Today, The Grandma has been reading about CarlDavid Anderson, the American physicist, who discovered the positron on a day like today in 1932.
Carl David Anderson (September 3, 1905-January 11, 1991) was an American physicist. He is best known for his discovery of the positron in 1932, an achievement for which hereceivedthe 1936 Nobel Prize in Physics, and of the muon in 1936.
Anderson was born in New York City,the son of Swedish immigrants. He studied physics and engineering at Caltech (B.S., 1927; Ph.D., 1930). Under the supervision of Robert A. Millikan, he began investigations into cosmic rays during the course of which he encountered unexpected particle tracks in his (modern versions now commonly referred to as an Anderson) cloud chamber photographs that he correctly interpreted as having been created by a particle with the same mass as the electron, but with opposite electrical charge.
This discovery, announced in 1932 and later confirmed by others, validated Paul Dirac's theoretical prediction of the existence of the positron. Anderson first detected the particles in cosmic rays. He then produced more conclusive proof by shooting gamma rays produced by the natural radioactive nuclide into other materials, resulting in the creation of positron-electron pairs. For this work, Anderson shared the 1936 Nobel Prize in Physics with Victor Hess.
Fifty years later, Anderson acknowledged that his discovery was inspired by the work of his Caltech classmate Chung-Yao Chao, whose research formed the foundation from which much of Anderson's work developed but was not credited at the time.
Anderson spent all of his academic and research career at Caltech. During World War II, he conducted research in rocketry there. He was elected to the United States National Academy of Sciences and the American Philosophical Society in 1938. He was elected a Fellow of the American Academy of Arts and Sciences in 1950. He received the Golden Plate Award of the American Academy of Achievement in 1975.
Anderson died on January 11, 1991, and his remains were interred in the Forest Lawn, Hollywood Hills Cemetery in Los Angeles, California
The positron or antielectron is the particle with an electric charge of +1e, a spin of 1/2 (the same as the electron), and the same mass as an electron. It is the antiparticle (antimatter counterpart) of the electron. When a positron collides with an electron, annihilation occurs. If this collision occurs at low energies, it results in the production of two or more photons.
Positrons can be created by positron emission radioactive decay (through weak interactions), or by pair production from a sufficiently energetic photon which is interacting with an atom in a material.
Today, The Grandma has been reading about the Bose-Einstein condensate,the state of matter that was first created on a day like today in 1995.
In condensed matter physics, a Bose-Einstein condensate (BEC) is a state of matter that is typically formed when a gas of bosons at very low densities is cooled to temperatures very close to absolute zero (-273.15 °C or -459.67 °F).
Under such conditions, a large fraction of bosons occupy the lowest quantum state, at which microscopic quantum-mechanical phenomena, particularly wavefunction interference, become apparent macroscopically.
More generally, condensation refers to the appearance of macroscopic occupation of one or several states: for example, in BCS theory, a superconductor is a condensate of Cooper pairs. As such, condensation can be associated with phase transition, and the macroscopic occupation of the state is the order parameter.
Bose-Einstein condensate was first predicted, generally, in 1924–1925 by Albert Einstein, crediting a pioneering paper by Satyendra Nath Bose on the new field now known as quantum statistics.
In 1995, the Bose-Einstein condensate was created by Eric Cornell and Carl Wieman of the University of Colorado Boulder using rubidium atoms; later that year, Wolfgang Ketterle of MIT produced a BEC using sodium atoms.
In 2001 Cornell, Wieman, and Ketterle shared the Nobel Prize in Physicsfor the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates. These early studies founded the
field of ultracold atoms, and hundreds of research groups around the
world now routinely produce BECs of dilute atomic vapors in their labs.
Bose first sent a paper to Einstein on the quantum statistics of light quanta, now called photons, in which he derived Planck's quantum radiation law without any reference to classical physics. Einstein was impressed, translated the paper himself from English to German and submitted it for Bose to the Zeitschrift für Physik,which published it in 1924. The Einstein manuscript, once believed to be lost, was found in a library at Leiden University in 2005.
