UA4 experiment

UA4 experiment (COULOMB) was a high-energy physics experiment at the Proton-Antiproton Collider at CERN. The UA4 collaboration consisted of physicists from Amsterdam, Genova, Napoli, Pisa, Roma, California and CERN. UA4 was approved on 18 January 1979, and the first phase of data taking lasted until 17 June 1985. The spokesperson of UA4 was Giorgi Matthiae.
UA4 was followed by UA4/2, a collaboration between Genova, Roma, Paris, Prague, Valencia and CERN. The purpose of UA4/2 was to measure the ratio of real to the imaginary part of the forward elastic scattering amplitude. It was approved in July 1990, and recorded data throughout 1991.
The objective of the UA4 experiment was to measure the antiproton-proton cross-section, in order to show that cross-sections rising with energy are true a characteristic of strong interaction. One had previously measured proton-antiproton cross-sections at the Intersecting Storage Rings, but as the Proton-Antiproton Collider — a modification of the Super Proton Synchrotron — began operating, the measurements could be done in a new energy range: up to 540 GeV center-of-mass energy.
Elastic events were detected by high resolution wire chambers and scintillation-counter hodoscopes. A system of drift chamber telescopes and counter telescopes were placed on the left and the right side of the crossing region to detect inelastic events.
After the period of data taking, the UA4 collaboration could conclude that proton-antiproton cross-section indeed rises with energy.


Oleg Zatsarinny

Oleg Ivanovich Zatsarinny (1953-2021) was a Ukrainian-American theoretical physicist noted for his contributions to all aspects of research related to electron scattering in atoms.
He was awarded the status of Fellow
in the American Physical Society,
after he was nominated by his Division of Atomic, Molecular & Optical Physics in 2008,
for "the development of the B-Spline R-matrix method with non-orthogonal orbital sets for atomic structure calculations of exceptional accuracy and benchmark calculations for excitation and ionization of complex atoms and ions by photon and electron impact."
Education and research.
Oleg was born in Uzhgorod, Ukraine. He obtained an MSc degree in 1977 from the Moscow Institute of Physics and Technology under the supervision of E.L. Nagaev. The title of his thesis was "Inhomogeneous ferromagnetism of conducting magnetics with ions in a singlet ground state". Upon completion, he obtained a position at Uzhgorod National University, first in the Department of Physical and Quantum Electronics and then in Theoretical Physics. Under the direction of V.I. Lendel of Vilnius University, he obtained a PhD degree in 1985 for a thesis entitled "Study of the Autoionization States of Alkaline and Alkaline Metal Atoms and Their Effects on Recombination and Photoionization processes". He was soon appointed Head of Theoretical Physics Division, Laboratory of Electron Collision Physics, Uzhgorod State University. Upon completing and defending his D.Sc. dissertation, he became a Senior Research Associate at the Institute of Electron Physics of the Ukrainian Academy of Science, a position he would hold from 1993 – 2001.
In 1995 he co-authored a book on elementary processes in plasmas.
It contained many of his results on electron-ion collision cross sections for
H-, He-, Li- and Be-like ions, obtained by different methods, including close-coupling and distorted-wave approaches.
Together with his supervisor and others, he also edited a book
that summarized the status of experiment and theory in his field at that time.
Immigration to the United States of America.
After the collapse of the Soviet Union he started a collaboration with W. Mehlhorn at Freiburg University in Germany. His work on non-orthogonal orbitals in atomic calculations lead to an invitiation to Vanderbilt University in 1997, where he was introduced to B-spline theory, its application to atomic theory, and computational algorithms.
In May, 2000, Oleg and his wife Tatyana immigrated to the USA. Oleg served as Research Associate, first with S. S. Tayal, at Clark Atlanta University, then with T.Gorczyca at Western Michigan University, and finally with K. Bartschat, at Drake University in Des Moines, Iowa.
There he stayed until the end of his life on March 2, 2021.
In 2006 Oleg published his BSR code that is his most cited work.
This code used the R-matrix method to calculate electron–atom and electron–ion collision processes, with options to calculate radiative data, photoionization, and electron scattering. A problem arose, because spurious solutions affected the R-matrix that joins the outer and inner regions. This problem was solved by expressing large and small components by splines of different order.
The unpublished Dirac version of BSR and the DBSR_HF program
 were among the most computationally accurate programs available at that time for atomic calculations.


Gerasimos Danilatos

Gerasimos D. Danilatos (also known as Gerry D. Danilatos) (born circa 1946) is a Greek-Australian physicist and inventor of the environmental scanning electron microscope (ESEM).
He was born in Cefalonia, Greece. After the 1953 Ionian earthquake, his family moved to Patras, where he attended elementary and high school.
After high school and military service, he graduated from the National and Kapodistrian University of Athens and completed his physics degree with distinction. In 1972, he emigrated to Australia, and got married in 1979. He received his Ph.D. from the University of New South Wales in January 1978 after completing his Thesis on "dynamic mechanical properties of keratin fibres". As a scientist at the same university, he then developed the ESEM, after prior attempts by other workers to examine wet specimens under the electron beam. For the most part, he received financial support from the Australian Wool Corporation until 1986. In 2003, he received the Ernst Abbe Memorial Award from the | New York Microscopical Society for his lifetime achievements.


