However, those annihilations depend on the properties of dark matter and visible matter.
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According to this estimate, should we be able to observe dark-matter annihilations today?
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So after the universe went through especially rapid expansion once, the annihilations stopped, and the proportion of dark matter was set.
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When cosmic rays interact with interstellar material, and—in theory—during dark-matter annihilations, they produce antiprotons, the antiparticle twin of a proton.
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For the past five decades, a violent past that no one can remember firsthand but everyone can imagine has been recreated by way of equally callous expulsions and annihilations.
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Depending upon America's dedicated analytic capacity to decipher sorely-complex strategic quandaries, this could become a relatively benign silence of protracted mutual deterrence, or, more ominously, a dreadful silence of mutually-reinforcing annihilations.
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Similar experiments are underway to detect neutrinos from WIMP annihilations within the Earth and from within the galactic center.
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First a molecule is tagged with a positron emitting isotope. These positrons annihilate with nearby electrons, emitting two 511 keV photons, directed 180 degrees apart in opposite directions. These photons are then detected by the scanner, which can estimate the density of positron annihilations in a specific area. When enough interactions and annihilations have occurred, the density of the original molecule may be measured in that area.
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Within the Pacific Ring of Fire, the Philippine Church of Calasiao, known as Earthquake Baroque, has powerful and most imposing buttresses and foundations but failed upon earthquakes' annihilations.
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Following his death, MCC was riddled by internal divisions. Chatterji's successor, Siveji, and his deputy, Ramadhar Singh, disagreed over the policy of individual annihilations. Singh broke away and joined Kanu Sanyal's group instead.
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SIMP annihilations would produce significant heat. DAMA set limits with NaI(Tl) crystals. Measurements of Uranus's heat excess exclude SIMPs from 150 MeV to 104 GeV. Earth's heat flow significantly constrains any cross section.
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These experiments can be divided into two classes: direct detection experiments, which search for the scattering of dark matter particles off atomic nuclei within a detector; and indirect detection, which look for the products of dark matter particle annihilations or decays.
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Singh supported the line of annihilations of class enemies of Charu Majumdar, and implemented it to a certain degree in Musahari and other areas in Bihar. However he disagreed with Majumdar on the issue of killing rich peasants.Dasgupta, Biplab. The Naxalite Movement.
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Supreme Commander Q&A; at gamespot.com (2005) The creators of XTA, a mod for Total Annihilation, independently developed the open-source 3D graphics Spring game engine. The Total Annihilation 3D project was begun in 2006. Other ex-members of Cavedog, including Total Annihilations game engine developer Jon Mavor, later went on to develop Planetary Annihilation in 2014, another game in the same vein as Total Annihilation.
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Rather than pursue investor funding, Planetary Annihilations developer Uber Entertainment chose to use the crowdfunding site Kickstarter for their financial backing. They revealed the game to the public on August 15, 2012, with their Kickstarter funding goal set at $900,000. The concept video used for the pledge campaign took approximately three months to go from initial pencil-and- paper designs to final animation. As the campaign began, pledges came in quickly, reaching $450,000 by the fifth day of the campaign.
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Antiparticles have exactly opposite additive quantum numbers from particles, so the sums of all quantum numbers of such an original pair are zero. Hence, any set of particles may be produced whose total quantum numbers are also zero as long as conservation of energy and conservation of momentum are obeyed. During a low-energy annihilation, photon production is favored, since these particles have no mass. However, high-energy particle colliders produce annihilations where a wide variety of exotic heavy particles are created.
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When an antiproton annihilates (disintegrates) the process typically results in the emission of 3–4 charged pions. These can be observed by the ALPHA detector and by reconstructing their tracks through the detector their origin, and thus the location of the annihilation, can be determined. These tracks are quite distinct from the tracks of cosmic rays which are also detected but are of high energy and pass straight through the detector. By carefully analyzing the tracks ALPHA distinguishes between cosmic rays and antiproton annihilations.
