Search Results

You are looking at 1 - 3 of 3 items for :

  • Author or Editor: J. François x
  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

The table presents computed values of effective threshold energies, Eeff, for (n, 2n) reactions induced in a fission neutron spectrum. Eeff-values are given for the (n, 2n) reactions for which the charge of the target nucleus is greater than 11 and for which the reaction product cannot be formed by (n, γ) reaction on another stable isotope. A closed expression is given for the integral of a fission neutron distribution of the Cranberg type, N(E), and for the mean energy of the fission neutrons with spectral distribution N(E).

Restricted access

Abstract  

Long-lived rhodium radionuclides were produced by the following reactions:103Rh(n, 2n)102(m)Rh;103Rh(γ,xn)100Rh,101Rh,102(m)Rh;104Pd(d, α)102(m)Rh; Ru(d, n)99Rh,101(m)Rh,102(m)Rh; and
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $${}^{104}Ru(n,\gamma )^{105} Ru\mathop \to \limits^{\beta - } {}^{105}Rh$$ \end{document}
. The average cross-section of the103Rh(n, 2n)102Rh reaction in a fission neutron spectrum is about 0.75 mb. Irradiation of rhodium in the bremsstrahlung spectrum of 50 MeV electrons yielded a102Rh activity of 0.11 μCi/g after 3 days at a power of 2 kW. The thick target yield of the reaction104Pd(d, α)102Rh was 0.002 μCi/μAh for 12 MeV deuterons. The thick target yield of the reaction Ru(d,xn)102Rh was 0.05 μCi/μAh for 12 MeV deuterons and 4.8 μCi/μAh for 18 MeV deuterons. The best yield was obtained by deuteron bombardment of ruthenium. The chemical separation of carrier-free Rh radionuclides from deuteron-irradiated ruthenium is described, with a chemical yield better than 90%. The same procedure has also been applied for the isolation of105Rh from neutron-irradiated ruthenium. γ-Ray spectra of99Rh,101(m)Rh and102(m)Rh from deuteron-irradiated ruthenium and of105Rh from neutron-irradiated ruthenium, taken with a Ge(Li) detector, are shown; a number of γ-rays, not reported in the literature, were observed. The γ-ray energies were determined with a precision of ca. 0.3–0.4 keV.
Restricted access

Abstract  

The average cross-section in a fission-type reactor spectrum was determined experimentally for the reactions:46Ti(n,p)46Sc,47Ti(n,p)47Sc,48Ti(n,p)48Ti(n,α)45Ca and50Ti(n,α)47Ca. In order to obtain the (n,p) cross-sections, reactor irradiation of titanium was followed by measurement of the induced scandium activities with a Ge(Li) detector of calibrated detection efficiency. For this no chemical separations had to be carried out. For the (n,α) reactions, however, the induced calcium activities were separeted and purified by oxalate precipitation, after the bulk of the radioactivity had been removed by precipitation of titanium hydroxide. The47Ca disintegration rate was determined in the same way as for the scandium isotopes, whereas for45Ca liquid scintillation counting was carried out. The shape of the reactor spectrum was investigated by irradiating reference threshold detectors with different effective threshold energies. To correct for (n,γ) interferences, irradiations were carried out with and without cadmium shielding. On the basis of
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\bar \sigma _F = 0.64$$ \end{document}
mb for the reaction27Al(n,α)24Na, the average cross-sections were as follows:46Ti(n,p)46Sc:10.5±0.4 mb;47Ti(n,p)47Sc: 16.3±0.6 mb;48Ti(n,p)48Sc:0.272±0.005 mb;48Ti(n,α)45Ca: 34μb;50Ti(n,α)47Ca: 8.1±0.3 μb.
Restricted access