Neutron cross section according to its neutron cross section and how it reacts to an incident neutron. Nuclides that tend to absorb a neutron and either decay or keep the neutron in its nucleus are neutron absorbers and will have a "capture cross section" for that reaction. Isotopes that fission, are fissionable fuels and have a corresponding "fission cross section". The remaining isotopes will simply scatter the neutron, and have a "scatter cross section". Some isotopes, like uranium-238, have nonzero cross sections of all three. Isotopes which have a large scatter cross section and a low mass are good neutron moderators (see chart
The African Americans: Many Rivers to Cross series, by episode, can be found on the PBS website. "The African Americans: Many Rivers to Cross" is Henry Louis Gates, Jr.’s 13th documentary film. Reviewing the series for "The New Yorker", writer and theater critic Hilton Als wrote: “The story Gates tells in his thirteenth documentary film is an epic one, and details how enslaved black Africans became African-Americans... Gates’s quest isn’t ideological; one could call the documentary a kind of ‘Pilgrim’s Progress,’ one in which the burdens are race and property. What becomes abundantly clear vis-à-vis Gates’s lyrical investigation is the innate genius it took for African-Americans to