Positron beams and their applications / editor, Paul Coleman.

Format:

Book

Contributor:

Coleman, Paul G., 1948-

Language:

English

Subjects (All):

Positron beams.

Positron beams--Industrial applications.

Physical Description:

xiii, 322 pages : illustrations ; 23 cm

Place of Publication:

Singapore ; River Edge, N.J. : World Scientific, [2000]

Summary:

This book provides a coherent and comprehensive overview of the generation and application of mono-energetic positron beams. It has been written by acknowledged experts, at a level accessible to graduate students working, or planning to work, with positron beams, and to scientists in other areas who want to know something about the field.

The book begins with a brief historical introduction and an overview of how positron beams are generated and transported. A description of the fate of slow positrons in gaseous and condensed matter, with reference to many of the fundamental measurements made possible by the advent of positron beams, is followed by a discussion on applications in the study of solid surfaces, defect profiling in subsurface regions, interfaces and thin films, and the probing of bulk properties in novel ways. The book ends with a look at the future, considering the prospects for intense positron beams and their potential for further research.

Contents:

Chapter 1 Introduction: A Brief History of Positron Beams / P.G. Coleman 1

1 Early days 1

2 Positron beams in the laboratory 3

3 Branching out 5

4 Applications 6

Chapter 2 The Generation and Transport of Positron Beams / P.G. Coleman 11

1 Positron sources 11

1.1 Radioactive sources 11

1.2 Pair production 13

2 Positron moderation 14

2.1 The physics of moderation 14

2.2 Moderating materials 17

2.3 Moderator geometries 19

2.4 Field-assisted moderators 21

3 Positron transport 22

3.1 Magnetic transport and focusing 22

3.2 Electrostatic transport and focusing 25

3.2.1 Brightness enhancement 26

3.3 Hybrid positron beams 27

4 Positron acceleration 28

5 Bunching and timing 29

6 Detectors 32

Chapter 3 Atomic and Molecular Physics with Positrons and Positronium / G. Laricchia, M. Charlton 41

