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 ferula Papal ferula The papal ferula (from Latin "ferula", "rod") is the pastoral staff used in the Catholic Church by the pope. It is a rod with a knob on top surmounted by a cross. It differs from a crosier, the staff carried by other bishops of Latin-rite churches, which is curved or bent at the top in the style of an shepherd's crook. Traditionally, the popes did not use any "ferula", crosier, or pastoral staff as part of the papal liturgy. The use of a staff is not mentioned in descriptions of Papal Masses in the "Ordines Romani" (Roman Ordinals).