Beijing Electron–Positron Collider II
The Beijing Electron–Positron Collider II is a Chinese electron–positron collider, a type of particle accelerator, located in Beijing, People's Republic of China. It has a circumference of 240.4 m. It continues the role CLEO-c detector; the center of mass energy can go up to 4.6 GeV with a design luminosity of 1033 cm−2·s−1. Operations began in summer 2008 and the machine has run at multiple energies; the BES III is the main detector for the upgraded BEPC II. BES III uses a large superconducting solenoid to provide a 1-tesla magnetic field, features a helium gas-based tracking chamber and an electromagnetic calorimeter using 6240 caesium iodide crystals. Large Electron–Positron Collider Electron–positron annihilation
The Soviet Union the Union of Soviet Socialist Republics, was a socialist state in Eurasia that existed from 1922 to 1991. Nominally a union of multiple national Soviet republics, its government and economy were centralized; the country was a one-party state, governed by the Communist Party with Moscow as its capital in its largest republic, the Russian Soviet Federative Socialist Republic. Other major urban centres were Leningrad, Minsk, Alma-Ata, Novosibirsk, it spanned over 10,000 kilometres east to west across 11 time zones, over 7,200 kilometres north to south. It had five climate zones: tundra, steppes and mountains; the Soviet Union had its roots in the 1917 October Revolution, when the Bolsheviks, led by Vladimir Lenin, overthrew the Russian Provisional Government which had replaced Tsar Nicholas II during World War I. In 1922, the Soviet Union was formed by a treaty which legalized the unification of the Russian, Transcaucasian and Byelorussian republics that had occurred from 1918. Following Lenin's death in 1924 and a brief power struggle, Joseph Stalin came to power in the mid-1920s.
Stalin committed the state's ideology to Marxism–Leninism and constructed a command economy which led to a period of rapid industrialization and collectivization. During his rule, political paranoia fermented and the Great Purge removed Stalin's opponents within and outside of the party via arbitrary arrests and persecutions of many people, resulting in at least 600,000 deaths. In 1933, a major famine struck the country. Before the start of World War II in 1939, the Soviets signed the Molotov–Ribbentrop Pact, agreeing to non-aggression with Nazi Germany, after which the USSR invaded Poland on 17 September 1939. In June 1941, Germany broke the pact and invaded the Soviet Union, opening the largest and bloodiest theatre of war in history. Soviet war casualties accounted for the highest proportion of the conflict in the effort of acquiring the upper hand over Axis forces at intense battles such as Stalingrad and Kursk; the territories overtaken by the Red Army became satellite states of the Soviet Union.
The post-war division of Europe into capitalist and communist halves would lead to increased tensions with the United States-led Western Bloc, known as the Cold War. Stalin died in 1953 and was succeeded by Nikita Khrushchev, who in 1956 denounced Stalin and began the de-Stalinization; the Cuban Missile Crisis occurred during Khrushchev's rule, among the many factors that led to his downfall in 1964. In the early 1970s, there was a brief détente of relations with the United States, but tensions resumed with the Soviet–Afghan War in 1979. In 1985, the last Soviet premier, Mikhail Gorbachev, sought to reform and liberalize the economy through his policies of glasnost and perestroika, which caused political instability. In 1989, Soviet satellite states in Eastern Europe overthrew their respective communist governments; as part of an attempt to prevent the country's dissolution due to rising nationalist and separatist movements, a referendum was held in March 1991, boycotted by some republics, that resulted in a majority of participating citizens voting in favor of preserving the union as a renewed federation.
Gorbachev's power was diminished after Russian President Boris Yeltsin's high-profile role in facing down a coup d'état attempted by Communist Party hardliners. In late 1991, Gorbachev resigned and the Supreme Soviet of the Soviet Union met and formally dissolved the Soviet Union; the remaining 12 constituent republics emerged as independent post-Soviet states, with the Russian Federation—formerly the Russian SFSR—assuming the Soviet Union's rights and obligations and being recognized as the successor state. The Soviet Union was a powerhouse of many significant technological achievements and innovations of the 20th century, including the world's first human-made satellite, the first humans in space and the first probe to land on another planet, Venus; the country had the largest standing military in the world. The Soviet Union was recognized as one of the five nuclear weapons states and possessed the largest stockpile of weapons of mass destruction, it was a founding permanent member of the United Nations Security Council as well as a member of the Organization for Security and Co-operation in Europe, the World Federation of Trade Unions and the leading member of the Council for Mutual Economic Assistance and the Warsaw Pact.
