Instruct: Given a question, retrieve documents that answer the question.
Query: What can we learn with nuclear physics?
Primary focus of the institute is nuclear physics, both theoretical and experimental. It carries out studies in the nuclear spectroscopy of beta and gamma radiation, nuclear reactions including the collisions of heavy ions and hyper-nuclear physics. Its work is also focused on related fields, such as the study of the solid phase using neutron scattering, mathematical physics and theoretical subnuclear physics.Isochronous cyclotron U-120M is the primary experimental facility of the institute and it is the only cyclotron in the Czech Republic. It has been operating since 1977. The cyclotron is used both for fundamental research and applications. It can accelerate ions within the range of the mass-to-charge ratio A/q = 1 - 2.8. The present internal radial ion source is suitable for acceleration of H^+, D^+, 4-He^+2 and 3-He^+2. Maximum proton energy is 36 MeV, and the maximum energy for heavier ions is given by 40 q^2/A MeV. Currents of an internal beam of protons and deuterons can reach 100 microA, and for extracted beams 5 microA. Particles are extracted from the cyclotron chamber by means of a 3-section deflection electrostatic system to the entrance of the beam lines.
In August 1939, Leo Szilard and Albert Einstein sent the Einstein–Szilárd letter to Roosevelt, warning of the possibility of a German project to develop nuclear weapons. Szilard realized that the recently discovered process of nuclear fission could be used to create a nuclear chain reaction that could be used as a weapon of mass destruction. Roosevelt feared the consequences of allowing Germany to have sole possession of the technology, and authorized preliminary research into nuclear weapons. After the attack on Pearl Harbor, the Roosevelt administration secured the funds needed to continue research and selected General Leslie Groves to oversee the Manhattan Project, which was charged with developing the first nuclear weapons. Roosevelt and Churchill agreed to jointly pursue the project, and Roosevelt helped ensure that American scientists cooperated with their British counterparts.
The United States is known to have possessed three types of weapons of mass destruction: nuclear weapons, chemical weapons, and biological weapons. The U.S. is the only country to have used nuclear weapons in combat, when it detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki during World War II. It had secretly developed the earliest form of the atomic weapon during the 1940s under the title "Manhattan Project". The United States pioneered the development of both the nuclear fission and hydrogen bombs (the latter involving nuclear fusion). It was the world's first and only nuclear power for four years (1945–1949), until the Soviet Union managed to produce its own nuclear weapon. The United States has the second largest number of deployed nuclear weapons in the world, after Russia.
In August 1939, Leo Szilard and Albert Einstein sent the Einstein–Szilárd letter to Roosevelt, warning of the possibility of a German project to develop nuclear weapons. Szilard realized that the recently discovered process of nuclear fission could be used to create a nuclear chain reaction that could be used as a weapon of mass destruction. Roosevelt feared the consequences of allowing Germany to have sole possession of the technology, and authorized preliminary research into nuclear weapons. After the attack on Pearl Harbor, the Roosevelt administration secured the funds needed to continue research and selected General Leslie Groves to oversee the Manhattan Project, which was charged with developing the first nuclear weapons. Roosevelt and Churchill agreed to jointly pursue the project with the Quebec Agreement, and Roosevelt helped ensure that American scientists cooperated with their British counterparts.
The notion of using a fission weapon to ignite a process of nuclear fusion can be dated back to 1942. At the first major theoretical conference on the development of an atomic bomb hosted by J. Robert Oppenheimer at the University of California, Berkeley, participant Edward Teller directed the majority of the discussion towards Enrico Fermi's idea of a "Super" bomb that would use the same reactions that powered the Sun itself.
Recent research at CERN's CLOUD facility examined links between cosmic rays and cloud condensation nuclei, demonstrating the effect of high-energy particulate radiation in nucleating aerosol particles that are precursors to cloud condensation nuclei. Kirby (CLOUD team leader) said, "At the moment, it [the experiment] actually says nothing about a possible cosmic-ray effect on clouds and climate." After further investigation, the team concluded that "variations in cosmic ray intensity do not appreciably affect climate through nucleation."
