Thomas Lamb

(2013)

Search for Majorana Fermions

Majorana fermions could arise from neutral spin-1/2 particles whose wave functions are real, implying them to be their own antiparticle. If this were the case, then Lepton number would be violated. There are ongoing and completed experiments searching for lepton number violating decays and pair productions.

Stefan Musser

(2013)

Muon-Catalyzed Fusion

Muon-catalyzed fusion is a subject of considerable interest from a purely scientific perspective and as a potential source of fusion energy from non-superheated matter. This paper will, after briefly placing the discovery of the phenomenon in its historical perspective, explain the physical basis of the phenomenon whereby muons interacting with gaseous hydrogen isotopes are able to bring about fusion of their nuclei. It will then explain both the theoretical and practical limitations of harnessing this phenomenon for practical power generation and consider proposed methods of overcoming or ameliorating them.

Brittney Myers

(2013)

The Continuing Search for Ultra-High Energy Cosmic Rays

For the past fifty-odd years, one of the great mysteries of astrophysics has been the elusive ultra-high energy cosmic ray. Every day we are bombarded by a plethora of cosmic rays, most in the range of 10⁹ eV-10¹⁸ eV; the ultra-high energy cosmic ray (UHECR), defined as a cosmic ray with energy greater than 10²⁰ eV, on the other hand, has only been observed, on average, once every 3.4 years since it was first detected. As our technology improves, we have developed better techniques for observing and analyzing these UHECRs, and have developed better, more informed theories as to their origins and compositions. The following is an overview of our current progress in search for, and identification of, the UHECR, starting with a brief history of its observation, and including the current detection and analysis methods, and the latest theories as to the origins/acceleration mechanisms.

Matthew Sheehan

(2013)

The Search for Magnetic Monopoles

Magnetic monopoles are hypothetical particles that have a net "magnetic charge" and have only one magnetic pole. In 1931 Paul Dirac published a new theory on the quantum nature of magnetic charge. He said that if magnetic monopoles were to exist, then all electric charge would be quantized. Though electric charge is quantized, this does not prove the existence of magnetic monopoles. Since Dirac’s publication, many researchers have sought to prove the existence of monopoles, with little success. It is still not known whether monopoles can exist in nature because they are too massive to be produced in a particle accelerator. Because of this reason, some of the most recent research has produced effective quasiparticle magnetic monopoles in condensed matter, such as magnetic spin ice, while others have produced artificial magnetic monopoles. This paper will present the theory behind monopoles, and several modern experiments and their results.

Victor Wong

(2013)

Proton Therapy

Proton therapy provides an alternative and less dangerous form of radiation treatment for patients suffering from tumors. Unlike x-ray and even electron beams, proton beams leave little collateral damage on surrounding tissue due to their high mass. In addition, the protons themselves release the highest amount of energy just before coming to a stop, allowing physicians to accurately target the cancerous mass without causing further harm to the rest of the body. In fact, this latter property is of particular interest. Since the energy loss of ionized particles through matter is mathematically described by the relativistic Bethe-Block equation, the proton’s properties may also be derived from here. Further analysis gives rise to what are known as Bragg peaks. It is these peaks that tell us when and where ionizing radiation, such as the protons within a beam, loses the most energy.

Equipment will also be analyzed, as it forms the technological basis for treatment delivery. Various means of proton beam generation and delivery will be explored, including the well known cyclotron, linear accelerator, and synchrotron. Hybrid models also exist and are designed to incorporate the best features of both the cyclotron and synchrotron. In addition, there are several mathematical and technological requirements that need to be met in order for treatment to be successful. More specifically, the protons within the beam must be calibrated so that their Bragg peaks overlap in a specific way. This generates a spread out Bragg peak (SOBP), which may be manipulated to fit the size and shape of the tumor being targeted.

Brandon Allen

(2012)

Recent Searches for Supersymmetry at the LHC

The recent discovery of the Higgs boson at the Large Hadron Collider provides confirmation for the final aspects of the Standard Model of particle physics. However, there are known problems with the Standard Model, such as hierarchy problem and the lack of a dark matter candidate, which motivate a search for new physics beyond the Standard Model. One natural extension of the Standard Model is supersymmetry, a proposed symmetry between fermions and bosons. There are strong theoretical motivations for evidence of supersymmetry appearing at the TeV scale, and thus, the CMS and ATLAS collaborations are currently conducting extensive experimental searches for supersymmetry.

