Chien-Shiung Wu in 1958 at Columbia University
|Died||February 16, 1997 84) (aged|
New York City, United States
|Alma mater|| National Central University |
University of California, Berkeley
Luke Chia-Liu Yuan (m. 1942)
|Children||Vincent Yuan (袁緯承)|
|Institutions||Institute of Physics, Academia Sinica |
University of California at Berkeley
|Thesis||I. The Continuous X-Rays Excited by the Beta-Particles of 32|
P. II. Radioactive Xenons (1940)
|Doctoral advisor||Ernest Lawrence|
Chien-Shiung Wu (simplified Chinese :吴健雄; traditional Chinese :吳健雄; pinyin :Wú Jiànxióng; May 31, 1912 – February 16, 1997) was a Chinese-American experimental physicist who made significant contributions in the field of nuclear physics. Wu worked on the Manhattan Project, where she helped develop the process for separating uranium into uranium-235 and uranium-238 isotopes by gaseous diffusion. She is best known for conducting the Wu experiment, which proved that parity is not conserved. This discovery resulted in her colleagues Tsung-Dao Lee and Chen-Ning Yang winning the 1957 Nobel Prize in Physics, while Wu herself was awarded the inaugural Wolf Prize in Physics in 1978. Her expertise in experimental physics evoked comparisons to Marie Curie. Her nicknames include the "First Lady of Physics", the "Chinese Madame Curie" and the "Queen of Nuclear Research".
Simplified Chinese characters are standardized Chinese characters prescribed in the Table of General Standard Chinese Characters for use in mainland China. Along with traditional Chinese characters, they are one of the two standard character sets of the contemporary Chinese written language. The government of the People's Republic of China in mainland China has promoted them for use in printing since the 1950s and 1960s to encourage literacy. They are officially used in the People's Republic of China and Singapore.
Traditional Chinese characters are Chinese characters in any character set that does not contain newly created characters or character substitutions performed after 1946. They are most commonly the characters in the standardized character sets of Taiwan, of Hong Kong and Macau, and in the Kangxi Dictionary. The modern shapes of traditional Chinese characters first appeared with the emergence of the clerical script during the Han Dynasty, and have been more or less stable since the 5th century.
Hanyu Pinyin, often abbreviated to pinyin, is the official romanization system for Standard Chinese in mainland China and to some extent in Taiwan. It is often used to teach Standard Mandarin Chinese, which is normally written using Chinese characters. The system includes four diacritics denoting tones. Pinyin without tone marks is used to spell Chinese names and words in languages written with the Latin alphabet, and also in certain computer input methods to enter Chinese characters.
Chien-Shiung Wu was born in the town of Liuhe in Taicang, Jiangsu province, China, 吳仲裔) and Fan Fu-Hua. The family custom was that children of this generation had Chien as the first character (generation name) of their forename, followed by the characters in the phrase Ying-Shiung-Hao-Jie, which means "heroes and outstanding figures". Accordingly, she had an older brother, Chien-Ying, and a younger brother, Chien-Hao. Wu and her father were extremely close, and he encouraged her interests passionately, creating an environment where she was surrounded by books, magazines, and newspapers.on May 31, 1912, the second of three children of Wu Zhong-Yi (
Liuhe is a town under the jurisdiction of Taicang county-level city in Jiangsu province, China. Liuhe has an area of 68 square kilometers (26 sq mi), with around 56 000 permanent residents.
Taicang is a county-level city under the jurisdiction of Suzhou, Jiangsu province. The city located in the south of the Yangtze River estuary opposite Nantong, being bordered by Shanghai proper to the south, while the river also delineates much of its northeastern boundary along Chongming Island.
