Nikita Nekrasov

Nikita Alexandrovich Nekrasov (; born 10 April 1973) is a mathematical and theoretical physicist at the Simons Center for Geometry and Physics and C.N.Yang Institute for Theoretical Physics at Stony Brook University in New York, and a Professor of the Russian Academy of Sciences.
Career.
Nekrasov studied at the Moscow State 57th School in 1986–1989. He graduated with honors from the Moscow Institute of Physics and Technology in 1995, and joined the theory division of the Institute for Theoretical and Experimental Physics. In parallel, in 1994–1996 Nekrasov did his graduate work at Princeton University, under the supervision of David Gross. His Ph.D. thesis on "Four Dimensional Holomorphic Theories" was defended in 1996.
He joined Harvard Society of Fellows at Harvard University as a Junior Fellow 1996–1999.
He was then a Robert. H. Dicke Fellow at Princeton University from 1999 to 2000. In 2000 he moved to France as a permanent professor at the Institut des Hautes Études Scientifiques. Since 2013, he is a full professor at the Simons Center for Geometry and Physics and C. N. Yang Institute for Theoretical Physics at Stony Brook University in New York.
Research.
Nekrasov is mostly known for his work on supersymmetric gauge theory, quantum integrability, and string theory. The Nekrasov partition function, which he introduced in his 2002 paper, relates in an intricate way the instantons in gauge theory, integrable systems, and representation theory of infinite-dimensional algebras.
Honours and awards.
For his discovery of noncommutative instantons together with Albert Schwarz in 1998, noncommutative monopoles and monopole strings with David Gross in 2000 and for his work with Alexander S. Gorsky on the relations between gauge theories and many-body systems he was awarded the of the French Academy of Sciences in 2004. For his contributions to topological string theory and the ADHM construction he received the Hermann Weyl Prize in 2004. In 2008 together with Davesh Maulik, Andrei Okounkov and Rahul Pandharipande he formulated a set of conjectures relating Gromov–Witten theory and Donaldson–Thomas theory, for which the four authors were awarded the Compositio Prize in 2009.


Stanislav Mikheyev

Stanislav Pavlovich Mikheyev (; 1940 – 23 April 2011) was a Russian physicist known for the discovery of the MSW effect.
Education and research.
Stanislav Mikheyev graduated from Faculty of Physics of Moscow State University in 1965. Then he became a researcher at Lebedev Physical Institute. Since 1970 he was a researcher at the Institute for Nuclear Research of the USSR Academy of Sciences (Russian Academy of Sciences since 1991), where he earned his Ph.D. in physics in 1983.
He worked on Baksan Underground Scintillator Telescope for a long time. He has been the leader of two experiments carried out on Baksan Telescope: observation of upward-going muons and searches for superheavy magnetic monopoles.
In 1985 Stanislav Mikheyev and Alexei Smirnov considered the propagation of oscillating neutrinos in matter with varying density and suggested an explanation for the solar neutrino problem (the MSW effect). From 1991 to 1998 Mikheyev worked on the MACRO detector. His activities were also related to the Baksan Neutrino Observatory, the Baikal Neutrino Telescope and the T2K experiment.
Awards.
Mikheyev was awarded the Bruno Pontecorvo Prize (2006, jointly with Smirnov and Wolfenstein) and the Sakurai Prize (2008, jointly with Smirnov).


Stephen Hopkins (musician)

