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Operation Freshman
Operation Freshman was the codename given to a British airborne operation conducted in November 1942 during World War II. It was the first British airborne operation conducted using Airspeed Horsa gliders, and its target was the Vemork ''Norsk Hydro'' hydrogen electrolysis plant in Telemark, Norway which produced heavy water as a byproduct. By 1942, the German nuclear weapons programme had come close to being able to develop a nuclear reactor, but in order for the reactor to function it would require a great deal of heavy water. The source of the heavy water was the Norsk Hydro plant, which had been occupied since 1940. When the British government learned of the German nuclear developments, it was decided that a raid would be launched to destroy the plant and deny the Germans the heavy water required to develop a nuclear weapon. Several different strategies were discussed and discarded as impractical; it was decided that a small airborne force composed of sappers from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing military alliances: the Allies and the Axis powers. World War II was a total war that directly involved more than 100 million personnel from more than 30 countries. The major participants in the war threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. Aircraft played a major role in the conflict, enabling the strategic bombing of population centres and deploying the only two nuclear weapons ever used in war. World War II was by far the deadliest conflict in human history; it resulted in 70 to 85 million fatalities, mostly among civilians. Tens of millions died due to genocides (including the Holocaust), starvation, ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sapper
A sapper, also called a pioneer (military), pioneer or combat engineer, is a combatant or soldier who performs a variety of military engineering duties, such as breaching fortifications, demolitions, bridge-building, laying or clearing minefields, preparing field defenses, and road and airfield construction and repair. They are also trained and equipped to serve as provisional infantry, fighting as such as a secondary mission. A sapper's duties facilitate and support movement, defense, and survival of allied forces and impede those of enemies. The term "sapper" is used in the British Army and Commonwealth of Nations, Commonwealth nations and the U.S. military. The word "sapper" comes from the French word ''sapeur'', itself being derived from the verb ''saper'' (to undermine, to dig under a wall or building to cause its collapse). Historical origin Sapping A sapper, in the sense first used by the French military, was one who dug trenches to allow besieging forces to advance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all isotopes of uranium are unstable; the half-lives of its naturally occurring isotopes range between 159,200 years and 4.5 billion years. The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99% of uranium on Earth) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238 (99. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy. These thermal neutrons are immensely more susceptible than fast neutrons to propagate a nuclear chain reaction of uranium-235 or other fissile isotope by colliding with their atomic nucleus. Water (sometimes called "light water" in this context) is the most commonly used moderator (roughly 75% of the world's reactors). Solid graphite (20% of reactors) and heavy water (5% of reactors) are the main alternatives. Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility. Moderation Neutrons are normally bound into an atomic nucleus, and do not exist free for long in nature. The unbound neutron has a half-life of 10 minutes and 11 seconds. The release of neutrons from the nucleus requires exceeding the binding energy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fission
Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay. Nuclear fission of heavy elements was discovered on Monday 19 December 1938, by German chemist Otto Hahn and his assistant Fritz Strassmann in cooperation with Austrian-Swedish physicist Lise Meitner. Hahn understood that a "burst" of the atomic nuclei had occurred. Meitner explained it theoretically in January 1939 along with her nephew Otto Robert Frisch. Frisch named the process by analogy with biological fission of living cells. For heavy nuclides, it is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place). Like nuclear fusion, for fission to produce energy, the total binding energy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nature (journal)
''Nature'' is a British weekly scientific journal founded and based in London, England. As a multidisciplinary publication, ''Nature'' features peer-reviewed research from a variety of academic disciplines, mainly in science and technology. It has core editorial offices across the United States, continental Europe, and Asia under the international scientific publishing company Springer Nature. ''Nature'' was one of the world's most cited scientific journals by the Science Edition of the 2019 ''Journal Citation Reports'' (with an ascribed impact factor of 42.778), making it one of the world's most-read and most prestigious academic journals. , it claimed an online readership of about three million unique readers per month. Founded in autumn 1869, ''Nature'' was first circulated by Norman Lockyer and Alexander Macmillan as a public forum for scientific innovations. The mid-20th century facilitated an editorial expansion for the journal; ''Nature'' redoubled its efforts in exp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. Content Articles in scientific journals are mostly written by active scientists such as students, researchers, and professors instead of professional journalists. There are thousands of scientific journals in publication, and many more have been published at various points in the past (see list of scientific journals). Most journals are highly specialized, although some of the oldest journals such as ''Nature'' publish articles and scientific papers across a wide range of scientific fields. Scientific journals contain articles that have been peer reviewed, in an attempt to ensure that articles meet the journal's standards of quality and scientific validity. Although scientific journals are superficially similar to professional magazines, they are actually quite different. Issues of a scientific journal are rarely read casuall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frédéric Joliot-Curie