NASU Institute of Physics

The Institute of Physics (IOP) of the National Academy of Sciences of Ukraine () founded in 1926 is the oldest research institution of physical science within the Academy. Being on the path of both infrastructure development and research diversification for more than 80 years, the Institute has eventually originated five more specialized research institutions.
Currently, the Institute employs more than 300 researchers (together with two Full Members and eight Corresponding Members of the NASU) and around 200 peoples of supporting personnel. It has more than 20 scientific units (including the state-of-the-art Femtosecond Laser Complex) which are grouped around four research programs
Traditionally, the Institute is focused on fundamental research. At the same time, applied research on cryogenics, LC displays, laser systems, pyroelectric detectors, biophysics and plasma technologies strengthen the Institute's activities.
The IOP is consistently ranked at the top of national academic institutions ranking. Besides, international reputation of IOP is growing constantly as prominent scientists from the Institute expand their activity to leading foreign research centers and universities.
History.
The origin of the Institute of Physics is dated back to 1921, when the Kyiv Regional Department of Education established the Physics research laboratory. The following year, it was transformed into the Kyiv Science-Research Department of Physics at Kyiv Polytechnic Institute.
The separate entity was established in 1929, when the Department was transformed into the Science-Research Institute of Physics of the People's Commissariat of Education of the Ukrainian SSR. It was eventually renamed as the Institute of Physics of the National Academy of Sciences of Ukraine. In 2009, the Institute celebrated its 80th anniversary.
Academician O.G. Goldman was the founder and the first director of the Institute, which has 20 employees in 1929, including 6 scientists and 10 graduate students. In the first years of existence, the Institute was mainly focused on the training of young scientists and finding its own areas of specialization. Many people who successfully defended their phd theses in that time then became famous scientists. Among them: academicians V.Ye. Lashkaryov, S.I. Pekar and V.P. Linnik, associate members of the Academy of Sciences N.D. Morgulis and P.G. Borzyak, doctors of science M.D. Gabovich, O.G. Miselyuk and others.
In 1938, the Institute has 3 major research specializations:
Semiconductor physics (heads O.G. Goldman, V.Ye. Lashkaryov since 1939);
Physics of electronic and electrovacuum processes (head N.D. Morgulis);
X-ray physics of metals (head S.D. Gertsriken)
Before the Soviet Union was attacked by Germany in 1941, the Institute employed 122 persons, including 36 scientists and 7 graduate students. The Institute has also experimental workshops with qualified staff and state-of-the-art equipment. "Ukrainian physical notes", a journal, was published between 1929 and 1936.
During World War II, the Institute was relocated in Ufa. Academician A.I. Leipunskii (he was the director between 1943 and 1949) and professor G.D. Latyshev from Ukrainian Physical-Technical Institute entered its management team. The focus of the research is directed towards military applications.
After the war, the Institute was quickly restored. In 1953, new buildings for laboratories, production and housing were brought into service on Nauky avenue near the Golosiyivskyi forest.
Some new areas of research activity were developed. Among them: nuclear physics (heads: A.I. Leipunskii and then M.V. Pasichnik), physics of crystals (academician A.F. Prikhot’ko), theoretical physics (academician O.S. Davydov and S.I. Pekar). Electrostatic generator, cyclotron laboratory, and nuclear reactor were put into operation in 1947, 1956, and 1960, correspondingly.
Some specialized research institutes originate from the Institute of Physics. In 1945, on the basis of Diffusion Process Department the Laboratory of Metal Physics was organized, which become the Institute of Metallophysics in 1955. On the basis of the Semiconductor Department, the Institute of Semiconductors was established in 1960. Then, the Institute for Theoretical Physics was established in 1966 from the Department of Elementary Particles. In 1970, some departments were transformed into the Institute for Nuclear Research of the Academy of Sciences of the USSR. And the Institute of Applied Optics was created on the basis of Optical Quantum Electronics Department.
As a result of such organizational transformations, many famous scientists moved to the new Institutions of the Academy of Sciences. But the Institute of Physics also developed significantly and did not lose its leadership. In the 1960s, new areas such quantum electronics, holography, nonlinear optics, pyroelectronics were developed. The Institute made significant contribution to some fields in physics, such as nuclear physics, semiconductor physics, solid state physics, liquid crystals, quantum electronics, plasma physics, and others. Its scientists received certificates for 5 discoveries – more than any other institution in Ukraine. Moreover, scientists of the Institute were awarded the Lenin Prize, 4 State Prizes of the USSR, and 18 State Prizes of Ukraine in physics.
In 1979, the Institute was awarded the Order of the Red Banner for its large-scale success in the development of physical science and training the highly qualified personnel.
Due to the unique architecture of the main building of the Institute and painting on its dome made by honoured Ukrainian artist M.A. Storozhenko, the main building of the Institute was recognized to have a significant historical value and listed among other monuments of architecture, history, and art.
Core research directions.
Condensed matter and soft matter physics.
The main focus is on the optical and spectroscopic investigations of composite materials, molecular crystals, semiconductors, and liquid crystals. The properties of excitons and other quasiparticles are also studied, as well as quantum-dimensional structures. Research interests extend to high-temperature superconductivity, magnetic phenomena such as magnetic resonance, magnetostriction, and magnetooptics, as well as optical and magnetic phenomena in semimagnetic semiconductors. Investigations of defects, both radiation and technological, in semiconductors are of high fundamental and practical importance, as well as developments of radiation techniques for machining semiconductor materials for microelectronics. Studies of biological systems, phototransformation in biomolecules, laser photochemistry and spectroscopy of biomolecules.
Nanophysics and nanoelectronics.
Such investigations began in the middle of the 1960s, when the Physical Electronics Department started studying discontinuous films and discovered the effect of cold electronic emission from such structures. Now, most of the departments work with nanoscale systems to investigate their optical, magnetic, transport, and photoelectric properties. Research activity is also directed to improving the methods for synthesis of nanoscale objects.
Laser physics, nonlinear and singular optics, and holography.
The Institute continues investigating the physics gas lasers, solid-state lasers and dye lasers. Also, scientific interest expand to investigations of nonlinear optical phenomena in semiconductor crystals, molecular crystals and liquid crystals, photorefractive materials, polymers, organic molecules, and photopolymer materials for holography and information recording. Many research projects involve nonlinear laser spectroscopy with ultrahigh resolution, photoacoustic laser spectroscopy and microscopy, or aimed at creating new methods for laser manipulation of free atom particles. There are some traditional research areas, such as dynamic holography, multi-beam optics, speckle fields and holographic correlation methods for laser beam transformation. Also, new investigations in singular optics are conducted.
Surface physics, emission and plasma electronics.
Investigations of small particles and their ensembles are conducted. Optical and emission properties of discontinuous films, physical phenomena in adsorbed films, gas and metal adsorption on solid state surfaces, electronic emission, atom structure and phase transitions in two-dimensional systems, characteristics of ordered thin-film molecular systems, solid state plasma phenomena, hot charge carriers and self-organization effects in semiconductors, and phonon transportation in semiconductors are studied.
Physics of ion-beam plasma, plasmodynamics and plasma kinetics are studied. Recently, new highly efficient plasma technologies and devices were created on the basis of fundamental investigations. They include high-current plasma lenses, devices for surface cleaning and coating, plasma sterilizers of medical equipment and materials.
Scientific schools.
Optics and spectroscopy of nonmetallic crystals.
Research was established by A.F. Prihot'ko (1906–1991), Hero of Socialist Labor, laureate of the Lenin Prize, State Prize of Ukraine, and Honored Scientist of Ukraine. Significant contributions to the formation of the scientific school were made by M.S. Brodyn, V.L. Broude, M.S. Soskin, and M.T. Shpak. Modern investigations in the field are conducted under the leadership of M.S. Brodyn, M.S. Soskin, I.V. Blonsky, S.M. Ryabchenko, I.P. Gnatenko, M.V. Kuryk, G.A. Puchkovska, Y.A. Reznikov.
Nonlinear optics and laser physics.
It was founded by students of A.F. Prihot'ko: academician Mykhailo S. Brodyn, laureate of the Lenin Prize and State Prize of the USSR, and Marat S. Soskin, who is a corresponding member of the Academy and a laureate of the State Prize of the USSR. Modern investigations are conducted by M. S Brodyn, M.S. Soskin, S.G. Odoulov, L.P. Yatsenko, A.O. Borshch, M.V. Vasnetsov, A.M. Negriyko, Ye.O. Tikhonov.
Physical electronics.
It was founded by the corresponding members of the Academy Naum D. Morgulis and Petr G. Borzyak. Modern scientific research is led by academician A.G. Naumovets, corresponding member of the Academy Yu.G. Ptushynskyi, O.G. Sarbei, B.A. Danilchenko, V.M. Poroshin.
Solid state physics.
It was founded by academicians Alexander Davydov, a laureate of the Lenin Prize, and Solomon Isaakovich Pekar. Significant contributions were made by Kirill Borisovich Tolpygo, a correspondent member of the Academy, and Emmanuel Rashba, laureate of the Lenin Prize. Their traditions are maintained by scientists under leadership of P.M. Tomchuk and E.A. Pashytskyi.
Physics of ion beams and ion sources.
Founders are M.D. Gabovich and I.O. Soloshenko.
Scientific discoveries.
The Institute has made five scientific discoveries that were registered in the USSR - more than any other Ukrainian academic institutions.
Certificate #31 (priority from 26 June 1963);
P.G. Borzyak, O.G. Sarbey, R.D. Fedorovych
Certificate #50 (priority from 1951); A.S. Davydov
Certificate #294 (priority from 10 June 1971 for theoretical explanation and from 2 June 1980 for experimental evidence);
O.G. Sarbey, Z.S. Gribnikov, V.V. Mitin, M. Ashe, K. Helmar
Certificate #323 (priority from 23 May 1957);
S.I. Pekar
Certificate #327 (priority from 7 October 1959);
E.I. Rashba
Technology transfer.
The Institute has developed many knowledge-intensive products which are based on the fundamental research.
Technology Transfer Office is the separate division of the Institute created on April 15, 2008. Its mission is to protect intellectual properties belonging to the Institute and support commercialization of promising R&D developments. Among the main tasks are the following:
Famous scientists.
Since 1929, the Institute employed many researchers famous for their contribution into both theoretical and applied physics. Especially in Soviet time, they were at the leading edge of scientific development. Now, many former employees of the Institute work for leading research institutions throughout the world. Collaboration with them allows domestic scientists to effectively share ideas with universities and laboratories throughout the world and employ the best facilities for elaborated experiments.


International Linear Collider

The International Linear Collider (ILC) is a proposed linear particle accelerator. It is planned to have a collision energy of 500 GeV initially, with the possibility for a later upgrade to 1000 GeV (1 TeV). Although early proposed locations for the ILC were Japan, Europe (CERN) and the USA (Fermilab), the Kitakami highland in the Iwate prefecture of northern Japan has been the focus of ILC design efforts since 2013. The Japanese government is willing to contribute half of the costs, according to the coordinator of study for detectors at the ILC.
The ILC would collide electrons with positrons. It will be between 30 km and 50 km (19–31 mi) long, more than 10 times as long as the 50 GeV Stanford Linear Accelerator, the longest existing linear particle accelerator. The proposal is based on previous similar proposals from Europe, the U.S., and Japan.
Studies for an alternative project, the Compact Linear Collider (CLIC) are also underway, which would operate at higher energies (up to 3 TeV) in a machine of length similar to the ILC. These two projects, CLIC and the ILC, have been unified under the Linear Collider Collaboration.
Background: linacs and synchrotrons.
There are two basic shapes of accelerators. Linear accelerators ("linacs") accelerate elementary particles along a straight path. Circular accelerators ("synchrotrons"), such as the Tevatron, the LEP, and the Large Hadron Collider (LHC), use circular paths. Circular geometry has significant advantages at energies up to and including tens of GeV: With a circular design, particles can be effectively accelerated over longer distances. Also, only a fraction of the particles brought onto a collision course actually collide. In a linear accelerator, the remaining particles are lost; in a ring accelerator, they keep circulating and are available for future collisions. The disadvantage of circular accelerators is that charged particles moving along bent paths will necessarily emit electromagnetic radiation known as synchrotron radiation. Energy loss through synchrotron radiation is inversely proportional to the fourth power of the mass of the particles in question. That is why it makes sense to build circular accelerators for heavy particles—hadron colliders such as the LHC for protons or, alternatively, for lead nuclei. An electron–positron collider of the same size would never be able to achieve the same collision energies. In fact, energies at the LEP which used to occupy the tunnel now given over to the LHC, were limited to 209 GeV by energy loss via synchrotron radiation.
Even though the nominal collision energy at the LHC will be higher than the ILC collision energy (14,000 GeV for the LHC vs. ~500 GeV for the ILC), measurements could be made more accurately at the ILC. Collisions between electrons and positrons are much simpler to analyze than collisions in which the energy is distributed among the constituent quarks, antiquarks and gluons of baryonic particles. As such, one of the roles of the ILC would be making precision measurements of the properties of particles discovered at the LHC.
ILC physics and detectors.
It is widely expected that effects of physics beyond that described in the current Standard Model will be detected by experiments at the proposed ILC. In addition, particles and interactions described by the Standard Model are expected to be discovered and measured. At the ILC physicists hope to be able to:
To achieve these goals, new generation particle detectors are necessary.
Merging of regional proposals into a worldwide project.
In August 2004, the International Technology Recommendation Panel (ITRP) recommended a superconducting radio frequency technology for the accelerator. After this decision the three existing linear collider projects – the Next Linear Collider (NLC), the Global Linear Collider (GLC) and Teraelectronvolt Energy Superconducting Linear Accelerator (TESLA) – joined their efforts into one single project (the ILC). In March 2005, the International Committee for Future Accelerators (ICFA) announced Prof. Barry Barish, director of the LIGO Laboratory at Caltech from 1997 to 2005, as the Director of the Global Design Effort (GDE). In August 2007, the Reference Design Report for the ILC was released. Physicists working on the GDE completed a detailed ILC design report, publishing it in June 2013.
Design.
The electron source for the ILC will use 2-nanosecond laser light pulses to eject electrons from a photocathode, a technique allowing for up to 80% of the electrons to be polarized; the electrons then will be accelerated to 5 GeV in a 370-meter linac stage. Synchrotron radiation from high energy electrons will produce electron-positron pairs on a titanium-alloy target, with as much as 60% polarization; the positrons from these collisions will be collected and accelerated to 5 GeV in a separate linac.
To compact the 5 GeV electron and positron bunches to a sufficiently small size to be usefully collided, they will circulate for 0.1–0.2 seconds in a pair of damping rings, 3.24 km in circumference, in which they will be reduced in size to 6 mm in length and a vertical and horizontal emittance of 2 pm and 0.6 nm, respectively.
From the damping rings the particle bunches will be sent to the superconducting radio frequency main linacs, each 11 km long, where they will be accelerated to 250 GeV. At this energy each beam will have an average power of about 5.3 megawatts. Five bunch trains will be produced and accelerated per second.
To maintain a sufficient luminosity to produce results in a reasonable time frame after acceleration the bunches will be focused to a few nanometers in height and a few hundred nanometers in width. The focused bunches then will be collided inside one of two large particle detectors.
Proposed sites.
Originally, three sites for the International Linear Collider were leading contenders at established High Energy Physics centers in Europe. At CERN in Geneva the tunnel is located deep underground in non-permeable bedrock. This site was considered favorable for a number of practical reasons but due to the LHC the site was disfavored. At DESY in Hamburg the tunnel is close to the surface in water saturated soil. Germany leads Europe for scientific funding and was therefore considered reliable in terms of funding. At JINR in Dubna the tunnel is close to the surface in non-permeable soil. Dubna has a pre-accelerator complex which could have been easily adapted for the needs for the ILC. But all three were more or less well suited for housing a Linear Collider and one had ample choice for a site selection process in Europe.
Outside Europe a number of countries expressed interest. Japan receives a large amount of funding for neutrino activities, such as the T2K experiment, a factor not in its favor, although 20 huge caverns with access tunnels have already been constructed in Japan for hydroelectric power plants (e.g. the Kannagawa Hydropower Plant). Following the closure of the Tevatron some groups within the USA had expressed interest, with Fermilab being a favored site because of the facilities and manpower already present. Much of the speculated interest from other countries was hearsay from within the scientific community, and very few facts were published officially. The information presented above is a summary of that contained in the International Workshop on Linear Colliders 2010 (ECFA-CLIC-ILC Joint Meeting) at CERN.
The 2008 economic crisis led the United States and United Kingdom to cut funds to the collider project, leading to Japan's position as the most likely host for the International Linear Collider. On August 23, 2013, the Japanese high-energy physics community's site evaluation committee proposed it should be located in the Kitakami Mountains of the Iwate and Miyagi Prefectures. As of March 7, 2019, the Japanese government has stated that it is not ready to support the construction of the Collider due to its high proposed cost of approximately $7 billion. This decision was informed partly by the Science Council of Japan. The Japanese government is currently seeking monetary support from other countries to help fund this project.
Cost.
The Reference Design Report estimated the cost of building the ILC, excluding R&D, prototyping, land acquisition, underground easement costs, detectors, contingencies, and inflation, at US$6.75 billion (in 2007 prices). From formal project approval, completion of the accelerator complex and detectors is expected to require seven years. The host country would be required to pay $1.8 billion for site-specific costs like digging tunnels and shafts and supplying water and electricity.
Former U.S. Secretary of Energy Steven Chu estimated the total cost to be US$25 billion. ILC Director Barish said this is likely to be an overestimate. Other Department of Energy officials have estimated a $20 billion total. Upon completion of the 2013 ILC Design Report, Barish said the cost of building the ILC was the equivalent of 7.78 billion 2012 U.S. dollars; it will require "22.6 million hours of labor and location-specific costs including site preparation, scientific detectors and facility operations."