Einstein then extended Bose's ideas to matter in two other papers. The result of their efforts is the concept of a Bose gas, governed by Bose-Einstein statistics, which describes the statistical distribution of identical particles with integer spin, now called bosons. Bosons, particles that include the photon and atoms with an even number of neutrons (such as helium-4 (4 He)), are allowed to share a quantum state. Einstein proposed that cooling bosonic atoms to a very low temperature would cause them to fall (or "condense") into the lowest accessible quantum state, resulting in a new form of matter.
In 1938, Fritz London proposed the BEC as a mechanism for superfluidity in 4 He and superconductivity.
The quest to produce a Bose-Einstein condensate in the laboratory was stimulated by a paper published in 1976 by two program directors at the National Science Foundation (William Stwalley and Lewis Nosanow). This led to the immediate pursuit of the idea by four independent research groups; these were led by Isaac Silvera (University of Amsterdam), Walter Hardy (University of British Columbia), Thomas Greytak (Massachusetts Institute of Technology) and David Lee (Cornell University).
On 5 June 1995, the first gaseous condensate was produced by Eric Cornell and Carl Wieman at the University of Colorado at Boulder NIST-JILA lab, in a gas of rubidium atoms cooled to 170 nanokelvins (nK).
Shortly thereafter, Wolfgang Ketterle at MIT produced a Bose–Einstein Condensate in a gas of sodium atoms.
Since 1995, many other atomic species have been condensed, and BECs have also been realized using molecules, quasi-particles, and photons.
Compared to more commonly encountered states of matter, Bose-Einsteincondensates are extremely fragile. The slightest interaction with the external environment can be enough to warm them past the condensation threshold, eliminating their interesting properties and forming a normal gas.
Bose-Einstein condensates composed of a wide range of isotopes have been produced.
Limitations of evaporative cooling have restricted atomic BECs to pulsed operation, involving a highly inefficient duty cycle that discards more than 99% of atoms to reach BEC. Achieving continuous BEC has been a major open problem of experimental BEC research, driven by the same motivations as continuous optical laser development: high flux, high coherence matter waves produced continuously would enable new sensing applications.
Continuous BEC was achieved for the first time in 2022.
Today, The Grandma has been readingabout WilhelmConrad Röntgen, theGerman mechanical engineer and physicistwho discovered X-rays on a day like todayin 1895.
Wilhelm Conrad Röntgen (27 March 1845-10 February 1923) was a Germanmechanical engineer and physicist, who, on 8 November 1895, producedand detected electromagneticradiationin a wavelength rangeknown as X-rays or Röntgenrays, anachievement that earned him theinaugural Nobel Prize in Physics in1901. In honour of Röntgen'saccomplishments, in 2004 the International Union of Pure and Applied Chemistry (IUPAC) namedelement 111, roentgenium, aradioactive element with multiple unstable isotopes, after him. The unit of measurement roentgen was also named after him.
He was born to Friedrich Conrad Röntgen, a German merchant and cloth manufacturer, and Charlotte Constanze Frowein. At age three his family moved to the Netherlands where his mother's family lived. Röntgen attended high school at Utrecht Technical School in Utrecht, Netherlands. He followed courses at the Technical School for almost two years.
In 1865, he was unfairly expelled from high school when one of his teachers intercepted a caricature of one of the teachers, which was drawn by someone else.
In 1874, Röntgen became a lecturer at the University of Strasbourg.
In 1875, he became a professor at the Academy of Agriculture at Hohenheim, Württemberg. He returned to Strasbourg as a professor of physics in 1876, and in 1879, he was appointed to the chair of physics at the University of Giessen.
In 1888, he obtained the physics chair at the University of Würzburg, and in 1900 at the University of Munich, by special request of the Bavarian government.
Röntgen had family in Iowa in the United States and planned to emigrate. He accepted an appointment at Columbia University in New York City and bought transatlantic tickets, before the outbreak of World War I changed his plans. Heremained in Munich for the rest of his career.
During 1895, at his laboratory in the Würzburg Physical Institute of the University of Würzburg, Röntgen was investigating the external effects from the various types of vacuum tube equipment -apparatuses from Heinrich Hertz, Johann Hittorf, William Crookes, Nikola Tesla and Philipp von Lenard- when an electrical discharge is passed through them.