The word "Soviet" is derived from a Russian word сове́т meaning council, advice, harmony and all deriving from the proto-Slavic verbal stem of vět-iti, related to Slavic věst, English "wise", the root in "ad-vis-or", or the Dutch weten. The word sovietnik means "councillor". A number of organizations in Russian history were called "council". For example, in the Russian Empire the State Council, which functioned from 1810 to 1917, was referred to as a Council of Ministers after the revolt of 1905. During the Georgian Affair, Vladimir Lenin envisioned an expression of Great Russian ethnic chauvinism by Joseph Stalin and his supporters, calling for these nation-states to join Russia as semi-independent parts of a greater union, which he named as the Union of Soviet Republics of Europe and Asia. Stalin resisted the proposal, but accepted it, although with Lenin's agreement changed the name of the newly proposed sta
Fermi National Accelerator Laboratory, located just outside Batavia, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, the Universities Research Association. Fermilab is a part of the Illinois Research Corridor. Fermilab's Tevatron was a landmark particle accelerator. At 3.9 miles, it was the world's fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron's CDF and DØ detectors, it was shut down in 2011. In addition to high-energy collider physics, Fermilab hosts fixed-target and neutrino experiments, such as MicroBooNE, NOνA and SeaQuest. Completed neutrino experiments include MINOS, MINOS+, MiniBooNE and SciBooNE; the MiniBooNE detector was a 40-foot diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors.
An estimated 1 million neutrino events were recorded each year. SciBooNE had fine-grained tracking capabilities; the NOνA experiment uses, the MINOS experiment used, Fermilab's NuMI beam, an intense beam of neutrinos that travels 455 miles through the Earth to the Soudan Mine in Minnesota and the Ash River, site of the NOνA far detector. In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia and contemporary music concerts, folk dancing and arts galleries; the site is open from dawn to dusk to visitors. Asteroid 11998 Fermilab is named in honor of the laboratory. Weston, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab; the laboratory was founded in 1967 as the National Accelerator Laboratory. The laboratory's first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation.
He is the namesake of the site's high-rise laboratory building, whose unique shape has become the symbol for Fermilab and, the center of activity on the campus. After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job, it was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman remains Director Emeritus; the science education center at the site was named in his honor. The directors include: John Peoples, 1989 to 1999 Michael S. Witherell, July 1999 to June 2005 Piermaria Oddone, July 2005 to July 2013 Nigel Lockyer, September 2013 to the presentFermilab continues to participate in the work at the Large Hadron Collider; as of 2014, the first stage in the acceleration process takes place in two ion sources which turn hydrogen gas into H− ions. The gas is introduced into a container lined with molybdenum electrodes, each a matchbox-sized, oval-shaped cathode and a surrounding anode, separated by 1 mm and held in place by glass ceramic insulators.
A magnetron generates a plasma to form the ions near the metal surface. The ions are accelerated by the source to 35 keV and matched by low energy beam transport into the radio-frequency quadrupole which applies a 750 keV electrostatic field giving the ions their second acceleration. At the exit of RFQ, the beam is matched by medium energy beam transport into the entrance of the linear accelerator; the next stage of acceleration is linear particle accelerator. This stage consists of two segments; the first segment has 5 vacuum vessel for drift tubes, operating at 201 MHz. The second stage has operating at 805 MHz. At the end of linac, the particles are accelerated to about 70 % of the speed of light. Before entering the next accelerator, the H− ions pass through a carbon foil, becoming H+ ions; the resulting protons enter the booster ring, a 468 m circumference circular accelerator whose magnets bend beams of protons around a circular path. The protons travel around the Booster about 20,000 times in 33 milliseconds, adding energy with each revolution until they leave the Booster accelerated to 8 GeV.