Jiangsu is an eastern-central coastal province of the People's Republic of China. It is one of the leading provinces in finance, education, technology, and tourism, with its capital in Nanjing. Jiangsu is the third smallest, but the fifth most populous and the most densely populated of the 23 provinces of the People's Republic of China. Jiangsu has the highest GDP per capita of Chinese provinces and second-highest GDP of Chinese provinces, after Guangdong. Jiangsu borders Shandong in the north, Anhui to the west, and Zhejiang and Shanghai to the south. Jiangsu has a coastline of over 1,000 kilometres (620 mi) along the Yellow Sea, and the Yangtze River passes through the southern part of the province.
Wu received her elementary school education at Ming De School, 2. This was a boarding school with classes for teacher training as well as for regular high school. Admission to teacher training was more competitive, as it did not charge for tuition or board and guaranteed a job on graduation. Although her family could have afforded to pay, Wu chose the more competitive option and was ranked ninth among around 10,000 applicants.a school for girls founded by her father. She left her hometown in 1923 at the age of 11 to go to the Suzhou Women's Normal School No.
Suzhou, alternately romanized as Soochow, is a major city located in southeastern Jiangsu Province of East China, about 100 km (62 mi) northwest of Shanghai. It is a major economic center and focal point of trade and commerce, and the second largest city in the province, after its capital Nanjing. The city is situated on the lower reaches of the Yangtze River and the shores of Lake Tai and belongs to the Yangtze River Delta region. Administratively, Suzhou is a prefecture-level city with a population of 4.33 million in its city proper, and a total resident population of 10.58 million in its administrative area. Its urban population grew at an unprecedented rate of 6.5% between 2000 and 2014, which is the highest among cities with more than 5 million people.
A boarding school provides education for pupils who live on the premises, as opposed to a day school. The word "boarding" is used in the sense of "room and board", i.e. lodging and meals. As they have existed for many centuries, and now extend across many countries, their function and ethos varies greatly. Traditionally, pupils stayed at the school for the length of the term; some schools facilitate returning home every weekend, and some welcome day pupils. Some are for either boys or girls while others are co-educational.
In 1929, Wu graduated at the top of her class and was admitted to National Central University in Nanjing. According to government regulations of the time, teacher-training college students wanting to move on to universities needed to serve as schoolteachers for one year. In Wu's case, this was only nominally enforced. She went to teach at a public school in Shanghai, the president of which was the philosopher Hu Shih, whose class she took.
National Central University was founded in 1915 with roots from 258 CE in mainland China. Founded in Nanjing in 1915, NCU was the leading academic center in southeast China; the phrase “North the Peking University, South the Central University” at that time revealed the significance of NCU. NCU was renamed Nanjing University in 1949, and the former campus has been used by Nanjing Institute of Technology, which was later renamed Southeast University since Nanjing University relocated in 1952. NCU was re-established in Taiwan in 1962. The school was initially located in Miaoli but relocated to Zhongli in 1968 and developed into a comprehensive university. It has become Taiwan's leading school in drama, film studies, cultural studies, and gender studies, Hakka studies, geophysics, space science, remote sensing, astronomy, optoelectronics, nanotechnology, and business management as well as the first university in Taiwan to research industrial economics and economic development. NCU is a member of AACSB. In 2001, NCU was selected by the Ministry of Education as one of the eleven research-oriented universities in Taiwan.
Nanjing, formerly romanized as Nanking and Nankin, is the capital of Jiangsu province of the People's Republic of China and the second largest city in the East China region, with an administrative area of 6,600 km2 (2,500 sq mi) and a total population of 8,270,500 as of 2016. The inner area of Nanjing enclosed by the city wall is Nanjing City (南京城), with an area of 55 km2 (21 sq mi), while the Nanjing Metropolitan Region includes surrounding cities and areas, covering over 60,000 km2 (23,000 sq mi), with a population of over 30 million.