In early November, he was repeating an experiment with one of Lenard's tubes in which a thin aluminium window had been added to permit the cathode rays to exit the tube but a cardboard covering was added to protect the aluminium from damage by the strong electrostatic field that produces the cathode rays.
Röntgen knew that the cardboard covering prevented light from escaping, yet he observed that the invisible cathode rays caused a fluorescent effect on a small cardboard screen painted with barium platinocyanide when it was placed close to the aluminium window. It occurred to Röntgen that the Crookes-Hittorf tube, which had a much thicker glass wall than the Lenard tube, might also cause this fluorescent effect.
In the late afternoon of 8 November 1895, Röntgen was determined to test his idea. He carefully constructed a black cardboard covering similar to the one he had used on the Lenard tube. He covered the Crookes-Hittorf tube with the cardboard and attached electrodes to a Ruhmkorff coil to generate an electrostatic charge. Before setting up the barium platinocyanide screen to test his idea, Röntgen darkened the room to test the opacity of his cardboard cover. As he passed the Ruhmkorff coil charge through the tube, he determined that the cover was light-tight and turned to prepare for the next step of the experiment. It was at this point that Röntgen noticed a faint shimmering from a bench a few feet away from the tube. To be sure, he tried several more discharges and saw the same shimmering each time. Striking a match, he discovered the shimmering had come from the location of the barium platinocyanide screen he had been intending to use next.
Röntgen speculated that a new kind of ray might be responsible. 8 November was a Friday, so he took advantage of the weekend to repeat his experiments and made his first notes. In the following weeks, he ate and slept in his laboratory as he investigated many properties of the new rays he temporarily termed X-rays, using the mathematical designation (X) for something unknown. The new rays came to bear his name in many languages as Röntgen rays (and the associated X-ray radiograms as Röntgenograms).
At one point while he was investigating the ability of various materials to stop the rays, Röntgen brought a small piece of lead into position while a discharge was occurring. Röntgen thus saw the first radiographic image: his own flickering ghostly skeleton on the barium platinocyanide screen. He later reported that it was at this point that he decided to continue his experiments in secrecy, fearing for his professional reputation if his observations were in error.
About six weeks after his discovery, he took a picture -a radiograph- using X-rays of his wife Anna Bertha's hand. When she saw her skeleton she exclaimed I have seen my death! He later took a better picture of his friend Albert von Kölliker's hand at a public lecture.
Röntgen's original paper, On A New Kind of Rays (Ueber eine neue Art von Strahlen), was published on 28 December 1895.
On 5 January 1896, an Austrian newspaper reported Röntgen's discovery of a new type of radiation. Röntgen was awarded an honorary Doctor of Medicine degree from the University of Würzburg after his discovery. He also received the Rumford Medal of the British Royal Society in 1896, jointly with Philipp Lenard, who had already shown that a portion of the cathode rays could pass through a thin film of a metal such as aluminium.
Röntgen published a total of three papers on X-rays between 1895 and 1897. Today, Röntgen is considered the father of diagnostic radiology, the medical speciality which uses imaging to diagnose disease.
A collection of his papers is held at the National Library of Medicine in Bethesda, Maryland.
In 1901, Röntgen was awarded the first Nobel Prize in Physics. The award was officially in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him.
Röntgen donated the 50,000 Swedish krona reward from his Nobel Prize to research at his university, the University of Würzburg. Like Marie and Pierre Curie, Röntgen refused to take out patents related to his discovery of X-rays, as he wanted society as a whole to benefit from practical applications of the phenomenon.
Röntgen was also awarded Barnard Medal for Meritorious Service to Science in 1900.
Today, The Grandma has been reading about Jack St. Clair Kilby, who filed the first patent for an integrated circuit on a day like today in 1959.
Jack St. Clair Kilby (November 8, 1923-June 20, 2005) was an American electrical engineer who took part (along with Robert Noyce of Fairchild) in the realization of the first integrated circuit while working at Texas Instruments (TI) in 1958.
He was awarded the Nobel Prize in Physics on December 10, 2000.