The final acceleration is applied by the Main Injector, the smaller of the two rings in the last picture below. Completed in 1999, it has become Fermilab's "particle switchyard" in that it can route protons to any of the experiments installed along the beam lines after accelerating them to 120 GeV; until 2011, the Main Injector provided protons to the antiproton ring and the Tevatron for further acceleration but now provides the last push before the particles reach the beam line experiments. Recognizing higher dema
Tsukuba is a city located in Ibaraki Prefecture, Japan. As of September 2015, the city had an estimated population of 223,151, a population density of 787 persons per km², its total area is 283.72 square kilometres. It is known as the location of the Tsukuba Science City, a planned science park developed in the 1960s. Located in southern Ibaraki Prefecture, Tsukuba is located to the south of Mount Tsukuba, from which it takes its name. Ibaraki Prefecture Tsukubamirai Jōsō Shimotsuma Chikusei Sakuragawa Ishioka Tsuchiura Ushiku Ryūgasaki Mount Tsukuba has been a place of pilgrimage since at least the Heian period. During the Edo period, parts of what became the city of Tsukuba were administered by a junior branch of the Hosokawa clan at Yatabe Domain, one of the feudal domains of the Tokugawa shogunate. With the creation of the municipalities system after the Meiji Restoration on April 1, 1889, the town Yatabe was established within Tsukuba District, Ibaraki). On November 30, 1987 the town of Yatabe merged with the neighboring towns of Ōho and Toyosato and the village of Sakura to create the city of Tsukuba.
The neighboring town of Tsukuba merged with the city of Tsukuba on January 1, 1988, followed by the town of Kukizaki on November 1, 2002. In 1985, Tuskuba hosted. On April 1, 2007 Tsukuba was designated a Special city with increased autonomy. Following the Fukushima I nuclear accidents in 2011, evacuees from the accident zone reported that municipal officials in Tsukuba refused to allow them access to shelters in the city unless they presented certificates from the Fukushima government declaring that the evacuees were "radiation free". On May 6, 2012, Tsukuba was struck by a tornado that caused heavy damage to numerous structures and left 20,000 residents without electricity; the storm injured 45 people. The tornado was rated an F-3 by the Japan Meteorological Agency, making it the most powerful tornado to hit Japan; some spots had F-4 damage. Intel Japan Cyberdyne Inc. SoftEther Corporation TonQ Corporation University of Tsukuba, Tsukuba Campus National University Corporation Tsukuba University of Technology Graduate University for Advanced Studies, Tsukuba Campus Tsukuba Gakuin University Tsukuba has 37 elementary schools, 15 middle schools, two combined middle school/high schools and six high schools, along with one special education school.
In addition, it has an international school, Tsukuba International School, a Brazilian school, the Instituto Educare. Metropolitan Intercity Railway Company – Tsukuba Express Midorino - Bampaku-kinenkōen - Kenkyū-gakuen - Tsukuba Mount Tsukuba Cable Car Mount Tsukuba Ropeway Jōban Expressway – Yatabe IC, Tsukuba JCT, Yatabe-Higashi PA, Sakura-Tsuchiura IC Ken-Ō Expressway – Tsukuba-Chuo IC, Tsukuba JCT, Tsukuba-Ushiku IC Japan National Route 6 Japan National Route 125 Japan National Route 354 Japan National Route 408 Japan National Route 468 Tsukuba Community Broadcast Inc. – Radio Tsukuba Academic Newtown Community Cable Service Beginning in the 1960s, the area was designated for development. Construction of the city centre, the University of Tsukuba and 46 public basic scientific research laboratories began in the 1970s. Tsukuba Science City became operational in the 1980s; the Expo'85 world's fair was held in the area of Tsukuba Science City, which at the time was still divided administratively between several small towns and villages.
Attractions at the event included the 85-metre Technocosmos, which at that time was the world's tallest Ferris wheel. By 2000, the city's 60 national research institutes and two national universities had been grouped into five zones: higher education and training, construction research, physical science and engineering research and agricultural research, common facilities; these zones were surrounded by more than 240 private research facilities. Among the most prominent institutions are the University of Tsukuba; the city has an international flair, with about 7,500 foreign students and researchers from as many as 133 countries living in Tsukuba at any one time. Over the past several decades, nearly half of Japan's public research and development budget has been spent in Tsukuba. Important scientific breakthroughs by its researchers include the identification and specification of the molecular structure of superconducting materials, the development of organic optical films that alter their electrical conductivity in response to changing light, the creation of extreme low-pressure vacuum chambers.