Craig Edward DeForest

Craig Edward DeForest (born August 13, 1968) is an American solar physicist and the Vice-Chair of the American Astronomical Society's Solar Physics Division. He leads the heliophysics research group at the Boulder, Colorado offices of the Southwest Research Institute and holds an adjunct faculty position at the University of Colorado, Boulder. His wide-ranging contributions to the field of experimental astrophysics of the Sun include: early work on the MSSTA, a sounding rocket that prototyped modern normal-incidence EUV optics such as are used on the Solar Dynamics Observatory; his discovery of sound waves in the solar corona in 1998; standardization of computer vision techniques that are used to measure and track magnetic fields on the solar surface; co-invention with colleague Charles Kankelborg of the fluxon semi-Lagrangian approach to numerical MHD modeling; and pioneering work on quantitative remote sensing of the solar wind via Thomson scattered light.
DeForest is noted outside the heliophysics science community for his contributions to open-source software, in particular PDL and Audacity; and for his extensive work on science outreach to the public.
DeForest is the Principal Investigator of the planned PUNCH mission launching in 2023 to study the solar corona and the origin of the solar wind.


William Arthur Coles

William Arthur Coles, from the University of California, San Diego, was awarded the status of Fellow in the American Physical Society, after they were nominated by their Topical Group in Plasma Astrophysics in 2006, for "his major contributions to our understanding of the effect of plasma turbulence on radio wave propagation, and the use of radio propagation measurements to infer properties of remote turbulent plasmas in interplanetary space and the interstellar medium."


Ann Nelson

Ann Elizabeth Nelson (April 29, 1958 – August 4, 2019) was a particle physicist and professor of physics in the Particle Theory Group at the University of Washington from 1994 until her death. Nelson received a Guggenheim Fellowship in 2004, and she was elected to the American Academy of Arts and Sciences in 2011 and the National Academy of Sciences in 2012. She was a recipient of the 2018 J. J. Sakurai Prize for Theoretical Particle Physics, presented annually by the American Physical Society and considered one of the most prestigious prizes in physics.
Education.
Born in Baton Rouge, Louisiana, Nelson earned her Bachelor of Science degree at Stanford University in 1980, and her Ph.D. degree at Harvard University under the supervision of Howard Georgi in 1984.
Career.
After a post doctoral fellowship at the Harvard Society of Fellows from 1984-1987, Nelson became an assistant professor at Stanford University in 1987. In 1990 Nelson moved to UC San Diego, and then in 1994 moved for the final time her career to the University of Washington.
Research.
Nelson and her collaborators are known for a number of theories, including:
Personal life.
Nelson was married to David B. Kaplan, also a professor of physics at the University of Washington. She had been an active member of The Mountaineers club in Seattle since 1994. She had two children.
Nelson was an activist for equal rights throughout her life. In 1980, when graduating from Stanford University, she and her husband wore colored ribbons to protest Stanford's investments in Apartheid South Africa. In 2017, she led physics lectures in Palestine to support social justice and promote diversity in science fields around the world. She advocated for greater representation of women in physics research.
Death.
On August 4, 2019, while hiking Iron Cap Mountain in the Alpine Lakes Wilderness with her husband and two friends, Nelson lost her footing and died after falling into a rocky crevasse. Her husband and fellow hikers were rescued on August 4 by a Spokane helicopter crew. Her body was recovered on August 6.


Optical downconverter

Optical DownConverter (ODC) is an example of a non-linear optical process, in which two beams of light of different frequencies formula_1 and formula_2 interact, creating microwave with frequency formula_3. It is a generalization of microwave. In the latter, formula_4, both of which can be provided by a single light source. From a quantum mechanical perspective, ODC can be seen as result of differencing two photons to produce a microwave. Since the energy of a photon is given by
formula_5
the frequency summing formula_3 is simply a statement that energy is conserved.
In a common ODC application, light from a tunable infrared laser is combined with light from a fixed frequency visible laser to produce a microwave created by a wave mixing process.
The ODC use milimeteric microwave cavity that include photonic crystal that provide by two signal frequency light source. The microwave is detected by the cavity antenna.


