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Tuesday, 20 June 2017

Radioactivity

Radiation is the emission of radiant energy as particles, waves, sound etc. Radioactivity is the spontaneous emission of radiation from the nucleus of atoms of certain substances, termed radioactive.

HISTORY

While experimenting with high voltages applied to an evacuated tube on November 8, 1895, German scientist Wilhelm Röntgen noticed a fluorescence on a nearby plate of coated glass. Within a month, he discovered that the radiation causing this was able to pass through everyday materials such as paper, wood and living tissue and it produced an image on photographic plates as well as a fluorescent screen. Röntgen could not determine how the radiation was carried through space or why it had such penetrating power. For this reason he called this type of radiation X rays.

First medical X-ray by Wilhelm Röntgen of his wife Anna Bertha Ludwig's hand

On March 1, 1896 French physicist Henri Becquerel discovered the principle of radioactive decay when he exposed photographic plates to uranium.

Becqurel's doctoral student, Marie Curie, discovered that only certain chemical elements gave off these rays of energy. She named this behavior radioactivity.

Hearing of Becquerel's experience with uranium, the New Zealand physicist Ernest Rutherford started to explore its radioactivity. He found through simple experimentation two different ways in which these particles penetrate matter. In 1899 he coined the the two distinct types of radiation that he'd found alpha ray and beta ray. Alpha rays had short penetration (it was stopped by paper) and a positive charge and beta rays were more penetrating (able to expose film through paper but not metal) and had a negative charge,

Ernest Rutherford at the McGill University in 1905

In 1900, the French scientist Paul Villard discovered a third neutrally charged and especially penetrating type of radiation from radium, and after he described it, Rutherford realized it must be yet a third type of radiation, which in 1903 he named gamma rays.

All three of Rutherford's terms are in standard use today – other types of radioactive decay have since been discovered, but Rutherford's three types are among the most common.

Marie Curie was awarded the Nobel Prize for physics in 1903 as a result of her work on radioactivity. However Marie and her husband, Pierre, had exposed themselves to massive doses of radiation poisoning. They had failed to see that radioactivity might be dangerous and ascribed their increasing fatigue, weight loss, aches and pains to overwork. It was not only the Curies who believed radiation to be harmless, many physicians used it as a treatment for a variety of ailments including minor ones such as acne and ringworm.

Pierre and Marie Curie in the laboratory

On August 6, 1945, Hiroshima doctors figured out what kind of bomb had been dropped when their x-ray film was exposed by the radiation.

Hibakusha, survivors of the atomic bombs, faced considerable discrimination in Japan following the war. Families forbade their children from marrying hibakusha, and they were often denied employment due to fears that the radiation they were exposed to was hereditary, or contagious.

In 1956, the actress Susan Hayward (1917-1975) starred with John Wayne in The Conqueror. The movie was filmed near a U.S. atomic bomb test site, radiation from which was probably the cause of her fatal brain cancer. By the end of 1980, 46 members of the film’s cast and crew had died from some form of the disease, including Wayne.

The Fukushima Daiichi Nuclear Power Plant suffered major damage from the magnitude 9.0 earthquake and tsunami that hit Japan on March 11, 2011. After the disaster, the radiation levels at were so high that the robots sent to remove the plant's melted fuel rods died.

FUN RADIOACTIVITY FACTS

Marie Curie's notebooks are still radioactive.

Full-body CT scans expose people to similar levels of radiation as the atomic bombs used in Hiroshima.


Gamma rays from space are the most energetic releases of energy known, even more energetic than supernovas.

On average, half of all false teeth have some form of radioactivity.

Fly ash emitted by a coal power plant carries  one hundred times more radiation into the surrounding environment than a nuclear power plant producing the same amount of energy.

All glossy magazines are radioactive.

Carrot juice is ten times more radioactive than beer.

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