Crossword clues for radioactivity
Longman Dictionary of Contemporary English
The Collaborative International Dictionary
radioactivity \ra`di*o*ac*tiv"i*ty\ (r[=a]`d[i^]*[-o]*[a^]k*t[i^]v"[i^]*t[y^]), n. (Physics) a form of instability which is a property of the atomic nuclei of certain isotopes, which causes a spontaneous change in the structure of the nucleus, accompanied by emission of energetic radiation. The radiation emitted is usually sufficient to cause ionization in matter through which it passes, and is therefore called ionizing radiation. The radiation emitted by most radioactive substances is one of three types: alpha rays, beta rays, or gamma rays. Some chemical elements have no stable isotopes, and these are referred to as radioactive elements, and the element itself is said to possess radioactivity.
Note: The changes in radioactive nuclei which cause radiation in most cases cause the chemical identity of the nucleus itself to change, as when tritium (an isotope of hydrogen) emits a beta ray and converts to helium. The radioactive decay process is a first-order reaction, and the rate of decay of a particular isotope can therefore be expressed as the half life of the isotope, which is the time it takes for one half of the remaining undecayed isotope to decay, and is a constant independent of the proportion of original material which has already decayed. The half life of tritium, for example, is 12.3 years.
Douglas Harper's Etymology Dictionary
1899, from French radioactivité, coined 1898 by the Curies; see radioactive.
Wiktionary
n. 1 spontaneous emission of ionizing radiation as a consequence of a nuclear reaction, or directly from the breakdown of an unstable nucleus. 2 The radiation so emitted; including gamma rays, alpha particles, neutrons, electrons, positrons, etc.
WordNet
n. the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay [syn: radiation]
Wikipedia
"Radioactivity" (German: "Radioaktivität") is a song written by Ralf Hütter, Florian Schneider and Emil Schult, and recorded by electronic band Kraftwerk as the title track of its 1975 album Radio-Activity.
The song peaked at number one in France, becoming Kraftwerk's first song to reach a number-one spot.
Radioactivity is the property of spontaneous nuclear decay, or the frequency of that decay.
Radioactivity may also refer to:
Usage examples of "radioactivity".
The assay involves using a radioactive drug which binds quantitatively to the acetylcholine receptor, the amount of radioactivity bound being proportional to the amount of receptor present.
ARPA guaranteed a minimum residual radioactivity and the proper shape of the crater in which the antenna subsequently would be placed.
The band of gel containing each protein can either be cut out with a razorblade and the radioactivity in it counted, or the whole gel can be placed against X-ray film and an autoradiogram made, just as with the 2-DG experiment.
I hoped that Jen and Larry would keep their attention up, watching an endless succession of buckets flash past them and checking each one for radioactivity count.
This fact, seen together with the characteristics of radioactivity, tells us that in such elements gravity has so far got the upper hand of levity that the physical substance is unable to persist as a spatially extended, coherent unit.
The assay involves using a radioactive drug which binds quantitatively to the acetylcholine receptor, the amount of radioactivity bound being proportional to the amount of receptor present.
Certain isotopes lost radioactivity very rapidly, in a matter of hours or minutes.
If I then measure much radioactivity is in the membranes - a relatively straightforward task with modern equipment - I shall be able to calculate how much sugar has been built into them.
Mutations are caused by radioactivity in the environment, by cosmic rays from space, or, as often happens, randomly-by spontaneous rearrangements of the nucleotides which statistically must occur every now and then.
They had discovered the X ray, the cathode ray, the electron, and radioactivity, invented the ohm, the watt, the Kelvin, the joule, the amp, and the little erg.
At the time of the Blowup, the radioactivity caused a cycle of mutations.
Koskinen knew only that during the initial postwar reconstruction there'd been too much radioactivity at the bombsites for habitation.
In theory, specialized submarine recovery vehicles would be able to salvage the freighter's cargo before seawater corroded the cylinders containing the plutonium, contaminating the local waters with radioactivity.
BOOK TWO CHAPTER Two When his scout ship was just two days flight out of Descartes Mining Platform 6, Illin Romsey began to pick up hopeful signs of radioactivity.
There "were no improvements in martial arts, only deteriorations, a slow dwindling away of essence, like radioactivity wearing out.