a Schematic Model for (p,xn) Cross Sections in Heavy Elements

A schematic model for the description of (p, xn) reactions in heavy elements is presented. Reactions are divided into two steps, a prompt multiple collision process, followed by an evaporation stage. The various prompt processes are given by the results of Monte Carlo calculations, while the evaporation processes are described by a simplified model assuming constant nuclear temperatures and only neutron evaporation. The resulting (p, xn), and to a minor degree (p, pxn), cross sections are compared with the experimental data of Bell and Skarsgard (1956) in the energy range up to 100 Mev. With an average neutron binding energy of around 7.3 Mev., a nuclear temperature of about 1.8 Mev., and a nuclear radius of 8.0 × 10−13 cm., a reasonable over-all fit can be made to the data for Pb206, Pb207, Pb208, and Bi209. Characteristic fluctuations in the experimental results for the (p, 2n), (p, 3n), and (p, 4n) reactions for all targets seem to be attributable to variations in the total reaction cross section, and ...

[1]  R. Diamond,et al.  Nuclear Reactions of Cobalt with Protons from 0- to 100-Mev Energy , 1956 .

[2]  R. Leachman.  Emission of Prompt Neutrons from Fission , 1956 .

[3]  S. Fernbach,et al.  OPTICAL MODEL ANALYSIS OF SCATTERING OF 14 MEV NEUTRONS , 1956 .

[4]  J. Huizenga,et al.  PROTON CROSS SECTIONS OF Bi$sup 20$$sup 9$ , 1956 .

[5]  R. Nakasima,et al.  The Cu(n; 2n) Excitation Function and the Knock-out Process in Nuclear Reactions , 1955 .

[6]  S. Hayakawa,et al.  Nuclear Reactions at Moderate Energies and Fermi Gas Model , 1955 .

[7]  E. O. Wiig,et al.  Reactions of Cobalt with Protons at 60, 100, 170, and 240 Mev , 1954 .

[8]  B. Cohen,et al.  FISSION AND TOTAL REACTION CROSS SECTIONS FOR 22-MEV PROTONS ON Th$sup 232$, U$sup 235$, AND U$sup 23$$sup 8$ , 1954 .

[9]  C. Porter,et al.  Model for Nuclear Reactions with Neutrons , 1954 .

[10]  E. O. Wiig,et al.  REACTIONS OF CESIUM WITH PROTONS AT 60, 80, 100, 150, AND 240 MEV , 1954 .

[11]  P. C. Gugelot.  Level Densities of Nuclei from the Inelastic Scattering of 18-Mev Protons , 1954 .

[12]  J. Meadows.  EXCITATION FUNCTIONS FOR PROTON-INDUCED REACTIONS WITH COPPER , 1953 .

[13]  V. Weisskopf,et al.  Theoretical Nuclear Physics , 1953 .

[14]  D. Peaslee.  Comparative Models in Nuclear Scattering , 1952 .

[15]  N. Knable,et al.  Nuclear Cross Sections for 95 Mev Neutrons , 1950 .

[16]  M. Goldberger,et al.  The interaction of high energy neutrons and heavy nuclei , 1948 .

[17]  W. Horning,et al.  Stars in Photographic Emulsions Initiated by Deuterons Part II. Theoretical , 1948 .