3rd Year Special Projects in 2014

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Particle Theory/Cosmology: Decoherence in Quantum Cosmology

Supervisor: Dr Archil Kobakhidze
Contact: Dr Archil Kobakhidze
Email: archilk AT physics.usyd.edu.au
Phone: (02) 9351 5349

Quantum cosmology is a field of research attempting the quantisation of restricted degrees of freedom in gravity, which is supposed to be relevant for the formation and evolution of the universe at very early times, just after the Big Bang. In this project we study quantum decoherence effects within the minisuperspace approach to unimodular gravity.


Particle Theory/Cosmology: Proton in accelerated reference frame

Supervisor: Dr Archil Kobakhidze
Contact: Dr Archil Kobakhidze
Email: archilk AT physics.usyd.edu.au
Phone: (02) 9351 5349

The proton is known to be a stable particle with a lifetime > 1032 years! However, a non-inertial observer with a sufficiently large acceleration may see a proton decaying. In this project we investigate this interesting phenomenon, which may also have applications in astrophysics.


Particle Experiment (ATLAS): The wonderful Higgs Boson

Supervisors: Dr Kevin Finelli & Dr Aldo Saavedra
Contact: Dr Kevin Finelli
Room: 366
Email: k.finelli AT physics.usyd.edu.au
Phone: 9351 5970

The Higgs boson is last piece of the Standard Model of Physics unearthed. Discovered recently, it provides a unique opportunity for the discovery of new physics through precision measurements. AIDA (An Inclusive Dilepton Analysis) is a software tool used to determine the production rate of a number of particle physics processes simultaneously, and to compare them to the predictions of the Standard Model of Particle Physics. Production of the Higgs boson is a natural candidate to include in this. Up until now, AIDA has been applied to 7 TeV data from the 2011 run of the ATLAS experiment, without accounting for Higgs production. This project will explore what improvements and extensions are necessary in order to be sensitive to Higgs production using the AIDA technique applied to 8 TeV data from the 2012 run, which contains four times as many collisions as were recorded in 2011.


Particle Experiment (ATLAS): The impact of new technology on physics measurements - a case study, the ATLAS Pixel upgrade

Supervisors: Dr Aldo Saavedra
Contact: Dr Aldo Saavedra
Room: 366
Email: a.saavedra AT physics.usyd.edu.au
Phone: 9351 5970

In the ATLAS detector, the Pixel detector is closest to the proton-proton collisions. It provides high resolution spatial measurements of the charged particles traversing the detector. Its sensitive volume is instrumented by 50 x 400 micro meter squared pixels and it is composed of three layers, resulting in a total of 80 million channels. The pixel detector contributes three high precision points to the overall track reconstruction. This allows the origin of the charged tracks to be resolved from the different individual proton-collisions that take place within a bunch crossing, and the reconstruction of decaying particles near the proton-proton collision. These decays, such those undergone by b quarks are important, because their production is associated with a number of Standard Model (SM) processes and new particles proposed by physics models beyond the SM.

In the ten years since detector design and construction, integrated electronics have shrunk a lot, and the same capability can in principle be achieved with pixels whose size is 50 x 50 micro metres squared and possibly 25 x 25 micro metres squared. In this project we will determine what would be gained by such a size reduction for the tagging of b quarks, the resolution of proton-proton collisions and for the discovery prospect of new particles.