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. Becquerel was trying to study the way that uranium atoms absorbed and emitted energy when he made his discovery. As part of his experiments, he placed a piece of uranium near some photographic plates wrapped in black paper, thinking that the uranium would produce some kind of energy that would be captured on the plates. When he developed the plates, he found that they had been fogged, even though the uranium had not been exposed to any external sources of energy like sunlight. This led him to conclude that the uranium must be spontaneously emitting some kind of energy, which he later dubbed "radioactivity."

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, the first atomic bomb was dropped on Hiroshima, Japan. The bomb, called Little Boy, was a uranium-235 gun-type fission bomb. It exploded with a force of about 20 kilotons of TNT, instantly killing an estimated 80,000 people and injuring another 70,000.

The doctors in Hiroshima were among the first to realize what kind of bomb had been dropped. They noticed that their x-ray film had been exposed by the radiation from the bomb. This was a clear indication that the bomb was nuclear, as conventional bombs do not emit enough radiation to expose x-ray film.

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.

When Richard Nixon was on a trip to the Soviet Union in 1959, high levels of radiation were detected the room he was staying in. Secret Service purposely argued about the radiation and how to handle it in an area they knew the Soviets had bugged. Three hours later, the radiation disappeared.

On March 21 1962, a ten-year-old boy found an unprotected industrial radiography source in Mexico City. For several days, the boy kept the capsule in his pocket, then placed it in the kitchen cabinet of his home. He died 38 days later, his pregnant mom died 3 months after that, then his 2 year old sister a month later. The father survived, presumably because he worked outside the home and his exposure was lower. 

On July 25, 1964, a criticality accident occurred at the Nuclear Materials and Equipment Corporation (NUMEC) facility in Apollo, Rhode Island. The accident resulted in the death of Harry Daghlian, Jr., a nuclear physicist who was working at the facility. Daghlian was working with americium-241, a radioactive element, when he accidentally created a critical mass of the material. This caused a sudden release of energy and radiation, which severely exposed Daghlian to radiation.

Daghlian was rushed to the hospital, but he died 49 hours later from radiation poisoning. His death was the first fatality from a criticality accident in the United States. The NUMEC accident was a major wake-up call for the nuclear industry. It led to changes in safety procedures and equipment at nuclear facilities around the world.

Firefighters responding to the Chernobyl disaster in 1986 described their experiences of the radiation as "tasting like metal", and feeling a sensation similar to that of pins and needles all over their faces.

Cows contaminated with radiation from the Chernobyl Nuclear accident caused nearby computers to crash.

The Goiânia accident, which occurred in Goiânia, Brazil in September 1987, happened when a radiotherapy unit containing cesium-137 was stolen from an abandoned hospital, The radioactive powder from the stolen radiotherapy unit was spread throughout Goiânia, as people were fascinated by its blue glow and handled it without protection. As a result, many people were exposed to dangerous levels of radiation, and 4 people died as a result of the accident. In the aftermath of the accident, around 112,000 people were tested for contamination, and many buildings and streets were decontaminated. The cleanup efforts lasted for several years, and the incident remains one of the worst radiation accidents in history.

In 2004, a massive starquake was detected from a magnetar called SGR 1806-20, located about 50,000 light-years away.  This celestial event released an immense amount of energy in a fraction of a second, more than the Sun emits in 150,000 years.  While it didn't pose a direct threat to Earth due to its vast distance, scientists calculated that if a similar event occurred within about 10 light-years of our planet, it could have catastrophic consequences. The intense radiation could strip away the ozone layer, leading to mass extinction.   

The Fukushima Daiichi Nuclear Power Plant suffered major damage from the magnitude 9.0 earthquake and tsunami that hit Japan on March 11, 2011. Three of the reactors overheated, causing meltdowns that eventually led to explosions, which released large amounts of radioactive material into the air. After the disaster, the radiation levels at were so high that the robots sent to remove the plant's melted fuel rods died.

By Digital Globe - Earthquake and Tsunami damage-Daiichi Power Plant

FUN RADIOACTIVITY FACTS

Marie Curie's notebooks are still radioactive.

Marie Curie's annex lab in Arcueil is sometimes called Chernobyl on the Seine. The lab closed in 1978 but radium has a half-life of 1,600 years, and there are traces of a uranium isotope at the Curie annex with a half-life of 4.5 billion years. The cleanup has so far cost about €10 million.

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

Airline crew members are exposed to so much cosmic radiation in their jobs that they're classified as radiation workers .

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.