 5 minute experiment of the paddles orientated vertically, and a 5 minute experiment orientated at approximately 45 degrees.

Data -   Orientation of paddles    Detector #1       Detector #2       Detector #3      Detector #4

                   Horizontal                       100                    78                 103                    78

Counts/

  Min.         Vertical                             23                     12                  23                      9

                  45 degrees                         70                      18                 72                     34

                   Shielding                         N/A                   N/A               87                     79      

Results  -  The data of each detector was written on the board & analyzed.  We discussed what causes the difference of these counts depending upon the orientation in a given detector.  Each group saw there was a much higher count when the paddles were orientated horizontally as opposed to vertically.  By seeing this difference it gave us confidence that we were detecting muons and not just electrical noise. There was also a discussion on why the two detectors had different counts. Then there was a detailed explanation on how voltage plays a role in the sensitivity of the paddles.  Too high of a voltage gives a runaway count, too low of a voltage gives no count.  Another detector was used to demonstrate when different voltages were applied to the paddles showing the difference of sensitivity to muon 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.

This activity gave the students a first-hand experience in understanding & working with particles. Working with detectors also helped the students understand the collection of subatomic particles on much larger scales such as in Sno+.

Further investigations could include different shielding materials, different elevations of detection, and different orientations such as East & West.