radiation
(reɪdɪˈeɪʃən)
[ad. L. radiātiōn-em n. of action from radiāre: see radiate v. and cf. F. radiation (1469).]
1. a. The action or condition of sending out rays of light. Now rare (see note to 2).
| 1626 Bacon Sylva §125 So it [sound] paralleleth in so many other things with the Sight, and Radiation of Things visible. 1646 Sir T. Browne Pseud. Ep. 260 As for Sciotericall Dialls, whether of the Sunne or Moon, they are only of use in the actuall radiation of those Luminaries. 1740 Cheyne Regimen 123 The glorious Appearance and Radiation of our Saviour's Body on the Mount. 1773 Encycl. Brit. III. 525/2 Radiation, the act of a body emitting or diffusing rays of light all round, as from a centre. |
b. A ray or quantity of light emitted by a radiant body (
usu. in
pl.). In
mod. use (
usu. in
sing.), energy transmitted in the form or rays, waves, or sub-atomic particles; in non-
techn. use
spec. ionizing radiation.
| 1570 Dee Math. Pref. b j, Perspective..demonstrateth the maner and properties, of all Radiations Direct, Broken, and Reflected. 1626 Bacon New Atl. 39 Wee haue also Perspectiue-Houses, wher wee make Demonstrations of all Lights and Radiations. 1792 Dalton Meteorol. Obs. (1834) 64 The beams lost their lateral motion, and were converted..into the flashing radiations. 1837 Brewster Magnet. 225 The part of the heavens where all these beams or radiations unite. 1871 Tyndall Fragm. Sci. (1879) II. xvi. 450 Dissolved in a proper vehicle, iodine cuts the visible radiation sharply off. 1896 Strand Mag. July 108/1 If a solid object is placed in the path of this [negative] stream..it may become the seat of the production of that..which is variously known as Röntgen radiation or X-radiation. At the solid object the new radiation springs into being, and then travels away from it in all directions, in very much the same way that ordinary light would do. 1899 Phil. Mag. XLVII. 109 The remarkable radiation emitted by uranium and its compounds has been studied by its discoverer, Becquerel. 1934 H. M. Vernon Princ. Heating & Ventilation iii. 50 The intensity of the radiation from a coal fire varies enormously. 1958 New Statesman 25 Oct. 545/3 This week's inquest on the second serviceman to die after the Christmas Island tests reveals once more the astonishing medical and scientific ignorance of the effects of radiation. 1962 A. Nisbett Technique Sound Studio iii. 52 With stringed instruments, very little of the sound we hear is directly from the strings; what we are actually listening to is the radiation from a sounding board to which the strings are coupled. 1966 McGraw-Hill Encycl. Sci. & Technol. XIV. 265/2 The trapped radiation consists of protons and electrons constrained to bound orbits by the geomagnetic field. 1972 Daily Tel. (Colour Suppl.) 3 Mar. 17 Our planet is constantly being bombarded by all kinds of radiation—from natural radio waves to infra-red, visible light, ultraviolet, X-rays and gamma radiation. 1978 Sci. Amer. July 82/1 Although bees are most sensitive to ultraviolet radiation, it is not the color that they learn best. To the bee ultraviolet radiation is sky radiation, and it seems not to be expected as a pure color at food sources. |
| fig. 1652 Jer. Collier Eccho in Benlowes Theoph., The Radiations of the Soul All splendors of the flesh controul. 1750 Johnson Rambler No. 29 ¶4 As the errors and follies of a great genius are seldom without some radiations of understanding, by which meaner minds may be enlightened. 1871 Farrar Witn. Hist. ii. 83 This life is not a type of any one excellence, but a radiation of them all. |
† c. Astrol. = aspect n. 4.
Obs. rare.
| 1555 Digges Prognos. B iv, The Sextile aspecte or radiation..is with in 60 degrees thone from the other. 1688 R. Holme Armoury ii. i. 27 Names or Terms used by Astronomers... Aspect or Radiation. |
2. Orig., the emission and diffusion of heat-rays. Now, the emission of energy of any kind in the form of rays or waves,
esp. electromagnetic waves.