Hu Shih (Chinese: 胡適 Hú Shì was a Chinese philosopher, essayist and diplomat. Hu is widely recognized today as a key contributor to Chinese liberalism and language reform in his advocacy for the use of written vernacular Chinese. He was influential in the May Fourth Movement, one of the leaders of China's New Culture Movement, was a president of Peking University, and in 1939 was nominated for a Nobel Prize in literature. He had a wide range of interests such as literature, philosophy, history, textual criticism, and pedagogy. He was also an influential redology scholar and held the famous Jiaxu manuscript for many years until his death.
From 1930 to 1934, Wu studied at National Central University (later renamed Nanjing University and reinstated in Taiwan), first in mathematics, but later transferring to physics.She became involved in student politics. Relations between China and Japan were tense at this time, and students were urging the government to take a stronger line with Japan. Wu was elected as one of the student leaders by her colleagues because they felt that since she was one of the top students at the university, her involvement would be forgiven, or at least overlooked, by the authorities. That being the case, she was careful not to neglect her studies. She led protests that included a sit-in at the Presidential Palace in Nanjing, where the students were met by Chiang Kai-shek.
Nanjing University, known as Nanda, is a major public university, the oldest institution of higher learning in Nanjing, Jiangsu, and a member of the elite C9 League of Chinese universities.
Taiwan, officially the Republic of China (ROC), is a state in East Asia. Neighbouring states include the People's Republic of China (PRC) to the west, Japan to the northeast, and the Philippines to the south. The island of Taiwan has an area of 35,808 square kilometres (13,826 sq mi), with mountain ranges dominating the eastern two thirds and plains in the western third, where its highly urbanised population is concentrated. Taipei is the capital and largest metropolitan area. Other major cities include Kaohsiung, Taichung, Tainan and Taoyuan. With 23.5 million inhabitants, Taiwan is among the most densely populated states, and is the most populous state and largest economy that is not a member of the United Nations (UN).
A sit-in or sit-down is a form of direct action that involves one or more people occupying an area for a protest, often to promote political, social, or economic change.
For two years after graduation, she did graduate-level study in physics and worked as an assistant at Zhejiang University. She became a researcher at the Institute of Physics of the Academia Sinica. Her supervisor was Gu Jing-Wei, who had earned her PhD abroad at University of Michigan and encouraged Wu to do the same. Wu was accepted by University of Michigan, and her uncle, Wu Zhou-Zhi, provided the necessary funds. She embarked for the United States with a female friend, Dong Ruo-Fen (董若芬), a chemist from Taicang, on the SS President Hoover in August 1936. Her parents and uncle saw her off. She would never see her parents again.
Zhejiang University, usually referred to as Zhèdà (浙大), is an elite C9 League university in Zhejiang province. It is also a Chinese Ministry of Education Class A Double First Class University. Founded in 1897, Zhejiang University is one of China's oldest, most selective and most prestigious institutions of higher education. It is also a member of the Yangtze Delta Universities Alliance and the Association of Pacific Rim Universities.
Academia Sinica, headquartered in Nangang District, Taipei, is the national academy of the Republic of China. It supports research activities in a wide variety of disciplines, ranging from mathematical and physical sciences, to life sciences, and to humanities and social sciences. As an educational institute, it provides PhD training and scholarship through its English-language Taiwan International Graduate Program in biology, agriculture, chemistry, physics, informatics, and earth and environmental sciences. Academia Sinica is ranked 144th in Nature Publishing Index - 2014 Global Top 200 and 22nd in Reuters World's Most Innovative Research Institutions. The current president since 2016 is James C. Liao, an expert in metabolic engineering, systems biology and synthetic biology.
The University of Michigan, often simply referred to as Michigan, is a public research university in Ann Arbor, Michigan. The university is Michigan's oldest; it was founded in 1817 in Detroit, as the Catholepistemiad, or University of Michigania, 20 years before the territory became a state. The school was moved to Ann Arbor in 1837 onto 40 acres (16 ha) of what is now known as Central Campus. Since its establishment in Ann Arbor, the university campus has expanded to include more than 584 major buildings with a combined area of more than 34 million gross square feet spread out over a Central Campus and North Campus, two regional campuses in Flint and Dearborn, and a Center in Detroit. The university is a founding member of the Association of American Universities.
