Nuclear and Particle Physics - Fisica.net

415 Pages·2006·19.69 MB·English

Nuclear and Particle Physics
Nuclear and Particle Physics B. R. Martin
# 2006 John Wiley & Sons, Ltd. ISBN: 0-470-01999-9
Nuclear and Particle Physics
B. R. Martin
Department of Physics and Astronomy, University College London
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LibraryofCongressCataloging-in-PublicationData
Martin,B.R.(BrianRobert)
Nuclearandparticlephysics/B.R.Martin.
p.cm.
ISBN-13:978-0-470-01999-3(HB)
ISBN-10:0-470-01999-9(HB)
ISBN-13:978-0-470-02532-1(pbk.)
ISBN-10:0-470-02532-8(pbk.)
1. Nuclearphysics–Textbooks. 2. Particlephysics–Textbooks. I. Title.
QC776.M342006
539.702–dc22
2005036437
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ISBN-13978-0470019999(HB) ISBN-100470019999(HB)
978-0470025328(PB) 0470025328(PB)
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To Claire
Contents
Preface xi
Notes xiii
Physical Constants and Conversion Factors xv
1 Basic Concepts 1
1.1 History 1
1.1.1 The originsofnuclearphysics 1
1.1.2 The emergenceofparticlephysics:thestandardmodeland hadrons 4
1.2 Relativityandantiparticles 7
1.3 Symmetriesandconservationlaws 9
1.3.1 Parity 10
1.3.2 Chargeconjugation 12
1.4 Interactions andFeynmandiagrams 13
1.4.1 Interactions 13
1.4.2 Feynmandiagrams 15
1.5 Particleexchange:forces andpotentials 17
1.5.1 Range offorces 17
1.5.2 The Yukawapotential 19
1.6 Observable quantities:crosssectionsanddecayrates 20
1.6.1 Amplitudes 21
1.6.2 Cross-sections 23
1.6.3 Unstable states 27
1.7 Units: length,mass andenergy 29
Problems 30
2 Nuclear Phenomenology 33
2.1 Massspectroscopyand bindingenergies 33
2.2 Nuclear shapesandsizes 37
2.2.1 Chargedistribution 37
2.2.2 Matter distribution 42
2.3 Nuclear instability 45
2.4 Radioactivedecay 47
2.5 Semi-empirical massformula:theliquiddrop model 50
2.6 (cid:1)-decay phenomenology 55
2.6.1 Odd-massnuclei 55
2.6.2 Even-massnuclei 58
viii CONTENTS
2.7 Fission 59
2.8 (cid:2)-decays 62
2.9 Nuclear reactions 62
Problems 67
3 Particle Phenomenology 71
3.1 Leptons 71
3.1.1 Leptonmultipletsandleptonnumbers 71
3.1.2 Neutrinos 74
3.1.3 Neutrino mixingandoscillations 76
3.1.4 Neutrino masses 79
3.1.5 Universallepton interactions–thenumberofneutrinos 84
3.2 Quarks 86
3.2.1 Evidence forquarks 86
3.2.2 Quark generationsandquarknumbers 89
3.3 Hadrons 92
3.3.1 Flavour independenceandchargemultiplets 92
3.3.2 Quark modelspectroscopy 96
3.3.3 Hadronmassesandmagneticmoments 102
Problems 108
4 Experimental Methods 111
4.1 Overview 111
4.2 Acceleratorsand beams 113
4.2.1 DCaccelerators 113
4.2.2 ACaccelerators 115
4.2.3 Neutralandunstableparticlebeams 122
4.3 Particleinteractionswithmatter 123
4.3.1 Short-rangeinteractions withnuclei 123
4.3.2 Ionizationenergylosses 125
4.3.3 Radiationenergylosses 128
4.3.4 Interactions ofphotonsinmatter 129
4.4 Particledetectors 131
4.4.1 Gasdetectors 131
4.4.2 Scintillation counters 137
4.4.3 Semiconductor detectors 138
4.4.4 Particleidentification 139
4.4.5 Calorimeters 142
4.5 Layered detectors 145
Problems 148
5 Quark Dynamics: the Strong Interaction 151
5.1 Colour 151
5.2 Quantumchromodynamics(QCD) 153
5.3 Heavyquarkboundstates 156
5.4 Thestrongcouplingconstantandasymptoticfreedom 160
5.5 Jetsand gluons 164
5.6 Colourcounting 166
CONTENTS ix
5.7 Deep inelastic scatteringand nucleonstructure 168
Problems 177
6 Electroweak Interactions 181
6.1 Chargedandneutralcurrents 181
6.2 Symmetriesoftheweak interaction 182
6.3 Spinstructure oftheweak interactions 186
6.3.1 Neutrinos 187
6.3.2 Particleswithmass:chirality 189
6.4 W(cid:1) andZ0 bosons 192
6.5 Weakinteractionsofhadrons 194
6.5.1 Semileptonic decays 194
6.5.2 Neutrino scattering 198
6.6 Neutral mesondecays 201
6.6.1 CPviolation 202
6.6.2 Flavouroscillations 206
6.7 Neutral currentsand theunifiedtheory 208
Problems 213
7 Models and Theories of Nuclear Physics 217
7.1 The nucleon–nucleonpotential 217
7.2 Fermigasmodel 220
7.3 Shell model 223
7.3.1 Shell structureofatoms 223
7.3.2 Nuclear magicnumbers 225
7.3.3 Spins,paritiesandmagneticdipole moments 228