Kilby was also the co-inventor of the handheldcalculator and the thermal printer, for which he had the patents. He also had patents for seven other inventions.
Jack Kilby was born in 1923 in Jefferson City, Missouri to Hubert and Vina Freitag Kilby. Both parents had Bachelor of Science degrees from the University of Illinois. His father was a manager at a local utility company.
Kilby grew up and attended school in Great Bend, Kansas, graduating from the Great Bend High School. Road signs at the entrances to the town commemorate his time there, and the Commons Area at Great Bend High School has been named The Jack Kilby Commons Area.
Kilby received his Bachelor of Science degree from the University of Illinois at Urbana-Champaign, where he was an honorary member of Acacia fraternity.
In 1947, he received a degree in electrical engineering. He earned his Master of Science in electrical engineering from the University of Wisconsin-Milwaukee in 1950, while working at Centralab, a division of Globe-Union corporation in Milwaukee.
In mid-1958, Kilby, a newly employed engineer at Texas Instruments (TI), did not yet have the right to a summer vacation. He spent the summer working on the problem in circuit design that was commonly called the tyranny of numbers, and he finally came to the conclusion that the manufacturing of circuit components en masse in a single piece of semiconductor material could provide a solution. On September 12, he presented his findings to company's management, which included Mark Shepherd.
He showed them a piece of germanium with an oscilloscope attached, pressed a switch, and the oscilloscope showed a continuous sine wave, proving that his integrated circuit worked, and thus that he had solved the problem.
U.S. Patent 3,138,743 for Miniaturized Electronic Circuits, the first integrated circuit, was filed on February 6, 1959. Along with Robert Noyce (who independently made a similar circuit a few months later), Kilby is generally credited as co-inventor of the integrated circuit.
Jack Kilby went on to pioneer military, industrial, and commercial applications of microchip technology. He headed teams that created the first military system and the first computer incorporating integrated circuits. He invented the handheld calculator, along with Jerry Merryman and James Van Tassel. He was also responsible for the thermal printer that was used in early portable data terminals.
In 1970, he took a leave of absence from TI to work as an independent inventor. He explored, among other subjects, the use of silicon technology for generating electrical power from sunlight.
From 1978 to 1984 he held the position of Distinguished Professor of Electrical Engineering at Texas A&M University.
In 1983, Kilby retired from Texas Instruments.
He died in June 20, 2005 at the age of 81, in Dallas, Texas.
I think I thought it would be important for electronics as we knew it then, but that was a much simpler business and electronics was mostly radio and television and the first computers.
Today, The Grandma has been reading about PierreCurie, the French physicist who died on a day like today in 1906.
Pierre Curie (15 May 1859-19 April 1906) was aFrench physicist, a pioneer in crystallography, magnetism, piezoelectricity, and radioactivity.
In 1903, he received the Nobel Prize in Physics with his wife, Marie Curie, andHenri Becquerel,inrecognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel. With their win, the Curies became the first ever married couple to win the NobelPrize, launching the Curiefamily legacy of five Nobel Prizes.
Born in Paris on 15 May 1859, Pierre Curie was the son of Eugène Curie (1827–1910), a doctor of French Catholic origin from Alsace, and Sophie-Claire Curie. He was educated by his father and in his early teens showed a strong aptitude for mathematics and geometry. When he was 16, he earned his Bachelor of Science in mathematics.
By the age of 18, he earned his license, the equivalent of a U.S. masters degree, in physical sciences from the Faculty of Sciences at the Sorbonne, also known as the University of Paris.
He did not proceed immediately to a doctorate due to lack of money. Instead, he worked as a laboratory instructor. When Pierre Curie was preparing for his Bachelor of Science degree, he worked in the laboratory of Jean-Gustave Bourbouze in the Faculty of Science.
In 1895, he went on to receive his doctorate at the University of Paris. The submission material for his doctorate consisted of his research over magnetism. After obtaining his doctorate, he became professor of physics and in 1900, he became professor in the faculty of sciences.
In
1880, Pierre and his older brother Paul-Jacques (1856-1941) demonstrated
that an electric potential was generated when crystals were compressed.
