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 Base Count (Bottom Paddle) Reading 1 7611 counts Error 87 counts
Average
7937 counts
139 counts
Base Line Reading (Set 1)
Reading 1
3174 counts
Error
56 counts
Reading 2
3018 counts
55 counts
Reading 3
2951 count
54 counts
Average
3048 counts
Reading with 25 Watt Light Bulb
Reading 1
3080 counts
Error
55 counts
Reading 2
3021 counts
Reading 3
2998 counts
Average
3033 counts
20 counts
Reading with 75 Watt Light Bulb (Bottom Paddle)
Reading 1
7794 counts
Error
88 counts
Reading 2
7704 counts
Reading 3
7803 counts
Average
7767 counts
26 counts
Reading with 60 Watt Black Light (Bottom Paddle)
Reading 1
7779 counts
Error
88 counts
Reading 2
7803 counts
Reading 3
7892 counts
89 counts
Average
7825 counts
28 counts
Reading with 75 Watt Light Bulb
Reading 1
26385 counts
Error
162 counts
Reading 2
26186 counts
Reading 3
7252 counts
85 counts
Average
19941 counts
5181 counts

13. Data Base Count (Counter 2) Reading 1 3214 counts Error 57 counts
Average
3481 counts
114 counts
Reading with 75 Watt Light Bulb (Counter 2)
Reading 1
2991 counts
Error
55 counts
Reading 2
2488 counts
50 counts
Reading 3
2837 counts
53 counts
Average
2772 counts
121 counts
Reading with 60 Watt Black Light (Counter 2)
Reading 1
3311 counts
Error
58 counts
Reading 2
3605 counts
60 counts
Reading 3
3126 counts
56 counts
Average
3347 counts
114 counts

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