The Griffin model, complex particles and direct nuclear reactions

The basic approximations of the Griffin model for nuclear reactions are reexamined. Proton-neutron distinguishability and the Pauli exclusion principle are treated in an improved way. Several improvements in the model input values are suggested. Direct reaction mechanisms are systematically considered, and semi-empirical descriptions are proposed for those not included in the Griffin model calculations (knockout and inelastic processes involving alpha particles and stripping and pickup). When all of these points are considered, good agreement with experimental energy spectra for emitted particles are obtained without arbitrary and unphysical factors in the particle emission rates and without the artificial projectile dependence previously needed for the average residual two-body matrix element.

[1]  G. Igo,et al.  Theoretical reaction cross sections for alpha particles with an optical model , 1962 .

[2]  J. W. Kennedy,et al.  Nuclear and Radiochemistry , 1965 .

[3]  A. G. W. Cameron,et al.  A COMPOSITE NUCLEAR-LEVEL DENSITY FORMULA WITH SHELL CORRECTIONS , 1965 .

[4]  C. B. Fulmer,et al.  DIRECT-INTERACTION (p,$alpha$) REACTIONS IN $sup 89$Y AND $sup 90$Zr , 1965 .

[5]  R. West.  Proton Emission in 42-MeV Alpha-Particle Bombardments of Several Elements , 1966 .

[6]  N. B. Gove,et al.  Part II. Nuclear-reaction and separation energies , 1971 .

[7]  F. C. Williams.  Particle-hole state density in the uniform spacing model , 1971 .

[8]  M. Blann,et al.  The pre-equilibrium statistical model: Description of the nuclear equilibration process and parameterization of the model , 1971 .

[9]  P. Obložinský,et al.  Calculations of the excitation functions and isomer ratios of the 41K(α, n)44Sc reaction in the equilibrium and pre-equilibrium statistical models , 1972 .

[10]  L. Colli-Milazzo,et al.  The preformation of α particles in heavy nuclei by the analysis of n, α reactions , 1972 .

[11]  C. Cline.  Extensions to the pre-equilibrium statistical model and a study of complex particle emission , 1972 .

[12]  L. Milazzo-Colli,et al.  α-Emission by pre-equilibrium processes in (n,α) reactions , 1973 .

[13]  L. Colli,et al.  The pre-compound emission mechanism in nuclear reactions , 1973 .

[14]  C. Kalbach-Cline.  Residual two-body matrix elements for pre-equilibrium calculations , 1973 .

[15]  E. Gadioli,et al.  Intermediate-state decay rates in the exciton model , 1973 .

[16]  G. Strini,et al.  PRE-EQUILIBRIUM PROCESSES IN (p,n) REACTIONS. , 1973 .

[17]  P. Obložinský,et al.  Emission of complex particles in the exciton model , 1973 .

[18]  P. Obložinský,et al.  Pre-equilibrium decay and the exciton model , 1973 .

[19]  L. Milazzo-Colli,et al.  Pre-equilibrium α-particle emission in the115in(p, α)112Cd , 1973 .

[20]  P. Obložinský,et al.  Intermediate-state transition rates in the exciton model , 1974 .

[21]  F. Bertrand,et al.  Differential cross sections for charged-particle emission in reactions of 58-MeV $alpha$ particles with $sup 12$C, $sup 16$O, and $sup 54$Fe: comparison with the exciton model of pre-equilibrium particle emission , 1974 .

[22]  M. Milazzo,et al.  Preformation probability of ga-clusters in rare earth nuclei measured by means of the (p, α) reaction☆ , 1974 .

[23]  S. Grimes,et al.  Comparison of proton and neutron spectra: The extended Griffin model, pairing and isospin , 1975 .

[24]  C. Kalbach.  The shell-shifted equi-spacing model for particle-hole state densities , 1975 .

[25]  A. Chevarier,et al.  Continuous proton spectra emitted in 3He and deuteron induced reactions , 1975 .

[26]  H. Weidenmüller,et al.  The statistical theory of nuclear reactions for strongly overlapping resonances as a theory of transport phenomena , 1975 .

[27]  M. Milazzo,et al.  Further measurements of the probability of α cluster pre-formation by means of (p, α) reactions in heavy elements , 1975 .

[28]  L. Moretto.  Thermodynamical properties of a paired nucleus with a fixed number of quasi-particles☆ , 1975 .

[29]  J. Ernst,et al.  Continuous particle spectra and angular distributions from different entrance channels forming 65Zn∗ at 37.4 MeV excitation , 1976 .

[30]  L. Sajo-Bohus,et al.  An exciton model approach to the analysis of α-particle-induced nuclear reactions , 1976 .

[31]  H. Weidenmüller,et al.  Generalized exciton model for the description of preequilibrium angular distributions , 1976 .

[32]  Y. Iwasaki.  Global viewpoint on nuclear-particle-emission cross sections at intermediate energies. [235 MeV] , 1976 .

[33]  R. Siemssen,et al.  Semi-microscopic description of three-nucleon transfer and the Sn(p, α)In reaction☆ , 1976 .

[34]  Y. Iwasaki.  Cross-sections for several-nucleon pick-up reactions and unitarity , 1976 .