To aid this work they invented the piezoelectric quartz electrometer.
The
following year they demonstrated the reverse effect: that crystals
could be made to deform when subject to an electric field. Almost all
digital electronic circuits now rely on this in the form of crystal
oscillators. In subsequent work on magnetism Pierre Curie defined the
Curie scale. This work also involved delicate equipment -balances,
electrometers.
Pierre Curie was introduced to Maria Skłodowska by their friend, physicist Józef Wierusz-Kowalski. Curie took her into his laboratory as his student. His admiration for her grew when he realized that she would not inhibit his research. He began to regard Skłodowska as his muse. She refused his initial proposal, but finally agreed to marry him on 26 July 1895.
The Curies had a happy, affectionate marriage, and they were known for their devotion to each other.
Before his famous doctoral studies on magnetism, he designed and perfected an
extremely sensitive torsion balance for measuring magnetic
coefficients. Variations on this equipment were commonly used by future
workers in that area. Pierre Curie studied ferromagnetism,
paramagnetism, and diamagnetism for his doctoral thesis, and discovered
the effect of temperature on paramagnetism which is now known as Curie's
law.
The
material constant in Curie's law is known as the Curie constant. He
also discovered that ferromagnetic substances exhibited a critical
temperature transition, above which the substances lost their
ferromagnetic behavior. This is now known as the Curie temperature.
The
Curie temperature is used to study plate tectonics, treat hypothermia,
measure caffeine, and to understand extraterrestrial magnetic fields.
The Curie is a unit of measurement used to describe the intensity of a
sample of radioactive material and is named after Marie and Pierre
Curie.
Pierre Curie formulated what is now known as the Curie Dissymmetry Principle: a physical effect cannot have a dissymmetry absent from its efficient cause. Introduce a gravitational field, and there is a dissymmetry because of the direction of the field. Then the sand grains can self-sort with the density increasing with depth. But this new arrangement, with the directional arrangement of sand grains, actually reflects the dissymmetry of the gravitational field that causes the separation.
Curie worked with his wife in isolating polonium and radium. They were the first to use the term radioactivity, and were pioneers in its study. Their work, including Marie Curie's celebrated doctoral work, made use of a sensitive piezoelectric electrometer constructed by Pierre and his brother Jacques Curie.
Pierre Curie's 1898 publication with his wife and M. G. Bémont for their discovery of radium and polonium was honored by a Citation for Chemical Breakthrough Award from the Division of History of Chemistry of the American Chemical Society presented to the ESPCI ParisTech, officially the École supérieure de physique et de Chimie industrielles de la Ville de Paris, in 2015.
In 1903, to honor the Curies' work, the Royal Society of London invited Pierre to present their research.
Marie Curie was not permitted to give the lecture so Lord Kelvin sat beside her while Pierre spoke on their research. After this, Lord Kelvin held a luncheon for Pierre. While in London, Pierre and Marie were awarded the Davy Medal of the Royal Society of London. In the same year, Pierre and Marie Curie, as well as Henri Becquerel, were awarded a Nobel Prize in physics for their research of radioactivity.
Curie and one of his students, Albert Laborde, made the first discovery of nuclear energy, by identifying the continuous emission of heat from radium particles.
Curie also investigated the radiation emissions of radioactive substances, and through the use of magnetic fields was able to show that some of the emissions were positively charged, some were negative and some were neutral. These correspond to alpha, beta and gamma radiation.
The Curie is a unit of radioactivity (3.7×1010 decays per second or 37 gigabecquerels) originally named in honor of Curie by the Radiology Congress in 1910, after his death. Subsequently, there has been some controversy over whether the naming was in honor of Pierre, Marie, or both.
Pierre Curie died in a street accident in Paris on 19 April 1906.
Is it right to probe so deeply into Nature's secrets? The question must here be raised whether it will benefit mankind, or whether the knowledge will be harmful.
Today, The Grandma has received the visit of Joseph de Ca'th Lon, one of her closest friends. They have been talking about Christmas holiday and the arrival of the new year. They expect interesting events for this new year, especially new technologic discoveries. We are living under the effects of a digital revolution and our society has changed a lot in the last decade thanks to it but it is also time to remember and homage old discoveries that are still important and needed in our times.