Area

Area is the quantity that expresses the extent of a two-dimensional region, shape, or planar lamina, in the plane. Surface area is its analog on the two-dimensional surface of a three-dimensional object. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat. It is the two-dimensional analog of the length of a curve (a one-dimensional concept) or the volume of a solid (a three-dimensional concept).
The area of a shape can be measured by comparing the shape to squares of a fixed size. In the International System of Units (SI), the standard unit of area is the square metre (written as m2), which is the area of a square whose sides are one metre long. A shape with an area of three square metres would have the same area as three such squares. In mathematics, the unit square is defined to have area one, and the area of any other shape or surface is a dimensionless real number.
There are several well-known formulas for the areas of simple shapes such as triangles, rectangles, and circles. Using these formulas, the area of any polygon can be found by dividing the polygon into triangles. For shapes with curved boundary, calculus is usually required to compute the area. Indeed, the problem of determining the area of plane figures was a major motivation for the historical development of calculus.
For a solid shape such as a sphere, cone, or cylinder, the area of its boundary surface is called the surface area. Formulas for the surface areas of simple shapes were computed by the ancient Greeks, but computing the surface area of a more complicated shape usually requires multivariable calculus.
Area plays an important role in modern mathematics. In addition to its obvious importance in geometry and calculus, area is related to the definition of determinants in linear algebra, and is a basic property of surfaces in differential geometry. In analysis, the area of a subset of the plane is defined using Lebesgue measure, though not every subset is measurable. In general, area in higher mathematics is seen as a special case of volume for two-dimensional regions.
Area can be defined through the use of axioms, defining it as a function of a collection of certain plane figures to the set of real numbers. It can be proved that such a function exists.
Formal definition.
An approach to defining what is meant by "area" is through axioms. "Area" can be defined as a function from a collection M of a special kinds of plane figures (termed measurable sets) to the set of real numbers, which satisfies the following properties:
It can be proved that such an area function actually exists.
Units.
Every unit of length has a corresponding unit of area, namely the area of a square with the given side length. Thus areas can be measured in square metres (m2), square centimetres (cm2), square millimetres (mm2), square kilometres (km2), square feet (ft2), square yards (yd2), square miles (mi2), and so forth. Algebraically, these units can be thought of as the squares of the corresponding length units.
The SI unit of area is the square metre, which is considered an SI derived unit.
Conversions.
Calculation of the area of a square whose length and width are 1 metre would be:
1 metre × 1 metre = 1 m2
and so, a rectangle with different sides (say length of 3 metres and width of 2 metres) would have an area in square units that can be calculated as:
3 metres × 2 metres = 6 m2. This is equivalent to 6 million square millimetres. Other useful conversions are:
Non-metric units.
In non-metric units, the conversion between two square units is the square of the conversion between the corresponding length units.
the relationship between square feet and square inches is
where 144 = 122 = 12 × 12. Similarly:
In addition, conversion factors include:
Other units including historical.
There are several other common units for area. The are was the original unit of area in the metric system, with:
Though the are has fallen out of use, the hectare is still commonly used to measure land:
Other uncommon metric units of area include the tetrad, the hectad, and the myriad.
The acre is also commonly used to measure land areas, where
An acre is approximately 40% of a hectare.
On the atomic scale, area is measured in units of barns, such that:
The barn is commonly used in describing the cross-sectional area of interaction in nuclear physics.
In India,
History.
Circle area.
In the 5th century BCE, Hippocrates of Chios was the first to show that the area of a disk (the region enclosed by a circle) is proportional to the square of its diameter, as part of his quadrature of the lune of Hippocrates, but did not identify the constant of proportionality. Eudoxus of Cnidus, also in the 5th century BCE, also found that the area of a disk is proportional to its radius squared.
Subsequently, Book I of Euclid's "Elements" dealt with equality of areas between two-dimensional figures. The mathematician Archimedes used the tools of Euclidean geometry to show that the area inside a circle is equal to that of a right triangle whose base has the length of the circle's circumference and whose height equals the circle's radius, in his book "Measurement of a Circle". (The circumference is 2"r", and the area of a triangle is half the base times the height, yielding the area "r"2 for the disk.) Archimedes approximated the value of π (and hence the area of a unit-radius circle) with his doubling method, in which he inscribed a regular triangle in a circle and noted its area, then doubled the number of sides to give a regular hexagon, then repeatedly doubled the number of sides as the polygon's area got closer and closer to that of the circle (and did the same with circumscribed polygons).
Swiss scientist Johann Heinrich Lambert in 1761 proved that π, the ratio of a circle's area to its squared radius, is irrational, meaning it is not equal to the quotient of any two whole numbers. In 1794 French mathematician Adrien-Marie Legendre proved that π2 is irrational; this also proves that π is irrational. In 1882, German mathematician Ferdinand von Lindemann proved that π is transcendental (not the solution of any polynomial equation with rational coefficients), confirming a conjecture made by both Legendre and Euler.
Triangle area.
Heron (or Hero) of Alexandria found what is known as Heron's formula for the area of a triangle in terms of its sides, and a proof can be found in his book, "Metrica", written around 60 CE. It has been suggested that Archimedes knew the formula over two centuries earlier, and since "Metrica" is a collection of the mathematical knowledge available in the ancient world, it is possible that the formula predates the reference given in that work.
In 499 Aryabhata, a great mathematician-astronomer from the classical age of Indian mathematics and Indian astronomy, expressed the area of a triangle as one-half the base times the height in the "Aryabhatiya" (section 2.6).
A formula equivalent to Heron's was discovered by the Chinese independently of the Greeks. It was published in 1247 in "Shushu Jiuzhang" ("Mathematical Treatise in Nine Sections"), written by Qin Jiushao.
Quadrilateral area.
In the 7th century CE, Brahmagupta developed a formula, now known as Brahmagupta's formula, for the area of a cyclic quadrilateral (a quadrilateral inscribed in a circle) in terms of its sides. In 1842 the German mathematicians Carl Anton Bretschneider and Karl Georg Christian von Staudt independently found a formula, known as Bretschneider's formula, for the area of any quadrilateral.
General polygon area.
The development of Cartesian coordinates by René Descartes in the 17th century allowed the development of the surveyor's formula for the area of any polygon with known vertex locations by Gauss in the 19th century.
Areas determined using calculus.
The development of integral calculus in the late 17th century provided tools that could subsequently be used for computing more complicated areas, such as the area of an ellipse and the surface areas of various curved three-dimensional objects.
Area formulas.
Polygon formulas.
For a non-self-intersecting (simple) polygon, the Cartesian coordinates formula_1 ("i"=0, 1, ..., "n"-1) of whose "n" vertices are known, the area is given by the surveyor's formula:
where when "i"="n"-1, then "i"+1 is expressed as modulus "n" and so refers to 0.
Rectangles.
The most basic area formula is the formula for the area of a rectangle. Given a rectangle with length and width , the formula for the area is:
That is, the area of the rectangle is the length multiplied by the width. As a special case, as in the case of a square, the area of a square with side length is given by the formula:
The formula for the area of a rectangle follows directly from the basic properties of area, and is sometimes taken as a definition or axiom. On the other hand, if geometry is developed before arithmetic, this formula can be used to define multiplication of real numbers.
Dissection, parallelograms, and triangles.
Most other simple formulas for area follow from the method of dissection.
This involves cutting a shape into pieces, whose areas must sum to the area of the original shape.
For an example, any parallelogram can be subdivided into a trapezoid and a right triangle, as shown in figure to the left. If the triangle is moved to the other side of the trapezoid, then the resulting figure is a rectangle. It follows that the area of the parallelogram is the same as the area of the rectangle:
However, the same parallelogram can also be cut along a diagonal into two congruent triangles, as shown in the figure to the right. It follows that the area of each triangle is half the area of the parallelogram:
Similar arguments can be used to find area formulas for the trapezoid as well as more complicated polygons.
Area of curved shapes.
Circles.
The formula for the area of a circle (more properly called the area enclosed by a circle or the area of a disk) is based on a similar method. Given a circle of radius , it is possible to partition the circle into sectors, as shown in the figure to the right. Each sector is approximately triangular in shape, and the sectors can be rearranged to form an approximate parallelogram. The height of this parallelogram is , and the width is half the circumference of the circle, or . Thus, the total area of the circle is :
Though the dissection used in this formula is only approximate, the error becomes smaller and smaller as the circle is partitioned into more and more sectors. The limit of the areas of the approximate parallelograms is exactly , which is the area of the circle.
This argument is actually a simple application of the ideas of calculus. In ancient times, the method of exhaustion was used in a similar way to find the area of the circle, and this method is now recognized as a precursor to integral calculus. Using modern methods, the area of a circle can be computed using a definite integral:
Ellipses.
The formula for the area enclosed by an ellipse is related to the formula of a circle; for an ellipse with semi-major and semi-minor axes and the formula is:
Surface area.
Most basic formulas for surface area can be obtained by cutting surfaces and flattening them out. For example, if the side surface of a cylinder (or any prism) is cut lengthwise, the surface can be flattened out into a rectangle. Similarly, if a cut is made along the side of a cone, the side surface can be flattened out into a sector of a circle, and the resulting area computed.
The formula for the surface area of a sphere is more difficult to derive: because a sphere has nonzero Gaussian curvature, it cannot be flattened out. The formula for the surface area of a sphere was first obtained by Archimedes in his work "On the Sphere and Cylinder". The formula is:
where is the radius of the sphere. As with the formula for the area of a circle, any derivation of this formula inherently uses methods similar to calculus.
General formulas.
Bounded area between two quadratic functions.
To find the bounded area between two quadratic functions, we subtract one from the other to write the difference as
where "f"("x") is the quadratic upper bound and "g"("x") is the quadratic lower bound. Define the discriminant of "f"("x")-"g"("x") as
By simplifying the integral formula between the graphs of two functions (as given in the section above) and using Vieta's formula, we can obtain
The above remains valid if one of the bounding functions is linear instead of quadratic.
General formula for surface area.
The general formula for the surface area of the graph of a continuously differentiable function formula_36 where formula_37 and formula_38 is a region in the xy-plane with the smooth boundary:
An even more general formula for the area of the graph of a parametric surface in the vector form formula_40 where formula_41 is a continuously differentiable vector function of formula_42 is:
List of formulas.
The above calculations show how to find the areas of many common shapes.
The areas of irregular (and thus arbitrary) polygons can be calculated using the "Surveyor's formula" (shoelace formula).
Relation of area to perimeter.
The isoperimetric inequality states that, for a closed curve of length "L" (so the region it encloses has perimeter "L") and for area "A" of the region that it encloses,
and equality holds if and only if the curve is a circle. Thus a circle has the largest area of any closed figure with a given perimeter.
At the other extreme, a figure with given perimeter "L" could have an arbitrarily small area, as illustrated by a rhombus that is "tipped over" arbitrarily far so that two of its angles are arbitrarily close to 0° and the other two are arbitrarily close to 180°.
For a circle, the ratio of the area to the circumference (the term for the perimeter of a circle) equals half the radius "r". This can be seen from the area formula "πr"2 and the circumference formula 2"πr".
The area of a regular polygon is half its perimeter times the apothem (where the apothem is the distance from the center to the nearest point on any side).
Fractals.
Doubling the edge lengths of a polygon multiplies its area by four, which is two (the ratio of the new to the old side length) raised to the power of two (the dimension of the space the polygon resides in). But if the one-dimensional lengths of a fractal drawn in two dimensions are all doubled, the spatial content of the fractal scales by a power of two that is not necessarily an integer. This power is called the fractal dimension of the fractal.
Area bisectors.
There are an infinitude of lines that bisect the area of a triangle. Three of them are the medians of the triangle (which connect the sides' midpoints with the opposite vertices), and these are concurrent at the triangle's centroid; indeed, they are the only area bisectors that go through the centroid. Any line through a triangle that splits both the triangle's area and its perimeter in half goes through the triangle's incenter (the center of its incircle). There are either one, two, or three of these for any given triangle.
Any line through the midpoint of a parallelogram bisects the area.
All area bisectors of a circle or other ellipse go through the center, and any chords through the center bisect the area. In the case of a circle they are the diameters of the circle.
Optimization.
Given a wire contour, the surface of least area spanning ("filling") it is a minimal surface. Familiar examples include soap bubbles.
The question of the filling area of the Riemannian circle remains open.
The circle has the largest area of any two-dimensional object having the same perimeter.
A cyclic polygon (one inscribed in a circle) has the largest area of any polygon with a given number of sides of the same lengths.
A version of the isoperimetric inequality for triangles states that the triangle of greatest area among all those with a given perimeter is equilateral.
The triangle of largest area of all those inscribed in a given circle is equilateral; and the triangle of smallest area of all those circumscribed around a given circle is equilateral.
The ratio of the area of the incircle to the area of an equilateral triangle, formula_45, is larger than that of any non-equilateral triangle.
The ratio of the area to the square of the perimeter of an equilateral triangle, formula_46 is larger than that for any other triangle.


Mark Birkinshaw

Mark Birkinshaw is a British physicist, who currently holds the William P. Coldrick chair in Cosmology and Astrophysics at the University of Bristol. He was the first to detect the Sunyaev–Zel'dovich effect.


Savas Dimopoulos

Savas Dimopoulos (; ; born 1952) is a particle physicist at Stanford University. He worked at CERN from 1994 to 1997. Dimopoulos is well known for his work on constructing theories beyond the Standard Model.
Life.
He was born an ethnic Greek in Istanbul, Turkey and later moved to Athens due to ethnic tensions in Turkey during the 1950s and 1960s.
Education and career.
Dimopoulos studied as an undergraduate at the University of Houston. He went to the University of Chicago and studied under Yoichiro Nambu for his doctoral studies. After completing his Ph.D. in 1979, he briefly went to Columbia University before taking a faculty position at Stanford University in 1980. During 1981 and 1982 he was also affiliated with the University of Michigan, Harvard University and the University of California, Santa Barbara. From 1994 to 1997 he was on leave from Stanford University and was employed by CERN.
Dimopoulos is well known for his work on constructing theories beyond the Standard Model, which are currently being searched for and tested at particle colliders like LHC at CERN and at experiments all over the world. For example, in 1981 he proposed a softly broken SU(5) GUT model with Howard Georgi, which is one of the foundational papers of the Minimal Supersymmetric Standard Model (MSSM). He also proposed the ADD model of large extra dimensions with Nima Arkani-Hamed and Gia Dvali.
Awards.
In 2006, the American Physical Society awarded Dimopoulos the Sakurai Prize, "For his creative ideas on dynamical symmetry breaking, supersymmetry, and extra spatial dimensions, which have shaped theoretical research on TeV-scale physics, thereby inspiring a wide range of experiments." In 2006, he received the Caterina Tomassoni and Felice Pietro Chisesi Prize at the University of Rome, Italy. "The prize recognizes and encourages outstanding achievements in physics. Dimopoulos was lauded by the Tomassoni Committee as "one of the leading figures in theoretical particle physics. His proposal of the supersymmetric standard model has aided the understanding of high-energy physics mechanisms."
He appeared in the 2013 documentary film "Particle Fever", about the work of the Large Hadron Collider.