In its widest sense, radiation denotes the manner in which the energy of a vibrating body is transmitted in all directions by a surrounding medium. When this energy is imparted to the ether, it produces waves which, according to their frequency, affect the senses either as light or heat.
| 1812–16 Playfair Nat. Phil. (1819) I. 229 Heat escapes from bodies..by radiation, or by passing in straight lines through the air with great rapidity. 1845 Darwin Voy. Nat. xi. (1879) 249 The winter is rendered excessively cold by the radiation from a large area of land into a clear sky. 1880 Haughton Phys. Geog. ii. 50 This process..goes on in every planet, as long as it is losing heat by radiation. 1908 C. C. F. Monckton Radio-Telegr. iv. 69 There will be a certain amount of radiation possibly from the tree back towards the radiator, and a consequent distortion of the field. 1934 Discovery Dec. 347/2 The noise in aeroplanes can be reduced..; little can be done for reducing the external radiation of noise. 1956 B.B.C. Handbk. 1957 9 The radiation of signals from the transmitting aerial. |
| fig. 1827 Hare Guesses Ser. i. (1873) 44 Under the impulses of a mighty passion, he..fuses every object by its intense radiation. |
3. a. Divergence from a central point; radial arrangement or structure.
| 1658 Sir T. Browne Gard. Cyrus iii. 59 The motion of vegetation upward, and of radiation into all quarters. 1856 Ruskin Mod. Paint. IV. v. xv. §8 The beauty of a crest or bird's wing consists..in the radiation of the plumes. 1868 Stanley Westm. Abb. iii. 129 The radiation of the polygonal chapels round the Choir. |
b. One of a set of radiating things or parts.
| 1843 Youatt Horse vi. (1847) 110 Rays or radiations of bone extend thence in every direction. 1899 Allbutt's Syst. Med. VI. 756 Division of the optic radiations was attended by a descending degeneration. |
c. Biol. The spread of an animal or plant group from an area in which its greatest concentration is or was found.
Cf. adaptive radiation s.v. adaptive a.
| 1949 W. C. Allee et al. Princ. Animal Ecol. xxxiv. 662/2 The early radiation of the orders of insects is even more remarkable than that of the orders of mammals. 1957 P. J. Darlington Zoogeography vii. 414 The most profound patterns of geographical radiation, reflecting spread of great, dominant groups from definite centers, are found among the animals which disperse most slowly over land. 1977 Sci. Amer. May 28/3 In the course of their wide and long-lasting radiation these apes seem to have encountered increasingly cooler environments. 1978 Nature 17 Aug. 662/1 The Dicroidium complex, a diverse group of seed ferns characteristic of the Triassic, became nearly entirely extinct and was replaced by a Jurassic radiation of conifers. |
4. In
mod. use
freq. attrib. with the sense ‘ionizing radiation’, as
radiation dosage,
radiation dose,
radiation dosimetry,
radiation level,
radiation meter,
radiation monitor;
radiation,
radiation induced,
radiation-proof adjs.; in the names of bodily disorders caused by ionizing radiation, as
radiation cachexia,
radiation carcinogenesis,
radiation dermatitis,
radiation osteitis,
radiation ulcer.
Comb. as
radiation accident, an accident involving potentially hazardous exposure to ionizing radiation;
radiation badge, a badge that changes its appearance when a prescribed dose of ionizing radiation has been received;
cf. film badge s.v. film n. 7 b;
radiation belt Astr., a region surrounding a planet where charged particles accumulate under the influence of the planet's magnetic field;
radiation burn, a burn caused by over-exposure to ionizing radiation;
radiation chemistry, the study of chemical changes arising from the impact of ionizing radiation; (
cf. radiochemistry); hence
radiation-chemical adj.;
radiation chemist;
radiation counter = counter n.2 3 b;
radiation damage, damage caused by ionizing radiation;
radiation efficiency Telecommunications (see
quot. 1977);
radiation field, an extent of space in which there is radiation;
spec. the space around an aerial in which there is a continuous outward flow of energy, separated from the aerial by the induction field;
radiation fog, fog formed when the ground loses heat by radiation and cools overlying moist air;
radiation frost, frost which occurs when the ground loses heat by radiation;
radiation genetics, the branch of biology concerned with the genetic effects of ionizing radiation;
radiation hazard, a risk to health owing to the presence of ionizing radiation;
radiation injury, an injury caused by over-exposure to ionizing radiation;
radiation pattern, the way in which the intensity of the radiation from an aerial or other source varies in different directions from it;
radiation pressure, mechanical pressure exerted by electromagnetic radiation or by sound waves;
radiation pyrometer, a pyrometer which functions by measuring radiant energy; hence
radiation pyrometry;
radiation resistance, the part of the electrical resistance of an aerial that is due to its radiating properties, being the ratio of the radiated power to the mean square current in the aerial; an analogous property of a sound radiator;
radiation sickness, disease caused by exposure of the body to ionizing radiation;
radiation therapy,
treatment, medical treatment by means of radiation, such as X-rays or ultraviolet light;
radiation-thermometer, a thermometer specially adapted for measuring the effects of radiation.