Joseph and The Grandma have been talking about the transistor, a semiconductor device used to amplify or switch electronic signals and electrical power, that was first demonstrated at Bell Laboratories on a day like today in 1947. A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.
Austro-Hungarian physicist Julius Edgar Lilienfeld proposed the concept of a field-effect transistor in 1926, but it was not possible to actually construct a working device at that time.
The first working device to be built was a point-contact transistor invented in 1947 by American physicists John Bardeen and Walter Brattain while working under William Shockley at Bell Labs.
They shared the 1956 Nobel Prize in Physics for their achievement. The most widely used transistor is the MOSFET (metal–oxide–semiconductor field-effect transistor), also known as the MOS transistor, which was invented by Egyptian engineer Mohamed Atalla with Korean engineer Dawon Kahng at Bell Labs in 1959. The MOSFET was the first truly compact transistor that could be miniaturised and mass-produced for a wide range of uses.
Transistors revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things. The first transistor and the MOSFET are on the list of IEEE milestones in electronics. The MOSFET is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. An estimated total of 13 sextillion MOSFETs have been manufactured between 1960 and 2018 (at least 99.9% of all transistors), making the MOSFET the most widely manufactured device in history.
Transistors
Most transistors are made from very pure silicon, andsome from germanium, but certain other semiconductor materials can also be used. A transistor may have only one kind of charge carrier, in a field-effect transistor, or may have two kinds of charge carriers in bipolar junction transistor devices.
Compared with the vacuum tube, transistors are generally smaller, and require less power to operate. Certain vacuum tubes have advantages over transistors at very high operating frequencies or high operating voltages. Many types of transistors are made to standardized specifications by multiple manufacturers.
The thermionic triode, a vacuum tube invented in 1907, enabled amplified radio technology and long-distance telephony. The triode, however, was a fragile device that consumed a substantial amount of power. In 1909, physicist William Eccles discovered the crystal diode oscillator. Austro-Hungarian physicist Julius Edgar Lilienfeld filed a patent for a field-effect transistor (FET) in Canada in 1925, which was intended to be a solid-state replacement for the triode.
Lilienfeld also filed identical patents in the United States in 1926 and 1928. However, Lilienfeld did not publish any research articles about his devices nor did his patents cite any specific examples of a working prototype. Because the production of high-quality semiconductor materials was still decades away, Lilienfeld's solid-state amplifier ideas would not have found practical use in the 1920s and 1930s, even if such a device had been built. In 1934, German inventor Oskar Heil patented a similar device in Europe.
From November 17, 1947,
to December 23, 1947, John Bardeen and WalterBrattain at AT&T's
Bell Labs in Murray Hill, New Jersey, performed experiments and observed
that when two gold point contacts were applied to a crystal of
germanium, a signal was produced with the output power greater than the
input.
Solid State Physics
Group leader William Shockley saw the potential in this, and over the
next few months worked to greatly expand the knowledge of
semiconductors.
Transistor as a Switch
The term transistor was coined by John R. Pierce as a contraction of the term transresistance. According to Lillian Hoddeson and Vicki Daitch, authors of a biography of John Bardeen, Shockley had proposed that Bell Labs' first patent for a transistor should be based on the field-effect and that he be named as the inventor.
Having unearthed Lilienfeld's patents that went into obscurity years earlier, lawyers at Bell Labs advised against Shockley's proposal because the idea of a field-effect transistor that used an electric field as a grid was not new. Instead, what Bardeen, Brattain, and Shockley invented in 1947 was the first point-contact transistor. In acknowledgement of this accomplishment, Shockley, Bardeen, and Brattain were jointly awarded the 1956 Nobel Prize in Physicsfor their researches on semiconductors and their discovery of the transistor effect.
Shockley's research team initially attempted to build a field-effect transistor (FET), by trying to modulate the conductivity of a semiconductor, but was unsuccessful, mainly due to problems with the surface states, the dangling bond, and the germanium and copper compound materials. In the course of trying to understand the mysterious reasons behind their failure to build a working FET,this led them to instead inventing the bipolar point-contact and junction transistors.
