Nuclear and Particle Physics

Transcription

1 Nuclear and Particle Physics Contact Details Course Organisers Daniel Watts (Nuclear Physics) JCMB Room 8209 Tel: Dr Daniel Watts 3 rd Year Junior Honours Course Mondays & Thursdays 10am Victoria Martin (Particle Physics) Victoria.martin@ed.ac.uk JCMB Room 4405 Tel: Course handouts will be available on course web portal after each lecture (useful as in colour!)

2 Tutorial arrangements 1 tutorial every two lectures. Class split into two groups. Notes Start on Mon 14 th January Mondays 12:10 13:00 Room 5327, JCMB All Astro students Tuesday 14:00 14:50 Room 3317, JCMB All other students Group problem solving with Lecturer & Postdoctoral research assistant

3 Notes Military nuclear weapons Industry power plants energy source materials tracing Research condensed matter element analysis (bio)chemistry Nuclear Physics Medicine computed tomography magnetic resonance imaging radiation therapy Astrophysics Archaeology & Geology dating analysis energy production in stars nucleosynthesis of elements LIFE

4 Today s nuclear physics research Hadron Structure: The structure of the nucleon and of hadrons in general Hadron Spectroscopy: The search for glueballs, hybrids, multiquark states Heavy Ion Physics: Quark-gluon plasma, new phases of matter Nuclear Astrophysics: Understanding stars, super-novae etc. Exotic Nuclei: Nuclei far from stability My Research interests Using electromagnetic probes (intense photon/electron beams) to probe matter from scale of atomic nuclei down to nucleons and quarks. In Germany USA and Sweden Research topics include: Structure of the proton and neutron Violent short range nucleon-nucleon interactions in nuclei Use a wide variety of particle detection systems Large acceptance magnetic spectrometers Three-nucleon forces in nuclei High intensity superconducting electron Accelerator (Jefferson Lab) High precision magnetic spectrometers Hyper pure Ge arrays Large acceptance magnetic spectrometers Large acceptance high energy γ detectors

5 Course layout Notes Third year nuclear force binding energies properties models radioactivity NUCLEUS structure applications nuclear reactions astrophysics medicine industry models Fourth year

6 Notes Nuclear Physics Course Outline Introduction and basic concepts Brief historical overview The nucleus and its constituents Nomenclature The forces of nature Basic concepts of quantum mechanics Nuclear properties External: mass, charge, size, mass and charge distribution Internal: angular momentum, spin, parity, magnetic moment excited states Nuclear structure Masses and binding energies Semi-empirical mass formula The beta stability valley Properties of nuclear forces Nuclear models 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

7 Suggested textbooks Notes 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

8 Notes Brief historical overview In search of the building blocks of the universe Greek philosophers 4 building blocks earth air 5 th BC - Democritus atomic hypothesis water fire 18 th -19 th century Lavoisier, Dalton, put atomic hypothesis on firm basis distinction between compounds and pure elements 1896 Mendeleev 92 building blocks (chemical elements) 1 H, 2 He, 92 U 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

9 Notes Notes

10 ~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 observed some α s deflected backwards to 180 o!! Conclusion: all +ve charge (and ~all mass) concentrated in tiny region at the centre planetary model of atom Atom = nucleus + electron (10-10 m) Heisenberg simplest atom = H its nucleus = proton 1920 Aston s mass spectrograph measure masses of atoms mass He ~ 4 H C ~ 12 H O ~ 16 H. Concept of atomic NUCLEUS is born! charge He = 2 H C = 6 H O = 8 H. hypothesis of neutral particle in nucleus with m ~ m p 1932 Chadwick discovers the neutron +Ze -e 3 building blocks electron + proton + neutron Nucleus = protons + neutrons 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 NUCLEAR PHYSICS (10-15 m) 1934 Joliot, Curie - Artificial radioactivity 1940 Flerov, Petrjak - Spontaneous fission

11 Notes Notes

12 Origin of nuclear matter (Background) Energy, time and density scales s s 10-6 s o C o C Universe goes through superfast inflation Post inflation soup of electrons, quarks and other particles Quarks clump into protons and neutrons Typical energy scale in nuclei (MeV) is much higher than in atomic case (ev). Lifetimes of excited states are typically of order s compared with 10-8 s for atomic physics 10 2 s 10 8 o C Superhot fog (protons and electrons not yet bound into atoms). Primordial nucleosysnthesis (up to 4 He) Nuclei are dense objects: 1cm 3 has mass ~ 2.3x10 11 kg (equivalent to 630 empire state buildings!!) 3x10 5 yr 1x10 9 yr 15x10 9 yr 10 5 o C -200 o C -270 o C Electrons combine with protons and neutrons to form atoms (H, He) Star/Galaxy formation synthesis of heavier nuclei First stars die and eject heavy nuclei into space further star formation (and planets) The collisions of nucleons in the nucleus are rarely of sufficient energy to excite the protons/neutrons they are a very effective degree of freedom to describe nuclei White Dwarf Solid state Neutron star Black hole Time water Nuclear matter g/cm 3 density