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Unnilnilium
Fermium is a synthetic element with the symbol Fm and atomic number 100. It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared. A total of 19 isotopes are known, with 257Fm being the longest-lived with a half-life of 100.5 days. It was discovered in the debris of the first hydrogen bomb explosion in 1952, and named after Enrico Fermi, one of the pioneers of nuclear physics. Its chemistry is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced fermium and all of its isotopes having relatively short half-lives, there are currently no uses for it outside basic scientific research. Discovery Fermium was first discovered in the fallout from the 'Ivy Mike' nuclear test (1 November 1952), the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthetic Element
A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; thus, they are called "synthetic", "artificial", or "man-made". The synthetic elements are those with atomic numbers 95–118, as shown in purple on the accompanying periodic table: these 24 elements were first created between 1944 and 2010. The mechanism for the creation of a synthetic element is to force additional protons into the nucleus of an element with an atomic number lower than 95. All synthetic elements are unstable, but they decay at widely varying rates: the half-lives of their longest-lived isotopes range from microseconds to millions of years. Five more elements that were created artificially are strictly speaking not ''synthetic'' because they were later found in nature in trace quantities: 43Tc, 61Pm, 85At, 93Np, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Einsteinium
Einsteinium is a synthetic element with the symbol Es and atomic number 99. Einsteinium is a member of the actinide series and it is the seventh transuranium element. It was named in honor of Albert Einstein. Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952. Its most common isotope, einsteinium-253 (half-life 20.47 days), is produced artificially from decay of californium-253 in a few dedicated high-power nuclear reactors with a total yield on the order of one milligram per year. The reactor synthesis is followed by a complex process of separating einsteinium-253 from other actinides and products of their decay. Other isotopes are synthesized in various laboratories, but in much smaller amounts, by bombarding heavy actinide elements with light ions. Owing to the small amounts of produced einsteinium and the short half-life of its most easily produced isotope, there are currently almost no practical applications for it outside bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen-16
Oxygen-16 (16O) is a stable isotope of oxygen, having 8 neutrons and 8 protons in its nucleus. It has a mass of . Oxygen-16 is the most abundant isotope of oxygen and accounts for 99.762% of oxygen's natural abundance. The relative and absolute abundance of 16O are high because it is a principal product of stellar evolution and because it is a primordial isotope, meaning it can be made by stars that were initially made exclusively of hydrogen. Most 16O is synthesized at the end of the helium fusion process in stars; the triple-alpha process creates 12C, which captures an additional 4He to make 16O. The neon-burning process creates additional 16O. Oxygen-16 is doubly magic. Solid samples (organic and inorganic) for 16O studies are usually stored in silver cups and measured with pyrolysis and mass spectrometry. Researchers need to avoid improper or prolonged storage of the samples for accurate measurements. Oxygen-16 was originally the standard from which the atomic masses of al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) due to different numbers of neutrons in their nuclei. While all isotopes of a given element have almost the same chemical properties, they have different atomic masses and physical properties. The term isotope is formed from the Greek roots isos ( ἴσος "equal") and topos ( τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. It was coined by Scottish doctor and writer Margaret Todd in 1913 in a suggestion to the British chemist Frederick Soddy. The number of protons within the atom's nucleus is called its atomic number and is equal to the number of electrons in the neutral (non-ionized) atom. Each atomic numbe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutonium-239
Plutonium-239 (239Pu or Pu-239) is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 is also used for that purpose. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in thermal spectrum nuclear reactors, along with uranium-235 and uranium-233. Plutonium-239 has a half-life of 24,110 years. Nuclear properties The nuclear properties of plutonium-239, as well as the ability to produce large amounts of nearly pure 239Pu more cheaply than highly enriched weapons-grade uranium-235, led to its use in nuclear weapons and nuclear power plants. The fissioning of an atom of uranium-235 in the reactor of a nuclear power plant produces two to three neutrons, and these neutrons can be absorbed by uranium-238 to produce plutonium-239 and other isotopes. Plutonium-239 can also absorb neutrons and fission along with the uranium-235 in a reactor. Of all the common nuclear fuels ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cold War
The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because there was no large-scale fighting directly between the two superpowers, but they each supported major regional conflicts known as proxy wars. The conflict was based around the ideological and geopolitical struggle for global influence by these two superpowers, following their temporary alliance and victory against Nazi Germany and Imperial Japan in 1945. Aside from the nuclear arsenal development and conventional military deployment, the struggle for dominance was expressed via indirect means such as psychological warfare, propaganda campaigns, espionage, far-reaching embargoes, rivalry at sports events, and technological competitions such as the Space Race. The Western Bloc was led by the United States as well as a number of other First W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
