Atomic Physics: Accelerators

669 Pages·1980·26.4 MB·English

by  Patrick Richard (Eds.)

Methods of
Experimental Physics
VOLUME 17
ATOMIC PHYSICS: ACCELERATORS
METHODS OF
EXPERIMENTAL PHYSICS:
L. Marton and C. Marton, Editors-in-Chief
Volume 17
ATOMIC PHYSICS
Accelerators
Edited by
PATRICK RICHARD
Department of Physics
Kansas State University
Manhattan, Kansas
@
I980
ACADEMIC PRESS
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United Kingdom Edition published by
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Library of Congress Cataloging in Publication Data
Main entry under title:
Atomic physics: Accelerators
(Methods in experimental physics ; v. 17)
Includes bibliographical references and index.
1. Collisions (Nuclear physics)--Addresses, essays,
lectures. 2. Ion bombardment--Addresses, essays,
lectures. I. Marton, Ladislaus Laszlo. 11. Marton,
C. 111. Richard, Patrick, Date IV. Series.
QC794.6 .C6 A25 539 .7’3 80- 15602
ISBN 0-12-475959-9 (v. 17)
PRINTED IN THE UNITED STATES OF AMERICA
80 81 82 83 9 8 7 6 5 4 3 2 1
This work is dedicated to the memory of James R. Macdonald, whose
career was devoted to the study ojatomic collisions. Jim made many
valuable contributions through his diligent and uncompromising search
for correct solutions to atomic problems. Probably his last written con-
tribution to science is contained in this volume. He did not see a printed
version of his contribution.
This Page Intentionally Left Blank
CONTENTS
CONTRIBUTOR.S . . . . . . . . . . . . . . . . . . . . . . xvii
FORWE ORD . . . . . . . . . . . . . . . . . . . . . . . . . xix
PREFACE... . . . . . . . . . . . . . . . . . . . . . . . xxi
VOLUMESIN SERIES.. . . . . . . . . . . . . . . , . . . . xxiii
1. Introduction
by PATRICKR ICHARD
1.1. Atomic Collisions with Accelerated Ions . . . . . . . . 1
1.2. Accelerated Ions for Atomic Collisions . . . . . . . . 3
1.2.1. Impetus from Nuclear Physics for Accelerated
Ions . . . . . . . . . . . . . . . . . . . 3
1.2.2. The Accelerated-Ion Method . . . . . . . . 4
1.2.3. Use of Accelerated Ions for Atomic Collisions . 20
2. Energy Loss of High-Velocity Ions in Matter
by WEI-KANC HU
2.1. Introduction . . . . . . . . . . . . . . . . . . . . 25
2.2. General Concepts of Energy Loss . . . . . . . . . . 26
2: .3. Energy Loss Theories: General Background. . . . . . 30
2.3.1. Coulomb Scattering and Energy Loss . . . . . 3 1
2.3.2. Perturbation Method and Dielectric Description. 33
2.3.3. Bethe Formula . . . . . . . . . . . . . . . 34
2.3.4. Mean Excitation and Ionization Energy I. . . . 35
vii
viii CONTENTS
2.3.5. Shell Correction . . . . . . . . . . . . . . . 36
2.3.6. Dependence of Energy Loss on Z1 . . . . . . 37
2.3.7. Low-Velocity Electronic Energy Loss . . . . . 39
2.3.8. Nuclear Energy Loss . . . . . . . . . . . . 41
2.3.9. Electronic Energy Loss in the
Medium-Velocity Region . . . . . . . . . . . 45
2.4. Experimental Methods on Energy Loss . . . . . . . . 46
2.4.1. Transmission Measurements on Thin Foils . . . 47
2.4.2. Transmission Measurements on Gaseous Targets 51
2.4.3. Transmission Measurements on Supported Films 53
2.4.4. Transmission Measurements on a Thin Layer on
