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P1Y Quantum Phenomena Question Revision Atomic –Question sheet 1-7, 6 Particle Physics –Question sheet 8-12, 11 Cosmology –Question sheet 13-16, 15 Last May’s exam: Anti-Hydrogen (atomic + particle physics) b anti-b quark production at LEP

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Exam hints Answer five questions –Twenty five minutes per question –If you attempt more than five, indicate your best five Including one from each section –Extra section for P1Y* candidates So, you must answer either one or two from quantum section. Choose your questions carefully –Spend 5 minutes reading through –Look at the mark allocation for each bit of the question. –Don’t waste time e.g. last years’ paper had a question which required a graph. Some students clearly wasted time drawing perfect graphs. The plotting of the graph, line, and axis labelling was only worth 2 marks

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Marking No negative marking –In practice we will mark all questions you’ve done and give you the best mark we can! –We also mark work you crossed out, as long as we can still read it! Explain what you are doing. –E.g. spectroscopic notation for Argon –(1s 2 2s 2 2p 6 3s 2 3p 6 ) [3] If you write down fill electron levels in order Fill all n,l,m states l<n m=-l,…,+l You’d get 1.5 Make your working/ rough work readable If your numerical answer is physically unrealistic say that you realised this.

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May 2003 Cold Anti-Hydrogen was produced for the first time at CERN in 2002. (i)What is anti-hydrogen and what fundamental particles does it consist of ?{4} (ii) An anti-hydrogen atom is in an excited state with an energy Describe the quantum numbers of the atom and list the possible atomic states. {6} (iii) An anti-hydrogen atom hits the wall of a vessel containing it. We observe several pions and a few ns later two photons. Describe what happened, estimating the sum of the energy of all the observed particles. {6} [proton/neutron mass 940 MeV, electron mass 0.5MeV ]

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May 2003 An electron-positron collider is operated with beam energies of 45.5 GeV each. (i) Draw the lowest order electromagnetic and weak interaction Feynman diagrams for production of a b anti-b quark pair in this collider.{4} (ii) Calculate how far does a b quark travels before decaying.{4} (iii) Draw one example Feynman diagram for the decay of the b quark.{3} (iv) Describe what is observed in the particle physics detector{5} [mass of b quark 5GeV, lifetime 1.5ps]

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