|  | G |
SECTION G — PHYSICS

|  | G |
Note(s) In this section, the following term is used with the meaning indicated: "variable" (as a noun) means a feature or property (e.g., a dimension, a physical condition such as temperature, a quality such as density or colour) which, in respect of a particular entity (e.g., an object, a quantity of a substance, a beam of light) and at a particular instant, is capable of being measured; the variable may change, so that its numerical expression may assume different values at different times, in different conditions or in individual cases, but may be constant in respect of a particular entity in certain conditions or for practical purposes (e.g., the length of a bar may be regarded as constant for many purposes). Attention is drawn to the definitions of terms or expressions used, appearing in the notes of several of the classes in this section, in particular those of "measuring" in class Fulltext... Hierarchy... Expanded...G01 and "control" and "regulation" in class Fulltext... Hierarchy... Expanded...G05. Classification in this section may present more difficulty than in other sections, because the distinction between different fields of use rests to a considerable extent on differences in the intention of the user rather than on any constructional differences or differences in the manner of use, and because the subjects dealt with are often in effect systems or combinations, which have features or parts in common, rather than "things", which are readily distinguishable as a whole. For example, information (e.g., a set of figures) may be displayed for the purpose of education or advertising (Fulltext... Hierarchy... Expanded...G09), for enabling the result of a measurement to be known (Fulltext... Hierarchy... Expanded...G01), for signalling the information to a distant point or for giving information which has been signalled from a distant point (Fulltext... Hierarchy... Expanded...G08). The words used to describe the purpose depend on features that may be irrelevant to the form of the apparatus concerned, for example, such features as the desired effect on the person who sees the display, or whether the display is controlled from a remote point. Again, a device which responds to some change in a condition, e.g., in the pressure of a fluid, may be used, without modification of the device itself, to give information about the pressure (Fulltext... Hierarchy... Expanded...G01L) or about some other condition linked to the pressure (another subclass of class Fulltext... Hierarchy... Expanded...G01, e.g., Fulltext... Hierarchy... Expanded...G01K for temperature), to make a record of the pressure or of its occurrence (Fulltext... Hierarchy... Expanded...G07C), to give an alarm (Fulltext... Hierarchy... Expanded...G08B), or to control another apparatus (Fulltext... Hierarchy... Expanded...G05). The classification scheme is intended to enable things of a similar nature (as indicated above) to be classified together. It is therefore particularly necessary for the real nature of any technical subject to be decided before it can be properly classified.

NUCLEONICS

|  | G21 |
NUCLEAR PHYSICS; NUCLEAR ENGINEERING

|  | G21H |
OBTAINING ENERGY FROM RADIOACTIVE SOURCES; APPLICATIONS OF RADIATION FROM RADIOACTIVE SOURCES; UTILISING COSMIC RADIATION (measurement of nuclear or X-radiation Fulltext... Hierarchy... Expanded...G01T; fusion reactors Fulltext... Hierarchy... Expanded...G21B; nuclear reactors Fulltext... Hierarchy... Expanded...G21C; semiconductor devices sensitive to electromagnetic or corpuscular radiation Fulltext... Hierarchy... Expanded...H01L 31/00)

|  | G21H 1/00 |
Arrangements for obtaining electrical energy from radioactive sources, e.g. from radioactive isotopes

|  | G21H 1/02 |
· | Cells charged directly by beta radiation

|  | G21H 1/04 |
· | Cells using secondary emission induced by alpha radiation, beta radiation, or gamma radiation (discharge tubes Fulltext... Hierarchy... Expanded...H01J 40/00, Fulltext... Hierarchy... Expanded...H01J 47/00)

|  | G21H 1/06 |
· | Cells wherein radiation is applied to the junction of different semiconductor materials

|  | G21H 1/08 |
· | Cells in which radiation ionises a gas in the presence of a junction of two dissimilar metals, i.e. contact potential-difference cells (discharge tubes Fulltext... Hierarchy... Expanded...H01J)

|  | G21H 1/10 |
· | Cells in which radiation heats a thermoelectric junction or a thermionic converter (discharge tubes functioning as thermionic generators Fulltext... Hierarchy... Expanded...H01J 45/00; thermoelectric devices comprising a junction of dissimilar materials Fulltext... Hierarchy... Expanded...H01L 35/00) [2]

|  | G21H 1/12 |
· | Cells using conversion of the radiation into light combined with subsequent photoelectric conversion into electric energy

|  | G21H 3/00 |
Arrangements for direct conversion of radiation energy from radioactive sources into forms of energy other than electric energy, e.g. light (lasers Fulltext... Hierarchy... Expanded...H01S 3/00)

|  | G21H 3/02 |
· | in which material is excited to luminesce by the radiation (lamps in which a gas filling or screen or coating is excited to luminesce by radioactive material structurally associated with the lamp Fulltext... Hierarchy... Expanded...H01J 65/00)

|  | G21H 5/00 |
Applications of radiation from radioactive sources or arrangements therefor (producing mutation in plants Fulltext... Hierarchy... Expanded...A01H 1/06; preservation of dairy products Fulltext... Hierarchy... Expanded...A23C; preservation of foodstuffs Fulltext... Hierarchy... Expanded...A23L 3/26; for therapeutic purposes Fulltext... Hierarchy... Expanded...A61N 5/10; in chemical, physical or physicochemical processes in general Fulltext... Hierarchy... Expanded...B01J 19/08; in electrostatic separation Fulltext... Hierarchy... Expanded...B03C 3/38; for after-treatment of coatings applied as liquids or other fluent materials Fulltext... Hierarchy... Expanded...B05D 3/06; for action between electric vehicles and tracked apparatus Fulltext... Hierarchy... Expanded...B61L 1/10, Fulltext... Hierarchy... Expanded...B61L 3/06; introducing isotopes into organic compounds Fulltext... Hierarchy... Expanded...C07B 59/00; for preparation of organic chemical compounds Fulltext... Hierarchy... Expanded...C07, Fulltext... Hierarchy... Expanded...C08, e.g. Fulltext... Hierarchy... Expanded...C08F 2/46; for treating macromolecular substances or articles made therefrom Fulltext... Hierarchy... Expanded...B29C 71/04, Fulltext... Hierarchy... Expanded...C08J 3/28, Fulltext... Hierarchy... Expanded...C08J 7/18; for cracking of hydrocarbon oils Fulltext... Hierarchy... Expanded...C10G 15/00, Fulltext... Hierarchy... Expanded...C10G 32/04; for reforming naphtha Fulltext... Hierarchy... Expanded...C10G 35/16; preservation or ageing of products obtained from fermentation processes Fulltext... Hierarchy... Expanded...C12H 1/06, Fulltext... Hierarchy... Expanded...C12H 1/16; for bleaching fibres Fulltext... Hierarchy... Expanded...D06L 3/04; measuring Fulltext... Hierarchy... Expanded...G01; irradiation devices, gamma- or X-ray microscopes Fulltext... Hierarchy... Expanded...G21K; in discharge tubes Fulltext... Hierarchy... Expanded...H01J; apparatus for generating ions to be introduced into non-enclosed gases, e.g. into the atmosphere, Fulltext... Hierarchy... Expanded...H01T 23/00; for carrying-off electrostatic charges Fulltext... Hierarchy... Expanded...H05F 3/06)

|  | G21H 5/02 |
· | as tracers

|  | G21H 7/00 |
Use of effects of cosmic radiation