英语词汇“roentgen unit”的英英意思、用法、释义、翻译、读音、例句、短语、词组-英语词典

2. Usually with lower-case initial. A unit of exposure to X or gamma radiation, now defined as equal to the quantity of radiation that gives rise to ions carrying a total positive or negative charge of 2·58 × 10⁻⁴ coulomb per kg of air under standard conditions. Formerly also roentgen unit. Symbol R or r. The precise definition of this unit has been altered several times (cf. quot. 1950). Exposure to ionizing radiation is now usually measured according to the SI system, in which the unit is coulombs per kg. Cf. rem n.¹, rep n.⁹

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the world > matter > physics > atomic nucleus > measurement of ionizing radiation > [noun] > unit of exposure

Roentgen1922

the world > matter > physics > atomic nucleus > radioactivity > X-rays > [noun] > unit of exposure

Roentgen1922

the world > matter > physics > atomic nucleus > measurement of ionizing radiation > [noun] > units of radioactivity > roentgen unit

R1922

roentgen unit1922

1922 Physics Abstr. A. 25 508 The instrument is calibrated in terms of a unit R (the Röntgen), i.e. the ionisation produced in 1 sec. by 1 gm. of Ra at a distance of 20 mm. after filtration by 0·5 mm. of Pt.

1932 Radiology 18 95/2 At the second International Congress of Radiology in 1928..the measurement of air ionization was accepted as the basis of international dosage measurement and a definition was given of the unit of dosage designating a roentgen unit and written in abbreviated form as ‘r’.

1938 R. W. Lawson tr. G. von Hevesy & F. A. Paneth Man. Radioactivity (ed. 2) xxiv. 258 The maximum daily dosage of γ-rays that a human being can tolerate without apparent harm is 0·1 röntgen unit.

1950 Radiology 55 744/1 As our exciting energies increased, we were placed in a position of having continually to modify the definition of the roentgen in order to cope with the new properties of the higher-energy radiations. Because of this situation, minor modifications in the definition of the roentgen were made in 1931, 1934 and 1937.

1955 Bull. Atomic Scientists Sept. 257/2 Radiation dosages in the levels of 400 roentgen units..are lethal to about half the individuals exposed.

1970 R. Passmore & J. S. Robson Compan. Med. Stud. II. xxxiii. 4/2 The same exposure (in roentgens) may result in different absorbed doses (in rads) in different tissues.

1989 C. Caufield Multiple Exposures (1990) vi. 48 The US Committee on X-Ray and Radium Protection decreed that workers could tolerate one-tenth of a roentgen of X-rays or gamma rays a day.

2008 S. LeVay When Sci. goes Wrong vii. 147 By the time they were halfway up the staircase, their radiation detector was pegging out an 500 roentgens per hour.

单词	roentgen unit
释义	> as lemmas roentgen unit 2. Usually with lower-case initial. A unit of exposure to X or gamma radiation, now defined as equal to the quantity of radiation that gives rise to ions carrying a total positive or negative charge of 2·58 × 10⁻⁴ coulomb per kg of air under standard conditions. Formerly also roentgen unit. Symbol R or r. The precise definition of this unit has been altered several times (cf. quot. 1950). Exposure to ionizing radiation is now usually measured according to the SI system, in which the unit is coulombs per kg. Cf. rem n.¹, rep n.⁹ ΘΚΠ the world > matter > physics > atomic nucleus > measurement of ionizing radiation > [noun] > unit of exposure Roentgen1922 the world > matter > physics > atomic nucleus > radioactivity > X-rays > [noun] > unit of exposure Roentgen1922 the world > matter > physics > atomic nucleus > measurement of ionizing radiation > [noun] > units of radioactivity > roentgen unit R1922 roentgen unit1922 1922 Physics Abstr. A. 25 508 The instrument is calibrated in terms of a unit R (the Röntgen), i.e. the ionisation produced in 1 sec. by 1 gm. of Ra at a distance of 20 mm. after filtration by 0·5 mm. of Pt. 1932 Radiology 18 95/2 At the second International Congress of Radiology in 1928..the measurement of air ionization was accepted as the basis of international dosage measurement and a definition was given of the unit of dosage designating a roentgen unit and written in abbreviated form as ‘r’. 1938 R. W. Lawson tr. G. von Hevesy & F. A. Paneth Man. Radioactivity (ed. 2) xxiv. 258 The maximum daily dosage of γ-rays that a human being can tolerate without apparent harm is 0·1 röntgen unit. 1950 Radiology 55 744/1 As our exciting energies increased, we were placed in a position of having continually to modify the definition of the roentgen in order to cope with the new properties of the higher-energy radiations. Because of this situation, minor modifications in the definition of the roentgen were made in 1931, 1934 and 1937. 1955 Bull. Atomic Scientists Sept. 257/2 Radiation dosages in the levels of 400 roentgen units..are lethal to about half the individuals exposed. 1970 R. Passmore & J. S. Robson Compan. Med. Stud. II. xxxiii. 4/2 The same exposure (in roentgens) may result in different absorbed doses (in rads) in different tissues. 1989 C. Caufield Multiple Exposures (1990) vi. 48 The US Committee on X-Ray and Radium Protection decreed that workers could tolerate one-tenth of a roentgen of X-rays or gamma rays a day. 2008 S. LeVay When Sci. goes Wrong vii. 147 By the time they were halfway up the staircase, their radiation detector was pegging out an 500 roentgens per hour. extracted from Roentgenn. < as lemmas
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