Tsukuba has become one of the world's key sites for government-industry collaborations in basic research. Earthquake safety, environmental degradation, studies of roadways, fermentation science and plant genetics are some of the broad research topics having close public-private partnerships. Tsukuba Science City is a center for research and education in the city of Tsukuba, located northeast of Tokyo; the idea of constructing the science city was by the late Ichiro Kono, former minister of construction, Kniomi Umezawa, former vice minister of the science and technology agency. Another key figure for the development of the Science City is Leo Esaki. What sets Tsukuba apart from other town developments in Japan is the large scale and fast pace of its development into a place with high quality of scientific innovation. In September 1963, the national government of Japan, led by Ichiro Kono and Kniomi Umezawa, ord
Brookhaven National Laboratory
Brookhaven National Laboratory is a United States Department of Energy national laboratory located in Upton, New York, on Long Island, was formally established in 1947 at the site of Camp Upton, a former U. S. Army base, its name stems from its location within the Town of Brookhaven 60 miles east of New York City. Research at BNL specializes in nuclear and high energy physics, energy science and technology and bioscience, nanoscience and national security; the 5,300 acre campus contains several large research facilities, including the Relativistic Heavy Ion Collider and National Synchrotron Light Source II. Seven Nobel prizes have been awarded for work conducted at Brookhaven lab. BNL is staffed by 2,750 scientists, engineers and support personnel, hosts 4,000 guest investigators every year; the laboratory has its own police station, fire department, ZIP code. In total, the lab spans a 5,265-acre area, coterminous with the hamlet of Upton, New York. BNL is served by a rail spur operated as-needed by the New Atlantic Railway.
Co-located with the laboratory is the Upton, New York, forecast office of the National Weather Service. Although conceived as a nuclear research facility, Brookhaven Lab's mission has expanded, its foci are now: Nuclear and high-energy physics Physics and chemistry of materials Environmental and climate research Nanomaterials Energy research Nonproliferation Structural biology Accelerator physics Brookhaven National Lab was owned by the Atomic Energy Commission and is now owned by that agency's successor, the United States Department of Energy. DOE subcontracts the operation to universities and research organizations, it is operated by Brookhaven Science Associates LLC, an equal partnership of Stony Brook University and Battelle Memorial Institute. From 1947 to 1998, it was operated by Associated Universities, Inc. but AUI lost its contract in the wake of two incidents: a 1994 fire at the facility's high-beam flux reactor that exposed several workers to radiation and reports in 1997 of a tritium leak into the groundwater of the Long Island Central Pine Barrens on which the facility sits.
Following World War II, the US Atomic Energy Commission was created to support government-sponsored peacetime research on atomic energy. The effort to build a nuclear reactor in the American northeast was fostered by physicists Isidor Isaac Rabi and Norman Foster Ramsey Jr. who during the war witnessed many of their colleagues at Columbia University leave for new remote research sites following the departure of the Manhattan Project from its campus. Their effort to house this reactor near New York City was rivalled by a similar effort at the Massachusetts Institute of Technology to have a facility near Boston. Involvement was solicited from representatives of northeastern universities to the south and west of New York City such that this city would be at their geographic center. In March 1946 a nonprofit corporation was established that consisted of representatives from nine major research universities — Columbia, Harvard, Johns Hopkins, MIT, University of Pennsylvania, University of Rochester, Yale University.
Out of 17 considered sites in the Boston-Washington corridor, Camp Upton on Long Island was chosen as the most suitable in consideration of space and availability. The camp had been a training center from the US Army during both World War I and World War II. After the latter war, Camp Upton became available for reuse. A plan was conceived to convert the military camp into a research facility. On March 21, 1947, the Camp Upton site was transferred from the U. S. War Department to the new U. S. Atomic Energy Commission, predecessor to the U. S. Department of Energy. In 1947 construction began on the first nuclear reactor at Brookhaven, the Brookhaven Graphite Research Reactor; this reactor, which opened in 1950, was the first reactor to be constructed in the United States after World War II. The High Flux Beam Reactor operated from 1965 to 1999. In 1959 Brookhaven built the first US reactor tailored to medical research, the Brookhaven Medical Research Reactor, which operated until 2000. In 1952 Brookhaven began using the Cosmotron.
At the time the Cosmotron was the world's highest energy accelerator, being the first to impart more than 1 GeV of energy to a particle. The Cosmotron was retired in 1966, after it was superseded in 1960 by the new Alternating Gradient Synchrotron; the AGS was used in research that resulted in 3 Nobel prizes, including the discovery of the muon neutrino, the charm quark, CP violation. In 1970 in BNL started the ISABELLE project to develop and build two proton intersecting storage rings; the groundbreaking for the project was in October 1978. In 1981, with the tunnel for the accelerator excavated, problems with the superconducting magnets needed for the ISABELLE accelerator brought the project to a halt, the project was cancelled in 1983; the National Synchrotron Light Source operated from 1982 to 2014 and was involved with two Nobel Prize-winning discoveries. It has since been replaced by the National Synchrotron Light Source II. After ISABELLE'S cancellation, physicist at BNL proposed that the excavated tunnel and parts of the magnet assembly be used in another accelerator.