In practice, buildup of reactor poisons in nuclear fuel is what determines the lifetime of nuclear fuel in a reactor: long before all possible fissions have taken place, buildup of long-lived neutron absorbing fission products damps out the chain reaction. This is the reason that nuclear reprocessing is a useful activity: spent nuclear fuel contains about 96% of the original fissionable material present in newly manufactured nuclear fuel. Chemical separation of the fission products restores the nuclear fuel so that it can be used again.
The only country to have used a nuclear weapon in war is the United States, which dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki during World War II. There are eight countries that have declared they possess nuclear weapons and are known to have tested a nuclear weapon, only five of which are members of the NPT. The eight are China, France, India, North Korea, Pakistan, Russia, the United Kingdom, and the United States.
The United States developed the first nuclear weapons during World War II in cooperation with the United Kingdom and Canada as part of the Manhattan Project, out of the fear that Nazi Germany would develop them first. It tested the first nuclear weapon on July 16, 1945 ("Trinity") at 5:30 am, and remains the only country to have used nuclear weapons in war, devastating the Japanese cities of Hiroshima and Nagasaki. It was the first nation to develop the hydrogen bomb, testing an experimental prototype in 1952 ("Ivy Mike") and a deployable weapon in 1954 ("Castle Bravo"). Throughout the Cold War it continued to modernize and enlarge its nuclear arsenal, but from 1992 on has been involved primarily in a program of Stockpile stewardship. The U.S. nuclear arsenal contained 31,175 warheads at its Cold War height (in 1966). During the Cold War, the United States built approximately 70,000 nuclear warheads, more than all other nuclear-weapon states combined.
In the United States, where Fermi and Szilárd had both emigrated, the discovery of the nuclear chain reaction led to the creation of the first man-made reactor, the research reactor known as Chicago Pile-1, which achieved self-sustaining power/criticality on December 2, 1942. The reactor's development was part of the Manhattan Project, the Allied effort to create atomic bombs during World War II. It led to the building of larger single-purpose production reactors, such as the X-10 Pile, for the production of weapons-grade plutonium for use in the first nuclear weapons. The United States tested the first nuclear weapon in July 1945, the Trinity test, with the atomic bombings of Hiroshima and Nagasaki taking place one month later.
In 1968, deep inelastic scattering experiments at the Stanford Linear Accelerator Center (SLAC) showed that the proton contained much smaller, point-like objects and was therefore not an elementary particle. Physicists were reluctant to firmly identify these objects with quarks at the time, instead calling them "partons"—a term coined by Richard Feynman. The objects that were observed at SLAC would later be identified as up and down quarks as the other flavors were discovered. Nevertheless, "parton" remains in use as a collective term for the constituents of hadrons (quarks, antiquarks, and gluons).
After World War II, nuclear weapons were also developed by the Soviet Union (1949), the United Kingdom (1952), France (1960), and the People's Republic of China (1964), which contributed to the state of conflict and extreme tension that became known as the Cold War. In 1974, India, and in 1998, Pakistan, two countries that were openly hostile toward each other, developed nuclear weapons. Israel (1960s) and North Korea (2006) are also thought to have developed stocks of nuclear weapons, though it is not known how many. The Israeli government has never admitted or denied to having nuclear weapons, although it is known to have constructed the reactor and reprocessing plant necessary for building nuclear weapons. South Africa also manufactured several complete nuclear weapons in the 1980s, but subsequently became the first country to voluntarily destroy their domestically made weapons stocks and abandon further production (1990s). Nuclear weapons have been detonated on over 2,000 occasions for testing purposes and demonstrations.
The quark bomb explodes at the moment of construction at the factory. The rest of its existence is a slow process of quark fission, which turns the avalanche-like destruction of atoms into a slow, rhythmical, gradual destruction of 10 grams of copper dust - the best known explosive trigger. If the bomb is shot at, which destroys its mechanisms, then the unstoppable process of atomic fission begins at full strength. The only way to get rid of a quark bomb is to jettison it in deep space at least 3-4 light years from the nearest stellar body or nebula. Occasionally, quark fission can be transferred from one planet to another through tiny meteorites, dust particles, molecules of ionized gas, etc.