Decays with multiple leptons in the final state are an especially promising class of experimental signatures. Leptons are easily identified and provide a cleaner signal than jets from all hadronic decays, plus most supersymmetric particles have a natural decay chain with leptons in the final state. Particular focus is given to top quark mediated gluino decay chains, which contain multiple leptons and b-jets, another easily identifiable object, in the final state. Current searches have managed to probe gluino masses up to 850 GeV.

Alexander Chisholm

(2012)

Exploring the Motivation and Detection of the Axion Dark Matter Particle

The strong force does not appear to violate CP symmetry, but there is no reason to assume that is the case because the parameter θ in the QCD Lagrangian is naturally periodic; however based on experimental evidence, θ is valued at very near to zero. Peccei and Quinn proposed that θ is not a static value by introducing a symmetry that is spontaneously broken and conserves CP. The axion particle is the boson associated with this spontaneously broken symmetry. In addition, the axion has a role in the beginning of the universe, which will be explored in this paper.

The axion has very little mass and couples quite weakly to ordinary matter, which makes it very hard to detect. Based on astrophysics data, there is a good chance that dark matter (includes axions and other dark matter candidates) tend to form halos within galaxies, allowing axions to possibly decay within a laboratory on Earth. Axion decay is very hard to analyze because the power of the event signal is extremely weak due to the axion’s small mass and weak coupling. Experiments searching for the axion are continually trying to detect a wider range of the axion’s possible mass and improve the sensitivity of the apparatus.

(2012)

The Island of Stability

The “Island of Stability” is a theory that gives rise to theoretical superheavy transuranium elements whose stability results in long lived nuclei. The theory states that the nucleus of an atom is built up of shells of quantum energy levels, much like the electron shells surrounding the nucleus. When a shell is full, it is said to contain the “magic number” of protons and neutrons. A full shell provides the maximum binding energy between the protons and neutrons, resulting in a stable nucleus. All known transuranium elements have very short half-lives, so these new elements on the island of stability will provide for new science.

Synthesis of these new elements requires the use of a particle collider. The beams of the colliders collide neutron rich heavy ions with lighter charged particles, such as alpha particles, at a low energies to force protons and neutrons to stick together. Finding the “magic numbers” of protons and neutrons lays in accurate measurements of the binding energies of nucleons. Weighing elements with an ion-trap will provide these binding energies, resulting in more accurate predictions about these “magic numbers.”

(2012)

Tokamak Fusion Reactors: Steady state fusion via ITER

The world is becoming increasingly aware of a fundamental issue with our approach to production and use of energy. While some industries and gov- ernments are either genuinely or reluctantly pursuing sources of alternative energy, there remain questions about the viability of replacing petroleum based fuels with options such as solar and wind. However, steady state fusion exists as an option separate from concerns and drawbacks of other alternative energy solutions.

In environments with large pressures and temperatures, such as the cen- ter of a star, two or more atomic nuclei may combine to form a composite nucleus with a larger atomic number. If the atomic masses of the constituent nuclei is low enough such that their composite nucleus has a mass lower than or equal to Iron, then this process releases energy. This process is what pow- ers active stars such as our sun. The aim of this paper is to describe how in principle one could engineer a power plant using this process as an energy source on Earth, as well as review the current state of development of this technology.

We will review the theory that explains why fusion is exothermic, de- scribe the two most common approaches to steady state fusion power plants: the tokamak fusion reactor (or magnetic connement reactor) and inertial connement fusion. The focus of our discussion will be the development of tokamak reactors, citing proof of concept examples such as the TFR (Toka- mak de Fontenay aux Roses) reactor in France and the JET (Joint European Torus) reactor in the United Kingdom. Finally, we will discuss ITER (In- ternational Thermonuclear Experimental Reactor), which is the next gener- ation experimental tokamak reactor that is currently being constructed in France.

Rupika Madhavan

(2012)

The Search for Free Quarks

Quarks are fundamental particles that compose hadrons and participate in the strong nuclear force. Their interactions are explained by quantum chromodynamics (QCD). The existence of quarks has been proven, and yet quarks have not been seen in isolation; QCD predicts that as quarks get father apart, the color force between them gets stronger. Thus, it gets harder to pull two quarks apart the farther apart they are. At some point, the potential energy holding together the two quarks exceeds the energy required to create a quark-antiquark pair, and the pair of quarks becomes two pairs of quarks. Another result drawn from QCD the concept of asymptotic freedom; as the distance between two quarks goes to zero, the color force also goes to zero, and the quarks interact only weakly. This has given physicists one route to witnessing free quarks by overlapping protons and neutrons in nuclei.

