Serber Says

The following sections are included:

• CONTENTS

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The following sections are included:

• The Deuteron

• Neutron–Proton Scattering

• The Scattering Length

• The Zero Range Approximation

• The Singlet Scattering

• The Effective Range

The following sections are included:

• Effect of Chemical Bonding

• Scattering Of Slow Neutrons By Hydrogen Molecules

• Diffraction Scattering

• The Optical Theorem

• Total Internal Reflection Of Neutrons

The following sections are included:

• Electric Dipole Disintegration

• Magnetic Dipole Disintegration

• The Neutron–Proton Capture Reaction

The following sections are included:

• Slowing in Hydrogen

• Slowing by Heavier Nuclei

• Spatial Diffusion of Neutrons

The following sections are included:

• Magnetic Moment of The Proton

• Electric Quadrupole Moment of The Deuteron

• The Tensor Force

• Neutron Magnetic Moment

• Neutron-Electron Interaction

The following sections are included:

• Coulomb Scattering

• Scattering With P–P Force

• The Mirror Nuclei

• P–P Effective Range

The following sections are included:

• Symmetry of The Nuclear Forces

• Selection Rules and Multiplets

The following sections are included:

• Nucleon-Nucleon Scattering

• Higher Energy Reactions

The following sections are included:

• Decay of a Resonance Level

• The Stationary States

• The Decay Wave Function At Large Γ

• The Scattering Cross Section

• Scattering With Several Decay Channels

A nuclear model is considered in which the nuclear forces are taken to be a Yukawa potential acting between nucleons, such as would be produced by a neutral scalar meson, and a repulsive core. The model is very similar to the Fermi–Thomas model of the atom. It is first worked out in the absence of the Coulomb interaction, and it is shown how the binding energy, surface energy, and shape of the nuclear density at the surface of the nucleus are determined. The Coulomb interaction is then included and the model is worked out for a heavy nucleus, the parameters of the model being chosen to give the correct radius and binding energy. One predicts the right value of Z/A, and obtains a charge density distribution not too different from that deduced from electron scattering experiments.

When a target is bombarded with high energy deuterons, a narrow beam of high energy neutrons is produced by a process in which the proton in the deuteron strikes the edge of the nucleus and is stripped off, while the neutron misses and continues on its way. The cross section for this stripping process is , where R is the nuclear radius and R_d is the deuteron radius , or . The yield of neutrons from a . Be target (in which the energy loss for 190-Mev deuterons is 20 Mev) is nearly 2 percent. The neutrons come out with an energy spread around having a half-width Here E_d is the kinetic energy of the deuteron, E_d its binding energy. For light nuclei the half-width of the neutron angular distribution is The half-width increases somewhat with atomic number, primarily because of the deflection of the deuteron by the Coulomb field as it approaches the nucleus, and, to a lesser extent, because of multiple scattering in the target . The increase in half-width from Be to U is about 25 percent. The calculated half-widths and angular distributions agree well with the measurements of Helmholz, McMillan, and Sewell.

An equal number of high energy protons are produced by stripping processes in which it is the neutron that hits the nucleus.

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The experiments of Cook, McMillan, Peterson, and Sewell on the cross sections of nuclei for neutrons of about 90 Mev indicate that the nuclei are partially transparent to high energy neutrons. It is shown that the result scan be explained quite satisfactorily using a nuclear radius R = 1.37A^t × 10⁻¹²cm, a potential energy for the neutron in the nucleus of 31 Mev, and a mean free path for the neutron in nuclear matter of 4.5 × 10⁻¹³cm. This mean free path agrees with that estimated from the high energy n-p cross section, but the results are not sensitive to the choice of mean free path.

The following sections are included:

• Author Index

• Subject Index