7.3.4 Excitedstates 230
7.4 Non-spherical nuclei 232
7.4.1 Electricquadrupole moments 232
7.4.2 Collectivemodel 236
7.5 Summary ofnuclearstructuremodels 236
7.6 (cid:1)-decay 238
7.7 (cid:2)-decay 242
7.7.1 Fermitheory 242
7.7.2 Electronmomentumdistribution 244
7.7.3 Kurieplotsandtheneutrinomass 246
7.8 (cid:3)-emissionandinternalconversion 248
7.8.1 Selection rules 248
7.8.2 Transitionrates 250
Problems 252
8 Applications of Nuclear Physics 255
8.1 Fission 255
8.1.1 Inducedfission–fissilematerials 255
8.1.2 Fissionchainreactions 258
8.1.3 Nuclear powerreactors 260
8.2 Fusion 266
8.2.1 Coulombbarrier 266
x CONTENTS
8.2.2 Stellarfusion 267
8.2.3 Fusionreaction rates 270
8.2.4 Fusionreactors 273
8.3 Biomedicalapplications 278
8.3.1 Biologicaleffectsofradiation:radiationtherapy 278
8.3.2 Medical imagingusingradiation 282
8.3.3 Magnetic resonanceimaging 290
Problems 294
9 Outstanding Questions and Future Prospects 297
9.1 Particlephysics 297
9.1.1 TheHiggs boson 297
9.1.2 Grand unification 300
9.1.3 Supersymmetry 304
9.1.4 Particleastrophysics 307
9.2 Nuclear physics 315
9.2.1 Thestructure ofhadronsandnuclei 316
9.2.2 Quark–gluonplasma, astrophysicsand cosmology 320
9.2.3 Symmetriesandthestandardmodel 323
9.2.4 Nuclear medicine 324
9.2.5 Power productionandnuclearwaste 326
Appendix A: Some Results in Quantum Mechanics 331
A.1 Barrierpenetration 331
A.2 Densityofstates 333
A.3 Perturbationtheory andtheSecond GoldenRule 335
Appendix B: Relativistic Kinematics 339
B.1 Lorentztransformations andfour-vectors 339
B.2 Framesofreference 341
B.3 Invariants 344
Problems 345
Appendix C: Rutherford Scattering 349
C.1 Classical physics 349
C.2 Quantummechanics 352
Problems 354
Appendix D: Solutions to Problems 355
References 393
Bibliography 397
Index 401
Preface
It is common practice to teach nuclear physics and particle physics together in an
introductorycourseanditisforsuchacoursethatthisbookhasbeenwritten.The
material ispresentedsothatdifferent selectionscanbemadeforashortcourseof
about 25–30 lectures depending on the lecturer’s preferences and the students’
backgrounds. On the latter, students should have taken a first course in quantum
physics, covering the traditional topics in non-relativistic quantum mechanics and
atomicphysics.Afewlecturesonrelativistickinematicswouldalsobeuseful,but
thisisnotessentialasthenecessarybackgroundisgiveninappendixBandisonly
used in a few places in the book.I have not tried to be rigorous, or present proofs
of all the statements in the text. Rather, I have taken the view that it is more
important that students see an overview of the subject which for many – possibly
the majority – will be the only time they study nuclear and particle physics. For
future specialists, the details will form part of more advanced courses. Never-
theless, space restrictions have still meant that it has been necessary to make a
choice of topics covered and doubtless other, equally valid, choices could have
beenmade.ThisisparticularlytrueinChapter8,whichdealswithapplicationsof
nuclearphysics,whereIhavechosenjustthreemajorareastodiscuss.Nuclearand
particle physics have been, and still are, very important parts of the entire subject
of physics and its practitioners have won an impressive number of Nobel Prizes.
For historical interest, I have noted in the footnotes many of the awards for work
related to the field.
Somepartsofthebookdealingwithparticlephysicsowemuchtoapreviousbook,
Particle Physics, written with Graham Shaw of Manchester University, and I am
gratefultohimandthepublisher,JohnWileyandSons,forpermissiontoadaptsome
ofthatmaterialforusehere.IalsothankColinWilkinforcommentsonallthechapters
of the book, David Miller and Peter Hobson for comments on Chapter 4 and Bob
Speller for comments on the medical physics section of Chapter 8. If errors or
misunderstandingsstillremain(andanysuchareofcourseduetomealone)Iwouldbe
grateful to hear about them. I have set up a website (www.hep.ucl.ac.uk/(cid:1)brm/
npbook.html)whereIwillpostanycorrectionsandcomments.
Brian R. Martin
January 2006