Nuclear Fission

PrefaceI. Introduction A. Discovery of Fission B. Scope of the Book ReferencesII. The Fission Barrier A. Liquid Drop Model 1. Introduction 2. Potential Energy Mapping and the Fission Barrier 3. Barrier Curvature B. Single Particle Model 1. Introduction 2. Single Particle Calculation of Deformation Energy C. Strutinsky Hybrid Model 1. The Shell Correction Method 2. Predicted Barriers for Superheavy Elements 3. Extension of the Strutinsky Method to Reflection-Asymmetric Saddle-Point Shapes D. Fission Barrier Height Systematics E. Excitations at the Saddle Point ReferencesIII. Spontaneous Fission A. Introduction B. Systematics of Ground State Spontaneous Fission Half Lives C. Penetration of the Fission Barrier D. Spontaneously Fissionable Isomers ReferencesIV. Fission Widths from Neutron Resonance Studies A. Resonance Spin Determinations 1. Neutron Scattering 2. Interference between Levels 3. Nuclear Orientation 4. Transmission of Polarized Neutrons through Polarized Targets 5. Gamma-Ray Multiplicities 6. Relative Intensity of Specific Capture Gamma Rays B. Average Fission Widths C. Width Distributions D. Fission Characteristics which Apparently Depend on Resonance Spin 1. Mass Asymmetry 2. Kinetic Energy Release 3. Neutron Multiplicity 4. Ratio of Ternary to Binary Fission E. Intermediate Levels in the Two Potential Wells of Heavy Nuclei F. The n, γf Process ReferencesV. Properties of Low-Lying Levels of Transition Nuclei Determined from Reaction Studies A. Introduction B. Photofission 1. Even Nucleus Targets 2. Odd Mass Targets C. Neutron-Induced Fission 1. Odd-Mass Transition Nuclei (Formed by Neutron Fission of Even-Even Targets) 2. Odd-Mass Transition Nuclei (Two-Humped Barrier Penetration) 3. Even-Even Transition Nuclei (Formed by Neutron Fission of Odd-N Targets) D. Fission of Nuclei Excited in Direct Reactions 1. Introduction 2. Fission of Even-Even Transition Nuclei 3. Fission of Odd-A Transition Nuclei ReferencesVI. Fission-Fragment Angular Distributions at Moderate to High Excitation Energies A. Introduction B. Theory of Angular Distributions for Transition States Described by a Statistical Model 1. Exact Theoretical Expression 2. Approximate Theoretical Expressions 3. Comparisons of the Various Theoretical Expressions C. Experimental Fission-Fragment Angular Distributions D. Modification in Theory to Account for Nuclear Pairing E. Shape of the Transition Nucleus F. Angular Anisotrophy of Fission Fragments of Particular Mass G. Angular Correlation Between Fission Fragments ReferencesVII. Competition Between Fission and Neutron Emission A. Experimental Determination of Γn/Γf Values at Low and Moderate Excitation Energy 1. Fission Cross Sections 2. Photofission and Photoneutron Cross Sections 3. Mean Values of Гn/Гf Deduced from Higher Energy Neutron Fission Cross Sections 4. Mean Values of Гn/Гf Derived from Charged Particle-Induced Spallation Cross Sections 5. Summary of Experimental Values of Гn/Гf B. Theoretical Expectations for Гn/Гf 1. The Neutron and Fission Widths at Low Energies 2. Excitation Energy Dependence of Гn/Гf 3. Deformation Dependence of the Level Density Parameter a C. Effect of Angular Momentum on Гn/Гf 1. Theoretical Considerations 2. Comparison with Experiment 3. Direct Fission ReferencesVIII. Fission Barrier Heights A. Experimental Values of Fission Barrier Heights B. Methods of Determining Fission Barrier Heights from Reactions 1. Barrier Heights from Excitation Energy Dependence of Гn/Гf 2. Barrier Heights from (n, f), (t, pf), (t, df), and (d, pf) Excitation Functions 3. Barrier Heights from Photofission Excitation Functions 4. Barrier Heights for Nuclei Exhibiting a Double Barrier ReferencesIX. Motion from Saddle to Scission: Theories of Mass and Energy Distributions A. Introduction B. Adiabatic Models 1. The Liquid Drop Model 2. Single Particle Effects on the Potential Energy Surface and on the Dynamics of the Descent from Saddle to Scission C. Nonadiabatic Models of Fission 1. Statistical Theory of Fission 2. A Model of Kinetic Dominance ReferencesX. Kinetic Energy Release in Fission A. Dependence of the Total Kinetic Energy on the Charge and Mass of the Fissioning Nucleous B. Dependence of the Total Kinetic Energy on the Mass Division C. Dependence of the Total Kinetic Energy on Excitation Energy D. Dependence of the Total Kinetic Energy on Angular Momentum E. Dependence of the Total Kinetic Energy Release on Charge Division ReferencesXI. Distribution of Mass and Charge in Fission A. Mass Distributions 1. Introduction 2. Spontaneous Fission 3. Particle-Induced Fission 4. Fine Structure in Primary Fission-Fragment and Fission Product Mass Distributions 5. Mass Distribution for Spontaneous Fission Isomers B. Charge Distributions 1. Charge Distributions in Low Energy Fission 2. Dependence of Charge Division on Excitation Energy ReferencesXII. Prompt Neutrons from Fission A. Introduction B. Total Neutron Yield in Low Energy Fission 1. Time Scale of Neutron Emission 2. Average Neutron Yield v for Various Fissioning Species 3. Distribution of Neutron Emission Numbers 4. Dependence of Neutron Yield on Excitation Energy 5. The Neutron Energy Spectrum C. Dependence on Neutron Yield in Low Energy Fission D. Correlation Between Neutron Yields of Complementary Fragments E. Dependence of Neutron Kinetic Energy on Fragment Mass ReferencesXIII. Gamma Rays from Primary Fission Products A. Introduction B. Gamma Rays from Fragments of All Masses 1. The Time of Emission 2. The Gamma-Ray Energy Spectrum 3. Angular Distribution of Fission Gamma Rays C. Dependence of Gamma-Ray Yield and Energy on Fragment Mass D. K x Rays and Conversion Electrons E. Isomeric Yield Ratios and Rotational State Populations as a Measure of Fragment Angular Momentum 1. Isomeric Yield Ratios 2. Gound State Band Populations 3. Anisotropies of Specific Deexcitation Gamma Rays F. Theoretical Estimates of Fission-Fragment Angular Momentum ReferencesXIV. Ternary Fission A. Light-Particle-Accompanied Fission 1. Mechanism for Charged Particle Emission During Fission 2. Dependence of Yield on Nuclear Species and Excitation Energy 3. Relative Yields of the Different Light Particles 4. Angular and Energy Distributions of the Light Charged Particles 5. Dependence of the Probability of Alpha-Particle-Accompanied Fission on Mass Division 6. Energy Balance in Alpha-Accompanied Fission B. Fission in which Three Fragments of Comparable Mass are Produced ReferencesAuthor IndexSubject Index