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=Compact Muon Solenoid Particle Physics=

CMS physics is a field in which physicists are working with a Large Hadron Collider (LHC) and many advanced detectors in an attempt to answer questions about the universe, regarding both the earliest history, and the present composition.

CMS Questions/Areas of Interest
One sought after question is the support for the Higgs boson. Historically, the Higgs boson explains the hypothesis that particles immediately after the Big Bang contained no mass, and it was the creation of the 'Higgs field' that resulted in particles with mass. In fact, this Higgs field exists all over the universe, and the interaction of particles with this field is what gives them mass. With the LHC, physicists hope to discover and pinpoint the exact mass in which the Higgs field exists, which would support the hypothesis that this field caused particles to have mass. CMS scientists are also searching for an answer to the questions about the nature of dark matter. With 23 percent of the universe estimated to be dark matter, it is certainly considerable. Predicted to be supersymmetric particles, dark matter could be better understood, or even found, using CMS particle physics. This particle that contributes such a great deal of mass to the universe is understood little, thus physicists are interested in learning more about it. Another goal of CMS research is the better understanding of dimensions. As Einstein theorized in his string theory, more dimensions do exist, and CERN is working to perhaps show that such a theory can be displayed with evidence. In trials done with great amounts of energy, as Einstein predicted, it is hopeful that particles may escape the dimension of space, and advance into other spectrums. This extreme energy put into particles may do just that.

The detector used in the CMS experiment is designed in a way such that it can detect the muons as they alter course due to extreme magnetism up to 100,000 times that of the earth. This magnetism allows the change in course to be recorded, and its affects on the mass allow physicists to understand what kind of particle they are looking at. With a detector of such capabilities, it is possible to detect accelerated particles, which is what gives rise to research in finding the correct mass, say, for instance, the Higgs boson. With a mass so precise, the Higgs boson is trying to be pinpointed, and the detector is what may allow for that mass to be found, due to the manipulative capabilities of mass and magnetism.

CMS Detector
The CMS detector is configured in sections of different materials that all serve different purposes. Able to detect momentum and particle direction, their transmissions can shed light on the type of particles passing through. Different particles penetrate the detectors differently. The great size of the CMS detector is necessary in carrying out the experiments. In fact, the detector is 21 meters long, 15 m tall, and 15 m wide. This size is necessary due to the intense energy carried within the particles as they move through. Over 12,000 pounds of iron is used in stopping the remaining energy from escaping. This long, cylindrical, and thick shape is necessary in recording the pathway, momentum, and penetration of each particles as it leaves the LHC. A further explanation of the design and function of the CMS detector will proceed.

The CMS detector consists of a great deal of parts and layers. The first, inner layer of the detector is called the silicon tracker. Comprised of 13 layers in the central region, and 14 on the endcaps, the silicon tracker also has 205 square meters of silicon sensors, which accomplish its designated task. This, like other trackers, is designed to record the curvature of the particles as it passes through. In recording the curvature, the momentum is calculated due to the designated magnetic force applied to each particle. All tested and recorded particles penetrate this layer, as only direction is recorded at this point. The next layer of the CMS detector is called the Electromagnetic Calorimeter (ECAL). The ECAL measures the energy contained in electrons and photons, as it absorbs them while conveying their momentum. This is the job of a calorimeter. Particularly in this calorimeter, lead tungstate plays the role of further layers that absorb the electrons and photons. The hadronic calorimeter is next in the CMS. The role of this type of layer is to note the energy of hadrons, which are produced each experiment. In addition, this area keeps track of the particles that are constructed of quarks, most notably protons and neutrons. Whether or not the particles (hadrons in particular) are charged, this calorimeter will record the pathway, and neutral hadrons will be absorbed on a straight course, while the magnetic field alters the course of any hadron with a charge. To absorb these particles, the hadron calorimeter is built of dense materials, often brass or steel. The CMS detector is known to be able to detect muons. Muons are particles almost identical to electrons, but around 200 times heavier than both electrons and positrons. Because of these properties, muons are not hindered by any calorimeters, and instead penetrate to the end of the detector. The muon chambers record when they are hit by the particle. As it moves across the waves of muon chambers, a curve is created based on the locations that the particle crosses the chambers. The 1400 muon chambers that are constructed around the outer edge record the momentum by the muon's curve the same way that previous layers measure. The last topic of analysis is the magnetic system in the CMS detector. The magnet is a solenoid magnet that is used to put curve on the particles as they pass through. By analyzing the curves, momentum is equated. A slower momentum yields a greater curve. This magnet is basically the heart of the detector, and the remaining parts are centered around it. The coiled wires inside are superconducting, while supplying a uniform magnetic field across it all. WIth a power of 4 Tesla, the magnet supplies 100,000 times the force as Earth's gravity. This makes it the largest superconducting magnet in the world.

*July 4th Higgs Boson Update*
As of July 4th, 2012, CERN reported that a new particle had been detected. This news is more than exciting, as it is consistent with the theorized Higgs boson. With a mass 132 times that of a proton, this particle is truly unique, and is undoubtedly a boson. With such overwhelming evidence, this new particle has been prepared in the very recent past for publication in the Physics Letters B Journal, officially instituting this discovery as a scientific breakthrough. Because this is still in the very early stages, and within the recent hours, has been officially published, more testing will need to be done to find for certain the complete role of the Higgs boson in the creation of the universe.

