| Description |
vii, 70 leaves : illustrations ; 29 cm |
| Summary |
"A Fermi neutron chopper and control system has been constructed and put into operation at the end of the UMR Reactor thermal column. The operation of the chopper has been demonstrated by reproducing the slow neutron cross section data for aluminum and by measuring the previously undetermined slow cross section of cobalt. The chopper which is powered by a series DC motor consists of 34 cadmium plated stainless steel blades separated by 1/16 inch aluminum spacers. The design incorporates the better characteristics of the Brookhaven and Argonne slow choppers. Speed regulation is accomplished using a silicon controlled rectifier feed back system which permits speeds from 50 to 15,000 rpm. The speed variation at all speeds is less than one percent. Aluminum cross sections in an energy range from 0.006 to 0.08 eV were shown to duplicate the Argonne results except for one additional peak which appeared at about 0.02 eV. Additional investigation is planned to explain this peak. Cobalt cross sections were determined as a function of energy from 0.005 to 0.1 eV. These data are believed to be the first published for cobalt in this energy range"--Abstract, leaf ii. |
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