John R. Cunningham

John Robert Cunningham, , (January 5, 1927 – January 4, 2020) was a Canadian medical physicist noted for his contributions in the development of computerized radiation treatment planning dose calculations in radiation therapy.
Early life and education.
Cunningham, known as Jack, received his B.Eng. in Engineering Physics (1950) and M.Sc. in Radiation Physics (1951) from the University of Saskatchewan in Saskatoon. In 1955 he completed his Ph.D. from the University of Toronto in Physics. After working for the Canada's Defense Research Board, he became a staff Medical Physicist at Toronto's Ontario Cancer Institute / Princess Margaret Cancer Centre in 1958.
Career.
During his medical physics career, Cunningham published over 70 peer-reviewed papers, book chapters, and conference proceedings, and is widely known for co-authoring "The Physics of Radiology" (1953) with Dr. Harold E. Johns. The final fourth edition (1983) remains a staple in medical physics education for medical physicists, technologists, and physicians. He is a pioneer in developing computational techniques for calculating absorbed dose from radiation beams, and computer software and algorithms he developed continue to be used in both commercial and open source treatment planning systems. Upon retirement from clinical medical physics in 1989, Cunningham became a consultant with Theratronics/MDS Nordion (Kanata, Ontario) until 1998 when he moved to Camrose Alberta.
Teaching.
He was an Adjunct Professor at the University of Alberta in Edmonton and regularly lectured at the Cross Cancer Institute in the Department of Medical Physics until 2018. He and his wife Sheila lived in Calgary, Alberta, until his death on January 4, 2020, one day before his 93rd birthday.
Awards and recognition.
In 1988 he was awarded the highest award given by the American Association of Physicists in Medicine, the William D. Coolidge Award for his contributions to the field. In 2005, Cunningham was inducted as an Officer of the Order of Canada. In 2006, he received the Canadian Organization of Medical Physicists Gold Medal Award for "outstanding contribution[s] to the field of medical physics in Canada".


Infralateral arc

An infralateral arc (or lower lateral tangent arc) is a rare halo, an optical phenomenon appearing similar to a rainbow under a white parhelic circle. Together with the supralateral arc they are always located outside the seldom observable 46° halo, but in contrast to supralateral arcs, infralateral arcs are always located below the parhelic circle.
The shape of an infralateral arc varies with the elevation of the Sun. Between sunrise and before the observed Sun reaches about 50° over Earth's horizon, two infralateral arcs are located on either side (e.g. ) of the 46° halo, their convex apexes lying tangent to the 46° halo. As the observed Sun reaches above 68° the two arcs unite to a single concave arc tangent to the 46° halo vertically under the Sun.
Infralateral arcs form when sunlight enters horizontally oriented, rod-shaped hexagonal ice crystals through a hexagonal base and exits through one of the prism sides. Infralateral arcs occur about once a year. They are often observed together with circumscribed halos and upper tangent arcs.


Max Planck Institute for the Physics of Complex Systems

The Max Planck Institute for the Physics of Complex systems is one of the 80 institutes of the Max-Planck-Gesellschaft, located in Dresden, Germany.
Research.
The research at the institute in the field of the physics of complex systems ranges from classical to quantum physics and focuses on three main areas (see Departments). Additionally, independent research groups strengthen and interpolate the research in and between the divisions on a broad range of topics (see Research groups).
Collaborations.
The Institute hosts a Phd program (International Max Planck Research School - IMPRS) for Many Particle Systems in Structured Environments (previously: IMPRS for Dynamical Processes in Atoms, Molecules and Solids). The degree is usually awarded by the Technische Universität Dresden. Apart from this, the institute closely collaborates with numerous institutes at home and overseas including, for example the Leibniz Institute for Solid State and Materials Research (IFW), the Max Planck Institute for Chemical Physics of Solids (MPI-CPfS) and the Max Planck Institute of Molecular Cell Biology and Genetics. MPI PKS forms together with TU Dresden and the other non-university research institutions in Dresden the research alliance Dresden-concept.


Harold L. Brode

Harold L. Brode is a nuclear weapons effects physicist who pioneered computer simulations of nuclear explosions at the RAND Corporation in the 1950s. In 1951 he received his PhD from Cornell University where his supervisor was Hans A. Bethe. He is co-founder of R&D Associates, Vice-President of Strategic Systems at Pacific-Sierra Research Corporation and Chairman of the U.S. Defense Nuclear Agency's Scientific Advisory Group for Effects (SAGE) .
One of his critics commented in "Physics Today", vol. 58: "Harold Brode probably knows more about nuclear weapons effects than any other person alive."


Allan Rosencwaig

Allan Rosencwaig (born Poland, c.1942) is an American physicist.
He worked at Bell Laboratories on photoacoustics, the study of the sound echoes created by light waves, for 7 years before leaving to join the Lawrence Livermore Laboratory in California.
In 1982 he founded the company of Therma-Wave Inc, and was awarded the status of Fellow of the American Physical Society in 1983, after being nominated by their Division of Condensed Matter Physics, for "pioneering work in the development of photoacoustics for solid-state spectroscopy and in the development of thermal-wave physics".


George Dawson Preston

George Dawson Preston FRSE (1896–1972) was a 20th century British physicist specialising in crystallography and the structure of alloys. He was one of the first to use x-rays and electron diffraction to study the crystal structure of metals and alloys. Along with André Guinier, Preston gives his name to the Guinier-Preston zone, discovered in 1938.
Life.
He was born in the village of Rathgar slightly south of Dublin on 8 August 1896 the eldest son of Prof Thomas Preston FRS, and his wife, Katherine Mary McEwen. His father died when George was only four years old. George was educated at Oundle School in Northamptonshire.
In the First World War he served in the Princess of Wales' Own Regiment and was wounded in the leg.
He studied Science at Cambridge University graduating MA then gaining a postgraduate doctorate (DSc) in 1921. He found immediate employment in the Metallurgy Division of the National Physical Laboratory. He stayed there until 1943 when he replaced William Peddie as Professor of Physics at University College, Dundee.
He was elected a Fellow of the Royal Society of Edinburgh in 1944. His proposers were Edward Thomas Copson, Charles Alfred Coulson, Robert Campbell Garry and Alexander David Peacock.
He died in Meigle, Perthshire on 22 June 1972.
Family.
In 1923 he married Margaret Chrystal.
They were parents of George Dawson Chrystal Preston (b.1931).


Sarah E. Gibson

Sarah E. Gibson is an American solar physicist. She leads the Solar Frontiers Section of the High Altitude Observatory in Boulder, Colorado. She is noted for extensive work developing the theory of coronal mass ejections (CMEs) and their precursors, and for organizing scientific collaborations that advance global understanding of the Sun and heliosphere. She is a recipient of the Solar Physics Division's Karen Harvey Prize for early achievement in solar physics, is a current member of the National Academy's Space Studies Board and co-chair of its Committee on Solar and Space Physics, and is President of the IAU's Division E (Sun and Heliosphere). As of 2019, Dr. Gibson is the project scientist for the PUNCH Small Explorer mission being built for NASA.
Education.
Gibson received her Bachelor of Science degree in Physics from the University of Stanford in 1989, then a Master of Science degree in Astrophysics from the University of Colorado in 1993. Shortly after, she completed her PhD, also at the University of Colorado.
Research and career.
Gibson's research interests include solar physics and space weather phenomena.


Ann-Cecilie Larsen

Ann-Cecilie Larsen (born 14 February 1980) is a Norwegian nuclear physicist and nuclear astrophysicist, whose research interests include reaction rates in the astrophysical creation of heavy elements. She is an associate professor of nuclear and energy physics at the University of Oslo.
Education and career.
Larsen is originally from Fredrikstad, on the southern coast of Norway near the Swedish border. She was inspired by high school physics teacher Erik Svendsen to continue her study of physics at the University of Oslo, where she earned a master's degree in 2002, a candidate of science in 2004, and a Ph.D. in 2008.
She stayed in Oslo as a postdoctoral researcher and, eventually, faculty member, and has also visited Michigan State University, the University of California, Berkeley, and the Lawrence Berkeley National Laboratory as a Fulbright Scholar.
Recognition.
Larsen was given the Young Excellent Researcher prize of the Research Council of Norway in 2016, and was elected to the Norwegian Academy of Science and Letters in 2017.


Raymond Stora

Raymond Félix Stora (18 September 1930 – 20 July 2015) was a French theoretical physicist. He was a research director at the French National Centre for Scientific Research (CNRS), as well as a member of CERN's theory group. His work focused on particle physics.
Stora studied at the École Polytechnique from 1951 to 1953, and then at Massachusetts Institute of Technology (MIT), where he received a doctorate in 1958 under the supervision of Victor Weisskopf. Stora's most influential contribution to physics was his work with Carlo Becchi and Alain Rouet on a rigorous mathematical procedure for quantizing non-abelian gauge field theories, which dates from the mid 1970s and is now known as BRST quantization.
Stora was elected as a correspondent to the physics section of the French Academy of Sciences in 1994. In 2009, he was awarded the Dannie Heineman Prize for Mathematical Physics.


