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Abstract  

The average cross-section in a fission-type reactor spectrum
\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} $$\bar \sigma _F$$ \end{document}
was experimentally determined for the reactions42Ca(n, p)42K,43Ca(n, p)43K and44Ca(n, p)44K. Calcium carbonate samples and fast neutron flux monitors were irradiated with and without cadmium shielding in the Thetis reactor (Institute for Nuclear Sciences, Rijksuniversiteit, Gent). The potassium activities induced in the calcium carbonate samples were separated and purified by tetraphenylborate precipitation, after which they were measured with a Ge(Li)-detector of calibrated detection efficiency. 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:42Ca(n, p)42K: 2.82±0.07mb;43Ca(n, p)43K: 1.89±0.05 mb;44Ca(n, p)44Ca(n, p)44K: 0.065±0.003 mb.
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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.
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Abstract  

Several methods are in use for the determination of the thermal to epithermal neutron fluence rate ratio (f) and the deviation of the epithermal neutron spectrum from the 1/E shape parameter (α). In our former work, it was proven that the recently developed and characterized Synthetic Multi-ELement Standard (SMELS) can be used for the fast verification of the stability of the irradiation parameters using the Au-Zr bare monitor method. However, this latter method using SMELS had a too low precision for an accurate determination of f and α. Therefore, the Cd-ratio for multi-monitor method using SMELS was investigated for two irradiation channels. As shown the material can also be used as a monitor for the calibration of an irradiation facility.

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