α-particle
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways. Alpha particles are named after the first letter in the Greek alphabet, α. The symbol for the alpha particle is α or α2+. Because they are identical to helium nuclei, they are also sometimes written as or indicating a helium ion with a +2 charge (missing its two electrons). Once the ion gains electrons from its environment, the alpha particle becomes a normal (electrically neutral) helium atom . Alpha particles have a net spin of zero. Due to the mechanism of their production in standard alpha radioactive decay, alpha particles generally have a kinetic energy of about 5 MeV, and a velocity in the vicinity of 4% of the speed of light. (See discussion below for the limits of these figures in alpha decay.) They are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkeley, California
Berkeley ( ) is a city on the eastern shore of San Francisco Bay in northern Alameda County, California, United States. It is named after the 18th-century Irish bishop and philosopher George Berkeley. It borders the cities of Oakland and Emeryville to the south and the city of Albany and the unincorporated community of Kensington to the north. Its eastern border with Contra Costa County generally follows the ridge of the Berkeley Hills. The 2020 census recorded a population of 124,321. Berkeley is home to the oldest campus in the University of California System, the University of California, Berkeley, and the Lawrence Berkeley National Laboratory, which is managed and operated by the university. It also has the Graduate Theological Union, one of the largest religious studies institutions in the world. Berkeley is considered one of the most socially progressive cities in the United States. History Indigenous history The site of today's City of Berkeley was the territo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of California Radiation Laboratory
Lawrence Berkeley National Laboratory (LBNL), commonly referred to as the Berkeley Lab, is a United States national laboratory that is owned by, and conducts scientific research on behalf of, the United States Department of Energy. Located in the hills of Berkeley, California, the lab overlooks the campus of the University of California, Berkeley, and is managed by the University of California system. History 1931–1941 The laboratory was founded on August 26, 1931, by Ernest Lawrence, as the Radiation Laboratory of the University of California, Berkeley, associated with the Physics Department. It centered physics research around his new instrument, the cyclotron, a type of particle accelerator for which he was awarded the Nobel Prize in Physics in 1939. Throughout the 1930s, Lawrence pushed to create larger and larger machines for physics research, courting private philanthropists for funding. He was the first to develop a large team to build big projects to make discoveries ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enewetak Atoll
Enewetak Atoll (; also spelled Eniwetok Atoll or sometimes Eniewetok; mh, Ānewetak, , or , ; known to the Japanese as Brown Atoll or Brown Island; ja, ブラウン環礁) is a large coral atoll of 40 islands in the Pacific Ocean and with its 664 people (as of 2011) forms a legislative district of the Ralik Chain of the Marshall Islands. With a land area total less than , it is no higher than and surrounds a deep central lagoon, in circumference. It is the second-westernmost atoll of the Ralik Chain and is west from Bikini Atoll. It was held by the Japanese from 1914 until its capture by the United States in February 1944, during World War II, then became Naval Base Eniwetok. Nuclear testing by the US totaling the equivalent of over 30 megatons of TNT took place during the Cold War; in 1977–1980, a concrete dome (the Runit Dome) was built on Runit Island to deposit radioactive soil and debris. The Runit Dome is deteriorating and could be breached by a typhoon, though ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Decay
In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For example, beta decay of a neutron transforms it into a proton by the emission of an electron accompanied by an antineutrino; or, conversely a proton is converted into a neutron by the emission of a positron with a neutrino in so-called ''positron emission''. Neither the beta particle nor its associated (anti-)neutrino exist within the nucleus prior to beta decay, but are created in the decay process. By this process, unstable atoms obtain a more stable ratio of protons to neutrons. The probability of a nuclide decaying due to beta and other forms of decay is determined by its nuclear binding energy. The binding energies of all existing nuclides form what is called the nuclear band or valley of stability. For either electron or positron em ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Capture
Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, which are repelled electrostatically. Neutron capture plays a significant role in the cosmic nucleosynthesis of heavy elements. In stars it can proceed in two ways: as a rapid process (r-process) or a slow process (s-process). Nuclei of masses greater than 56 cannot be formed by thermonuclear reactions (i.e., by nuclear fusion) but can be formed by neutron capture. Neutron capture on protons yields a line at 2.223 MeV predicted and commonly observed in solar flares. Neutron capture at small neutron flux At small neutron flux, as in a nuclear reactor, a single neutron is captured by a nucleus. For example, when natural gold (197Au) is irradiated by neutrons (n), the isotope 198Au is formed in a highly excited state, and quickly deca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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