| 1954 A. Hollaender Radiation Biology I. 1255/2 (Index), *Radiation accidents. 1970 Passmore & Robson Compan. Med. Stud. II. xxxiii. 1/1 Further knowledge of the acute effects of high doses of radiation in man has been provided by the outcome of radiation accidents. |
| 1964 C. Hodder-Williams Main Experiment i. i. 18 Some of you are not wearing *radiation badges. |
| 1959 Times 14 Feb. 8/4 By a ‘*radiation belt’ is meant a region in which incoming charged particles are trapped and held captive by the magnetic field of the earth. 1959 Sci. Amer. Mar. 47/2 The radiation belts obviously present an obstacle to space flight. 1962 Daily Tel. 2 May 1/8 American scientists have said it may take 10 or even 100 years before the radiation belts return to their present conditions [after the explosion of a hydrogen bomb]. 1977 F. N. Bash Astron. xiii. 398 Jupiter's radiation belts are not only more intense, but also much larger than the similar Van Allen belts that girdle the earth. |
| 1949 Surg., Gynecol., & Obstetr. LXXXVIII. 609 (heading) Surgical treatment of *radiation burns. 1960 Gloss. Atomic Terms (Atomic Energy Authority) 42 Patients subject to intense irradiation, e.g. in cancer therapy by X or gamma rays sometimes get surface or skin radiation burns. |
| 1961 R. D. Baker Essent. Path. vii. 127 Heavy dosages of x-ray, especially to the upper abdomen, may lead to radiation sickness, nausea and vomiting shortly after the radiation; *radiation cachexia, weakness, anemia, and leukopenia several weeks after exposures. |
| 1947 Radiology XLIX. 359/2 The question of *radiation carcinogenesis in the lungs cannot be fully dismissed. |
| 1951 Jrnl. Chem. Educ. XXVIII. 419/2 From the more theoretical point of view *radiation chemical reactions should be studied to determine how internal conversion and energy transfer affect yields. Ibid. 407/2 Not all instruments shown in Table 1 are equally useful for the *radiation chemist. |
| 1940 Chem. Abstr. XXXVI. 229 (heading) The significance of *radiation chemistry and its procedures for the science and technology of glass. 1951 Jrnl. Chem. Educ. XXVIII. 416/2 We may note finally in the radiation chemistry of water the anisotropic distribution of H3O+ and OH- ions, particularly in cases of heavy particle bombardment. 1961 G. R. Choppin Exper. Nuclear Chem. xii. 192 Most of the early research in radiation chemistry used natural nuclear emissions. 1974 J. E. Wilson Radiation Chem. of Monomers, Polymers, & Plastics iv. 185 A study of the radiation chemistry of small molecules is helpful in understanding the radiation chemistry of polymers. 1979 Nature 15 Feb. 583/3 Work was soon under way in the β and γ-ray spectrometry of (mainly) naturally radio⁓active species, and in radiation chemistry. |
| 1947 Nucleonics Sept. 23/1 (heading) Crystal and Cerenkov *radiation counters. |
| 1941 Jrnl. Appl. Physics XII. 293/1 Cases of severe *radiation damage to the hands of radiologists and technicians. 1957 Benedict & Pigford Nuclear Chem. Engin. iii. 66 The extent to which fuel elements of a power reactor can be irradiated may be limited..by physical changes in the fuel caused by radiation damage. 1970 Passmore & Robson Compan. Med. Stud. II. xxxiii. 7/2 That harmful mutations may result from radiation seems almost certain... The demonstration of microscopic radiation damage to human chromosomes makes the occurrence of finer damage almost beyond question. |
| 1961 R. D. Baker Essent. Path. xx. 542 *Radiation dermatitis, usually from overexposure to X-rays and less commonly to radium, results in similar atrophic changes in the skin..which, after a number of years, become squamous cell carcinoma. |
| 1934 Radiology XXIII. 738 (heading) Some mathematical aspects of *radiation dosage. |
| 1922 tr. Friedrich & Glasser in Kroenig & Friedrich Princ. Physics & Biol. of Radiation Therapy 241 (heading) The distribution of the *radiation dose in intracorporeal radium and mesothorium therapy. 1970 Passmore & Robson Compan. Med. Stud. II. xxxiii. 1/2 Other important aspects of radiation dose are the rate of delivery, whether it is fractionated in time and the duration of the radiation-free periods between doses. |
