Breaking of isospin symmetry in compound-nucleus reactions

Journal Article · Tue Jul 01 04:00:00 EDT 1986 · Rev. Mod. Phys.; (United States)

DOI:https://doi.org/10.1103/RevModPhys.58.607· OSTI ID:5081414

Harney, H L; Richter, A

The authors present an analysis of all extant data on isospin mixing in statistical compound-nucleus reactions. The analysis is based on a generalization of the Hauser-Feshbach formula allowing for isospin mixing. The strength of the mixing is described by a single parameter z-italic. The theory is applicable when all compound-nucleus resonances overlap strongly. It is derived from a statistical theory of nuclear reactions allowing for the mixing of two classes of states. The parameter z-italic comprises both internal mixing (via the Coulomb interaction) and external mixig (via the channels). The theory contains both the static criterion (Coulomb matrix elements compared with spacings) and the dynamical criterion (spreading widths compared with decay widths) for isospin symmetry breaking. The theory yields the dependence on z-italic of observables like average cross sections, and auto- and cross-correlation functions. The data show that isospin symmetry breaking is neither so weak as to be altogether negligible, nor so strong as to reduce our theory to a Hauser-Feshbach formalism without any reference to the isospin quantum number. The authors argue in favor of a parametrization of isospin symmetry breaking in the data in terms of a spreading width rather than a Coulomb matrix element. They find that internal mixing dominates, and that the associated spreading width is nearly independent of mass number and excitation energy.

• Research Organization: Max-Planck-Institut fuer Kernphysik, D-6900 Heidelberg, Federal Republic of Germany
• OSTI ID: 5081414
• Journal Information: Rev. Mod. Phys.; (United States), Journal Name: Rev. Mod. Phys.; (United States) Vol. 58:3; ISSN RMPHA
• Country of Publication: United States
• Language: English

Related Subjects

653003* -- Nuclear Theory-- Nuclear Reactions & Scattering
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA REACTIONS
ALUMINIUM 26
ALUMINIUM ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CAPTURE
CHARGED-PARTICLE REACTIONS
COMPOUND-NUCLEUS REACTIONS
CORRELATION FUNCTIONS
CROSS SECTIONS
DEUTERON REACTIONS
EVEN-EVEN NUCLEI
FLUCTUATIONS
FUNCTIONS
GIANT RESONANCE
HAUSER-FESHBACH THEORY
HEAVY ION REACTIONS
ISOSPIN
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
NUCLEAR REACTIONS
NUCLEAR THEORY
NUCLEI
ODD-ODD NUCLEI
PARTICLE PROPERTIES
RADIOISOTOPES
RESONANCE
SECONDS LIVING RADIOISOTOPES
STATISTICAL MODELS
SULFUR 28
SULFUR ISOTOPES
SYMMETRY BREAKING
TARGETS
VARIATIONS
YEARS LIVING RADIOISOTOPES