PHYS 400/506 -- Some Suggested Topics for your Seminar and Essay

Remember, you are encouraged to come up with a topic of your choice not mentioned on this list... This list is to give you just a few ideas of potentially interesting topics. Or you may want to make your own variation of one the suggested topics below. For the topics of a historical nature, many excellent references may be found in campus libraries. I can provide some help with locating journal articles on specific experiments mentioned.

Want to browse for ideas? Get a current list of articles on Subatomic Physics and related topics from: Scientific American , Physics Today , New Scientist , Science or Nature from the SPIRES database. These journals, and most academic physics journals, are available in several libraries on campus, including the Main Library, TRIUMF, and many of these journals are available online as Electronic Journals accessible to you from any on-campus site (....ubc.ca) thanks to the UBC Library's sitewide licenses.

The Big Bang
The highest energies reached at man-made accelerators is presently in the 2x10**5 GeV range, while energies of about 10**19 GeV were real just after the Big Bang. Review the basic stages of the universe from about 10**-45 sec after the Big Bang, to the present time ( approx. 10**17 sec). Steven Weinberg's book, The First Three Minutes, is an excellent reference for this topic.
Baryon Asymmetry of the Universe
We still don't know why matter dominates over anti-matter in our universe... Many models assume that the universe began in a symmetric state with zero overall baryon number, and introducing a large baryon asymmetry is not a simple task. Review some of the physical processes which may introduce such an asymmetry and discuss the implications.
Dark Matter
Astronomical observations of the motion of galaxies and interstellar gases suggest that most of our universe composed of dark matter, that is matter which we don't see. Review the astronomical evidence that infers the existence of dark matter, and discuss possible particle physics (and other) candidates for dark matter.
Grand Unification
It is speculated that the four forces of nature are all related and hence can be unified at some large mass scale. Explain the running of the coupling constants of these forces and discuss some candidates for a GUT theory. String theory and M-theory are currently hot topics in this field.
Supersymmetry
What is it? How does it relate to the Standard Model? What kind of expectations do we have for discovering supersymmetric particles? Many experiments have conducted fruitless searches for SUSY particles. Describe and review an analysis and results of a SUSY search conducted by one of the LEP experiments, or some other recent experiment.
Neutrino mass
Several experiments have performed to measurements of the neutrino mass by examining the endpoint of the electron spectrum in beta decay. Explain the types of experiments and experimental techniques used (for example, you might want to show examples of and describe what a Kurie plot is)
Solar Neutrinos
Several recent experiments have measured the neutrino flux from the sun and find that it appears to fall short of predictions of a standard solar model. Briefly describe the solar model and its predictions and review some recent experimental results. Most notably, the Super Kamiokande experiment, in an underground mine in Japan observes a discrepancy in the standard solar model. The Sudbury Neutrino Observatory (SNO) in Ontario started taking data this year and has already detected solar neutrinos. Describe either one of these experiments.
Magnetic Monopoles
What are they? Can they fit into the electromagnetic theory of Maxwell? What experimental techniques have been used to search for them, and what are the results of these experiments?
J.J.Thompson's theoretical and experimental work in which he discovered the electron
Describe Thompson's Nobel Prize winning work, and describe the apparatus and the experiment he performed and how he was able to deduce that he had discovered a new particle, the electron.
Rutherford's scattering experiment
Describe Rutherford's Nobel Prize winning work on the structure of the atom, including his famous Coulomb-scattering experiment in which he showed that most of the mass of an atom is concentrated in a tiny nucleus at the center of the atom - describe with examples his prediction and experimental results for cross-section as a function of incoming alpha particle angle.
The discovery of parity violation
What is parity violation? - explain Yang and Lee's postulate that parity is violated, based on deductions from observations in nonleptonic kaon decays. (This work won them a Nobel Prize) Describe the beta decay experiment using polarized cobalt of C.S. Wu, in which she discovered parity violation.
