Finding the Direction of Cosmic Rays

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                                 Direction of Cosmic Rays

Date performed: April 25, 2006

Nicole Alimario

Zubaria Iram

Komal Majahid

Youstina Michael

Abstract

The objective of this experiment was to find the direction of cosmic rays. Basically we were looking at the number of coincidences for each position and whichever position had the highest number of coincidences over a certain time interval was where the cosmic rays were coming from.

Theory

The counter counted the number of coincidences for each position. When each position was changed, the number of coincidences would changed depending on the possibility of more cosmic rays coming from that direction or less. We used four minutes for the time interval because it fit the alotted time we had in the class for the experiment. Our theory was for this lab was that the number of coincidences would be highest from the direction of cosmic rays and lowest where the cosmic rays are perpendicular to the two scintillators.

Procedure

Introduction

Cosmic rays pheasibly affect a general given area from all different, possible directions. As we have learned, when cosmic rays approach the Earth from whatever source, upon striking the atmosphere of Earth a cascade effect of a showering of particles (among other things)occurs. Thus it is pheasible to conclude that the direction of a Cosmic Ray particle, based on an unknown source and the multitude of particles involved, is sporadic at best. However it is possible to determine the direction of perhaps a portion of this 'wave' of particles.

Materials:

2 scintillators

1 oscilloscope

1 scintillator 'place holding' apparatus

1 measuring tape

Method:

Taking four scintillators already established to be at a set distance apart (to be taken note of and held constant for this exercise), preferably a good deal of distance between the two devices, and utilize the oscilloscope to determine the number of particles passing through each scintillator. Taking note in particular of the numbers calculated by the oscilloscope that predict particles passing through both devices, we repeat the process but turn the scintillators in different directions and repeating the process. We will compare the number of coincidences in each position, and whichever postition has the highest number of coincidences will be the most favorable directions of cosmic rays. If there is time, the process should also be repeated with a variable set distance between the two scintillators to get a general feel for error.

Data:

(Data obtained over a period of four minutes per degree of angle measured.)

An angle of zero degree gave us 1118 coincidences, an angle of 22.5 degrees gave 1056 coincidences, an angle of 45 degrees yielded 490 coincidences, and a 90 degree angle yielded 40 coincidences. It is evident by the the graph and the data table above, that the number of coincidences decreased as the angle measure increased.

Conclusion

As the angle measurments increased the number of coincidences decreased. The most plausible reason for this is that the direction of most cosmic rays is from top to bottom in a straight line. There are some cosmic rays that come from different direction with angles other than zero degree. It is evident in our data that cosmic rays do come from different directions other than from the top, but they tend to be in smaller amounts. The 90 degree angle recieved coincidences, thus detecting cosmic rays, even if they were in a considerably small number.

Remarks

The wheel that was used to detect the direction of cosmic rays proved to be an efficient mechanism for the most part. As expected, it helped us to confirm the fact, proven by many scientists, that cosmic rays are directed from the top. Although the data collected poved our hypothesis, we would have collected a more accurate data by considering a large number of different angles. A graph of a straight line would have been a better observatin at the relationship between the angel size versus the number of coincidences. As seen in our data, the 90 degree angel detected the least amount of cosmic rays. Could this have been due to the distance between the scientillators? It might have been due to the position of these scientillators that we were able to detect cosmic rays coming from other directions other that the top.