In 1984 the first proposal for the accelerator now known as the Relativistic Heavy Ion Collider was put forward. The construction got funded in 1991and RHIC has been operational since 2000. One of the world's only two operating heavy-ion colliders, RHIC is as of 2010 the second-highest
A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to high speeds and energies, to contain them in well-defined beams. Large accelerators are used for basic research in particle physics; the most powerful accelerator is the Large Hadron Collider near Geneva, built by the European collaboration CERN. It is a collider accelerator, which can accelerate two beams of protons to an energy of 6.5 TeV and cause them to collide head-on, creating center-of-mass energies of 13 TeV. Other powerful accelerators are KEKB at KEK in Japan, RHIC at Brookhaven National Laboratory, the Tevatron at Fermilab, Illinois. Accelerators are used as synchrotron light sources for the study of condensed matter physics. Smaller particle accelerators are used in a wide variety of applications, including particle therapy for oncological purposes, radioisotope production for medical diagnostics, ion implanters for manufacture of semiconductors, accelerator mass spectrometers for measurements of rare isotopes such as radiocarbon.
There are more than 30,000 accelerators in operation around the world. There are two basic classes of accelerators: electrodynamic accelerators. Electrostatic accelerators use static electric fields to accelerate particles; the most common types are the Cockcroft -- the Van de Graaff generator. A small-scale example of this class is the cathode ray tube in an ordinary old television set; the achievable kinetic energy for particles in these devices is determined by the accelerating voltage, limited by electrical breakdown. Electrodynamic or electromagnetic accelerators, on the other hand, use changing electromagnetic fields to accelerate particles. Since in these types the particles can pass through the same accelerating field multiple times, the output energy is not limited by the strength of the accelerating field; this class, first developed in the 1920s, is the basis for most modern large-scale accelerators. Rolf Widerøe, Gustav Ising, Leó Szilárd, Max Steenbeck, Ernest Lawrence are considered pioneers of this field and building the first operational linear particle accelerator, the betatron, the cyclotron.
Because colliders can give evidence of the structure of the subatomic world, accelerators were referred to as atom smashers in the 20th century. Despite the fact that most accelerators propel subatomic particles, the term persists in popular usage when referring to particle accelerators in general. Beams of high-energy particles are useful for fundamental and applied research in the sciences, in many technical and industrial fields unrelated to fundamental research, it has been estimated that there are 30,000 accelerators worldwide. Of these, only about 1% are research machines with energies above 1 GeV, while about 44% are for radiotherapy, 41% for ion implantation, 9% for industrial processing and research, 4% for biomedical and other low-energy research; the bar graph shows the breakdown of the number of industrial accelerators according to their applications. The numbers are based on 2012 statistics available from various sources, including production and sales data published in presentations or market surveys, data provided by a number of manufacturers.
For the most basic inquiries into the dynamics and structure of matter and time, physicists seek the simplest kinds of interactions at the highest possible energies. These entail particle energies of many GeV, the interactions of the simplest kinds of particles: leptons and quarks for the matter, or photons and gluons for the field quanta. Since isolated quarks are experimentally unavailable due to color confinement, the simplest available experiments involve the interactions of, leptons with each other, second, of leptons with nucleons, which are composed of quarks and gluons. To study the collisions of quarks with each other, scientists resort to collisions of nucleons, which at high energy may be usefully considered as 2-body interactions of the quarks and gluons of which they are composed, thus elementary particle physicists tend to use machines creating beams of electrons, positrons and antiprotons, interacting with each other or with the simplest nuclei at the highest possible energies hundreds of GeV or more.
