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Nuclear and Particle Physics Dr Daniel Watts 3rd Year Junior Honours Course Mondays & Thursdays 10am Industry power plants energy source materials tracing Military Research condensed matter element analysis (bio)chemistry nuclear weapons Nuclear Physics Medicine Archaeology & Geology computed tomography magnetic resonance imaging radiation therapy dating analysis Astrophysics energy production in stars nucleosynthesis of elements LIFE Today’s nuclear physics research Hadron Structure: The structure of the nucleon and of hadrons in general Hadron Spectroscopy: The search for “glueballs”, “hybrids” and multiquark states (eg. Pentaquark) Heavy Ion Physics: Quark-gluon plasma, new phases of matter Nuclear Astrophysics: Understanding stars, supernovae etc. Course layout Third year nuclear force binding energies properties models radioactivity NUCLEUS structure applications nuclear reactions astrophysics medicine industry … models Fourth year Nuclear Physics Course Syllabus • Introduction and basic concepts (lecture 1 & 2) Brief historical overview The nucleus and its constituents Nomenclature The forces of nature Basic concepts of quantum mechanics • Nuclear properties (lecture 3 & 4) External: mass, charge, size, mass and charge distribution Internal: angular momentum, spin, parity, magnetic moment excited states • Nuclear structure (lecture 5 ) Masses and binding energies Semi-empirical mass formula The beta stability valley Properties of nuclear forces • Nuclear models (lecture 6, 7 and 8) Liquid drop model Shell model and evidence for shell structure Single particle features Magic numbers, spin-orbit coupling Predicted angular momenta of nuclear ground states Collective model. Vibrational and rotational states • Nuclear instability Occurrence and stability of nuclei α- β- γ- decay modes (lecture 9) Suggested textbooks J. Lilley Nuclear physics Principles and applications John Wiley and Sons, 2001 Clear and concise. Not too advanced, makes a very good starting point. Interesting chapters on applications W.N. Cottingham and D.A Greenwood An introduction to nuclear physics Oxford Science Publications, 1997 Nicely concise and still rich in content. K.S. Krane Introductory nuclear physics John Wiley and Sons, 1988 Very didactic and clear. The textbook for the more advanced, dedicated student. R. Eisberg and R. Resnick Quantum physics of atoms, molecules, solids, nuclei and particles John Wiley and Sons, 1985 Exceptionally clear + very didactic. Optimum for review of quantum ideas in atomic & nuclear physics P.E. Hodgson, E. Gadioli and E. Gadioli Erba Introductory nuclear physics Oxford Science Publications, 1997 Very comprehensive + somewhat more advanced. Deeper mathematical treatment Brief historical overview In search of the building blocks of the universe… Greek philosophers 4 building blocks 5th BC - Democritus earth water atomic hypothesis 18th-19th century Lavoisier, Dalton, … put atomic hypothesis on firm basis distinction between compounds and pure elements 1896 Mendeleev 92 building blocks (chemical elements) 1H, 2He, …92U 1896 Becquerel discovers radioactivity ⇒ emission of radiation from atoms ⇒ 3 types observed: α, β and γ α and β deflected in opposite direction ⇒ opposite charge α deflected less than β ⇒ α must have larger mass γ not deflected ⇒ uncharged air fire ~1900 Rutherford investigates new radiations α and β emissions change nature of element α‘s charge = +2e α’s mass ~ 4H β radiation = electrons γ = electromagnetic radiation (photons) 1911 Rutherford tests Thomson’s model of the atom Clear experimental evidence that atoms contain electrons – where are they? “plum pudding model” -ve electrons embedded in +ve charge uniformly distributed over atomic volume use α particles (positively charged) on golden foil expected +ve α’s pushed a little to the side by +ve charge of atom In Rutherford’s own words: “…it was as incredible as if you had fired a 15-inch shell at a piece of tissue paper and it came back and hit you” observed some α’s deflected backwards to 180o !! Conclusion: all +ve charge (and ~all mass) concentrated in tiny region at the centre Concept of atomic NUCLEUS is born ! Atom = nucleus + electron -e planetary model of atom (10-10 m) Heisenberg ⇒ simplest atom = H +Ze its nucleus = proton 1920 Aston’s mass spectrograph ⇒ measure masses of atoms mass charge He ~ 4 H C ~ 12 H O ~ 16 H …. He = 2 H C =6H O =8H …. ⇒ hypothesis of neutral particle in nucleus with m ~ mp 1932 Chadwick discovers the neutron 3 building blocks electron + proton + neutron NUCLEAR PHYSICS Nucleus = protons + neutrons (10-15 m) Are protons and neutron the ultimate building blocks? Are they fundamental particles? Energy and density scales Typical energy scale in nuclei (MeV) is much higher than in atomic case (eV) Nuclei are dense objects: 1cm3 has mass ~ 2.3x1011 kg (equivalent to 630 empire state buildings!!) White Dwarf Solid state 100 water 105 Neutron star 1010 Black hole 3 1015 g/cm density Nuclear matter