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These annihilations generated several bosonic particles and some of them led to the formation of pairs of K mesons. Also, it allowed the study and eventually the discovery of mesonic resonances with emphasis on kaon production. Subsequently, the chamber was exposed to various particles such as π+, π−, K+, K− and antiprotons, at various momenta up to 10 GeV/c. The experiments with low energy K− beams resulted in the systematic studies of quasi elastic reactions on protons directly correlated to strange baryonic resonances.
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The detector is designed to provide unambiguous evidence for antihydrogen production by detecting the temporally and spatially coincident annihilations of the antiproton and positron when a neutral antihydrogen atom escapes the electromagnetic trap and strikes the trap electrodes. An antiproton typically annihilates into a few charged or neutral pions. The charged pions are detected by two layers of double-sided, position sensitive, silicon microstrips. The path of a charged particle passing through both layers can be reconstructed, and two or more intersecting tracks allow determination of the position, or vertex, of the antiproton annihilation.
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The 81 cm Saclay Bubble Chamber was a liquid hydrogen bubble chamber built at Saclay, in collaboration with the École Polytechnique (Orsay), to study particle physics. The team led by Bernard Gregory completed the construction of the chamber in 1960 and later it was moved to CERN and installed at the Proton Synchrotron(PS) . A series of experiments began in 1961 which provided data on the properties of hadronic resonances. Firstly, the chamber was irradiated by a beam (rich) of low energy antiprotons enabling the study of antiproton-proton annihilations at rest.
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He was the general secretary of CERN at its early stages when operations were still provisional, before September's 1954 official foundation. He pioneered in Europe the search for gravitational waves. His main scientific results were on slow neutrons in the Fermi group, and the evidence for antiproton annihilations with emulsion techniques, somewhat contemporary to its production in accelerators by Emilio Segrè and collaborators. Amaldi co-authored about 200 scientific publications ranging from atomic spectroscopy and nuclear physics to elementary particle physics and experimental gravitation, as well as textbooks for secondary schools and universities.
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The idea of using antimatter to power an electric space drive has also been proposed. These proposed designs are typically similar to those suggested for nuclear electric rockets. Antimatter annihilations are used to directly or indirectly heat a working fluid, as in a nuclear thermal rocket, but the fluid is used to generate electricity, which is then used to power some form of electric space propulsion system. The resulting system shares many of the characteristics of other charged particle/electric propulsion proposals (typically high specific impulse and low thrust).
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Though hindered by atmospheric absorption of the escaping gamma rays, these theories do not require the exceptionally intense lightning that high altitude theories of TGF generation rely on. The role of TGFs and their relationship to lightning remains a subject of ongoing scientific study. In 2009, the Fermi Gamma-ray Space Telescope in Earth orbit observed intense burst of gamma rays corresponding to positron annihilations coming out of a storm formation. Scientists wouldn't have been surprised to see a few positrons accompanying any intense gamma ray burst, but the lightning flash detected by Fermi appeared to have produced about 100 trillion positrons.
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Raj ended up working alongside Sheldon (or "for" him, as Sheldon insists), "exploring the string theory implications of gamma rays from dark matter annihilations". Ironically, he noted that he once wanted to be the "Indira Gandhi of particle astrophysics (but with a penis, of course)". During season 6, Raj has developed a talent to be a party planner that was demonstrated at the time of Howard and Bernadette's wedding, and the Halloween, and Valentine's Day parties, at the comic book store. In the season 11 episode "The Comet Polarization", he sets up a telescope on the roof of Leonard and Sheldon's apartment building.