Stephen Hopkins (born 14 May 1951) is a British former musician who worked (as Steve Hopkins) with different Manchester punk and new wave artists including John Cooper Clarke, Pauline Murray, Morrissey and Ed Garrity amongst others. After retiring as a musician, he pursued a career in experimental cold atom physics.
Biography.
Between 1970 and 1990, Hopkins worked as a musician. He was primarily a session keyboard player and pianist. However, during his career he also worked as a composer, programmer, lounge lizard, record producer, teacher and recording engineer. His role began to be shown with his collaboration with John Cooper Clarke, playing keyboards and co-producing his discs alongside producer Martin Hannett. Both formed The Invisible Girls in Salford to be the Cooper Clarke's backing band in the rest of the years. However, the band also helped to relaunch the careers of former Penetration singer Pauline Murray, with whom they released one album and two singles between 1980 and 1981, and of Nico, of Velvet Underground fame.
Hopkins also collaborated with Jilted John, Ed Garrity (former Ed Banger and the Nosebleeds frontman), and later with Morrissey and Distant Cousins.
Following his music career, in 1991, he began a PhD in experimental atomic physics at the Open University. This was followed by postdoctoral positions at Oxford and Sussex, as well as a teaching fellow post at the Manchester Photon Science Institute. In 2010 he joined the Atomic and Molecular Physics group at Durham University where he worked as a postdoctoral researcher until 2016.
His father is Billy Hopkins, author of seven bestsellers, including "Our Kid" and "Kate's Story". His sister is the author Cathy Hopkins, best known for her teenage books "Mates, Dates series".


Fast fission

Fast fission is fission that occurs when a heavy atom absorbs a high-energy neutron, called a fast neutron, and splits. Most fissionable materials need thermal neutrons, which move more slowly.
Fast reactors vs. thermal reactors.
Fast neutron reactors use fast fission to produce energy, unlike most nuclear reactors. In a conventional reactor, a moderator is needed to slow down the neutrons so that they are more likely to fission atoms. A fast neutron reactor uses fast neutrons, so it does not use a moderator. Moderators may absorb a lot of neutrons in a thermal reactor, and fast fission produces a higher average number of neutrons per fission, so fast reactors have better neutron economy making a plutonium breeder reactor possible. However, a fast neutron reactor must use relatively highly enriched uranium or plutonium so that the neutrons have a better chance of fissioning atoms.
Fissionable but not fissile.
Some atoms, notably uranium-238, do not usually undergo fission when struck by slow neutrons, but do split when struck with neutrons of high enough energy. The fast neutrons produced in a hydrogen bomb by fusion of deuterium and tritium have even higher energy than the fast neutrons produced in a nuclear reactor. This makes it possible to increase the yield of any given fusion weapon by the simple expedient of adding layers of cheap natural (or even depleted) uranium. Fast fission of uranium-238 provides a large part of the explosive yield, and fallout, in many designs of hydrogen bomb.
Differences in fission product yield.
A graph of fission product yield against the mass number of the fission fragments has two pronounced but fairly flat peaks, at around 90 to 100, and 130 to 140. With thermal neutrons, yields of fission products with mass between the peaks, such as 113mCd, 119mSn, 121mSn, 123Sn, 125Sb, 126Sn, and 127Sb are very low.
The higher the energy of the state that undergoes nuclear fission, the more likely a symmetric fission is, hence as the neutron energy increases and/or the energy of the fissioning atom increases, the valley between the two peaks becomes more shallow; for instance, the curve of yield against mass for 239Pu has a more shallow valley than that observed for 235U, when the neutrons are thermal neutrons. The curves for the fission of the later actinides tend to make even more shallow valleys. In extreme cases such as 259Fm, only one peak is seen.


