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Cosmic Rays
As I begin to research cosmic rays, I have found that they are muons that enter the earth's atmosphere at a heavy mass and high velocity. Other than photons, all particles have mass to varying degrees. This mass is measured by observing the pathway inside a detector, taking into account the particle's natural momentum. Physicists know that cosmic rays have a heavy mass, as the particles continue a relatively straight path through the magnetic field, as the kinetic energy pushes it in a straight line. In the CMS experiment, cosmic rays are giving researches extra data that is not desired. This can interfere with the data that they receive. Unfortunately, I was forced to miss the experimentation days after school, so I have instead been working online at the Many Eyes website to learn how to decipher these plots. It is essential to understand the coordinate system when deciphering the meaning of the graphs. Because the graphs must represent all dimensions, there are a few axes that are examined. I have been working with Many Eyes graphs, and I feel that I have been able to manipulate them such that they can show me where the cosmic rays exist in the data. It is a notable characteristic of cosmic rays that they enter the earth's atmosphere vertically, or at an almost vertical angle. Because of this, the axes in the CMS should shed light on the position of the atmospheric muons. Another characteristic of muons is their extreme force involved. They move at a much higher energy, which translates directly to the mass that they contain. Furthermore, this higher energy and mass forces these cosmic rays to move in a straight trajectory through the CMS detector. Based on the following principles of cosmic rays, they should be noticeable in the data by looking at and isolating these variables.

The first graph that I chose to observe is a graph of the mass of the particles. In this graph, the Y-axis is indicative of the Phi1 objective. This is like looking at the detector on the inside from the Z-axis. Looking at this, we can see the mass of the particles relative to the Phi1 coordinates. A clear trend in the data is in the fact that the heavier particles seem to stand out on the higher X-values. These larger masses I feel are the cosmic rays in this data. This would make sense with the notion that they are traveling at great velocities, as this would cause larger masses to result. Also, the position relative to the Phi1 axis is indicative towards them being cosmic rays. They gather at a value of -2.2 to 1.8 with just a few outliers. The next graph that I will display is where more conclusive evidence points toward the cosmic ray hypothesis. This is the graph again of mass on the X-axis, but instead of Phi1 on the Y, it is now Phi2. I noticed that this graph looks very much the same as the previous graph, which is significant. The Phi axis works in a way that uses trigonometric principles. The values measured are in relation to the basic unit circle, with pi radians meaning 180 degrees. Instead of continuing to 2pi radians to make 360, the Phi axis instead goes to negative pi, moving clockwise. This understanding means that Phi2 is looking at the other side of the Phi1 axis. Now, with that in mind, it is clear that this graph has similar properties. The larger masses are still located at the same range, but most importantly, positive instead of negative. In the first graph, they are concentrated slightly under zero at -.2 - -2.2, whereas the next graph shows them around .2- 2.2. This means that they moved through the detector at an almost straight trajectory, which means that they did not change course and move as do particles that are shed in events inside the detector. Because they are in a straight line, it is almost definite that these huge, fast particles are cosmic rays that are unwanted in the data.

The next observations that I chose to look at are in the Eta axes. A graph of Eta1 and mass follows:

John explained to me that Eta1 graphed on the Y-axis of the graph shows the perspective of the looking at the detector from the X-axis. Because of this, we can similarly note the trajectory of the particles, as well as the mass. In the previous graphs, we concluded that the heavier particles are cosmic rays, and I can still assert the same in this graph. Another trend we can see is that most muons generated in the detector are present at .5 to 2.3, or -.5 to -2.5. For similar reasons, the heavier particles are moving at greater speed, causing a linear trajectory, as can be seen by examining the next graph, with Eta2:

As we look at the X-axis, Eta2 should show a similar graph if the particles take a straight trajectory. A the particles move straight across the X-axis, they should show a similar Eta value, which they do. Concentrating at -1 to .8, the cosmic rays are moving uniformly across the Eta axis. Also, these particles have a mass of about 55 to 105 GeV, substantially larger than the masses of about 20 and below GeV. I further played around with changing the axes using Many Eyes, and found more evidence pointing to cosmic rays. Looking at the graphs both below and above, I found another way to similarly show the trends that I have noticed. Graphing on the X-axis Phi1 (above) and Phi2 (below), it is clear to see the areas of concentration of cosmic rays. In the range discovered earlier of around zero for Eta, and 1.8 for Phi2, we are displaying similar information, just in another way. On the Phi axes, the cosmic rays move from negative to positive, showing their linear path. Alternatively, the Eta axes both show the cosmic rays in the same range due to the nature of the axis as it moves across Eta. I have found that graphing the Mass has helped tremendously in isolating the cosmic rays, as the mass is a very big indicator of the nature of the particle.