Jean Frédéric Joliot-Curie (; ; 19 March 1900 – 14 August 1958) was a French physicist and husband of Irène Joliot-Curie, with whom he was jointly awarded the Nobel Prize in Chemistry in 1935 for their discovery of Induced radioactivity. They were the second ever married couple, after his wife's parents, to win the Nobel Prize, adding to the Curie family legacy of five Nobel Prizes. Joliot-Curie and his wife also founded the Orsay Faculty of Sciences, part of the Paris-Saclay University. Biography Early years Born in Paris, France, Frédéric Joliot was a graduate of ESPCI Paris. In 1925 he became an assistant to Marie Curie, at the Radium Institute. He fell in love with her daughter Irène Curie, and soon after their marriage in 1926 they both changed their surnames to Joliot-Curie. At the insistence of Marie, Joliot-Curie obtained a second baccalauréat, a bachelor's degree, and a doctorate in science, doing his thesis on the electrochemistry of radio-elements. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irène Joliot-Curie
Irène Joliot-Curie (; ; 12 September 1897 – 17 March 1956) was a French chemist, physicist and politician, the elder daughter of Pierre and Marie Curie, and the wife of Frédéric Joliot-Curie. Jointly with her husband, Joliot-Curie was awarded the Nobel Prize in Chemistry in 1935 for their discovery of induced radioactivity, making them the second-ever married couple (after her parents) to win the Nobel Prize, while adding to the Curie family legacy of five Nobel Prizes. This made the Curies the family with the most Nobel laureates to date. She was also one of the first three women to be a member of a French government, becoming undersecretary for Scientific Research under the Popular Front in 1936. Both children of the Joliot-Curies, Hélène and Pierre, are also prominent scientists. In 1945, she was one of the six commissioners of the new French Alternative Energies and Atomic Energy Commission (CEA) created by de Gaulle and the Provisional Government of the French Rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Nuclear Energy Project
The Uranverein ( en, "Uranium Club") or Uranprojekt ( en, "Uranium Project") was the name given to the project in Germany to research nuclear technology, including nuclear weapons and nuclear reactors, during World War II. It went through several phases of work, but in the words of historian Mark Walker, it was ultimately "frozen at the laboratory level" with the "modest goal" to "build a nuclear reactor which could sustain a nuclear fission chain reaction for a significant amount of time and to achieve the complete separation of at least tiny amount of the uranium isotopes." The scholarly consensus is that it failed to achieve these goals, and that despite fears at the time, the Germans had never been close to producing nuclear weapons. The first effort started in April 1939, just months after the discovery of nuclear fission in December 1938, but ended only months later shortly ahead of the German invasion of Poland, when many notable physicists were drafted into the ''Wehr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Commandos
The Commandos, also known as the British Commandos, were formed during the Second World War in June 1940, following a request from Winston Churchill, for special forces that could carry out raids against German-occupied Europe. Initially drawn from within the British Army from soldiers who volunteered for the Special Service Brigade, the Commandos' ranks would eventually be filled by members of all branches of the British Armed Forces and a number of foreign volunteers from German-occupied countries. By the end of the war 25,000 men had passed through the Commando course at Achnacarry. This total includes not only the British volunteers, but volunteers from Greece, France, Belgium, Netherlands, Canada, Norway, Poland, and the United States Army Rangers and Marine Raiders, US Marine Corps Raiders, which were modelled on the Commandos.Moreman, p.40. Reaching a wartime strength of over 30 units and four assault brigades, the Commandos served in all theatres of war from the Arctic C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commando Order
The Commando Order () was issued by the OKW, the high command of the German armed forces, on 18 October 1942. This order stated that all Allies of World War II, Allied commandos captured in Europe and Africa should be summary execution, summarily executed without trial, even if in proper uniforms or if they attempted to surrender. Any commando or small group of commandos or a similar unit, agents, and saboteurs not in proper uniforms who fell into the hands of the German forces by some means other than direct combat (by being apprehended by the police in occupied territories, for instance), were to be handed over immediately to the ' (SD, or Security Service) for immediate execution. According to the OKW, this was to be done in retaliation for their opponents "employing in their conduct of the war, methods which contravene the International Convention of Geneva". The German high command alleged that they had ascertained from "captured orders" that Allied commandos were "instructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