Avi Loeb

Abraham "Avi" Loeb (; born February 26, 1962) is an Israeli-American theoretical physicist who works on astrophysics and cosmology. Loeb is the Frank B. Baird Jr. Professor of Science at Harvard University. He had been the longest serving Chair of Harvard's Department of Astronomy (2011–2020), Founding Director of Harvard's Black Hole Initiative (since 2016) and Director of the Institute for Theory and Computation (since 2007) within the Harvard-Smithsonian Center for Astrophysics.
Loeb is a fellow of the American Academy of Arts and Sciences, the American Physical Society, and the International Academy of Astronautics. In July 2018, he was appointed as chair of the Board on Physics and Astronomy (BPA) of the National Academies, which is the Academies' forum for issues connected with the fields of physics and astronomy, including oversight of their decadal surveys.
In June 2020, Loeb was sworn in as a member of the President's Council of Advisors on Science and Technology (PCAST) at the White House. In December 2012, "TIME" magazine selected Loeb as one of the 25 most influential people in space. In 2015, Loeb was appointed as the Science Theory Director for the Breakthrough Initiatives of the Breakthrough Prize Foundation. In 2018, he attracted media attention for suggesting that alien space craft may be in our solar system, using the anomalous behavior of 'Oumuamua as an example. In 2019, and together with his Harvard undergraduate student, Amir Siraj, Loeb reported discovering a meteor that potentially originated outside the Solar System.
Career.
Loeb was born in Beit Hanan, Israel in 1962. He took part in the national Talpiot program before receiving a PhD in plasma physics, at age 24, from the Hebrew University in Jerusalem, in 1986. From 1983 to 1988, he led the first international project supported by the U.S. Strategic Defense Initiative. Between 1988 and 1993, Loeb was a long-term member at the Institute for Advanced Study in Princeton, where he started to work in theoretical astrophysics. In 1993, he moved to Harvard University as an assistant professor in the department of astronomy, where he was tenured three years later.
Loeb has written eight books and authored or co-authored about 800 papers on a broad range of research areas in astrophysics and cosmology, including the first stars, the epoch of reionization, the formation and evolution of massive black holes, the search for extraterrestrial life, gravitational lensing by planets, gamma-ray bursts (GRBs) at high redshifts, 21-cm cosmology, the use of the Lyman-alpha forest to measure the acceleration/deceleration of the universe in real time (the so-called "Sandage–Loeb test"), the future collision between the Milky Way and Andromeda galaxies, the future state of extragalactic astronomy, astrophysical implications of black hole recoil in galaxy mergers, tidal disruption of stars, and imaging black hole silhouettes. In 2010, he wrote a textbook entitled "How Did the First Stars and Galaxies Form?"
In 1992, Loeb suggested, with Andy Gould, that exoplanets could be detected through gravitational microlensing. In 1993, he proposed the use of the C+ fine-structure line to discover galaxies at high redshifts. In 2005, he predicted, in a series of papers with his postdoc at the time, Avery Broderick, how a hot spot in orbit around a black hole would appear; their predictions were confirmed in 2018 by the GRAVITY instrument on the VLT which observed a circular motion of the centroid of light of the black hole at the center of the Milky Way, Sagittarius A*. In 2009, Broderick and Loeb predicted the shadow of the black hole in the giant elliptical galaxy Messier 87, which was imaged in 2019 by the Event Horizon Telescope. In 2013, a report was published on the discovery of the "Einstein Planet" Kepler-76b, the first Jupiter size exoplanet identified through the detection of relativistic beaming of its parent star, based on a technique proposed by Loeb and Gaudi in 2003. In addition, a pulsar was discovered around the supermassive black hole, Sagittarius A*, following a prediction by Pfahl and Loeb in 2004. Also, a hypervelocity star candidate from the Andromeda galaxy was discovered, as predicted by Sherwin, Loeb, and O'Leary in 2008. Together with his postdoc, James Guillochon, Loeb predicted the existence of a new population of stars moving near the speed of light throughout the universe. Together with his postdoc John Forbes and Howard Chen of Northwestern University, Loeb made another prediction that sub-Neptune sized exoplanets have been transformed into rocky super-Earths by the activity of Milky Way's central supermassive black hole Sagittarius A*.
Together with Paolo Pani, Loeb showed in 2013 that primordial black holes in the range between the masses of the Moon and the Sun cannot make up the dark matter.
Loeb led a team that reported tentative evidence for the birth of a black hole in the young nearby supernova SN 1979C.