| 1937 Brit. Jrnl. Radiol. X. 600 (heading) *Radiation dosimetry. 1968 Courier-Mail (Brisbane) 16 Nov. 15 (Advt.), The Australian Atomic Energy Commission is in the process of establishing a programme of research and development in the field of radiation dosimetry and radiation standards. |
| 1913 J. Erskine-Murray Handbk. Wireless Telegr. (ed. 4) xix. 367 (heading) A direct experimental method for the determination of the *radiation efficiency, earth resistance and other constants of a transmitter. 1977 S. W. Amos Radio, TV & Audio Technical Ref. Bk. xxi. 5 Antenna radiation efficiency = power radiated by antenna/input power to antenna. |
| 1924 Physical Rev. XXIV. 339 The energy which is removed from a *radiation field..by the positive absorption of quanta by N oscillators all in (n - 1) quantum states. 1928 Sterling & Kruse Radio Man. 663/1 (Index), Radiation field of antenna. 1948 A. L. Albert Radio Fund. xiii. 494 At a distance greater than, say, a few wavelengths from the antenna, the induction field approaches zero, and the radiation field exists... The energy in the radiation field does not return to the antenna when the antenna voltage and current die out. 1971 Nature 20 Aug. 572/1 The ultra⁓sonic field was monitored by a small, sensitized, thermistor probe which could be positioned at any point in the radiation field by means of a micromanipulator attached to the irradiation chamber. |
| 1857 Herschel Meteorol. (1861) 93 A *radiation-fog once formed tends to its own increase, by radiating off heat from its own particles. 1883 R. H. Scott Elem. Meteor. 121 A class of fogs, termed by Herschel ‘radiation fogs’. 1937 G. T. Trewartha Introd. Weather & Climate iii. 109 Radiation fog is at its worst in the vicinity of large cities where the air is rich in hygroscopic smoke particles. 1971 W. Hillen Blackwater River xiii. 121 Morning radiation fog shrouded the lake..and filled the lower valley. |
| 1889 Q. Jrnl. R. Meteorol. Soc. XV. 23 It was not an ordinary *radiation frost, but one in which the entire valley was filled with an almost uniformly cold atmosphere. 1906 Daily Chron. 8 Mar. 7/4 It will surprise many people..to know that a slight radiation frost actually occurred on the grass early yesterday morning. 1945 R. Bush Frost & Fruitgrower iii. 13 Cloud coming up when a radiation frost is beginning sends the temperature up surprisingly quickly. 1959 Chambers's Encycl. VI. 93/2 The occurrence of radiation frost at night is associated with the growth of an inversion in the surface layers of air. |
| 1934 Lancet 28 July 214/1 A new subject to many members is ‘*radiation genetics’. 1956 C. Auerbach Genetics in Atomic Age viii. 69 In the twenty-eight years since its beginning, radiation genetics has developed into a large and flourishing branch of research. |
| 1945 H. D. Smyth Gen. Acct. Devel. Atomic Energy Mil. Purposes vii. 73 Two types of *radiation hazard were anticipated—neutrons generated by the pile, and alpha-particles, beta-particles, and gamma rays emitted by products of the pile. 1964 C. Hodder-Williams Main Experiment i. iii. 34 She's batty on the subject of radiation hazards. She used to flirt with the CND. |
| 1946 U.S. Atomic Energy Comm. Rep. MDDC-700 (title) *Radiation-induced changes in ultraviolet absorption spectra of urine. 1962 Times 12 July 3/1 The effects of radiation-induced mutations on mouse populations. 1971 Brit. Med. Bull. XXVII. 66/1 The Survey is occasionally referred to as a source of information about mongols and leukaemia, but never in connexion with radiation-induced cancers. |
| 1942 Radiology XXXIX. 663 (heading) Influence of the medium on *radiation injury of sperm. 1970 Passmore & Robson Compan. Med. Stud. II. xxxiii. 7/2 In other respects the histological appearance of the tissue are those of a nonspecific inflammatory response although some features suggest a radiation injury. |
| 1947 Nucleonics Sept. 61/1 (heading) Beta and gamma *radiation meter. 1961 Economist 23 Dec. 1220/2 ‘Survival biscuits’.., water, first-aid kits and radiation meters. |
| 1951 Gray & Martens Radiation Monitoring in Atomic Defense xii. 91 Emergency workers, particularly *radiation monitors, should be equipped with dose meters for their own protection. 1955 [see film badge s.v. film n. 7 b]. 1964 C. Hodder-Williams Main Experiment i. iii. 29 Recessed radiation monitors placed at fifty-foot intervals. |
