Nuclear Reactions for Astrophysics :Principles, Calculation and Applications of Low-Energy Reactions

Publication subTitle :Principles, Calculation and Applications of Low-Energy Reactions

Author: Ian J. Thompson; Filomena M. Nunes  

Publisher: Cambridge University Press‎

Publication year: 2009

E-ISBN: 9780511577697

P-ISBN(Paperback): 9780521856355

Subject: P14 astrophysics

Keyword: 原子核物理学、高能物理学

Language: ENG

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Nuclear Reactions for Astrophysics

Description

Describing the processes in stars which produce the chemical elements for planets and life, this book shows how similar processes may be reproduced in laboratories using exotic beams, and how these results can be analyzed. Beginning with one-channel scattering theory, the book builds up to multi-channel reactions. Emphasis is placed on using transfer and breakup reactions to probe structure and predict capture processes, as well as R-matrix methods for modeling compound nucleus dynamics described by Hauser-Feshbach methods. Practical applications are prominent in this book, confronting theory predictions with data throughout. The associated reaction program Fresco is described, allowing readers to apply the methods to practical cases. Each chapter ends with exercises so readers can test their understanding of the materials covered. Supplementary materials at www.cambridge.org/9780521856355 include the Fresco program, input and output files for the examples given in the book, and hints and graphs related to the exercises.