Another method comes from the fact that at temperatures around 2 trillion Kelvin, matter melts and hadrons deionize, freeing quarks. This stage of matter is called the quark-gluon plasma, predicted to have been the state of matter a mere 10 picoseconds to 10 microseconds after the Big Bang. Many labs have embarked on a journey to attain this state of matter and possibly see, for the frist time, an isolated quark, including CERN and RHIC. This paper gives an introduction to the quark model, provides an overview of QCD, discusses vacuum properties, and describes previous searches for free quarks. Furthermore, it gives a basic discussion on the quark-gluon plasma and the implications of nding free quarks for grand unication theories (GUTs), and ventures into present and future experiments with the goal of isolating quarks.

(2012)

Sterile Neutrinos: A Primer

This research document will be concerned with the experimental analysis, and underlying physics corresponding to the three flavor neutrino mixing model and the potential existence of a fourth generation neutrino which does not interact via the weak interaction, the so-called sterile neutrino. Experimental evidence for the sterile neutrino is statistically significant at or near 3σ in select cases, and demonstrable both through nuclear reactor processes, and accelerator manufactured events. Much of the experimental data analysis has previously been performed and is well documented, therefore the aim of this paper is not to provide new insight but rather to serve as a primer for this diverse and complex field. Requisite concepts and mathematics will be presented as necessary in a condensed, and more comprehensible form.

Phil Mclaughlin

(2012)

Experimental verification of electroweak theory

One of the major milestones in particle physics has been the establishment of electroweak theory, or the unification of the electromagnetic and weak forces. In the 1960's, Sheldon Lee Glashow, Abdus Salam, and Steven Weinberg showed that a gauge-invariant theory for the weak force could be constructed if the electric force was included. They predicted the existence of four new particles and the existence of neutral current. These predictions were vindicated with the discovery of neutral current in the Gargamelle experiment at CERN and later, the discovery of the W and Z bosons by UA1 and UA2. More noteworthy experiments at colliders, including HERA, the LEP, and later the LHC have since made precise measurements of these particles.

Despite the successes, there remain many unanswered questions in electroweak theory. The biggest of these questions is what breaks electroweak symmetry? It is predicted that the Higgs boson is responsible for this symmetry breaking. Ongoing experiments at the LHC hope to confirm the existence of the Higgs and confirm its properties. Recent experiments suggest the Higgs exists and has a mass of around 125 GeV. More experiments are necessary though to confirm that it is, in fact, the standard model Higgs. Future experiments will look to measure its decay rates, spin, and parity.

(2012)

A Review of the Z Boson History and Measurements of its Production and Decay Properties

I begin with a historical review of the Z boson, discussing its prediction by the unification theory of electromagnetic and weak interactions. The unification conditions will be briefly explored, as it lies beyond the depth of the course. The experiments conducted at CERN, the physicists associated with them, and their results leading up to the verification of the Z boson’s discovery will then be surveyed.

Theoretical calculations of the Z boson’s properties are then explored. I first examine the formation processes of the Z boson, deriving an expression for its production cross-section as described by a mass-dependent Breit-Wigner formula. The Z boson decay channels are covered next, with a focus on the importance of the l¯l and q¯q channels. Finally, I discuss how these theoretical predictions and the decay kinematics motivated the design parameters of experiments to detect the Z.

Measurements of the Z boson mass, width, and cross-sections from analyses by CMS at CERN and past historical experiments will then be presented. Experimental considerations with regards to selecting a Z boson signal versus background event in data, systematic uncertainties, and uncertainties from theoretical predictions will be discussed. Lastly, agreement between the measured values of the properties and those predicted by robust statistical simulation are compared.

(2012)

WIMP Detection

The rotational velocity of galaxies is not consistent with the amount of matter that we observe in them. At their current rate of rotation, galaxies would be ripped apart, that is, unless they had extra mass and thus gravitational force holding them together. While is it not the only proposal, the addition of dark matter to the total mass of galaxies satisfactorily resolves the discrepancy. There are many theories that try to explain what dark matter is, however, currently the most widely accepted explanation is that dark matter is made up of particles called WIMPs, or Weakly Interacting Massive Particles. These particles do not interact strongly so they are dicult to nd, and as of today no WIMPs have been found yet despite huge collaborations partaking in the search. One method for detecting these dark matter particles that will be discussed below is by having them fall on a calorimeter that is highly sensitive and responds very quickly. The detectors are kept at low enough temperatures that the germanium they are made of is superconducting, but, they are maintained at the interface between superconducting and normal state such that even tiny amounts of energy deposited on them can be detected because it is absorbed as heat and causes a spike in the resistivity as the germanium goes to a non-superconducting state. The CDMS collaboration uses this method, yet there are still other methods that are employed by CoGent and DAMA. This is important and allows for data comparisons even between dierent approaches. There have been a few instances where it was believed that dark matter had nally been directly detected but after further review, that was not the case.