| 1926 Acta Radiol. VI. 399 (heading) *Radiation osteitis. |
| 1948 A. L. Albert Radio Fund. xiii. 496 (caption) The *radiation patterns of a half-wave antenna. 1978 Nature 5 Jan. 48/2 The radiation pattern of the antenna is similar to that of a half-wave dipole. 1978 Sci. Amer. Aug. 120 (caption) Flask arrangement for measuring the radiation pattern from a conventional grate. |
| 1901 Physical Rev. XIII. 308 *Radiation pressure, from its nature, must reach its maximum value instantly. 1905 [see radiometer 2]. 1926 H. C. Macpherson Mod. Astron. vi. 96 It is now generally admitted that the chief factor in producing comets' tails is the radiation pressure. 1966 McGraw-Hill Encycl. Sci. & Technol. XI. 317/1 Since the radiation pressure is p = 2E, where E is the energy of the acoustic wave per unit area, a direct measurement of this pressure will determine the energy of a plane wave. 1976 Nature 2 Sept. 15/2 Theoreticians..remained frustrated in their attempts to explain motions in the great straight tails [of comets] by means of solar radiation pressure alone. |
| 1952 B. Wolfe Limbo '90 (1953) iv. xiv. 220 Heat-proof and *radiation-proof name plates. |
| 1904 Physical Rev. XIX. 422 The best types of *radiation pyrometers that are at present available to the experimentalist. 1959 Techn. Survey Dorman Long (Steel) Ltd. (Iron & Coal Trades Rev.) 59/2 Each furnace also has two radiation pyrometers focussed on the crown of the roof ten feet on either side of the tap-hole. 1972 G. F. Warnke in H. H. Plumb Temperature IV. i. ii. 503/2 The instrument engineer seeking to employ infrared radiation pyrometers for process temperature measurement and control. |
| 1904 Physical Rev. XIX. 422 Under the term *radiation pyrometry may be grouped all those methods in which the temperature of bodies is estimated from the radiant energy emitted, either in the form of visible light radiation or of the longer infra red waves. 1922 Glazebrook Dict. Appl. Physics I. 643/1 In radiation pyrometry generally the term ‘full radiator’ or ‘black body’ denotes one that will absorb all the radiation it receives. |
| 1913 J. Erskine-Murray Handbk. Wireless Telegr. (ed. 4) xiv. 223 The fourth numeric of the antenna, namely r, the radiation coefficient or ‘*radiation resistance’, is that on which transmission actually depends. 1938 F. E. Terman Fund. of Radio xiv. 389 The magnitude of the radiation resistance depends..upon the point in the antenna system at which the resistance is considered as being inserted. Ibid. xvii. 435 The presence of the air in contact with the vibrating diaphragm produces a mechanical radiation resistance..which varies with frequency. 1975 D. G. Fink Electronics Engineers' Handbk. xix. 55 A loudspeaker designed to resonate at a low frequency combines decreasing velocity with increasing radiation resistance to yield a uniform response within the frequency range where the assumptions hold. |
| 1924 Lancet 23 Aug. 365/1 Dodds and Webster have recently summarised the literature of *radiation sickness in The Lancet. 1948 Sci. News VII. 8 Radiation sickness, its prevention, its treatment, is..a problem for the medical services. 1961 R. D. Baker Essent. Path. vii. 127 Heavy dosages of x-ray, especially to the upper abdomen, may lead to radiation sickness, nausea and vomiting shortly after the radiation. 1978 Sci. Amer. May 49/3, 10 percent of the people exposed to 150 rads will die from radiation sickness. |
| 1922 tr. Krönig & Friedrich (title) The principles of physics and biology of *radiation therapy. 1961 R. D. Baker Essent. Path. vii. 127 Radiation therapy of the cervix under abnormal circumstances may result in damage to the mucosa of the rectum or of the urinary bladder. 1980 Daily Tel. 4 Dec. 6/8 It can implant radioactive seeds by needle when..patients can no longer sustain external radiation therapy. |
| 1868 Symons's Meteorol. Mag. III. 7 The sensitiveness of a terrestrial *radiation thermometer. |
| 1924 Lancet 4 Oct. 725/1 (heading) Chloride metabolism in *radiation treatment. 1968 Brit. Med. Bull. XXIV. 190/1 Someone without training using the computer procedure can produce a competent radiation-treatment plan. |
| 1970 Passmore & Robson Compan. Med. Stud. II. xxxiii. 7/2 A *radiation ulcer of the skin often fails to heal. |