Nikolai Borisovich Delone

Nikolai Delaunay, Jr. (aka Delone, Nikolai Borisovich) (22 May 1926 – 11 September 2008) was a born in Leningrad, USSR (now Saint Petersburg, Russia).
Life.
Delone was born in Leningrad on 22 May 1922. He was the son of Boris Delone, a mathematician. He graduated from the Moscow Engineering Physics Institute in 1951, and obtained his Ph.D at the Lebedev Physical Institute in the late 1950s.
Delone is recognized for the first observations of multiphoton ionization, in 1965. Delone, along with Maxim Ammosov and Vladimir P. Krainov, developed the ADK formula, relating tunneling ionization in laser fields. He was also a lecturer at the Moscow Institute of Physics and Technology. After the dissolution of the Soviet Union, he travelled abroad and worked on international collaborations on multiphoton physics.
His son was Vadim Delaunay, a poet and dissident, who participated in the 1968 Red Square demonstration of protest against military suppression of the Prague Spring.
Publications.
Delone published over 200 scientific papers, a four-book series on the physics of strong laser fields and on multiphoton physics, and a series of high-school level Russian textbooks.


Fiber-optic adapter

A fiber-optic adapter connects two optical fiber connectors in the fiber optic lines.
Bare fiber adapter.
Bare fiber adapter is used as the medium to temporarily link the bare optical fiber to fiber optic equipment. Available with FC, SC, ST. LC, MU, SMA connectors with round or square type press button.
Couplers.
A fiber optic coupler is a device used in optical fiber systems with one or more input fibers and one or several output fibers. Light entering an input fiber can appear at one or more outputs and its power distribution potentially depending on the wavelength and polarization. Such couplers can be fabricated in different ways, for example by thermally fusing fibers so that their cores get into intimate contact. If all involved fibers are single-mode (supporting only a single mode per polarization direction for a given wavelength), there are certain physical restrictions on the performance of the coupler. In particular, it is not possible to combine two or more inputs of the same optical frequency into one single-polarization output without significant excess losses. However, such a restriction does not occur for different input wavelengths: there are couplers that can combine two inputs at different wavelengths into one output without exhibiting significant losses. Wavelength-sensitive couplers are used as multiplexers in wavelength-division multiplexing (WDM) telecom systems to combine several input channels with different wavelengths, or to separate channels.


Beta-decay stable isobars

Beta-decay stable isobars are the set of nuclides which cannot undergo beta decay, that is, the transformation of a neutron to a proton or a proton to a neutron within the nucleus. A subset of these nuclides are also stable with regards to double beta decay or theoretically higher simultaneous beta decay, as they have the lowest energy of all nuclides with the same mass number.
This set of nuclides is also known as the line of beta stability, a term already in common use in 1965. This line lies along the bottom of the nuclear valley of stability.
Introduction.
The line of beta stability can be defined mathematically by finding the nuclide with the greatest binding energy for a given mass number, by a model such as the classical semi-empirical mass formula developed by C. F. Weizsäcker. These nuclides are local maxima in terms of binding energy for a given mass number.
All odd mass numbers have only one beta decay stable nuclide.
Among even mass number, seven (96, 124, 130, 136, 148, 150, 154) have three beta-stable nuclides. None have more than three, all others have either one or two.
All primordial nuclides are beta decay stable, with the exception of 40K, 50V, 87Rb, 113Cd, 115In, 138La, 176Lu, and 187Re. In addition, 123Te and 180mTa have not been observed to decay, but are believed to undergo beta decay with an extremely long half-life (over 1015 years). All elements up to and including nobelium, except technetium and promethium, are known to have at least one beta-stable isotope.
List of known beta-decay stable isobars.
350 beta-decay stable nuclides are currently known. Theoretically predicted or experimentally observed double beta-decay is shown by arrows, i.e. arrows point towards the lightest-mass isobar. (This is sometimes dominated by alpha decay or spontaneous fission, especially for the heavy elements.)
No beta-decay stable nuclide has proton number 43 or 61 and no beta-decay stable nuclide has neutron number 19, 21, 35, 39, 45, 61, 71, 89, 115, 123, or 147.
All beta-decay stable nuclides with A ≥ 209 were observed to decay by alpha decay except some where spontaneous fission dominates. With the exception of 262No, no nuclides with A ≥ 260 have been definitively identified as beta-stable, although 260Fm and 262No are unconfirmed.
The general patterns of beta-stability are expected to continue into the region of superheavy elements, though the exact location of the center of the valley of stability is model dependent. It is widely believed that an island of stability exists along the beta stability line for isotopes of elements around copernicium that are stabilized by shell closures in the region; such isotopes would decay primarily through alpha decay or spontaneous fission. Beyond the island of stability, various models that correctly predict the known beta-stable isotopes predict anomalies in the beta-stability line that are unobserved in any known nuclides, such as the existence of two beta-stable nuclides with the same odd mass number. This is a consequence of the fact that a semi-empirical mass formula must consider shell correction and nuclear deformation, which become far more pronounced for heavy nuclides.
Beta decay toward minimum mass.
Beta decay generally causes isotopes to decay toward the isobar with the lowest mass (which is often, but not always, the one with highest binding energy) with the same mass number, those not in italics in the table above. Thus, those with lower atomic number and higher neutron number than the minimum-mass isobar undergo beta-minus decay, while those with higher atomic number and lower neutron number undergo beta-plus decay or electron capture. However, there are four nuclides that are exceptions, in that the majority of their decays are in the opposite direction:


Albert Stolow

Albert Stolow (born 1959) is a Canadian physicist. He is the Canada Research Chair in Molecular Photonics, Full Professor of Chemistry & Biomolecular Sciences and of Physics, and a Member of the Ottawa Institute for Systems Biology at the University of Ottawa. He is the founder and an ongoing member of the Molecular Photonics Group at the National Research Council of Canada. He is Adjunct Professor of Chemistry and of Physics at Queen's University in Kingston, and a Graduate Faculty Scholar in the Department of Physics, University of Central Florida and a Fellow of the Max-Planck-uOttawa Centre for Extreme and Quantum Photonics. In 2008, he was elected a Fellow in the American Physical Society, nominated by its Division of Chemical Physics in 2008, for "contributions to ultrafast laser science as applied to molecular physics, including time-resolved studies of non-adiabatic dynamics in excited molecules, non-perturbative quantum control of molecular dynamics, and dynamics of polyatomic molecules in strong laser fields". In 2008, Stolow won the Keith Laidler Award of the Canadian Society for Chemistry, for "a distinguished contribution to the field of physical chemistry, recognizing early career achievement". In 2009, he was elected a Fellow of the Optical Society of America for "the application of ultrafast optical techniques to molecular dynamics and control, in particular, studies of molecules in strong laser fields and the development of new methods of optical quantum control". In 2013, he was awarded the Queen Elizabeth II Diamond Jubilee Medal (Canada). In 2017, Stolow was awarded the Earle K. Plyler Prize for Molecular Spectroscopy and Dynamics of the American Physical Society for "the development of methods for probing and controlling ultrafast dynamics in polyatomic molecules, including time-resolved photoelectron spectroscopy and imaging, strong field molecular ionization, and dynamic Stark quantum control". In 2018, Stolow was awarded the John C. Polanyi Award of the Canadian Society for Chemistry “for excellence by a scientist carrying out research in Canada in physical, theoretical or computational chemistry or chemical physics”. In 2020, he became Chair of the Division of Chemical Physics of the American Physical Society. His group's research interests include ultrafast molecular dynamics and quantum control, time-resolved photoelectron spectroscopy and imaging, strong field & attosecond physics of polyatomic molecules, and coherent non-linear optical microscopy of live cells/tissues, materials and geological samples. In 2020, Stolow launched a major new high power (500 W) ultrafast laser facility at the University of Ottawa producing high energy, phase-controlled few-cycle pulses of 2 micron wavelength at 10 kHz repetition rate. These are used for High Harmonic Generation to produce bright ultrafast Soft X-ray pulses (up to 600 eV) for a new Ultrafast Xray Science Laboratory.
He is the son of Nathan Stolow (1926–2014), an art and document conservator. Stolow studied Chemistry and Physics at Queen's University and then obtained his Ph.D. degree in Chemical Physics from the University of Toronto in 1988, studying under Nobel Laureate John C. Polanyi. Stolow was an NSERC post-doctoral fellow at the University of California, Berkeley from 1989 to 1992 where he worked with Nobel Laureate Yuan T. Lee. In fall 1992, Stolow joined the National Research Council in Ottawa where he established laboratories and research programs for the study of ultrafast molecular dynamics and quantum control. In 2014, he assumed the Canada Research Chair in Molecular Photonics at the University of Ottawa."


William Harold Joseph Childs

Prof William Harold Joseph Childs FRSE (19 January 1905 – 26 April 1983) was a British physicist and academic author.
Life.
He was born in Bromley-by-Bow in London on 19 January 1905, the son of William and Elizabeth Jane Childs. He was educated at East Ham Grammar School and then attended the University of London graduating BSc in 1924. He continued as a postgraduate, being awarded a PhD in 1928.
He then received a position on the Davy-Faraday Research Laboratory (forming part of the Royal Institution where he worked 1931 to 1940.
During the Second World War he served on the Armaments Research Department, and stayed in this role until demobbed in 1947.
In 1947 he received a Professorship from Heriot-Watt University in Edinburgh and lectured in Physics there until retiral in 1969. He was elected a Fellow of the Royal Society of Edinburgh in 1949, his proposers including Norman Feather and C T R Wilson.
He died on 26 April 1983.
Family.
In 1934 he married Helen Simpson Gilchrist (d. 1984).


L. Douglas Bell

L. Douglas Bell (born 1958) is an American physicist, focusing in nanoscale electronic and structural characterization of materials and devices using scanning probe methods, tunnel-effect and hot-electron devices for detection and sensing, and novel memory concepts using nanoscale structures. He currently works at the Jet Propulsion Laboratory. Bell is an elected Fellow of the American Physical Society.