Confirmation of 3 and only 3 generations of massless neutrinos
Review the experimental and theoretical limitations on the number of generations in the Standard Model. Describe the experiment which was first performed at the SLAC linear collider, (later confirmed and measured to extremely high precision at the LEP accelerator at CERN ) in which it was established that there are three and only three similar generations with Standard Model massless neutrinos.
Accelerators
Ernest Lawrence proposed the idea of a magnetic resonance accelerator (the cyclotron), and in the 1930's he and a graduate student, Stanley Livingston built and operated the first cyclotron. (It won Lawrence a Nobel Prize) Describe their apparatus and explain how it was used to accelerate protons to 1.2MeV. A modern synchrotron, such as the one at TRIUMF, is based on a principle similar to that of the cyclotron, except that the magnetic bending field, B and the RF frequency must increase and be synchronized with the particle velocity as it increases. Outline briefly how the TRIUMF synchrotron (or any particle accelerator of your choice) works.
The parton model -- structure of the proton
Describe the parton model and and its confirmation in deep-inelastic electron-proton scattering experiments, which showed that there are quasi-free point-like constituents, which we now call quarks, in the proton (and all nucleons). Describe the deep inelastic electron-proton scattering experiment performed at the Stanford Linear Accelerator Center which provided evidence for the existence of quarks and won a Nobel prize for Canadian Dick Taylor and his colleagues Kendall and Friedman.
Quarkonium - quark-antiquark bound states - QCD Potential Models
discuss the standard Coulomb plus linear QCD-inspired potential often used to model and solve QCD bound state problems.. Compare the energy levels of a heavy (c or b ) quarkonium system (to those of the positronium system (bound e+ e- state), emphasizing similarities and differences.
QCD (Quantum ChromoDynamics)
What is a gluon and what is its role in the non-Abelian gauge theory of QCD? Evidence for quarks radiating a hard gluon was first observed at the PETRA storage ring in Germany - Discuss and explain the experimental signature seen at the PETRA experiments at the DESY laboratory in which the gluon was unambiguously observed.
QED (Quantum ElectroDynamics)
QED is an Abelian gauge theory. Feynman, Dyson, Tomonaga and Schwinger developed the theory of QED in the late 40's. Perhaps the most precise tests in physics have been in testing the predictions of QED. Describe the theory and some of the extremely high precision tests.
CP-violation in the K system
Describe the famous Nobel-prize winning experiment of Christenson, Cronin and Fitch in which they studied 2 pi and 3 pi K0 decays and discovered CP-violation. - how does this CP-violation fit into the Standard Model and the Kobayashi-Maskawa quark mixing scheme?
The W and Z Bosons, the intermediate vector bosons of the Standard Model
What are they? Describe how they were discovered at CERN's SPPS proton-antiproton collider, in particularly clean leptonic decay channels in the 1980's. The development of stochastic cooling for the antiproton beam and the subsequent discovery of the W and Z bosons won a Nobel prize for Simon van der Meer and Carlo Rubbia.
Semileptonic decays of heavy quarks
Non-hadronic decays of heavy quarks have recently contributed much to our understanding of the Standard Model, in particular in deducing the elements of the Kobayashi-Maskawa mixing matrix, and understanding the interplay between the weak (exactly calculable) and QCD (hard to calculate) contributions in weak decays of bound quarks. Review the physics of the weak force in heavy quark decay and how KM matrix parameters may be deduced from the study of heavy quark decays
Kobayashi-Maskawa-like mixing in the lepton sector
While not in the Standard Model, it is possible that there is mixing in the lepton sector. What implications does this have on neutrino oscillations and neutrino masses? Several experiments have placed limits on neutrino masses from the non-observation of muon neutrino to tau neutrino oscillations, most notably the E531 emulsion experiment at Fermilab, which ran in the early 1980's, and two just recently started experiments at CERN: NOMAD and CHORUS. Describe the apparatus and techniques used to measure neutrino mixing limits from any one or more of these 3 experiments. Recently an underground water experiment, SuperKamiokande, has seen experimental evidence that neutrinos may indeed have non-zero mass. Review this experiment and its results and implications.
e+ e- --> Z0 reactions to determine sin**2 (theta_W), the weak mixing angle