Much of the stimulus for the treaty was increasing public unease about radioactive fallout as a result of above-ground or underwater nuclear testing, particularly given the increasing power of nuclear devices, as well as concern about the general environmental damage caused by testing. In 1952–53, the US and Soviet Union detonated their first thermonuclear weapons (hydrogen bombs), far more powerful than the atomic bombs tested and deployed since 1945. In 1954, the US Castle Bravo test at Bikini Atoll (part of Operation Castle) had a yield of 15 megatons of TNT, more than doubling the expected yield. The Castle Bravo test resulted in the worst radiological event in US history as radioactive particles spread over more than , affected inhabited areas (including Rongelap Atoll and Utirik Atoll), and sickened Japanese fishermen aboard the "Lucky Dragon" upon whom "ashes of death" had rained. In the same year, a Soviet test sent radioactive particles over Japan. Around the same time, victims of the atomic bombing of Hiroshima visited the US for medical care, which attracted significant public attention. In 1961, the Soviet Union tested the Tsar Bomba, which had a yield of 50 megatons and remains the most powerful man-made explosion in history, though due to a highly efficient detonation fallout was relatively limited. Between 1951 and 1958, the US conducted 166 atmospheric tests, the Soviet Union conducted 82, and Britain conducted 21; only 22 underground tests were conducted in this period (all by the US).
Before the Castle Bravo nuclear weapons test in 1954, it was thought that only the less common isotope lithium-6 would breed tritium when struck with fast neutrons. The Castle Bravo test showed (accidentally) that the more plentiful lithium-7 also does so under extreme conditions, albeit by an endothermic reaction.
Any mass defect due to nuclear binding energy is experimentally a small fraction (less than 1%) of the mass of equal number of free nucleons. When compared to the average mass per nucleon in carbon-12, which is moderately strongly-bound compared with other atoms, the mass defect of binding for most atoms is an even smaller fraction of a dalton (unified atomic mass unit, based on carbon-12). Since free protons and neutrons differ from each other in mass by a small fraction of a dalton (about 0.0014 u), rounding the relative isotopic mass, or the atomic mass of any given nuclide given in daltons to the nearest whole number always gives the nucleon count, or mass number. Additionally, the neutron count (neutron number) may then be derived by subtracting the number of protons (atomic number) from the mass number (nucleon count).
The primary application to date has been military (i.e. nuclear weapons), and the remainder of explosions include the following:Only two nuclear weapons have been deployed in combat—both by the United States against Japan in World War II. The first event occurred on the morning of 6 August 1945, when the United States Army Air Forces dropped a uranium gun-type device, code-named "Little Boy", on the city of Hiroshima, killing 70,000 people, including 20,000 Japanese combatants and 20,000 Korean slave laborers. The second event occurred three days later when the United States Army Air Forces dropped a plutonium implosion-type device, code-named "Fat Man", on the city of Nagasaki. It killed 39,000 people, including 27,778 Japanese munitions employees, 2,000 Korean slave laborers, and 150 Japanese combatants. In total, around 109,000 people were killed in these bombings. (See "Atomic bombings of Hiroshima and Nagasaki" for a full discussion). Nuclear weapons are largely seen as a 'deterrent' by most governments; the sheer scale of the destruction caused by a nuclear weapon has prevented serious consideration of their use in warfare, rendering the concept of total war completely useless.
Israel is known to have nuclear-capable aircraft and land-base missiles, with the addition of nuclear-armed submarines this would mean that they now have a full triad of land-, air-, and sea-based nuclear delivery systems some of which would be invulnerable to a first strike by an enemy for the first time in their country's history. No other nation in the Middle East in known to be in possession of nuclear weapons, even though Iran, Iraq, Syria and Libya have started development programs that were never completed.
Of the 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope (except for technetium, element 43 and promethium, element 61, which have no stable isotopes). Isotopes considered stable are those for which no radioactive decay has yet been observed. Elements with atomic numbers 83 through 94 are unstable to the point that radioactive decay of all isotopes can be detected. Some of these elements, notably bismuth (atomic number 83), thorium (atomic number 90), and uranium (atomic number 92), have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy metals before the formation of our Solar System. At over 1.9 years, over a billion times longer than the current estimated age of the universe, bismuth-209 (atomic number 83) has the longest known alpha decay half-life of any naturally occurring element, and is almost always considered on par with the 80 stable elements. The very heaviest elements (those beyond plutonium, element 94) undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized.