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A design proposed in the 1950s by Eugen Sänger used positron-electron annihilation to produce gamma rays. Sänger was unable to solve the problem of how to reflect, and collimate the gamma rays created by positron-electron annihilation; however, by shielding the reactions (or other annihilations) and absorbing their energy, a similar blackbody propulsion system could be created. An antimatter-matter powered photon rocket would (disregarding the shielding) obtain the maximum c specific impulse; for this reason, an antimatter-matter annihilation powered photon rocket could potentially be used for interstellar spaceflight. Theoretically, other designs such as spacecrafts using a Kugelblitz blackhole could also be used for interstellar travel given the efficiency of black holes in converting matter into energy.
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Working with Dimitri Nanopoulos and Mary Gaillard, he proposed in 1976 the so-called "Higgs-strahlung" process in which a Higgs boson is radiated from a Z-boson (this proved to be the best way to search for the Higgs boson at the Large Electron–Positron Collider), and in the same year estimated the direct CP-violation contribution to rare neutral kaon decays (which led to the success of the NA31 and NA48 experiments at CERN). Also in 1976, he published two papers suggesting techniques for finding the gluon in annihilations. The following year he predicted the mass of the bottom quark on the basis of Grand Unified Theory, before this quark was observed in experiment. In 1978 he published a frequently cited general paper on such theories, with Andrzej J. Buras, Gaillard and Nanopoulos.
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Alfvén–Klein cosmology was proposed in part to explain the observed baryon asymmetry in the universe, starting from an initial condition of exact symmetry between matter and antimatter. According to Alfvén and Klein, ambiplasma would naturally form pockets of matter and pockets of antimatter that would expand outwards as annihilation between matter and antimatter occurred in the double layer at the boundaries. They concluded that we must just happen to live in one of the pockets that was mostly baryons rather than antibaryons, explaining the baryon asymmetry. The pockets, or bubbles, of matter or antimatter would expand because of annihilations at the boundaries, which Alfvén considered as a possible explanation for the observed expansion of the universe, which would be merely a local phase of a much larger history.
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The most significant fraction of electron–positron annihilations results in two 511 keV gamma photons being emitted at almost 180 degrees to each other; hence, it is possible to localize their source along a straight line of coincidence (also called the line of response, or LOR). In practice, the LOR has a non-zero width as the emitted photons are not exactly 180 degrees apart. If the resolving time of the detectors is less than 500 picoseconds rather than about 10 nanoseconds, it is possible to localize the event to a segment of a chord, whose length is determined by the detector timing resolution. As the timing resolution improves, the signal-to-noise ratio (SNR) of the image will improve, requiring fewer events to achieve the same image quality.
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The gravitational interaction of antimatter with matter or antimatter has not been conclusively observed by physicists. While the consensus among physicists is that gravity will attract both matter and antimatter at the same rate that matter attracts matter, there is a strong desire to confirm this experimentally- although simple algebra shows that the presence of two photons with positive energies following electron/positron annihilations observed frequently in nature is extremely strong evidence that antimatter has positive mass and thus would act like regular matter under gravity. Antimatter's rarity and tendency to annihilate when brought into contact with matter makes its study a technically demanding task. Furthermore, gravity is much weaker than the other fundamental forces, for reasons still of interest to physicists, complicating efforts to study gravity in systems small enough to be feasibly created in lab, including antimatter systems.
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He is patient but his patience has limits, and while he is as cautious as anyone he can sometimes act without thinking, a trait that would have gotten him killed if Shaeffer had not talked him out of landing on the protosun's planet when they visited it in 2645, as the planet, named "Cannonball Express" by Pelton and Shaeffer, was composed of antimatter, which would have destroyed even Pelton's General Products-hulled ship, the Slower Than Infinity. Indeed, the hull eventually disintegrated due to annihilations by antimatter particles but Pelton and Shaeffer were able to escape and managed to return to Jinx. After Shaeffer and Pelton returned from Cannonball Express Pelton made plans to return but when government agencies became involved the plan bogged down in details. Ander Smittarasheed told Shaeffer that as of 2655 it was unclear whether Pelton was still involved in the project at all.
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