Neutron Radiative Capture

List of Abbreviations

Introduction

I. Theory of Slow Neutron Radiative Capture

I.A Introduction

I.A.1 The Electromagnetic Interaction

I.A.2 Photons in Reaction Theory

I.B Statistical Theory of Radiative Capture

I.B.1 Premises

I.B.2 Partial Radiative Widths

I.B.3 Gamma-ray Spectrum

I.B.4 Total Radiative Widths

I.B.5 Width Distributions

I.C Systematic Properties of Radiative Neutron Capture

I.C.1 Resonance-averaged Cross Sections

I.C.2 Formalism for Averaged Capture Cross Sections

I.C.3 The Distribution of Radiative Strength in Nuclei

II. Fast Neutron Radiative Capture

II.A Direct and Semi-direct Capture Reactions

II.A.l The Symmetry Potential

II.A.2 The Giant Dipole Resonance

II.A.3 Derivation of the Direct-Semi-direct Cross SectionH

II.A.4 The Direct-Semi-direct Cross Section

II.A.5 Isospin Splitting of the Giant Dipole Resonance

II.A.6 Direct-Semi-direct Capture in Deformed Nuclei

II.A.7 Contribution of Other Giant Multipole Resonances 52

II.B Experimental Results

II.B.l Gamma-ray Spectra

II.B.2 Partial Capture Cross Sections

II.B.3 Systematics of 14-15 MeV Capture Cross Sections

II.B.4 Angular Distribution of γ Rays

III. Methods for Calculating Neutron Capture Cross Sections and Gamma-ray Energy Spectra

III.A Scope

III.B Statistical Model Calculations

III.B.l The Hauser-Feshbach (HF) Equation

III.B.2 The Gamma-Ray Cascade

III.B.3 Neutron Transmission Coefficients

III.B.4 Total Radiative Widths

III.C Expressions for E1 Photon Strengths

III.D Giant Dipole Resonance Systematics

III.E Nuclear Level Densities

III.E.l The Gilbert-Cameron Formalism

III.E.2 The Spin Cut-off Parameter

III.E.3 The Yrast Limit

III.F Sample Calculation: 89Υ(n,γ)90CΥ

III.F.l Specifications of the 89Y+n Problem

III.F.2 Results from the 89Y+n Calculation

III.G Summary

IV. Measurement Techniques for Radiative Neutron Capture

IV.A Introduction

IV.A.1 The Radiative Neutron Capture Reaction

IV.A.2 Neutron Sources

IV.A.3 Flux Measurements

IV.B Capture Event Detection

IV.B.l Indirect Techniques

IV.B.2 Prompt Radiation Detection

IV.B.3 Gamma-ray Spectral Measurements

IV.C Analysis of Measurements

IV.C.l Thermal and Fast Neutron Energy Range

IV.C.2 Resonance Neutron Range

V. Neutron Capture Processes in Fission Reactors

V.A Introduction

V.B Capture in Fertile and Fissile Nuclei

V.B.l Fertile Nuclei

V.B.2 Fissile Nuclei

V.C Capture in Structural, Coolant and Shielding Materials

V.D Capture in Fission Product Nuclei

V.D.l Thermal Reactors

V.D.2 Fast Reactors

V.E The Production of Higher Actinides

VI. Applications to Stellar Nucleosynthesis

VI.A Introduction

VI.B s-Process Nucleosynthesis

VI.C Age of the s-Process and the Stellar Environment

VI.D r-Process Chronometer and the Age of the Universe

VI.E Summary

VII. Practical Uses of Neutron Capture Gamma-ray Spectroscopy

VII.A Introduction

VII.B Fundamentals

VII.C The Prompt Gamma-ray Technique (PGA)

VII.C.1 Sensitivity

VII.C.2 Sources and Detectors

VII.C.3 Applications of Reactor-based PGA

VII.C.4 Mobile Systems

VII.C.5 Biomedicine

VII.C.6 Elemental Analyses for Petroleum and Mineral Exploration

VII.C.7 Process Stream Analysis of Coal

VII.D Non-analytical Uses of Neutron Capture

VII.E Conclusions

VIII. Summary and Concluding Remarks

References

Glossary

Subject Index