Properties of Protons
Protons are made of quarks, which comprise all hadrons, but the proton and neutron is the most stable hadron known. Along with quarks, gluons and antiquarks, the quarks move around the inside of the proton at speeds almost reaching the speed of light. Inside the LHC, the chaotic proton reacts with residual nuclei from the atoms inside the beam pipe. As protons are lost from the atoms inside, they collide together, casting off radiation as they spread and disperse their particles throughout the detector. The primary interactions inside the LHC describe this process of shedding the protons through counter-rotating beams that lead to the eventual collision of two protons. In addition, the properties of protons lead more to the reactions that occur. For example, protons have spin, while other particles may have orbital angular momentum, like electrons. This spin means leads to the likelihood of two protons colliding greatly increase. Two protons that both are spin up are about 4 times more likely to collide than two protons of spin down. The tiny protons, though seemingly simple in many books and summaries, contains depth that is intrinsic to the core of the proton itself.

Particle Detection
By the design of the CMS detector, particles can be detected even if they are not specifically being observed. With the multitude of layers, various calorimeters, and the inclusion of muon chambers, any particle that may be moving through the system will beabsorbed somewhere along the lines. The only particle known to travel to the edge of the CMS detector is the muon, and it is then absorbed into the multiple tons of iron which surrounds. In particular, during experiments, cascades of SUSY particles are picked up on the detector. This is because the final decay products that are made are pairs of leptons. Although not aiming for leptons, they show up as the final of each experiment, and channel through the detector so that they may be observed.

Z Particle Decay Events
The decay of Z particles are watched very closely in the events that take place in the LHC and CMS. By looking at the characteristics of each event, either large, with millions of collisions, or small, with a focused collision, physicists are able to see and record patterns that shed light onto the nature of particles and their intrinsic properties. There are a few possibilities that emerge from LEP events, including two electrons, two muons, and two jets.

Two Electrons:
This event of electrons is made up of two electrons being shed, while triggering two records in the electromagnetic calorimeter. The Z particle decays in scarcely nanoseconds into the two electrons, one being an electron, the other a positron. This happens each time, as a Z particle has no "lepton flavor," meaning that it is neither positive nor negative in what it sheds. Thus, it sheds its electron (-) in accompaniment with its antimatter positron (+) to preserve this lack of lepton flavor. In addition, the electron and positron separate in opposite directions, as to conserve the zero momentum of the Z particle. The path that the products take is a straight path to the electromagnetic calorimeter, where the particles are absorbed create a particle shower.

Two Muons
The characteristics of muon formation are similar to that of the electrons. In the detector, the Z particle, lacking lepton flavor and momentum, will radiate two muons. These muons are are particles about 200 times the mass of electrons, and behave very similarly. In fact, the Z particle splits the same method, and the muons radiate almost identically. With a muon and antimuon, one positive, and one negative, the similarities to electrons is shocking. The difference is in the penetrating power. Instead of being absorbed by the ECAL, muons travel further and penetrate through the detector to reach the muon chambers. If a particle penetrates with such power, it is almost certainly a muon.

Two Jets
This showing is consistent with a Z particle breaking down into two quarks. The quarks, as they are given off, appear as jets, and each quark, whether 2, 4, or 6 are given off, accounts for one jet. Thus, there is a number of consistent looking jets in numbers of 2, 4, or 6. These jets are the result of quarks breaking off and leading to a protruding cloud of particles called mesons that show up on the detector.

CMS Subsystems
The CMS detector has an array of systems that all work to create an accurate representation of each dielectron, dimuon, and dijet event. A tracker surrounds the interaction point, and its role is to detect the immediate expulsion of particles, while recording the path, allowing calculations to be made as to its mass and momentum. In a dielectron or dimuon event, this silicon tracker will pick up two paths shooting outwards in opposite directions, as the laws of physics provide reason for the particles to conserve the lack of momentum. This causes the Z particle to remain without momentum. The mass of the muon event will greatly exceed that of the electron, which means that a straighter line will result. However, when quarks are released in a dijet event, the results will appear differently. Still going along with the preservation of momentum, the jets will disperse oppositely, but it is not a single, straight path, and instead is a cluster of mesons extending outward from the interaction point. This is recorded in the early parts of the detector as well. Once the tracker records the path of the particles, they move through it and reach the electromagnetic calorimeter. This calorimeter is designed to absorb the lighter particles such as electrons and photons, yet muons can pass through easily. This is the part that will recognize whether a particle is an electron, or even a photon, as these particles cannot pass through, and instead leave their energy in a particles shower. After the ECAL, the Hadron calorimeter is next. This is the stage where hadrons can be identified. This calorimeter, made of very dense material, will register protons and quarks, and determine using the magnet if they are charged or neutral. If neutral, the pathway will be a straight line, whereas it will curve if it is charged. Muon chambers surround the detecter as the outermost detector region. These muon chambers record the passing of muons as they extend to the outside of the detector. These appear as straight-shot projections in opposite directions.

When physicists use the CMS director, they combine millions of events to chart the overall trends of the particles. With trillions of data points to plot, researchers use histograms that the detector puts together to plot the general trends of mass and types of collisions. Histograms are very helpful, as they can teach what kind of event should be expected, and the frequencies of each type. And with trillions of events recorded, each single one can be observed by itself, while combining all the events together to see the overall trend. For example, if researchers are looking to observe the invariant mass of the particles, a histogram can be made using the mass (GeV/c^2) on the x axis, and the number of events in that mass on the y axis.

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