Willi A. Kalender

Willi A. Kalender (born 1 August 1949) is a German Medical Physicist and Professor and Chairman of the Institute of Medical Physics of the University of Erlangen-Nuremberg. Kalender has produced several new technologies in the field of diagnostic radiology imaging.
Kalender is a Fellow of the American Association of Physicists in Medicine (AAPM) and Honorary Fellow of the British Institute of Radiology (BIR) and of the Institute of Physics and Engineering in Medicine (IPEM).
Education.
Kalender started his studies in physics and mathematics at the University of Bonn, Germany. He completed his Master's and Ph.D. degree in Medical Physics at the University of Wisconsin in 1974 and 1979, respectively. In 1988 he completed all postdoctoral lecturing qualifications (Habilitation) at the University of Tübingen, Germany. In order to get a better grasp of the subject, he took and successfully completed all courses in the pre-clinical medicine curriculum.
Career.
From 1979 to 1995 Kalender worked in the research laboratories of Siemens Medical Systems in Erlangen, Germany; he was appointed head of the Medical Physics group in 1988. In 1995 he was appointed full Professor and Chairman of the newly established Institute of Medical Physics at the Friedrich-Alexander-University Erlangen-Nuremberg, Germany. In 1999 he became Distinguished Visiting Professor to the Department of Radiology at Stanford University, Stanford, CA, USA.
Research and Development Achievements.
Kalender has conducted research mainly in the area of diagnostic radiology imaging with a clear focus on special CT applications. The goals of and motivation for his projects were mostly derived from observations during patient exams in clinical radiology.
Kalender was involved in the development of the world's first product options for dual-energy CT [1] in 1983 and for metal artifact reduction (MAR) [2] in 1987.
Kalender developed volumetric spiral computed tomography; the world's first clinical spiral CT studies were presented at RSNA 1989 [3] . The combination of continuous data acquisition with slip-ring-based data transmission and continuous table translation led to considerable reduction of examination times, to an essential reduction of motion artifacts and image quality significantly improved by providing isotropic spatial resolution as a decisive feature.
Kalender developed angio-CT [4] and heart phase-specific cardiac imaging [6]
Other highly important fields of W. Kalender's research have been radiation protection and the development of intelligent and very efficient dose reduction approaches such as tube current modulation [7] and the optimization of the choice of x-ray spectra [8]. They allow reducing the patient dose by an order of magnitude in many cases without impairing image quality.
Presently, Kalender's research focusses on the development of an efficient breast-CT system to improve the early detection of breast cancer [10]. The scanner and in particular the development of its high-resolution photon-counting detector design allow scanning the breast with a dose similar to that of digital mammography, but with much higher resolution and clarity than mammography due to superposition-free fully 3D-resolution of breast-CT [11]. The introduction into clinical practice was expected for 2018.
Kalender has founded several university spinoff companies to transfer scientific results into products and small business.
Publications.
Kalender so far has authored 963 publications, including 286 original scientific papers;
his Hirsch-index is cited with a 69 (ISI-Web of Knowledge, 2018)
Selected papers.
Twelve out of 286 original scientific papers:
[1] Kalender WA, Klotz E, Süß C. An integral approach to vertebral bone mineral analysis by X-ray computed tomography. Radiology 1987; 164:419-423
[2] Kalender WA, Hebel R. Fast routine for the reduction of artifacts caused by metallic implants in CT images. Radiology 1986; 161(P):345
[3] Kalender WA, Seissler W, Klotz E, Vock P. Spiral volumetric CT with single-breath-hold technique, continuous transport, and continuous scanner rotation. Radiology 1990; 176:181-183
[4] Kalender WA. Thin-section three-dimensional spiral CT: Is isotropic imaging possible?
Radiology 1995; 197: 578-580
[5] Bautz W, Strotzer M, Lenz M, Dittler HJ, Kalender WA. Preoperative evaluation of the vessels of the upper abdomen with spiral CT: Comparison with conventional CT and arterial DXA. Radiology 1991; 181(P):261
[6] Kachelrieß M, Kalender WA: ECG-correlated image reconstruction from sub second
multi-slice spiral CT scans of the heart. Med. Phys. 2000; 27 (8): 1881-1902
[7] Kalender WA, Wolf H, Suess C, Gies M, Greess H, Bautz WA: Dose reduction in CT
by online tube current control: principles and validation on phantoms and cadavers.
Eur. Radiol. 1999; 9: 323-328
[8] Kalender WA, Deak P, van Straten M, Vollmar SV. Application- and patient size-dependent optimization of x-ray spectra for CT. Med. Phys. 2009; 36:993-1007
[9] Kalender WA. Dose in x-ray computed tomography. Phys Med Biol 2014; 59 R129-R150
[10] Kalender WA, Beister M, Boone JM, Kolditz D, Vollmar SV, Weigel MCC . High-resolution spiral CT of the breast at very low dose: concept and feasibility considerations Eur Radiol 2012; 22: 1-8
[11] Kalender WA, Kolditz D, Steiding C, Ruth V, Lück F, Rößler AC, Wenkel E. Technical feasibility proof for high-resolution low-dose CT of the breast. Eur Radiol 2017; 27:1081-1087
[12] The 4th edition of the textbook “Computed Tomography” by WA Kalender, published
by Publicis Publishing Erlangen is expected for late 2018.


Nilsson model

The Nilsson model is a nuclear shell model treating the atomic nucleus as a deformed sphere. In 1953, the first experimental examples were found of rotational bands in nuclei, with their energy levels following the same J(J+1) pattern of energies as in rotating molecules. Quantum mechanically, it is impossible to have a collective rotation of a sphere, so this implied that the shape of these nuclei was nonspherical. In principle, these rotational states could have been described as coherent superpositions of particle-hole excitations in the basis consisting of single-particle states of the spherical potential. But in reality, the description of these states in this manner is intractable, due to the large number of valence particles—and this intractability was even greater in the 1950s, when computing power was extremely rudimentary. For these reasons, Aage Bohr, Ben Mottelson, and Sven Gösta Nilsson constructed models in which the potential was deformed into an ellipsoidal shape. The first successful model of this type is the one now known as the Nilsson model. It is essentially a nuclear shell model using a harmonic oscillator potential, but with anisotropy added, so that the oscillator frequencies along the three Cartesian axes are not all the same. Typically the shape is a prolate ellipsoid, with the axis of symmetry taken to be z.
Hamiltonian.
For an axially symmetric shape with the axis of symmetry being the z axis, the Hamiltonian is
formula_1
Here m is the mass of the nucleon, N is the total number of harmonic oscillator quanta in the spherical basis, formula_2 is the orbital angular momentum operator, formula_3 is its square (with eigenvalues formula_4), formula_5 is the average value of formula_3 over the N shell, and s is the intrinsic spin.
The anisotropy of the potential is such that the length of an equipotential along the "z" is greater than the length on the transverse axes in the ratio formula_7. This is conventionally expressed in terms of a deformation parameter δ so that the harmonic oscillator part of the potential can be written as the sum of a spherically symmetric harmonic oscillator and a term proportional to δ. Positive values of δ indicate prolate deformations, like an American football. Most nuclei in their ground states have equilibrium shapes such that δ ranges from 0 to 0.2, while superdeformed states have formula_8 (a 2-to-1 axis ratio).
The mathematical details of the deformation parameters are as follows. Considering the success of the nuclear liquid drop model, in which the nucleus is taken to be an incompressible fluid, the harmonic oscillator frequencies are constrained so that formula_9 remains constant with deformation, preserving the volume of equipotential surfaces. Reproducing the observed density of nuclear matter requires formula_10, where "A" is the mass number. The relation between δ and the anisotropy is formula_11, while the relation between δ and the axis ratio formula_12 is formula_13.
The remaining two terms in the Hamiltonian do not relate to deformation and are present in the spherical shell model as well. The spin-orbit term represents the spin-orbit dependence of the strong nuclear force; it is much larger than, and has the opposite sign compared to, the special-relativistic spin-orbit splitting. The purpose of the formula_3 term is to mock up the flat profile of the nuclear potential as a function of radius. For nuclear wavefunctions (unlike atomic wavefunctions) states with high angular momentum have their probability density concentrated at greater radii. The term formula_15 prevents this from shifting a major shell up or down as a whole. The two adjustable constants are conventionally parametrized as formula_16 and formula_17. Typical values of κ and μ for heavy nuclei are 0.06 and 0.5. With this parametrization, formula_18 occurs as a simple scaling factor throughout all the calculations.
Choice of basis and quantum numbers.
For ease of computation using the computational resources of the 1950s, Nilsson used a basis consisting of eigenstates of the spherical hamiltonian. The Nilsson quantum numbers are formula_19. The difference between the spherical and deformed Hamiltonian is proportional to formula_20, and this has matrix elements that are easy to calculate in this basis. They couple the different N shells. Eigenstates of the deformed Hamiltonian have good parity (corresponding to even or odd N) and Ω, the projection of the total angular momentum along the symmetry axis. In the absence of a cranking term (see below), time-reversal symmetry causes states with opposite signs of Ω to be degenerate, so that in the calculations only positive values of Ω need to be considered.
Interpretation.
In an odd, well-deformed nucleus, the single-particle levels are filled up to the Fermi level, and the odd particle's Ω and parity give the spin and parity of the ground state.
Cranking.
Because the potential is not spherically symmetric, the single-particle states are not states of good angular momentum J. However, a Lagrange multiplier formula_21, known as a "cranking" term, can be added to the Hamiltonian. Usually the angular frequency vector ω is taken to be perpendicular to the symmetry axis, although tilted-axis cranking can also be considered. Filling the single-particle states up to the Fermi level then produces states whose expected angular momentum along the cranking axis formula_22 has the desired value set by the Lagrange multiplier.
Total energy.
Often one wants to calculate a total energy as a function of deformation. Minima of this function are predicted equilibrium shapes. Adding the single-particle energies does not work for this purpose, partly because kinetic and potential terms are out of proportion by a factor of two, and partly because small errors in the energies accumulate in the sum. For this reason, such sums are usually renormalized using a procedure introduced by Strutinsky.
Plots of energy levels.
Single-particle levels can be shown in a "spaghetti plot," as functions of the deformation. A large gap between energy levels at zero deformation indicates a particle number at which there is a shell closure: the traditional "magic numbers." Any such gap, at a zero or nonzero deformation, indicates that when the Fermi level is at that height, the nucleus will be stable relative to the liquid drop model.


Robert R. Shannon

Robert R. Shannon is Professor Emeritus of Optical Sciences at the University of Arizona College of Optical Sciences.
He was president of the Optical Society of America in 1985.
Professor Shannon received his BS and MA from the University of Rochester in 1954 and 1957 respectively.
His research is on the use of computers for testing and optical design, the metrication of large optical systems, the design of synthetic-aperture optical systems, the analysis and design of unobscured-aperture optical systems, optical fabrication and test methods and optical data storage technology.


