Definition of radioactivity in US English:



  • 1The emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei.

    • ‘In 1899 he identified two forms of radioactivity, which he called alpha and beta particles.’
    • ‘Pierre and Marie Curie called Becquerel's radiation radioactivity.’
    • ‘The Bequerel is a unit of radioactivity, which is equivalent to the number of radioactive particles detected per second.’
    • ‘What makes dirty bombs particularly troublesome is that radioactivity, like fire, is something we deal with on a daily basis.’
    • ‘When this occurs, the electron shoots out of the atom and is called a beta particle, a type of radioactivity.’
    • ‘This year is the centennial of the Nobel Prize in Physics shared by Henri Becquerel and the Curies for their pioneering work on radioactivity.’
    • ‘The Curies resolved to learn as much as they could about the source of radioactivity in pitchblende, the ore with which Becquerel originally worked.’
    • ‘Each appropriate region was scraped individually and radioactivity was determined in a scintillation counter.’
    • ‘Early studies of radioactivity revealed that certain atomic nuclei were naturally radioactive.’
    • ‘Their temperature ranges between 27°C and 51°C and they vary in radioactivity and fluorine content.’
    • ‘TL is based on the continual accumulation of stored energy as a function of natural radioactivity.’
    • ‘They may also interact with nonmedical regulations, such as limits on electromagnetic emissions or radioactivity.’
    • ‘Indeed, many isotopes spontaneously convert to other elements through radioactivity.’
    • ‘In the first five years, the reactors will undergo mild surface-level deactivation to minimize their radioactivity.’
    • ‘The element itself was actively producing radiation, a property referred to as radioactivity.’
    • ‘The time interval needed to reduce the applied radioactivity to 50% was taken as the optimal pulsing time.’
    • ‘The becquerel is a unit of radioactivity and corresponds to one radioactive disintegration per second.’
    • ‘The results also point the way to the first direct measurements of the total radioactivity of the earth.’
    • ‘A station opened in the Chatham Islands to monitor radioactivity, will help police the worldwide ban on Nuclear Weapons Testing.’
    • ‘The idea that radioactive isotopes can be used for dating purposes is almost as old as Henri Becquerel's discovery of radioactivity itself in 1896.’
    1. 1.1 Radioactive substances, or the radiation emitted by these.
      ‘an escape of radioactivity’
      • ‘It is suspected that workers have brought home tiny particles of radioactivity attached to their clothing or their skin.’
      • ‘Its functions relate principally to the monitoring of radioactivity in the environment and of radiation doses received by Irish people in the course of their work.’
      • ‘Small amounts of radioactivity escaped into the atmosphere.’
      • ‘The devices could be equipped with sensors that detect various substances, from heat to chemicals or radioactivity.’
      • ‘Similar dangers exist of a structural collapse leading to an uncontrollable release of energy which could release radioactivity, he said.’
      • ‘He is one of nine authorities which have been supplied with the latest equipment for recording and detecting radioactivity after an atomic bomb explosion.’
      • ‘No access to the core is possible because of the levels of radioactivity, continuing high temperatures inside and fears about its stability.’
      • ‘In the event of slow release of radioactivity it would be particularly important that medical personnel could recognise and diagnose the early effects of radiation.’
      • ‘One example he gave was the leakage of radioactivity from Sellafield caused by pigeons.’
      • ‘The most common ill effects of exposure to radioactivity result from the ionization of water molecules by the radiation.’
      • ‘Scientists can compare the number of breakdowns in any given time and the intensity of the radioactivity among elements and isotopes.’
      • ‘They are comparing sediment taken from the Humber estuary - unpolluted by radioactivity - with other samples which contain the substance.’
      • ‘Over the six decades of the lab's operation, radioactivity has leaked in unknown quantities into the water and vegetation surrounding the facility.’
      • ‘Cattle seem to absorb less radioactivity than sheep, except for the milk, which is to be avoided at all costs because of the iodine.’
      • ‘The NRC says, even if a plane did attack a nuclear plant the likelihood of releasing radioactivity is low.’
      • ‘The technique is based on the detection of radioactivity emitted after a small amount of a radioactive tracer is injected into a peripheral vein.’
      • ‘The 60 cities with federally reported dietary levels of radioactivity are often not proximate to nuclear sites.’
      • ‘The lack of safeguards is leaving thousands of children across central Scotland at risk of thyroid cancer following an escape of radioactivity.’
      • ‘The accident, which didn't cause any leakage of radioactivity, occurred when the train was reversing at just 5mph.’
      • ‘So sensitive is the detector that a single speck of dust within it could emit enough natural radioactivity to queer the readings.’