The Effect of Artificial Lighting on a Cosmic Ray Detector

1. The Effect of Artificial Lighting on a Cosmic Ray Detector

2. The Fluorescent Starbursts on a Black Background Nasser Al Buloushi Jillian Avalon Graden Barnes Renee Batzloff Teacher: Tom Brestel

3. Background The purpose of a photomultiplier tube is to amplify light so that it is easier to detect. In a cosmic ray detector, photons emitted by the excited electrons from the scintillator are sent into the tube, and hit the photocathode, a plate coated with a light-sensitive material. When the photons strike the plate, electrons are produced. These electrons travel back and forth through the tube, hitting the plates, and colliding with each other, producing more electrons and photons. This activity continues until there is enough electrons to create a signal large enough for the detector to sense.

4. Background Due to the sensitivity of photomultiplier tubes, phototube noise is created. This occurs when an outside source excites electrons producing a signal, and essentially deceiving the cosmic ray counter, which causes the count to be higher. To minimize this noise, two scintillator paddles are used “in coincidence” , meaning that the particle must pass through both scintillators in order to register.

5. Objective To see how much artificial light affects the amount of cosmic ray counts.

6. Hypothesis An outside light source will cause the photomultiplier tube to increase the cosmic ray count.

7. Materials Cosmic Ray Detector Artificial Light Source Light Bulbs of Varying Wattage Aluminum Foil Cardboard

8. Procedure • Obtain a Cosmic Ray Detector • Set the detector to the following settings- upper single, infinite count, count mode. • Under room light, turn on the detector for 10 minutes, and record the cosmic ray count. • Repeat 2 more times , then calculate the baseline average.

10. Procedure 5. Set up the light so that it shines directly on the upper scintillator. 6. Cover the lamp shade with aluminum foil. 7. Before turning on the detector, let the lamp run for a few minutes. 8. Turn on the detector, and after 10 minutes, record the cosmic ray count. 9.Repeat 2 more times. Change the bulb every 3 trials.

12. Data

13. Data

14. Error Analysis

15. Error Analysis As you can see from the previous graph, the 75 watt bulb seemed to have a huge impact on the scintillator. However, when our group tried to confirm our results, we realized we had run into a systematical error, and the Cosmic Ray Detector was giving us inaccurate results. Based on our data, and background information, we made the logical conclusion that the heat from the light bulbs changed the sensitivity of the Cosmic Ray Detector.

16. Error Analysis When our group compared the error range of the base line readings and the trials with lights on the cosmic ray detector we found that the error ranges overlapped. Based on this information, we can make the conclusion that the light did not have as much of an effect as we had first thought.

17. Conclusion After analyzing the data, we believe that it proves inconclusive as to the effects of artificial lighting on cosmic ray detectors. However, based on our data, and background information, we have come to the logical conclusion that heat has a major effect on cosmic ray detectors. This is most likely what caused the systematical error we ran into.

18. The Fluorescent Starbursts on a Black Background