Dylan Billiodeaux

(2011)

Why Did the Universe Matter?: A Report on the Bayonic/Antibaryonic Matter Asymmetry

A quandry somewhere within the realms of particle physics and cosmology, there is as of yet no concencus between physicists as to why, given what we know about particle interactions and the conservation laws governing them, baryonic matter pervades the universe, and antibaryonic matter does not. THis report will dicuss several of the leading theories concerning baryogenisis in the early universe, with a highlight on the one beileved to be most plausible, CP violation. The report will also delve into alternative explanations, especially those considering possible differences between the intial conditions of the early universe and the state of the universe today.

(2011)

Neutrinos: Creation and Detection

This project will be based on current research involving neutrino creation and detection. Topics will include the natural creation of neutrinos in our universe (primarily, solar and supernovae neutrinos), how we detect them here on earth, and the insight we gain from these detections. Also, the project will cover the idea behind neutrino factories, and any current research involving them.

(2011)

On the Development of Experimental Equipment for the Measurement of a Charged Particle's Rest Mass

The Particle Data Group gives various particles' rest masses official experimental values, but these values have changed in both accuracy and precision over many decades. This paper seeks to explore the evolution in the development of tools for measuring the rest masses of charged subatomic particles, in particular the electron, proton, and muon. Has the goal of measuring particle mass been the impetus behind the development of the technology, or have the tools been mere applications of previous discoveries?

(2011)

Group Structure of Subatomic Particles

The development of the quark model and the prediction of subatomic par ticles has been crucial in the realm of experimental physics. This project will show how the quark model was derived from the Special Unitary Groups, how it led to the prediction of the Ω⁻ particle, and how that prediction was eventually confirmed by experimental results. The knowledge of how this model was con structed is important in continuing our understanding of subatomic particles as well as appreciating the future predictions these models may give us.

(2011)

Experimental tests for Lorentz and CPT violations

Lorentz symmetry is a postulate of Einstein's special theory of relativity stating that the laws of physics must be the same for all inertial reference frames. CPT symmetry is a requirement of the standard model of particle physics which states that charge, parity, and time symmetries cannot all be simultaneously broken. Numerous modern experiments from neutrino oscillation experiments (not unlike the Michaelson-Morley experiment) to observations of baryon asymmetry aim to show that violations of these two fundamental symmetries do occur and to gain a better understanding of such phenomena.

(2011)

Proton Decay and Its Consequences

Protons are the only particle in the universe that we believe to be stable because in order to decay it would have to break baryon conservation because it is the lightest baryon. If protons could decay, with a reasonable lifetime, atoms couldn’t exist and the universe wouldn’t have matter but every other particle ever observed decays except the proton and why does baryon number have to be conserved anyway? When the universe formed there had to be a reaction that broke baryon conservation in order to create more matter than antimatter, so when they annihilated, there was still all the matter there is today. I look to explore the research done searching for proton decay, how it would decay and the consequences of finding it decay.

(2011)

Supersymmetry

Supersymmetry is a theory of symmetry in nature that each fermion that exists should have a corresponding boson and vice versa. This symmetry is believed to have been broken in which the supersymmetric particles can only be seen at high energies. No direct evidence of supersymmetry has been found but it is a central concept of several theories which attempt to unify the fundamental interactions and experiments are underway to try and detect supersymmetric particles.

Nathaniel Amos

(2010)

The CMS muon system

The Muon System is a critical component of the Compact Muon Solenoid experiment at the Large Hadron Collider in Geneva, Switzerland. Comprised of 250 drift tubes (DTs), 540 cathode strip chambers (CSCs), and 610 resistive plate chambers (RPCs), it encapsulates the inner portions of the detector to track and verify muons - long lived particles similar to electrons with larger mass. It features a complex network of triggers to filter through an immediate, continuous stream of data and pass on the highest quality events to be analysed further for potential discoveries within and beyond the Standard Model of physics.