The largest and highest energy particle accelerator used for elementary particle physics is the Large Hadron Collider at CERN, operating since 2009. Nuclear physicists and cosmologists may use beams of bare atomic nuclei, stripped of electrons, to investigate the structure and properties of the nuclei themselves, of condensed matter at high temperatures and densities, such as might have occurred in the first moments of the Big Bang; these investigations involve collisions of heavy nuclei – of atoms like iron or gold – at energies of several GeV per nucleon. The largest such particle accelerator is the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Particle accelerators can produce proton beams, which can produce proton-rich medical or research isotopes as opposed to the neutron-rich ones made in fission reactors. An example of this type of machine is LANSCE at Los Alamos. Besides being of fundamental interest, electrons accelerated in the magnetic field causes the high energy electrons to emit extre
Deuterium is one of two stable isotopes of hydrogen. The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common protium has no neutron in the nucleus. Deuterium has a natural abundance in Earth's oceans of about one atom in 6420 of hydrogen, thus deuterium accounts for 0.0156% of all the occurring hydrogen in the oceans, while protium accounts for more than 99.98%. The abundance of deuterium changes from one kind of natural water to another; the deuterium isotope's name is formed from the Greek deuteros, meaning "second", to denote the two particles composing the nucleus. Deuterium was named in 1931 by Harold Urey; when the neutron was discovered in 1932, this made the nuclear structure of deuterium obvious, Urey won the Nobel Prize in 1934. Soon after deuterium's discovery and others produced samples of "heavy water" in which the deuterium content had been concentrated. Deuterium is destroyed in the interiors of stars faster. Other natural processes are thought to produce only an insignificant amount of deuterium.
Nearly all deuterium found in nature was produced in the Big Bang 13.8 billion years ago, as the basic or primordial ratio of hydrogen-1 to deuterium has its origin from that time. This is the ratio found in the gas giant planets, such as Jupiter. However, other astronomical bodies are found to have different ratios of deuterium to hydrogen-1; this is thought to be a result of natural isotope separation processes that occur from solar heating of ices in comets. Like the water cycle in Earth's weather, such heating processes may enrich deuterium with respect to protium; the analysis of deuterium/protium ratios in comets found results similar to the mean ratio in Earth's oceans. This reinforces theories; the deuterium/protium ratio of the comet 67P/Churyumov-Gerasimenko, as measured by the Rosetta space probe, is about three times that of earth water. This figure is the highest yet measured in a comet. Deuterium/protium ratios thus continue to be an active topic of research in both astronomy and climatology.
Deuterium is represented by the chemical symbol D. Since it is an isotope of hydrogen with mass number 2, it is represented by 2H. IUPAC allows 2H, although 2H is preferred. A distinct chemical symbol is used for convenience because of the isotope's common use in various scientific processes, its large mass difference with protium confers non-negligible chemical dissimilarities with protium-containing compounds, whereas the isotope weight ratios within other chemical elements are insignificant in this regard. In quantum mechanics the energy levels of electrons in atoms depend on the reduced mass of the system of electron and nucleus. For the hydrogen atom, the role of reduced mass is most seen in the Bohr model of the atom, where the reduced mass appears in a simple calculation of the Rydberg constant and Rydberg equation, but the reduced mass appears in the Schrödinger equation, the Dirac equation for calculating atomic energy levels; the reduced mass of the system in these equations is close to the mass of a single electron, but differs from it by a small amount about equal to the ratio of mass of the electron to the atomic nucleus.
For hydrogen, this amount is about 1837/1836, or 1.000545, for deuterium it is smaller: 3671/3670, or 1.0002725. The energies of spectroscopic lines for deuterium and light hydrogen therefore differ by the ratios of these two numbers, 1.000272. The wavelengths of all deuterium spectroscopic lines are shorter than the corresponding lines of light hydrogen, by a factor of 1.000272. In astronomical observation, this corresponds to a blue Doppler shift of 0.000272 times the speed of light, or 81.6 km/s. The differences are much more pronounced in vibrational spectroscopy such as infrared spectroscopy and Raman spectroscopy, in rotational spectra such as microwave spectroscopy because the reduced mass of the deuterium is markedly higher than that of protium. In nuclear magnetic resonance spectroscopy, deuterium has a different NMR frequency and is much less sensitive. Deuterated solvents are used in protium NMR to prevent the solvent from overlapping with the signal, although deuterium NMR on its own right is possible.
Deuterium is thought to have played an important role in setting the number and ratios of the elements that were formed in the Big Bang. Combining thermodynamics and the changes brought about by cosmic expansion, one can calculate the fraction of protons and neutrons based on the temperature at the point that the universe cooled enough to allow formation of nuclei; this calculation indicates seven protons for every neutron at the beginning of nucleogenesis, a ratio that would remain stable after nucleogenesis was over. This fraction was in favor of protons primarily because the lower mass of the proton favored their production; as the universe expanded, it cooled. Free neutrons and protons are less stable than helium nuclei, the protons and neutrons had a strong energetic reason to form helium-4. However, forming helium-4 requires the intermediate step of forming deuterium. Through much of the few minutes after the big bang during which nucleosynthesis could have occurred