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
Papal shoes shoe is very thin-soled and is sometimes called "pantofola liscia" or smooth slipper model. After 1958, Pope John XXIII added gold buckles to the outdoor papal shoes, making them similar to the red shoes worn by cardinals outside of Rome. Pope Paul VI eliminated the gold cross and completely discontinued the custom of kissing the papal foot. Paul VI can be seen wearing red buckled shoes in photographs from his 1964 trip to Jerusalem. In 1969, Paul VI abolished buckles from all ecclesiastical shoes, which had been customarily required at the Papal Court and for prelates. He also discontinued the