(2010)

Detectors for Particle Identification

Particle physics relies on detectors to track and identify the resulting high energy particles from collisions. This paper will discuss the underlying principles behind particle detection while including examples from existing machines. It will mostly focus on hermetic or 4π detectors that incorporate layers of sub-detectors (tracker, calorimeters, and muon system) to more closely cover the interaction point.

(2010)

Negative Pion Production and Delivery for Cancer Therapy

This paper presents the physics of producing and delivering a negative-pion beam for treatment of tumors. Topics of discussion will include particle production using an accelerator, beam control, particle lifetime, and interactions with anatomy. Also, characteristics of energy deposition along the beam to quantify dose will be presented.

(2010)

Some Like it Hot: Calorimetric Data in Particle Detectors

(2010)

Magnetic Monopoles: The Answer to Grand Unification

An in depth study of the role of magnetic monopoles as pertaining to the search for a grand unification theory and the experiments used to find them. Magnetic monopoles are theoretical point mass particles that contain only one magnetic pole. They were not invented as a bridging point to find a grand unification theory but are an unforeseen consequence of many existing theories. They are consequence that makes physical sense but have yet to be found though such particles have been hypothesized since the late 1800’s.

(2010)

Observable Implications of Extra Spacetime Dimensions

I will be exploring the empirical motivations for finding hidden spatial/temporal mediums of interactivity. Supported by analysis of leading peer-reviewed literature, I hope to assemble and communicate physical perspicacity, by focusing on the following distinct but cooperative tasks:

• Characterizing well-supported paradigm(s) for this scenario
• Identifying measurable relationships with collider and detection experiments
• Considering astrophysical and cosmological displays
• Concluding on the probabilities and constraints of high-dimensional spacetime I will document my report by using peer-reviewed figures, data, and analyses, before communicating my perspective and predictions on the subject.

(2010)

Comparison of Proton-Proton Accelerators and Proton-Antiproton Accelerators

The paper will cover proton-proton and proton-antiproton particle accelerators differences in their designs and the ideas behind their processes respectively. For example, because the antiprotons have opposite charge proton-antiproton accelerators would only need one magnet ring, compared to the two used in proton-proton accelerators. Proton-antiproton accelerators also enjoy a higher reaction rate at lower energies, around 1-3 TeV, but this disappears at higher energies, such as the range of proton-proton accelerators. This would make it easier to achieve results, due to the high reaction rates at low energies, with proton-antiproton accelerators, but a drawback is that antiprotons are harder to produce.

(2010)

The Discovery of the Electron Neutrino

The electron neutrino was proposed in 1930 by Wolfgang Pauli, who concluded it was needed in beta decay. It was discovered in 1956 by Clyde Cowan and Frederick Reines. This was an important development because it confirmed the existence of a very low mass particle. This helped to better develop and understand the standard model.

(2010)

Finding the Exact Mass of Neutrinos

(2010)

Advantages of Proton Radiation Therapy

An in-depth analysis of how protons are used for medical treatment. This will involve the way the protons interact with the body and the cancer cells. Also, the process by which the protons are prepared to be used via cyclotrons. I will also compare the use of protons with the standard photons used in conventional radiation.

(2010)

The Search for Dark Matter

Dark matter is undetectable matter theorized to exist due to discrepancies in the measured and observable mass of the universe, and its observed gravitational effects on visible matter. Current hypotheses about the composition of dark matter include baryonic and nonbaryonic possibilities, which are related to theories in particle physics and supersymmetry. Multiple experiments have been suggested and attempted for the detection of dark matter.

(2010)

Neutrino Oscillations and a look at the Different Origins of Oscillations and Experimental Evidence of their Existence

Neutrino oscillations are a consequence of interference between quantum mechanical mass eigenstates. This would imply that neutrinos have a non-zero mass because massless particles travel at the speed of light and can not change in time. There are few places where neutrino oscillations have been observed. Experiments have been conducted on these occurrences and we will examine the data collected.

(2010)

Circular Particle Accelerator Design

The cyclotron was first proposed to be used for particle acceleration in 1932. This was due to the fact that much higher energies could be obtained for particle collisions, without the problem of building prohibitively long linear accelerators. With the development of the cyclotron and the advent of the synchrotron, circular particle accelerators have been the workhorse of modern particle physics, and now involve multiple stages of cyclotrons to achieve the energies and particle beam luminosity needed for detecting elementary particles of interest.

(2010)

Measurement of Ultra-high Energy Cosmic Rays