It is common to use idealized models in physics to simplify things. Massless ropes, point particles, ideal gases and the particle in a box are among the many simplified models used in physics. The laws of physics are represented with simple equations such as Newton's laws, Maxwell's equations and the Schrödinger equation. These laws are such as a basis for making mathematical models of real situations. Many real situations are very complex and thus modeled approximate on a computer, a model that is computationally feasible to compute is made from the basic laws or from approximate models made from the basic laws. For example, molecules can be modeled by molecular orbital models that are approximate solutions to the Schrödinger equation. In engineering, physics models are often made by mathematical methods such as finite element analysis.
A 2007 calculation on the decay properties of unknown neutron-rich isotopes of superheavy elements suggested that the isotope Hs may be the most stable superheavy nucleus against alpha decay and spontaneous fission, as a consequence of the shell closure at "N" = 184. As such, it was considered as a candidate to exist in nature. However, this nucleus is predicted to be highly unstable toward beta decay, and any beta-stable isotopes of hassium (such as Hs) would be too unstable in the other decay channels to possibly be observed in nature. Indeed, a subsequent search for Hs in nature along with its congener osmium was unsuccessful, setting an upper limit to its abundance at 3×10 grams of hassium per gram of osmium.
Much of current research in nuclear physics relates to the study of nuclei under extreme conditions such as high spin and excitation energy. Nuclei may also have extreme shapes (similar to that of Rugby balls or even pears) or extreme neutron-to-proton ratios. Experimenters can create such nuclei using artificially induced fusion or nucleon transfer reactions, employing ion beams from an accelerator. Beams with even higher energies can be used to create nuclei at very high temperatures, and there are signs that these experiments have produced a phase transition from normal nuclear matter to a new state, the quark–gluon plasma, in which the quarks mingle with one another, rather than being segregated in triplets as they are in neutrons and protons.
From certain of the heaviest nuclei whose fission produces free neutrons, and which also easily absorb neutrons to initiate fission, a self-igniting type of neutron-initiated fission can be obtained, in a chain reaction. Chain reactions were known in chemistry before physics, and in fact many familiar processes like fires and chemical explosions are chemical chain reactions. The fission or "nuclear" chain-reaction, using fission-produced neutrons, is the source of energy for nuclear power plants and fission type nuclear bombs, such as those detonated in Hiroshima and Nagasaki, Japan, at the end of World War II. Heavy nuclei such as uranium and thorium may also undergo spontaneous fission, but they are much more likely to undergo decay by alpha decay.
The enzyme belongs to the group of oxidoreductases according to the EC classification and is dependent on FAD as cofactor, thus it was classified as an external flavoprotein monooxygenase (designated as type E). It forms a two-component system with a reductase (StyB, StyA2B). The reductase utilizes solely NADH to reduce the FAD, which is then transferred to the styrene monooxygenase (StyA, StyA1). Two types of that enzyme are described so far: StyA/StyB (designated E1), first described from "Pseudomonas" species, and StyA1/StyA2B (designated E2), first described from Actinobacteria. The E1-type is more abundant in nature and comprises a single monooxygenase (StyA) supported by a single reductase (StyB), whereas the E2-type has a major monooxygenase (StyA1) which is supported by fusion protein of a monooxygenase and reductase (StyA2B). The latter one is the source of reduced FAD for the monooxygenase subunits and has some side activity as a monooxygenase. So far all styrene monooxygenases perform enantioselective epoxidations of styrene and chemically analogous compounds, which makes them interesting for biotechnological applications.
With the discovery of the neutron, scientists could at last calculate what fraction of binding energy each nucleus had, by comparing the nuclear mass with that of the protons and neutrons which composed it. Differences between nuclear masses were calculated in this way. When nuclear reactions were measured, these were found to agree with Einstein's calculation of the equivalence of mass and energy to within 1% as of 1934.