The two women arrived in San Francisco,where Wu's plans for graduate study changed after visiting the University of California, Berkeley. She met physicist Luke Chia-Liu Yuan, a grandson of Yuan Shikai (the first President of the Republic of China and self-proclaimed Emperor of China). Yuan showed her the Radiation Laboratory, where the director was Ernest O. Lawrence, who would soon win the Nobel Prize for Physics in 1939 for his invention of the cyclotron particle accelerator.
Wu heard that at Michigan women were not even allowed to use the front entrance,and decided that she would prefer to study at Berkeley. Yuan took her to see Raymond T. Birge, the head of the physics department, and he offered Wu a place in the graduate school despite the fact that the academic year had already commenced. Wu then abandoned her plans to study at Michigan and enrolled at Berkeley. Her Berkeley classmates included Robert R. Wilson and George Volkoff; her friends included Ursula Schaefer, a history student who chose to remain in the United States rather than return to Nazi Germany, and Margaret Lewis, an American post-doctoral student. Wu applied for a scholarship at the end of her first year, but there was prejudice against Asian students, and Wu and Yuan were instead offered a readership with a lower stipend. Yuan then applied for, and secured, a scholarship at Caltech.
Wu made rapid progress in her education and her research. Although Lawrence was officially her supervisor, she also worked closely with Emilio Segrè.Her thesis had two separate parts. The first was on bremsstrahlung, the electromagnetic radiation produced by the deceleration of a charged particle when deflected by another charged particle, typically an electron by an atomic nucleus. She investigated this using beta-emitting phosphorus-32, a radioactive isotope easily produced in the cyclotron that Lawrence and his brother John H. Lawrence were evaluating for use in cancer treatment and as a radioactive tracer. This marked Wu's first work with beta decay, a subject on which she would become an authority. The second part of the thesis was about the production of radioactive isotopes of xenon produced by the nuclear fission of uranium with the 37-inch and 60-inch cyclotrons at the Radiation Laboratory.
Wu completed her Ph.D. in June 1940, and was elected to Phi Beta Kappa. In spite of Lawrence and Segrè's recommendations, she could not secure a position at a university, so she remained at the Radiation Laboratory as a post-doctoral fellow.
Wu and Yuan were married at the home of Robert Millikan, Yuan's academic supervisor and the President of Caltech, on May 30, 1942.Neither the bride's nor the groom's families were able to attend due to the outbreak of the Pacific War. Wu and Yuan moved to the East Coast of the United States, where Wu became a faculty member at Smith College, a private women's college in Northampton, Massachusetts, while Yuan worked on radar for RCA. She found the job frustrating, as her duties involved teaching only, and there was no opportunity for research. She appealed to Lawrence, who wrote letters of recommendation to a number of universities. Smith responded by making Wu an associate professor and increasing her salary. She accepted a job from Princeton University in New Jersey as an instructor for naval officers.
In March 1944, Wu joined the Manhattan Project's Substitute Alloy Materials (SAM) Laboratories at Columbia University. She lived in a dormitory there, returning to Princeton on the weekends.The role of the SAM Laboratories, headed by Harold Urey, was to support the Manhattan Project's gaseous diffusion (K-25) program for uranium enrichment. Wu worked alongside James Rainwater in a group led by William W. Havens, Jr., whose task was to develop radiation detector instrumentation.
In September 1944, Wu was contacted by the Manhattan District Engineer, Colonel Kenneth Nichols. The newly commissioned B Reactor at the Hanford Site had run into an unexpected problem, starting up and shutting down at regular intervals. John Archibald Wheeler suspected that a fission product, xenon-135, with a half-life of 9.4 hours, was the culprit, and might be a neutron poison. Segrè then remembered the work that Wu had done at Berkeley on the radioactive isotopes of xenon. The paper on the subject was still unpublished, but Wu and Nichols went to her dorm room and collected the typewritten draft prepared for the Physical Review . Xenon-135 was indeed the culprit; it turned out to have an unexpectedly large neutron absorption cross-section.