a Solid-state Detector . . . . . . . . . . . . 54
2.4.5. Backscattering Energy Loss . . . . . . . . . 58
2.4.6. Backscattering Thick-Target Yield . . . . . . . 61
2.4.7. Measurement of Energy Loss by the Inverted
Doppler Shift Attenuation (IDSA) Method . . . 65
2 .5 . Current Problems in Stopping Cross Sections . . . . . 68
2.5.1. Chemical Effect: Bragg’s Rule . . . . . . . . 69
. . . . . . . . . . . . . .
2.5.2. Solid-state Effect 69
2.5.3. Structure Effect . . . . . . . . . . . . . . . 70
2.5.4. Energy Straggling . . . . . . . . . . . . . . 70
2.5.5. Charge State of the Projectiles . . . . . . . . 71
2.5.6. The Barkas Effect . . . . . . . . . . . . . . 71
2.5.7. Ion Clusters Effect . . . . . . . . . . . . . 71
. . . . . . . . . . . .
2.5.8. Nuclear Energy Loss 72
3 . Charge Equilibration of High-Velocity Ions in Matter
by HANSD . BETZ
. . . . . . . . . . . . . . . . . . .
3.1. Introduction 73
3.1.1. Historic Background . . . . . . . . . . . . . 73
3.1.2. Present Situation . . . . . . . . . . . . . . 74
. . . . .
3.1.3. Review Articles and Data Collections 76
3.2. Fundamental Charge Exchange Processes . . . . . . . 78
3.2.1. Definitions and Basic Processes . . . . . . . . 78
3.2.2. Mathematical Description of Charge-State
Fractions under Nonequilibrium and
Equilibrium Conditions . . . . . . . . . . . . 80
CONTENTS ix
3.3. Experimental Techniques and Data Analysis . . . . . . 83
3.3.1. Measurement of Charge-State Fractions . . . . 83
3.3.2. Auxiliary Methods . . . . . . . . . . . . . . 87
3.4. Electron Capture . . . . . . . . . . . . . . . . . . 89
3.4.1. Theory of Electron Capture in Simple Collision
Systems . . . . . . . . . . . . . . . . . . 89
3.4.2. Electron Capture in Complex Systems . . . . . 94
3.4.3. Experimental Results on Electron Capture Cross
Sections . . . . . . . . . . . . . . . . . . 97
3.4.4. Multiple Electron Capture . . . . . . . . . . 104
. . .
3.4.5. Very Large Charge Exchange Probabilities 108
. . . .
3.4.6. Capture into Very High Quantum States 108
3.4.7. Capture into Continuum States . . . . . . . . 109
3.5. Electron Loss . . . . . . . . . . . . . . . . . . . 110
3.5.1. Target Ionization Due to Light Particles . . . . 110
3.5.2. Projectile Ionization . . . . . . . . . . . . . 113
3.5.3. Experimental Results on Electron Loss Cross
Sections . . . . . . . . . . . . . . . . . . 114
3.5.4. Multiple-Electron Loss . . . . . . . . . . . . 116
3.5.5. Small-Impact-Parameter Collisions and Multiple-
Electron Loss . . . . . . . . . . . . . . . . 117
3.6. Equilibrium Charge-State Distributions . . . . . . . . 118
3.6.1. Experimental Results . . . . . . . . . . . . 118
3.6.2. Semiempirical Descriptions of Equilibrium
Charge-State Distributions . . . . . . . . . . 122
3.7. Average Equilibrium Charge States . . . . . . . . . . 125
3.7.1. On the Lamb-Bohr (LB) Criterion . . . . . . 125
3.7.2. Experimental Average Equilibrium Charge States 127
3.7.3. Semiempirical Relationships for the Average
Equilibrium Charge . . . . . . . . . . . . . 129
3.8. Density Effects and Excited States . . . . . . . . . . 131
3.8.1. Density Effect in Gaseous Targets . . . . . . . 131
3.8.2. Density Effect in Solid Targets . . . . . . . . 134