Describe how the width, mass and cross-section of the Z0 in e+e- annihilation and the constraints of the Standard Model may be used to deduce sin**2 (theta_W), a fundamental parameter in the Model. There are four experiments presently running at the e+e- LEP accelerator at CERN which have measured these Z0 parameters to extreme precision.
CP-violation in the B system
Several B-factorys are presently under construction at several labs around the world. They aim to examine CP-violation in the heavy b quark system, providing complimentary information to what we know about CP-violation from kaon decays. The B factory studies will provide very stringent restrictions on or disprove(!!) the Standard Model. Describe the physics of the CP-violation in the B system, and review some of the techniques presently being studied to observe CP-violation in the B system at one of the experiments (BELLE at KEK, BaBar at SLAC, BTeV at Fermilab, HERA-B at DESY, CLEO at Cornell)
The LHC - Accelerator and the physics challenges
The Higgs boson may be discovered at the LHC, (the Large Hadron Collider) at CERN, in Switzerland in about a decade, or some wildly new unanticipated physics may turn up there. Describe the basic specifications of the LHC proton-proton collider, and review some of the search strategies currently being studied which might lead to the discovery of the Higgs boson(s).
Nuclear Fission
How does a nuclear reactor work? How does an atomic bomb work? Maybe you can tell us how to make one, or review the early attempts and history at Los Alamos in developing the atomic bomb.
Nuclear Fusion
What is fusion? Describe the evolution of stars and the role of nuclear fusion and the chain of nuclear reactions in stellar evolution, or H-bombs.
Drift Chambers
How do you make one? how does it work? How are they used to precisely measure momentum of the charged particles electron, muon, pion, kaon, and proton Describe how measuring specific ionization (energy deposition per unit length traversed in a gas, often referred to as dE/dx) may be useful in identifying the 5 above mentioned particle species. Georges Charpak won the Nobel Prize for his invention and development of wire chambers
Calorimetry
What is a calorimeter and how does it work? Choose one or more of the modern types calorimeters used for either electromagnetic or hadron calorimetry in particle physics (liquid argon, lead glass blocks, BGO, CsI or NaI crystals, proportional-tube iron sandwich.... ) and review how it works and describe the performance in any experiment of your choice.
Silicon Microvertex Detectors
Recently very high precision tracking (10-20 microns spatial resolution is typical) has been achieved with silicon wafer detectors positioned very near the interaction vertex. Explain the operational physics of a typical silicon vertex detector and discuss some examples of physics where such detectors are extremely valuable.
Fermi and the development of weak decay theory
In the 1930's, Enrico Fermi developed the -decay theory, coalescing previous work on radiation theory with Pauli's idea of the neutrino. Following the discovery by Curie and Joliot of artificial radioactivity, he demonstrated that nuclear transformation occurs in almost every element subjected to neutron bombardment. He won the Nobel Prize for this work. His PhD thesis is a fabulous 2 page wonder.
Renormalizability of the Standard Model
Just last year, t'Hooft and Veltman won the Nobel Prize for their work 2 decades ago, showing that the non-Abelian gauge theory of the Standard Model is indeed renormalizable. An interesting ingredient of this work is the yet-to-be-discovered Higgs particle.
Particle Identification Detectors
Recently, several new types of particle detectors have been developed which aid in identifying particle species. Some of the newer types are based on imaging Cerenkov light emitted by a particle traversing a tank of liquid, as the particle is travelling faster than the speed of light in that liquid. (These detectors are called RICH's or CRIDs or DIRCS for Cerenkov Ring Imaging Detector and variations thereof.) Describe one such operating detector and explain how it works and why it is useful.
String Theory
Are the real fundamental "particles" of our universe actually 1 dimensional strings, rather than 0-dimensional point-like objects? All the various particles we observe arise in string theory as excitations of a string. Included in the theory is the graviton, the boson mediating the gravitational force, so String Theories would incorporate all 4 fundamental forces, rather than 3 only in the Standard Model.

Resources and relevant Electronic Journals and Magazines


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Janis McKenna, UBC Department of Physics, August 2000