After the end of the war in August 1945, Wu accepted an offer of a position as an associate research professor at Columbia. Communication with China was restored, and Wu received a letter from her family, 袁緯承), who would grow up to become a physicist like his parents. In 1949, Yuan joined the Brookhaven National Laboratory, and the family moved to Long Island. After the communists came to power in China that year, Wu's father wrote urging her not to return. Since her passport had been issued by the Kuomintang government, she found it difficult to travel abroad. This eventually led to her decision to become a US citizen in 1954. She would remain at Columbia for the rest of her career. She became an associate professor in 1952, a full professor in 1958, and the Michael I. Pupin Professor of Physics in 1973. Her students called her the Dragon Lady, after the character of that name in the comic strip Terry and the Pirates .but plans to visit China were disrupted by the Chinese Civil War, and the birth in 1947 of a son, Vincent Yuan (
In her post-war research, Wu continued to investigate beta decay. Enrico Fermi had published his theory of beta decay in 1934, but an experiment by Luis Walter Alvarez had produced results at variance with the theory. Wu set out to repeat the experiment and verify the result. CuSO
4) was being used as a copper-64 beta ray source, which was causing the emitted electrons to lose energy. To get around this, she adapted an older form of spectrometer, a solenoidal spectrometer. She added detergent to the copper sulphate to produce a thin and even film. She was then able to demonstrate that the discrepancies observed were the result of experimental error; her results were consistent with Fermi's theory.
At Columbia, Wu knew the Chinese-born theoretical physicist Tsung-Dao Lee personally. In the mid-1950s, Lee and another Chinese theoretical physicist, Chen Ning Yang, grew to question a hypothetical law of elementary particle physics, the "law of conservation of parity". One example highlighting the problem was the puzzle of the theta and tau particles, two apparently different charged, strange mesons. They were so similar that they would ordinarily be considered to be the same particle;
were different particles, if parity is conserved:
Lee and Yang's research into existing experimental results convinced them that parity was conserved for electromagnetic interactions and for the strong interaction. For this reason, scientists had expected that it would also be true for the weak interaction, but it had not been tested, and Lee and Yang's theoretical studies showed that it might not hold true for the weak interaction. Lee and Yang worked out a pencil-and-paper design of an experiment for testing conservation of parity in the laboratory. Lee then turned to Wu for her expertise in choosing and then working out the hardware manufacture, set-up, and laboratory procedures for carrying out this experiment.
Wu chose to do this by taking a sample of radioactive cobalt-60 and cooling it to cryogenic temperatures with liquid gases. Cobalt-60 is an isotope that decays by beta particle emission, and Wu was also an expert on beta decay. The extremely low temperatures were needed to reduce the amount of thermal vibration of the cobalt atoms to practically nil. Also, Wu needed to apply a constant and uniform magnetic field across the sample of cobalt-60 in order to cause the spin axes of the atomic nuclei to line up in the same direction. For this cryogenic work, she needed the facilities of the National Bureau of Standards and its expertise in working with liquid gases, and traveled to its headquarters in Maryland with her equipment to carry out the experiments.
Lee and Yang's theoretical calculations predicted that the beta particles from the cobalt-60 atoms would be emitted asymmetrically and the hypothetical "law of conservation of parity" was invalid. Wu's experiment showed that this is indeed the case: parity is not conserved under the weak nuclear interactions.
are indeed the same particle, which is today known as a kaon,
. This result was soon confirmed by her colleagues at Columbia University in different experiments, and as soon as all of these results were published—in two different research papers in the same issue of the same physics journal—the results were also confirmed at many other laboratories and in many different experiments.