In collaboration with Dan Maoz, Loeb demonstrated in 2013 that biomarkers, such as molecular oxygen (), can be detected by the James Webb Space Telescope (JWST) in the atmosphere of Earth-mass planets in the habitable zone of white dwarfs.
Early universe.
In a series of papers with his students and postdocs, Loeb addressed how and when the first stars and black holes formed and what effects they had on the young universe.
Together with his former student Steve Furlanetto, Loeb published a textbook, "The First Galaxies in the Universe".
In 2013, Loeb introduced the new concept of "The Habitable Epoch of the Early Universe", and mentored Harvard undergraduate, Henry Lin, in the study of industrial pollution on exoplanets as a new method to search for extraterrestrial civilizations. In April 2021, Loeb presented an updated summary of his ideas of life in the early universe.
Panspermia.
In 2020, Loeb published a research paper about the possibility that life can propagate from one planet to another, followed by the opinion piece "Noah’s Spaceship" about directed panspermia.
ʻOumuamua.
In December 2017, Loeb cited ʻOumuamua's unusually elongated shape as one of the reasons why the Green Bank Telescope in West Virginia should listen for radio emissions from it to see if there were any unexpected signs that it might be of artificial origin, although earlier limited observations by other radio telescopes such as the SETI Institute's Allen Telescope Array had produced no such results. On 13 December 2017, the Green Bank Telescope observed the asteroid for six hours. No radio signals from ʻOumuamua have been detected.
On 26 October 2018, Loeb and his postdoctoral student Shmuel Bialy submitted a paper exploring the possibility of the interstellar object ʻOumuamua being an artificial thin solar sail accelerated by solar radiation pressure in an effort to help explain the object's non-gravitational acceleration. Other scientists have stated that the available evidence is insufficient to consider such a premise, and that a tumbling solar sail would not be able to accelerate. In response, Loeb wrote an article detailing six anomalous properties of `Oumuamua that make it unusual, unlike any comets or asteroids seen before.
On 27 November 2018, Loeb and Amir Siraj, an undergraduate student at Harvard College, proposed a search for `Oumuamua-like objects which might be trapped in the Solar System as a result of losing orbital energy through a close encounter with Jupiter. They identified four candidates (2011 SP25, 2017 RR2, 2017 SV13, and 2018 TL6) for trapped interstellar objects which could be visited by dedicated missions. The authors pointed out that future sky surveys, such as with LSST, could find many more.
In public interviews and private communications with reporters and academic colleagues, Loeb has become more and more vocal regarding the prospects of proving the existence of alien life.
On April 16, 2019, Loeb and Siraj reported the discovery of the first meteor of interstellar origin.
"", a popular science account concerning 'Oumuamua, written by Loeb, was published in 2021.
Media appearances.
In 2006, Loeb was featured in a "TIME" magazine cover story on the first stars, and in a "Scientific American" article on the Dark Ages of the universe. In 2008, he was featured in a Smithsonian magazine cover story on black holes, and in two "Astronomy Magazine" cover stories, one on the collision between the Milky Way and the Andromeda Galaxy and the second on the future state of our universe. In 2009, Loeb reviewed in a "Scientific American" article a new technique for imaging black hole silhouettes. Loeb received considerable media attention after proposing in 2011 (with E.L. Turner) a new technique for detecting artificially-illuminated objects in the Solar System and beyond, and showing in 2012 (with I. Ginsburg) that planets may transit hypervelocity stars or get kicked to a fraction of the speed of light near the black hole at the center of the Milky Way.
"Science" magazine published an article about Loeb's career in April 2013, and "Discover" reviewed his research on the first stars in April 2014. The "New York Times" published a science profile of Loeb in December 2014. In May 2015, "Astronomy" posted a podcast of an hour-long interview with Loeb in its series entitled "Superstars of Astronomy". In April 2016, Stephen Hawking visited Loeb's home and attended the inaugurations of the Starshot and Black Hole Initiatives that Loeb leads.
Loeb's eBook on Kindle details his career path from childhood on a farm with interests in philosophy to chairing the Harvard Astronomy department and directing the ITC, and includes opinion essays on the importance of taking risks in research and promoting diversity. Loeb writes opinion essays on science and policy.
On January 14, 2021 Loeb appeared on the "Lex Fridman Podcast" (#154), on January 16, 2021 on the "Joe Rogan Experience" podcast (#1596).
Honors and awards.
Loeb has received many honors, including:


Aiichiro Nakano

Aiichiro Nakano from the University of Southern California, was awarded the status of Fellow in the American Physical Society, after they were nominated by their Division of Computational Physics in 2009, for "the development and implementation of scalable parallel and distributed algorithms for large-scale atomistic simulations to predict, visualize, and analyze reaction processes for novel nano-mechano-chemical phenomena encompassing diverse spatiotemporal scales."


IonQ

IonQ is a quantum computing hardware and software company based in College Park, Maryland. They are developing a general-purpose trapped ion quantum computer and software to generate, optimize, and execute quantum circuits.
History.
IonQ was co-founded by Christopher Monroe and Jungsang Kim, professors at The University of Maryland and Duke University, respectively, in 2015, with the help of Harry Weller, a partner at venture firm New Enterprise Associates.
The company is an offshoot of the co-founders’ 25 years of academic research in quantum information science. Monroe's quantum computing research began as a Staff Researcher at the National Institute of Standards and Technology (NIST) with Nobel laureate David Wineland where he led a team using trapped ions to produce the first controllable qubits and the first controllable quantum logic gate, culminating in a proposed architecture for a large-scale trapped ion computer.
Kim and Monroe began collaborating formally as a result of larger research initiatives funded by the Intelligence Advanced Research Projects Activity (IARPA). They wrote a review paper for Science Magazine entitled "Scaling the Ion Trap Quantum Processor", pairing Monroe's research in trapped ions with Kim’s focus on scalable quantum information processing and quantum communication hardware.
This research partnership became the seed for IonQ’s founding. In 2015, New Enterprise Associates invested $2 million to commercialize the technology Monroe and Kim proposed in their "Science" paper.
In 2016, they brought on David Moehring from IARPA—where he was in charge of several quantum computing initiatives—to be the company’s chief executive. In 2017, they raised a $20 million series B, led by GV (formerly Google Ventures) and New Enterprise Associates, the first investment GV has made in quantum computing technology. They began hiring in earnest in 2017, with the intent to bring an offering to market by late 2018.
In May 2019, former Amazon Prime executive Peter Chapman was named new CEO of the company. IonQ then partnered to make its quantum computers available to the public through Amazon Web Services and Microsoft Azure.
In March of 2021, IonQ announced its plans to become publicly listed via a Special-purpose acquisition company.
Technology.
IonQ’s hardware is based on a trapped ion architecture, from technology that Monroe developed at the University of Maryland, and that Kim developed at Duke.
In November 2017, IonQ presented a paper at the IEEE International Conference on Rebooting Computing describing their technology strategy and current progress. It outlines using a microfabricated ion trap and several optical and acousto-optical systems to cool, initialize, and calculate. They also describe a cloud API, custom language bindings, and quantum computing simulators that take advantage of their trapped ion system's complete connectivity
IonQ and some experts claim that trapped ions could provide a number of benefits over other physical qubit types in several measures, such as accuracy, scalability, predictability, and coherence time. Others criticize the slow operational times and relative size of trapped ion hardware, claiming other qubit technologies are just as promising.


Emilio Zavattini

Emilio Zavattini (March 14, 1927 – January 9, 2007) was an Italian particle physicist.
Biography.
He was born in Rimini, Italy and enrolled in the University of Rome La Sapienza as a physics student in 1950 and earned his doctorate in 1954.
Zavattini joined CERN in 1955 and remained a staff member until he retired in 1992. Early in this period he made a short post-doctoral visit to Nevis Laboratory at Columbia University where he worked with Leon Lederman. After retirement, he held a position as a professor at the University of Trieste from 1988–1999.
Zavattini is known for the muon g-2 experiment and the PVLAS experiment at the INFN Laboratory in Legnaro (Padua, Italy). He made contributions within the fields of strong, weak and electromagnetic interactions—especially using muons—both at CERN and at other European and U.S. laboratories. In later years his studies focused on a better understanding of the structure of vacuum.
He was a member of the Accademia dei Lincei.
Zavattini died at the age of 79 of a heart attack.


