Ядерна фізика та енергетика Nuclear Physics and Atomic Energy   ISSN: 1818-331X (Print), 2074-0565 (Online)   Publisher: Institute for Nuclear Research of the National Academy of Sciences of Ukraine   Languages: Ukrainian, English   Periodicity: 4 times per year   Open access peer reviewed journal

Full text (en)

M. Adib, N. Habib, B. Fathalla

Reactor Physics Department, Nuclear Research Center, Atomic Energy Authority, Cairo, Egypt

Abstract: The transmission of neutrons through pyrolytic graphite (PG) crystals, set at different angles with respect to incident beam, were calculated using an additive formula. A computer program HOPG was developed to provide the required calculation. An overall agreement between the calculated neutron transmissions through a slab of 1.85 mm thick PG crystal with an angular spread of c-axes of 0.4°, set at different angles to the incident beam, and the available experimental ones in the wavelength range from 0.02 to 1.4 nm were obtained. A feasibility study for use of PG crystal as an efficient second-order neutron filter is detailed in terms of crystal thickness, angular spread of c-axes and its orientation with respect to the neutron beam. It was shown that a PG crystal with an angular spread of 0.8° is sufficient for optimum scattering of second-order neutrons in the wavelength band 0.384 - 0.183 nm, by adjusting the filter in an appropriate orientation.

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