2 Fundamentals 42

2.1 Positronium 42

2.1.1 Basic properties 42

2.1.2 Annihilation modes and lifetimes 43

2.1.3 Spectroscopic properties 44

2.1.4 Non-spectroscopic laser studies and exotic tests 46

2.2 The positronium negative ion 46

3 Interactions of positrons with atoms and molecules 47

3.2 Experimental systems 48

3.3 Total cross-sections, Q[subscript t] 49

3.4 Elastic scattering (Q[subscript el] and dQ[subscript el]/d[Omega]) 52

3.5 Positronium formation 53

3.5.1 Integrated cross-section, Q[subscript Ps] 54

3.5.2 Differential cross-section, dQ[subscript Ps]/d[Omega]) 58

3.6 Excitation 60

3.7 Ionization 61

3.7.1 Integrated cross-section, Q[subscript i superscript z+] 62

Single ionization 62

Multiple ionization 66

Dissociative ionization, dissociative attachment, positronium compounds 68

3.7.2 Differential studies 69

3.8 Annihilation 72

4 Interactions of positronium with atoms and molecules 75

4.2 Positronium beams 76

4.3 Total cross-sections 79

5 Antihydrogen 82

5.2 Prospects for the production of low energy antihydrogen 83

Chapter 4 The Fate of Slow Positrons in Condensed Matter / R.M. Nieminen 97

2 Elementary excitations and scattering 99

2.1 Inelastic scattering 99

2.1.1 Electronic excitations 99

2.1.2 Phonon scattering 101

2.2 Elastic scattering off stationary atoms 101

3 Ballistic motion, energy loss and implantation 104

3.1 Implantation profiles 104

3.2 Epithermal transport 106

4 Diffusive and quantum motion 106

4.1 Positron diffusion 107

4.2 Quantum reflection 108

5 Electron-positron correlation and annihilation 109

6 Trapping and detrapping 112

7 Surface and near-surface processes 114

7.1 Trapping at below-surface defects 114

7.2 Diffraction and reflection 115

7.3 Re-emission phenomena 116

7.3.1 Positron re-emission 117

7.3.2 Positronium re-emission 118

7.3.3 Branching ratios 119

7.3.4 Epithermal re-emission 120

7.4 Glancing-angle positronium formation 120

7.5 Capture to the surface state 120

7.6 Desorption from the surface 121

7.7 Positron-induced Auger emission 122

Chapter 5 Surface Science With Positrons / A.H. Weiss, P.G. Coleman 129

2 Positron re-emission studies 132

2.2 Work function positron emission 133

2.3 Positron tunneling spectroscopy 137

2.4 Re-emitted Positron Energy Loss Spectroscopy (REPELS) 140

3 Low Energy Positron Diffraction (LEPD) 141

3.2 Analysis of surface structure 144

3.3 Differences between LEED and LEPD 146

3.4 Advantages of LEPD over LEED for surface structure determination 149

3.5 LEPD theory 150

3.6 Future LEPD research 151

4 Positron Annihilation induced Auger Electron Spectroscopy (PAES) 152

4.1.1 The PAES mechanism 153

4.1.2 PAES experimental apparatus 154

4.1.3 Secondary electron background elimination 155

4.1.4 Surface sensitivity 156

4.2 Theoretical calculations 157

4.3 PAES intensities 159

4.4 Applications of PAES 160

4.4.1 Studies of the growth of ultrathin layers on metals and semiconductors 160

4.4.2 Adsorption studies 161

4.5 PAES sensitivity to impurities 162

4.6 Future PAES research 164

5 Positron-induced secondary electron emission 165

5.2 Experimental studies of secondary electron emission 166

6 Positron backscattering 170

7 Positronium at surfaces 174

7.1 Direct positronium formation 174

7.2 Thermal desorption of positronium from surfaces 175

7.3 Ps studies of non-metallic surfaces and thin films 176

7.3.1 Graphite 176

7.3.2 Alkali halides 176

7.3.3 SiO[subscript 2] 177

7.3.4 Polymers 177

7.3.5 Ice 177

7.3.6 Oxide films 178

7.4 Ps beam studies 178

7.5 Other Ps surface spectroscopies 179

Chapter 6 Depth-Profiling of Subsurface Regions, Interfaces and Thin Films / A. Van Veen, H. Schut, P.E. Mijnarends 191

2 Observables 193

3 Doppler broadening 194

3.1 S and W parameters 194

3.2 S-W mapping 195

3.3 Two-detector Doppler broadening measurements 197

4 2D-ACAR 199

5 Positron lifetime 199

6 Positronium fraction 201

7 Diffusion and trapping 202

8 Surface branching 204

9 Point defects and clusters 206

Ion implantation defects 206

Microcavities 208

Defects in deposited layers 210

10 Precipitates 211

Nitride precipitates in iron 212

Oxide precipitates in silver 213

11 Planar interfaces 214

12 Electric field effects 219

Chapter 7 Positron Microscopes and Microprobes / P.G. Coleman 227

1 Positron microbeams 227

2 Positron re-emission microscopes 229

3 Applications 232

3.1 Microbeams 232

3.2 Microscopes 233

Chapter 8 MeV Positron Beams / H. Stoll 237

2 The setting up of an MeV positron beam 238

2.1 Accelerator 238

2.2 Positron source 238

2.3 Positron beam

line 239

2.4 Energy stabilization 240

3 Beam-based positron lifetime measurements 241

3.1 [beta superscript +] [gamma] coincidence technique 241

4 Age-momentum correlation 243

4.1 Beam-based AMOC 243

4.2 The AMOC set-up and data acquisition 244

4.3 AMOC relief, lineshape function & "Tsukuba plot" 245

4.4 Two-dimensional data analysis 245

5 Selected experiments 246

5.1 Positron single quantum annihilation and channeling experiments 246

5.2 Beam-based positron lifetime and AMOC experiments 248

5.2.1 Positronium states in condensed rare gases 248

5.2.2 Positronium thermalization 251

Chapter 9 Spin-Polarized Positron Beams in Condensed-Matter Studies / J. Major 259

2 The principles of the spin-polarized positron set-up 262

3 Determination of the positron-spin polarization 269

(a) Specimen with spin-polarized electrons 270

(b) Specimen in which positronium can be formed 272

4 Positron-spin relaxation (e[superscript +]SR) experiments 275

5 e[superscript +]SR experiments on [alpha]-iron 276

6 Magnetic quenching of the positronium hyperfine interaction 284

7 e[superscript +]SR experiments on samples in which positronium may be formed 291

8 Summary and future prospects of the spin-polarized positron-beam technique 299

Chapter 10 The Future: Intense Beams / R.H. Howell 307

1 The need for intensity 307

2 Methods of production 308

2.1 Strong radioactive sources 309

2.1.1 Reactor production of positron sources 310

2.1.2 Accelerator production of positron emitters 312

2.2 Pair production 313

2.2.1 Linacs 313

2.2.2 Synchrotron radiation 318

2.2.3 Neutron capture gamma rays 319.

Notes:

Includes bibliographical references and index.

ISBN:

9810233949

OCLC:

43186035