The discovery of parity violation was a major contribution to particle physics and the development of the Standard Model.In recognition of their theoretical work, Lee and Yang were awarded the Nobel Prize for Physics in 1957. Wu's role in the discovery was not publicly honored until 1978, when she was awarded the inaugural Wolf Prize.
In 1963, Wu experimentally demonstrated a universal form of Fermi's beta decay model,confirming the Conserved Vector Current hypothesis of Richard Feynman and Murray Gell-Mann on the road to the Standard Model. Her demonstration that parity was not conserved brought other assumptions that physicists had made about the weak interaction into question. If parity is not conserved in weak force interaction, what about charge conjugation? This was an effect that held true for electromagnetism, gravity and the strong interaction, so it had been assumed that it would hold for the weak interaction too. Wu conducted a series of experiments on double beta decay in a salt mine under Lake Erie that proved that charge conjugation was not conserved either.
Another important experiment carried out by Wu was the first experimental confirmation of quantum results relevant to a pair of entangled photons as applicable to the Einstein-Podolsky-Rosen (EPR) paradox.Wu's results confirmed E.M.L. Pryce and John Clive Ward's calculations on the correlation of the quantum polarizations of two photons propagating in opposite directions. Wu later conducted research into the molecular changes in the deformation of hemoglobins that cause sickle-cell disease. She also did research on magnetism and the Mössbauer effect during the 1960s. She wrote a textbook with Steven Moszkowski , Beta Decay, which was published in 1966 and became a standard reference on the subject.
Wu's older brother died in 1958, her father in 1959 and her mother in 1962. The United States had severe restrictions on travel abroad by its citizens, so she was not permitted to visit mainland China to attend their funerals.She saw her uncle, Wu Zhou-Zhi, and younger brother, Wu Chien-Hao, on a trip to Hong Kong in 1965. After the 1972 Nixon visit to China, relations between the two countries improved, and she was able to visit China again in 1973. By this time her uncle and brother had perished in the Cultural Revolution and the tombs of her parents had been destroyed. She was greeted by Zhou Enlai, who personally apologized for the destruction of the tombs. After this, she returned to China several times.
In later life, Wu became more outspoken. She protested the imprisonment in Taiwan of relatives of physicist Kerson Huang in 1959 and of the journalist Lei Chen in 1960.In 1964, she spoke out against gender discrimination at a symposium at the Massachusetts Institute of Technology. "I wonder," she asked her audience, "whether the tiny atoms and nuclei, or the mathematical symbols, or the DNA molecules have any preference for either masculine or feminine treatment." When men referred to her as Professor Yuan, she immediately corrected them and told them that she was Professor Wu. In 1975, Robert Serber, the new chairman of the Physics Department at Columbia University, adjusted her pay to make it equal to that of her male counterparts. She protested the crackdown in China that followed the Tiananmen Square massacre of 1989.
Wu retired in 1981and became a professor emerita. She died on February 16, 1997, in New York City at the age of 84 after suffering a stroke. An ambulance rushed her to St. Luke's–Roosevelt Hospital Center, but she was pronounced dead on arrival. She was survived by her husband and son. In accordance with her wishes, her ashes were buried in the courtyard of the Ming De School that her father had founded and she had attended as a girl.
One way out of the difficulty is to assume that parity is not strictly conserved, so that
are two different decay modes of the same particle, which necessarily has a single mass value and a single lifetime.
In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta ray is emitted from an atomic nucleus. 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, thus changing the nuclide type. 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 emission to be energetically possible, the energy release or Q value must be positive.
A neutrino is a fermion that interacts only via the weak subatomic force and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small (-ino) that it was long thought to be zero. The mass of the neutrino is much smaller than that of the other known elementary particles. The weak force has a very short range, the gravitational interaction is extremely weak, and neutrinos, as leptons, do not participate in the strong interaction. Thus, neutrinos typically pass through normal matter unimpeded and undetected.
