Nuclear and ParticlePhysics

3rd Year Junior HonoursCourse

Mondays & Thursdays 10am

Dr Daniel Watts

NuclearPhysics

Medicinecomputed tomography

magnetic resonance imagingradiation therapy

Militarynuclear weapons

Researchcondensed matterelement analysis(bio)chemistry

Industrypower plants

energy sourcematerialstracing

Astrophysicsenergy production in stars

nucleosynthesis of elements

LIFE

Archaeology& Geology

datinganalysis

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, super-novae etc.

properties

NUCLEUS structure

models

radioactivity

nuclear force

nuclear reactions

models

binding energies

applications

astrophysicsmedicineindustry

…

Course layout

Third year

Fourth year

• Introduction and basic concepts (lecture 1 & 2) Brief historical overviewThe nucleus and its constituents NomenclatureThe forces of natureBasic concepts of quantum mechanics

• Nuclear properties (lecture 3 & 4) External: mass, charge, size, mass and charge distributionInternal: angular momentum, spin, parity, magnetic momentexcited states

• Nuclear structure (lecture 5 ) Masses and binding energiesSemi-empirical mass formulaThe beta stability valley Properties of nuclear forces

• Nuclear models (lecture 6, 7 and 8) Liquid drop model Shell model and evidence for shell structureSingle particle featuresMagic numbers, spin-orbit couplingPredicted angular momenta of nuclear ground statesCollective model. Vibrational and rotational states

• Nuclear instability (lecture 9) Occurrence and stability of nuclei α- β- γ- decay modes

Nuclear PhysicsCourse Syllabus

Suggested textbooks

K.S. Krane

Introductory nuclear physicsJohn Wiley and Sons, 1988

J. LilleyNuclear physics Principles and applicationsJohn Wiley and Sons, 2001

Clear and concise. Not too advanced, makes a very good starting point. Interesting chapters on applications

R. Eisberg and R. ResnickQuantum 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

Very didactic and clear. The textbook for the more advanced, dedicated student.

W.N. Cottingham and D.A Greenwood

An introduction to nuclear physicsOxford Science Publications, 1997

Nicely concise and still rich in content.

P.E. Hodgson, E. Gadioli and E. Gadioli Erba

Introductory nuclear physics

Oxford Science Publications, 1997

Very comprehensive + somewhat more advanced. Deeper mathematical treatment

In search of the building blocks of the universe…

Greek philosophers earth

water

4 building blocks air

fire

Brief historical overview

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

γ not deflected ⇒ unchargedα deflected less than β ⇒ α must have larger mass

18th-19th century Lavoisier, Dalton, …put atomic hypothesis on firm basisdistinction between compounds and pure elements

5th BC - Democritus

atomic hypothesis

1911 Rutherford tests Thomson’s model of the atom

~1900 Rutherford investigates new radiations

α and β emissions change nature of elementα‘s charge = +2e α’s mass ~ 4H β radiation = electronsγ = electromagnetic radiation (photons)

-ve electrons embedded in +ve charge uniformly distributed over atomic volume

“plum pudding model”

use α particles (positively charged) on golden foil

expected observed+ve α’s pushed a little to the side

by +ve charge of atomsome α’s deflected backwards to 180o !!

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 cameback and hit you”

Clear experimental evidence that atoms contain electrons – where are they?

1932 Chadwick discovers the neutron

3 building blockselectron + proton + neutron

Nucleus = protons + neutrons

NUCLEAR PHYSICS(10-15 m)

Atom = nucleus + electron

+Ze

-e

(10-10 m)

planetary model of atom

Heisenberg ⇒ simplest atom = H its nucleus = proton

1920 Aston’s mass spectrograph ⇒ measure masses of atoms

mass chargeHe ~ 4 H He = 2 HC ~ 12 H C = 6 HO ~ 16 H O = 8 H

…. ….

⇒ hypothesis of neutral particle in nucleus with m ~ mp

Conclusion:all +ve charge (and ~all mass) concentrated in tiny region at the centre

Concept of atomic NUCLEUS is born !

Are protons and neutron the ultimate building blocks?Are they fundamental particles?

Energy and density scales

100 1010 1015105

Solid stateWhite Dwarf

Neutron star Black hole

Nuclear matterwater

g/cm3

density

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!!)