Absorb. – To drink in, or suck up, as a sponge absorbs water.
Absorber. – In nuclear engineering, a sheet or other body of material placed between a source of radiation and a detector such as: (1) determining the nature or the energy of the radiation: (2) reducing the intensity of the radiation at the detector, as in shielding: or (3) giving the radiation some desired characteristic, as by preferential transmission of one component of the radiation. Such an absorber may function through a combination of processes of true absorption, scattering and slowing down. In a nuclear reactor, a substance absorbs neutrons without reproducing them. Such a substance may be useful in control of a reactor, or if unavoidably present, may produce an undesired impairment in neutron economy. Neutron absorption is an important function of the shield surrounding a reactor.
Absorption. – In optics, the partial destruction of light in passing through a medium; for example, a blue glass may absorb all rays but the blue rays, these latter being transmitted. Also the destruction of light by an opaque body, another form of energy (generally heat) being produced.
Absorption Control. – Control of reaction in a nuclear reactor by the use of a neutron absorber to remove part of the neutrons. Adjustment is made by varying the effective amount of absorber in or near the core. The most common arrangement is to incorporate the absorber in rods that can be moved in or out to a position where they have the desired effect. Useful absorbers for this purpose are cadmium and boron (the latter commonly in the form of boron steel). Since it is necessary to be able to raise as well as lower the neutron flux, the reactivity of the reactor with absorbers withdrawn must be somewhat higher than would be required for the reactor to be just critical. Therefore, at constant reaction rate, there is some consumption of neutrons in the control rods of an absorption-controlled reactor. Fertile material sometimes is used as control absorber to make this consumption useful and to improve over-all neutron economy.
Absorption Dynamometer. – An instrument for measuring power, in which the energy of a revolving wheel or shaft is absorbed by t he friction of a brake. The typical form of absorption dynamometer is the prony brake, which consists of a lever of definite length in frictional contact with a wheel or shaft and having adjustable screws by means of which the intensity of the friction may be varied. The end of the lever is attached to scales and the friction measured, from which the brake horsepower can be calculated. A brake dynamometer.