Leo James Rainwater was an American physicist who shared the Nobel Prize in Physics in 1975 for his part in determining the asymmetrical shapes of certain atomic nuclei.
R-parity is a concept in particle physics. In the Minimal Supersymmetric Standard Model, baryon number and lepton number are no longer conserved by all of the renormalizable couplings in the theory. Since baryon number and lepton number conservation have been tested very precisely, these couplings need to be very small in order not to be in conflict with experimental data. R-parity is a symmetry acting on the Minimal Supersymmetric Standard Model (MSSM) fields that forbids these couplings and can be defined as
In physics, mirror matter, also called shadow matter or Alice matter, is a hypothetical counterpart to ordinary matter.
A tetraquark, in particle physics, is an exotic meson composed of four valence quarks. A tetraquark state has long been suspected to be allowed by quantum chromodynamics, the modern theory of strong interactions. A tetraquark state is an example of an exotic hadron which lies outside the conventional quark model classification.
In particle physics, majorons are a hypothetical type of Goldstone boson that are theorized to mediate the neutrino mass violation of lepton number or B − L in certain high energy collisions such as
Jack Steinberger is an American physicist who, along with Leon M. Lederman and Melvin Schwartz, received the 1988 Nobel Prize in Physics for the discovery of the muon neutrino.
In particle physics, a hyperon is any baryon containing one or more strange quarks, but no charm, bottom, or top quark. This form of matter may exist in a stable form within the core of some neutron stars.
In quantum mechanics, a parity transformation is the flip in the sign of one spatial coordinate. In three dimensions, it can also refer to the simultaneous flip in the sign of all three spatial coordinates :
In particle physics, lepton number is a conserved quantum number representing the difference between the number of leptons and the number of antileptons in an elementary particle reaction. Lepton number is an additive quantum number, so its sum is preserved in interactions. Mathematically, the lepton number is defined by , where is the number of leptons and is the number of antileptons.
In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. As in single beta decay, this process allows the atom to move closer to the optimal ratio of protons and neutrons. As a result of this transformation, the nucleus emits two detectable beta particles, which are electrons or positrons.
The Daya Bay Reactor Neutrino Experiment is a China-based multinational particle physics project studying neutrinos. The multinational collaboration includes researchers from China, Chile, the United States, Taiwan, Russia, and the Czech Republic. The US side of the project is funded by the US Department of Energy's Office of High Energy Physics.
Luke Chia-Liu Yuan was a Chinese-American physicist and grandson of Yuan Shikai, the first president of the Republic of China from 1912 to 1916.
Noemie Benczer Koller is a nuclear physicist. She was the first tenured female professor of Rutgers College.
In particle physics, CP violation is a violation of CP-symmetry : the combination of C-symmetry and P-symmetry. CP-symmetry states that the laws of physics should be the same if a particle is interchanged with its antiparticle while its spatial coordinates are inverted. The discovery of CP violation in 1964 in the decays of neutral kaons resulted in the Nobel Prize in Physics in 1980 for its discoverers James Cronin and Val Fitch.
Renate Wiener Chasman was a physicist.
The Wu experiment was a nuclear physics experiment conducted in 1956 by the Chinese American physicist Chien-Shiung Wu in collaboration with the Low Temperature Group of the US National Bureau of Standards. The experiment's purpose was to establish whether or not conservation of parity (P-conservation), which was previously established in the electromagnetic and strong interactions, also applied to weak interactions. If P-conservation were true, a mirrored version of the world would behave as the mirror image of the current world. If P-conservation were violated, then it would be possible to distinguish between a mirrored version of the world and the mirror image of the current world.
The Zc(3900) is a hadron, a type of subatomic particle made of quarks, believed to be the first tetraquark that has been observed experimentally. The discovery was made in 2013 by two independent research groups: one using the BES III detector at the Chinese Beijing Electron Positron Collider, the other being part of the Belle experiment group at the Japanese KEK particle physics laboratory.
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