In
1948, the point-contact transistor was independently invented by German
physicists Herbert Mataré and Heinrich Welker while working at the
Compagnie des Freins et Signaux, a Westinghouse subsidiary located in
Paris. Mataré had previous experience in developing crystal rectifiers
from silicon and germanium in the German radar effort during World War
II. Using this knowledge, he began researching the phenomenon of interference in 1947.
By June 1948, witnessing
currents flowing through point-contacts, Mataré produced consistent
results using samples of germanium produced by Welker, similar to what
Bardeen and Brattain had accomplished earlier in December 1947.
Realizing that Bell Labs' scientists had already invented the transistor
before them, the company rushed to get its transistron into
production for amplified use in France's telephone network and filed for
his first transistor patent application on August 13,1948.
The first bipolar
junction transistors were invented by Bell Labs' William Shockley, which
applied for patent (2,569,347) on June 26, 1948. On April 12, 1950,
Bell Labs chemists Gordon Teal and Morgan Sparks had successfully
produced a working bipolar NPN junction amplifying germanium transistor.
Bell Labs had announced the discovery of this new sandwich transistor
in a press release on July 4, 1951.
The first high-frequency
transistor was the surface-barrier germaniumtransistor developed by
Philco in 1953, capable of operating up to 60 MHz. These were made by
etching depressions into an N-type germanium base from both sides with
jets of Indium(III) sulfate until it was a few ten-thousandths of an
inch thick. Indium electroplated into the depressions formed the
collector and emitter.
PNP Transistor
The first prototype pocket transistor radio was shown by INTERMETALL, a company founded by Herbert Mataré in 1952, at the Internationale Funkausstellung Düsseldorf between August 29, 1953 and September 9, 1953.
The first production pocket transistor radio was the Regency TR-1, released in October 1954. Produced as a joint venture between the Regency Division of Industrial Development Engineering Associates, I.D.E.A. and Texas Instruments of Dallas Texas, the TR-1 was manufactured in Indianapolis, Indiana. It was a near pocket-sized radio featuring 4 transistors and one germanium diode. The industrial design was outsourced to the Chicago firm of Painter, Teague and Petertil. It was initially released in one of four different colours: black, bone white, red, and gray. Other colours were to shortly follow.
The first production all-transistor car radio was developed by Chrysler and Philco
corporations and it was announced in the April 28th 1955 edition of the
Wall Street Journal. Chrysler had made the all-transistor car radio,
Mopar model 914HR, available as an option starting in fall 1955 for its
new line of 1956 Chrysler and Imperial cars which first hit the
dealership showroom floors on October 21, 1955.
The
Sony TR-63, released in 1957, was the first mass-produced transistor
radio, leading to the mass-market penetration of transistor radios. The
TR-63 went on to sell seven million units worldwide by the mid-1960s.
Sony's success with transistor radios led to transistors replacing
vacuum tubes as the dominant electronic technology in the late 1950s.
The first working silicon transistor was developed at Bell Labs on January 26, 1954 by Morris Tanenbaum. The first commercial silicon transistor was produced by Texas Instruments in 1954. This was the work of Gordon Teal, an expert in growing crystals of high purity, who had previously worked at Bell Labs.
The essential usefulness
of a transistor comes from its ability to use a small signal applied
between one pair of its terminals to control a much larger signal at
another pair of terminals. This property is called gain.
It can produce a stronger output signal, a voltage or current, which is
proportional to a weaker input signal; that is, it can act as an
amplifier. Alternatively, the transistor can be used to turn current on
or off in a circuit as an electrically controlled switch, where the
amount of current is determined by other circuit elements.
Bell Labs-Transistor Team
There are two types of transistors, which have slight differences in how they are used in a circuit. A bipolar transistor has terminals labeled base, collector, and emitter. A small current at the base terminal (that is, flowing between the base and the emitter) can control or switch a much larger current between the collector and emitter terminals. For a field-effect transistor, the terminals are labeled gate, source, and drain, and a voltage at the gate can control a current between source and drain.