NuMI

Neutrinos at the Main Injector, or NuMI, is a project at Fermilab which creates an intense beam of neutrinos aimed towards the Far Detector facility near Ash River, Minnesota for use by several particle detectors. , the MINOS, MINERνA and NOνA experiments use the NuMI beam.
Neutrino production.
The first step in the production of the NuMI beam is to direct a beam of protons from Fermilab's Main Injector onto a carbon target. Interactions of the proton beam in the target produce mesons, primarily pions and kaons, which are focused toward the beam axis by two magnetic horns. The mesons then decay into muons and neutrinos during their flight through a long decay tunnel. A hadron absorber downstream of the decay tunnel removes the remaining protons and mesons from the beam. The muons are absorbed by the subsequent earth shield, while the neutrinos continue through it to the MINERνA, MINOS, and NOvA near detectors on-site at Fermilab. The neutrinos then travel through the Earth to the MINOS far detector cavern in the Soudan Mine 735 km away and the NOvA far detector 810 km away at Ash River, MN, then onwards into space.
Naming.
Because of the close relationship between NuMI and the MINOS experiment, MINOS is sometimes conflated with NuMI. For instance, the MINOS webpage is at www-numi.fnal.gov instead of www-minos.fnal.gov.


Vladimir Kadyshevsky

Vladimir Kadyshevsky (5 May 1937 – 24 September 2014) was Russian theoretical physicist.
Biography.
Kadyshevsky was born on 5 May 1937 in Moscow. He studied at the Suvorov Military School in Sverdlovsk from 1946 to 1954, before entering the physics department of the Lomonosov Moscow State University (MSU).
He graduated in 1960 and continued his studies as a postgraduate under Nikolay Bogolyubov. He successfully defended his PhD thesis in 1962, before starting work at the Laboratory of Theoretical Physics of JINR.
In 1977-78 he headed the group of Soviet physicists working at Fermilab.
In 1983-85 he was leader of JINR’s programme for the DELPHI experiment at CERN’s LEP collider.
He was director of the JINR Laboratory of Theoretical Physics from 1987 to 1992, and director of JINR from
1992 to 2005.


Timeline of particle physics

The timeline of particle physics lists the sequence of particle physics theories and discoveries in chronological order. The most modern developments follow the scientific development of the discipline of particle physics.


Iain Stewart (physicist)

Iain William Stewart is a Canadian-American theoretical nuclear and particle physicist, and a Professor at the Massachusetts Institute of Technology, where he is the current Director of the MIT Center for Theoretical Physics (CTP). He is best known for his work on effective field theories and for developing the Soft Collinear Effective Theory (SCET).
Biography.
Stewart attended college at the University of Manitoba, where he received his B.Sc. with Joint Honors in Physics and Mathematics and M.Sc. in Theoretical Physics in 1994 and 1995, respectively, and won the Governor General’s Silver Medal for highest standing in his graduating class. He wrote his master’s thesis under the supervision of Peter Blunden.
Stewart then moved to the California Institute of Technology for four years, earning his Ph.D. in Theoretical Physics in 1999 under the supervision of Mark Wise. He then held a postdoctoral position at the University of California, San Diego until 2002 and a research assistant professorship at the University of Washington, Seattle for a year, before moving to the MIT Department of Physics in 2003, where he earned tenure in 2009. He became director of the MIT Center for Theoretical Physics in 2019.
Research and teaching.
Stewart “designs and applies effective field theories to describe physics at collider experiments and to explore the structure of quantum field theory.” Effective field theory is a technique used to circumvent the difficulty of carrying out calculations and approximations related to elementary particle physics, when the calculations involves working with quantities of vastly different magnitudes. Stewart is perhaps best known for developing the Soft Collinear Effective Theory (SCET) in the early 2000’s, which helps physicists analyze interactions between energetic quarks and gluons that are soft (low energy) or collinear (traveling in a similar direction).
He has also made major contributions to other areas of theoretical nuclear and particle physics, including the use of Euclidean distributions in lattice QCD, the use of SCET in collider physics and B physics, non-relativistic QED and QCD, and indirect detection methods for dark matter.
In addition to his research, Stewart engages in teaching and mentoring activities. He has supervised dozens of undergraduates, graduate students, and postdoctoral fellows, many of whom have gone on to faculty positions at universities and national labs. He developed a free online course on Effective Field Theory through the platform EdX, as well as a new MIT course, Classical Mechanics III. In 2015 MIT awarded him the Buechner Faculty Teaching Award.


Daniel Amit

Daniel J. Amit (Łódź, Poland, May 5, 1938 – Jerusalem, November 4, 2007) was an Israeli physicist and pacifist, who was one of the pioneers in the field of computational neuroscience. Amit, Hanoch Gutfreund and Haim Sompolinsky, in a set of papers referred to as the ASG papers, were the first to demonstrate the utility of statistical mechanics in neural network research and helped establish theoretical and computational neuroscience as a novel approach that brings into brain research unique powerful sets of concepts, models, and standards of rigour.
Early life.
Daniel Amit was born on May 5, 1938 in Łódź, Poland, to a wealthy Jewish family. In March 1940, several months after the German occupation of Poland, his parents managed to slip out of the country, and traveling through Italy, Turkey, Greece and Lebanon, reached Tel Aviv in July of the same year. Daniel grew up in a middle class neighbourhood of central Tel Aviv, met his wife to be, Dahlia, in high school and married her two years later at the age of 18. In 1961, he received a BA is Physics at the Hebrew University of Jerusalem, then completed his MA in Physics at the Weizmann institute, after which he served for two years in the newly established computer unit of the Israeli Army.
Scientific career.
Amit started his scientific activity in particle physics, obtaining a PhD from Brandeis University in 1963, under Eugene P. Gross. He was then active, in the 1970s, in statistical mechanics. In the 1980s he moved on to a more interdisciplinary research including neurosciences. He was a visiting scholar at the Institute for Advanced Study in 1982-83. He was professor at The Racah Institute of Physics of the Hebrew University in Jerusalem and professor of neural networks in the Department of Physics of the Sapienza University of Rome and was among the founders of the modern theory of neural networks.
Activism.
Amit's involvement with progressive causes started with the protest movement against the Vietnam War that intensified in the mid 1960's on campuses across the United States. It was during this period that he was first exposed to the Palestinian issue and other aspects of leftwing politics and ideas. He was widely known for his engagement for peace, especially between Israel and the Palestinians.
Later life.
Amit was naturalized as an Italian citizen in 1999. The last decade of his life saw him bitterly disappointed at the failure of the left to construct a real alternative to globalisation and the dominance of the USA. The disappointment weighed on him heavily and he took his life in his Jerusalem home on November 4, 2007.


Hayden-Preskill thought experiment

In quantum information, the Hayden-Preskill thought experiment (also known as the Hayden-Preskill protocol) is a thought experiment that investigates the black hole information paradox by hypothesizing on how long it takes to decode information thrown in a black hole from its Hawking radiation.
The thought experiment concerning Alice and Bob is as follows: Alice throws a "k" qubit quantum state into a black hole that is entangled with Bob's quantum computer. Bob collects the Hawking radiation emitted by the Black hole and feeds it into his quantum computer where he applies the appropriate quantum gates that will decode Alice's state. Bob only needs at least "k" qubits from the black hole's Hawking radiation to decode Alice's quantum state.
The black hole can be thought of as a quantum information mirror, because it returns scrambled information almost instantly. With a delay that can be account for by the scrambling time and the time it takes for the black hole to radiate the qubits. This decoding method, known as the Yoshida-Kitaev decoding scheme, can theoretically be applied to a small system thermalized with a large system. This opens up the possibility of testing the Hayden-Preskill thought experiment in real life.
Models.
Outlined below are models used to explore the Hayden Preskill thought experiment.
Toy Model for Heavy and Soft modes.
Non-symmetric modes with low energy are called soft, while modes with high energy are called heavy. Using energy conservation and a toy model, it becomes clear that hawking radiation corresponds to heavy modes classically. Only soft modes correspond to the Hayden-preskill protocol. The toy-model relies on a clear distinction between heavy and soft modes based on thermodynamics properties, energy, and charge.
Dicke Models.
In order to physically represent the Hayden-Preskill Protocol Dicke models can be used. Using a system of two Dicke models, it was found that when data is thrown into a black hole the initial spin information can be read after it has been scrambled into the cavity. In a single system, information scrambling prevents the ability to decode the information; however, if a thermofield double state is used, the scrambling of information allows for the initial state information to be read. Therefore, efficiency for decoding is at its maximum when scrambling is fastest, and when the system is most chaotic.
Decoding Fidelity.
If decoding fidelity is a constant, the black hole will act similarly to a mirror and reflect back any information that falls into it almost immediately. However, if experiments could be conducted the Hayden-Preskill protocol would result in some information loss. Recall that in decoding information from the black hole we need the early radiation that will be called B' and the late radiation that will be called D, to reconstruct the original state A. There is an error that emerges from storing early radiation B'. Qubits may be randomly lost while being stored. Additionally, the early radiation and the black hole are initially maximally entangled, but decoherence emerges over time. Ultimately, the information loss due to erasure in storage is much more impactful than the decoherence, because information loss from decoherence can be partially recovered with an understanding of entanglement.
Black Hole Complementarity and Firewalls.
The Hayden-Preskill thought experiment implies that information that falls into a black hole can be recovered via the hawking radiation, which raises the question: does the information that falls into a black hole fall in or radiate out? One approach to this is the concept of black hole complementarity, which claims that an observer orbiting a black hole observes the information radiating out as hawking radiation, while an observer that falls into the black hole observes the information falling inward. This does not seem to violate the no cloning principle of quantum mechanics since you can only measure one or the other; if you fall into a black hole and measure a qubit, you can't leave and then measure the hawking radiation. Black hole complementarity has four basic postulates:
According to Almheiri, Marolf, Polchinski, and Sully postulates 1, 2, and 4 feature a contradiction. Say we divide the hawking radiation leaving the black hole into two time frames: one "early," and one "late." Because the hawking radiation is a pure state based on the quantum wave function of the original mass, the late hawking radiation must be entangled with the early hawking radiation. However, black hole complementarity also implies that the outgoing hawking radiation is entangled with the information inside the black hole. This violates what is known as "monogamy of entanglement," the idea that a quantum system can only be entangled with one other quantum system. To fix this problem, either postulate 2 or postulate 4 must be false: if postulate 2 is false, then there must be some exotic dynamics extending beyond the event horizon that resolve this conflict; if postulate 4 is false, then the entanglement of the inner and outer information must be broken, leading to the creation of high-energy modes. These high-energy modes create a "firewall" that burns up anything that enters the black hole.