Chapter

2.2.3 Compound nucleus reactions

2.3 Collisions

2.3.1 Non-relativistic kinematics

2.3.2 Relative and center-of-mass wave functions

2.3.3 Relativistic kinematics

2.4 Cross sections

2.4.1 Differential cross sections

2.4.2 Laboratory and center of mass measures

2.4.3 Experimental and theoretical cross sections

2.4.4 Cross sections and scattering amplitudes

Exercises

References

3 Scattering theory

3.1 Elastic scattering from spherical potentials

3.1.1 Partial-wave scattering from a finite spherical potential

3.1.2 Coulomb and nuclear potentials

3.1.3 Resonances and virtual states

3.1.4 Nuclear currents or flux

3.1.5 Complex potentials

3.2 Multi-channel scattering

3.2.1 Multiple channels

3.2.2 Coupled equations

3.2.3 Unitarity of the multi-channel S matrix

3.2.4 Detailed balance

3.3 Integral forms

3.3.1 Green's function methods

3.3.2 Vector-form T matrix for plane waves

3.3.3 Two-potential formula

3.3.4 Vector-form T matrix for distorted waves

3.3.5 Born series and approximations

3.4 Identical particles

3.4.1 Isospin

3.4.2 Direct and exchange amplitudes in elastic scattering

3.4.3 Integrated cross sections

3.4.4 Exchange transfer

3.5 Electromagnetic channels

3.5.1 Maxwell equations and photon channels

3.5.2 Coupling photons and particles

3.5.3 Photon cross sections

3.5.4 Partial waves and vector spherical harmonics

3.5.5 Electric and magnetic parts in the Coulomb gauge

Appendix

Exercises

References

4 Reaction mechanisms

4.1 Optical potentials

4.1.1 Typical forms

4.1.2 Global optical potentials

4.1.3 Folding potentials

4.2 Single-nucleon binding potentials

4.2.1 Neutron and proton single-particle states in nuclei

4.2.2 Optical potentials extended to bound states

4.3 Coupling potentials

4.3.1 Multipole analysis of transition potentials

4.3.2 Spin-dependent potentials

4.4 Inelastic couplings

4.4.1 Collective inelastic processes

4.4.2 Single-particle inelastic processes

4.5 Particle rearrangements

4.5.1 Transfer reactions

4.5.2 Knockout reactions

4.5.3 Breakup reactions

4.5.4 Capture reactions

4.6 Isospin transitions

4.6.1 Charge-exchange reactions

4.6.2 Generalized multipole transitions

4.7 Photo-nuclear couplings

4.7.1 Single-photon reactions

4.7.2 Electric transitions using the Siegert theorem

4.7.3 Combining multiple-particle and γ channels

4.7.4 Connecting photon cross sections and B(EJ)

4.7.5 Magnetic transitions

Exercises

References

5 Connecting structure with reactions

5.1 Summary of structure models

5.1.1 Shell models

5.1.2 Cluster models

5.1.3 Mean-field models

5.1.4 Collective nuclear-matter descriptions

5.2 Folded potentials

5.2.1 Fourier methods

5.2.2 Deformed densities

5.2.3 Typical forms of effective interactions

5.3 Overlap functions

5.3.1 Non-antisymmetrized theory

5.3.2 Antisymmetrized theory

5.3.3 Cluster overlaps

5.4 General matrix elements

5.4.1 Coulomb and nuclear transitions

5.4.2 Allowed β-decays

Exercises

References

6 Solving the equations

6.1 Elastic scattering

6.2 Classifications

6.2.1 Local and non-local couplings

6.2.2 Simplified solutions

6.3 Multi-channel equations

6.3.1 Alternate methods

6.3.2 Close-coupling methods for local couplings

6.3.3 Iterative solutions

6.3.4 Numerical iterations

6.3.5 Convergence of iterative methods

6.4 Multi-channel bound states

6.4.1 Coupled-channels eigenvalue problem

6.5 R-matrix methods

6.5.1 One-channel R-matrix expansions

6.5.2 The multi-channel R matrix

6.6 Coupled asymptotic wave functions

Exercises

References

7 Approximate solutions

7.1 Few-body adiabatic scattering

7.1.1 Three-body adiabatic model

7.1.2 The Johnson and Soper potential for transfer reactions

7.1.3 The Johnson special three-body model

7.1.4 The adiabatic wave function for breakup

7.1.5 The adiabatic wave function for transfers

7.2 Eikonal methods

7.2.1 The eikonal wave function

7.2.2 Eikonal elastic scattering

7.2.3 Composite-body scattering and the optical limit

7.2.4 Eikonal cross sections

7.2.5 Stripping reactions

7.3 First-order semiclassical approximation

7.4 WKB approximation

7.4.1 Coulomb penetration factors

Exercises

References

8 Breakup

8.1 Three-body wave equations

8.1.1 Wave function components

8.1.2 Three-component Faddeev equations

8.1.3 Reduction to one Jacobi set

8.2 Continuum Discretized Coupled Channel method

8.2.1 Continuum bins

8.2.2 CDCC equations and couplings

8.2.3 Calculating differential cross sections

8.2.4 Model space and convergence of the CDCC equations

8.2.5 Relation to DWBA

8.2.6 Three-body observables

8.3 Other breakup measures and methods

8.3.1 Momentum distributions

8.3.2 Inclusive measurements

8.3.3 Semiclassical and time-dependent methods

8.3.4 Transfer to the continuum

Exercises

References

9 Three-body nuclei

9.1 Definitions of halo and deeply bound states

9.2 Three-body models for bound states

9.2.1 The hyperspherical coordinates

9.2.2 Hyperspherical expansions

9.2.3 Coupled hyper-radial equations

9.2.4 Pauli principle

9.3 Three-body continuum

9.4 Reactions with three-body projectiles

9.4.1 Born approximations

9.4.2 Adiabatic models

9.4.3 Three-body eikonal models

9.4.4 Four-body CDCC

Exercises

References

10 R-matrix phenomenology

10.1 R-matrix parameters

10.2 Single-channel R matrix

10.2.1 Phase shifts from the one-channel R matrix

10.2.2 Isolated poles in single-channel scattering

10.2.3 Multiple poles in one channel

10.3 Coupled-channels R matrix

10.3.1 Revised derivation of the scattering S matrix

10.3.2 Level-matrix formulation

10.4 Combining direct and resonant contributions

Exercises

References

11 Compound-nucleus averaging

11.1 Compound-nucleus phenomena

11.1.1 Porter-Thomas statistics

11.2 Approximations neglecting interference

11.2.1 Reich-Moore approximation

11.2.2 Multi-level Breit-Wigner approximation

11.3 Hauser-Feshbach models

11.3.1 Width fluctuation corrections

11.3.2 Transmission coefficients

11.3.3 Weisskopf-Ewing approximation

11.3.4 Strong couplings and overlapping resonances

11.3.5 Decay models

11.4 Level densities

11.5 Average amplitudes and the optical model

11.5.1 Sources of the optical potential

11.5.2 Effects of neglected direct-reaction channels

11.5.3 Effects of neglected compound-nucleus channels

Exercises

References

12 Stellar reaction rates and networks

12.1 Thermal averaging

12.1.1 Reaction rates (συ) and lifetimes

12.1.2 Maxwell-Boltzmann distributions

12.1.3 The Gamow peak

12.1.4 Averaging over resonances

12.1.5 Neutron and photon reaction rates

12.1.6 Inverse reaction rates

12.1.7 Electron screening

12.2 Reaction networks

12.2.1 Coupled rate equations

12.2.2 Explicit and implicit solution methods

12.3 Equilibria

12.3.1 Fixed points of the rate equations

12.3.2 The Saha equation

12.3.3 Reactions with excited states

12.3.4 Nuclear statistical equilibrium

12.3.5 Freeze-out

12.4 Sensitivities to nuclear data

Exercises

References

13 Connection to experiments

13.1 New accelerators and their methods

13.1.1 Beam production

13.1.2 An example of a fast-fragmentation facilty

13.1.3 An example of an ISOL facility

13.2 Detection

13.3 Direct measurements

13.3.1 Charged-particle beams

13.3.2 Neutron beams

13.3.3 Photon beams

Exercises

References

14 Spectroscopy

14.1 Transfer spectroscopy

14.1.1 DWBA transfer theory

14.1.2 Q-value sensitivity

14.1.3 Angular momentum sensitivity

14.1.4 Extraction of asymptotic normalization coefficients

14.1.5 Extraction of spectroscopic factors

14.1.6 Dependence on optical potentials

14.1.7 Dependence on single-particle parameters

14.1.8 Higher-order corrections

14.2 Knockout spectroscopy

14.3 Inelastic spectroscopy

14.4 Breakup spectroscopy

14.4.1 Coulomb dissociation method

14.4.2 Extracting an asymptotic normalization coefficient

Exercises

References

14.5 Charge-exchange spectroscopy

15 Fitting data

15.1 χ2 measures

15.1.1 Specifications

15.1.2 Multivariate theory

15.2 Fitting cross-section harmonic multipoles

15.3 Fitting optical potentials

15.3.1 Sensitivities

15.3.2 Ambiguities in optical potentials

15.4 Multi-channel fitting

15.4.1 Elastic fits

15.4.2 Fitting inelastic scattering

15.4.3 Transfer fits

15.4.4 A Progressive Improvement Policy

15.5 Searching

15.5.1 Strategies

15.5.2 Theoretical expectations and the Bayesian method

15.5.3 Error estimates from χ2 fitting

Exercises

References

Appendix A Symbols

Appendix B Getting started with FRESCO

B.1 General structure

B.1.1 Input file

B.1.2 Output files

B.2 Learning through examples

B.2.1 Elastic scattering

B.2.2 Inelastic scattering

B.2.3 Breakup

B.2.4 Transfer

B.2.5 Capture

B.3 Runtime errors

B.4 Fitting data: SFRESCO

B.5 System requirements, compilations and installation

References

Selected bibliography

Index

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