The image represents a typical bipolar transistor in a circuit. Charge will flow between emitter and collector terminals depending on the current in the base. Because internally the base and emitter connections behave like a semiconductor diode, a voltage drop develops between base and emitter while the base current exists. The amount of this voltage depends on the material the transistor is made from, and is referred to as VBE.
Transistors
are commonly used in digital circuits as electronic switches which can
be either in an on or off state, both for high-power applications
such as switched-mode power supplies and for low-power applications such
as logic gates. Important parameters for this application include the
current switched, the voltage handled, and the switching speed,
characterised by the rise and fall times.
In
a grounded-emitter transistor circuit, such as the light-switch circuit
shown, as the base voltage rises, the emitter and collector currents
rise exponentially. The collector voltage drops because of reduced
resistance from collector to emitter. If the voltage difference between
the collector and emitter were zero (or near zero), the collector
current would be limited only by the load resistance (light bulb) and
the supply voltage. This is called saturation because current is flowing
from collector to emitter freely. When saturated, the switch is said to
be on.
Providing sufficient base drive current is a key problem in the use of bipolar transistors as switches. The transistor provides current gain, allowing a relatively large current in the collector to be switched by a much smaller current into the base terminal. The ratio of these currents varies depending on the type of transistor, and even for a particular type, varies depending on the collector current. In the example light-switch circuit shown, the resistor is chosen to provide enough base current to ensure the transistor will be saturated.
In a switching circuit, the idea is to simulate, as near as possible, the ideal switch having the properties of open circuit when off, short circuit when on, and an instantaneous transition between the two states. Parameters are chosen such that the off output is limited to leakage currents too small to affect connected circuitry, the resistance of the transistor in the on state is too small to affect circuitry, and the transition between the two states is fast enough not to have a detrimental effect.
The common-emitter amplifier is designed so that a small change in voltage (Vin) changes the small current through the base of the transistor; the transistor's current amplification combined with the properties of the circuit means that small swings in Vin produce large changes in Vout.
Various configurations of single transistor amplifier are possible, with some providing current gain, some voltage gain, and some both.
From mobile phones to televisions, vast numbers of products include amplifiers for sound reproduction, radio transmission, and signal processing. The first discrete-transistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio fidelity gradually increased as better transistors became available and amplifier architecture evolved.
Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive.
Susan Jocelyn Bell Burnell (1943) is a Northern Irish astrophysicist. As a postgraduate student, she discovered the first radio pulsars while studying and advised by her thesis supervisor Antony Hewish, for which Hewish shared the Nobel Prize in Physics with astronomer Martin Ryle, while Bell Burnell was excluded, despite having been the first to observe and precisely analyse the pulsars.
Bell Burnell was President of the Royal Astronomical Society from 2002 to 2004, president of the Institute of Physics from October 2008 until October 2010, and was interim president following the death of her successor, Marshall Stoneham, in early 2011. She was succeeded in October 2011 by Sir Peter Knight. Bell Burnell was elected as President of the Royal Society of Edinburgh in October 2014. In March 2013 she was elected Pro-Chancellor of the University of Dublin.
The paper announcing the discovery of pulsars had five authors. Hewish's name was listed first, Bell's second. Hewish was awarded the Nobel Prize, along with Martin Ryle, without the inclusion of Bell as a co-recipient. Many prominent astronomers criticised this omission, including Sir Fred Hoyle The Royal Swedish Academy of Sciences, in their press release announcing the 1974 Nobel Prize in Physics, cited Ryle and Hewish for their pioneering work in radio-astrophysics, with particular mention of Ryle's work on aperture-synthesis technique, and Hewish's decisive role in the discovery of pulsars.
The fact that Bell did not receive recognition in the 1974 Nobel Prize in Physics has been a point of controversy ever since. She helped build the four-acre radio telescope over two years and initially noticed the anomaly, sometimes reviewing as much as 96 feet of paper data per night. Bell later claimed that she had to be persistent in reporting the anomaly in the face of scepticism from Hewish, who was initially insistent that it was due to interference and man-made. She spoke of meetings held by Hewish and Ryle to which she was not invited.
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