Stabilizer code

The theory of quantum error correction plays a prominent role in the practical realization and engineering of
quantum computing and quantum communication devices. The first quantum
error-correcting codes are strikingly similar to classical block codes in their
operation and performance. Quantum error-correcting codes restore a noisy,
decohered quantum state to a pure quantum state. A
stabilizer quantum error-correcting code appends ancilla qubits
to qubits that we want to protect. A unitary encoding circuit rotates the
global state into a subspace of a larger Hilbert space. This highly entangled,
encoded state corrects for local noisy errors. A quantum error-correcting code makes quantum computation
and quantum communication practical by providing a way for a sender and
receiver to simulate a noiseless qubit channel given a noisy qubit channel
whose noise conforms to a particular error model.
The stabilizer theory of quantum error correction allows one to import some
classical binary or quaternary codes for use as a quantum code. However, when importing the
classical code, it must satisfy the dual-containing (or self-orthogonality)
constraint. Researchers have found many examples of classical codes satisfying
this constraint, but most classical codes do not. Nevertheless, it is still useful to import classical codes in this way (though, see how the entanglement-assisted stabilizer formalism overcomes this difficulty).
Mathematical background.
The Stabilizer formalism exploits elements of
the Pauli group formula_1 in formulating quantum error-correcting codes. The set
formula_2 consists of the Pauli operators:
The above operators act on a single qubit---a state represented by a vector in a two-dimensional
Hilbert space. Operators in formula_1 have eigenvalues formula_5 and either commute
or anti-commute. The set formula_6 consists of formula_7-fold tensor products of
Pauli operators:
Elements of formula_6 act on a quantum register of formula_7 qubits. We
occasionally omit tensor product symbols in what follows so that
The formula_7-fold Pauli group
formula_6 plays an important role for both the encoding circuit and the
error-correction procedure of a quantum stabilizer code over formula_7 qubits.
Definition.
Let us define an formula_15 stabilizer quantum error-correcting
code to encode formula_16 logical qubits into formula_7 physical qubits. The rate of such a
code is formula_18. Its stabilizer formula_19 is an abelian subgroup of the
formula_7-fold Pauli group formula_6. formula_19
does not contain the operator formula_23. The simultaneous
formula_24-eigenspace of the operators constitutes the "codespace". The
codespace has dimension formula_25 so that we can encode formula_16 qubits into it. The
stabilizer formula_19 has a minimal representation in terms of formula_28
independent generators
The generators are
independent in the sense that none of them is a product of any other two (up
to a global phase). The operators formula_30 function in the same
way as a parity check matrix does for a classical linear block code.
Stabilizer error-correction conditions.
One of the fundamental notions in quantum error correction theory is that it
suffices to correct a discrete error set with support in the Pauli group
formula_6. Suppose that the errors affecting an
encoded quantum state are a subset formula_32 of the Pauli group formula_6:
Because formula_32 and formula_19 are both subsets of formula_6, an error formula_38 that affects an
encoded quantum state either commutes or anticommutes with any particular
element formula_39 in formula_19. The error formula_41 is correctable if it
anticommutes with an element formula_39 in formula_19. An anticommuting error
formula_41 is detectable by measuring each element formula_39 in formula_19 and
computing a syndrome formula_47 identifying formula_41. The syndrome is a binary
vector formula_47 with length formula_28 whose elements identify whether the
error formula_41 commutes or anticommutes with each formula_52. An error
formula_41 that commutes with every element formula_39 in formula_19 is correctable if
and only if it is in formula_19. It corrupts the encoded state if it
commutes with every element of formula_19 but does not lie in formula_58. So we compactly summarize the stabilizer error-correcting conditions: a
stabilizer code can correct any errors formula_59 in formula_32 if
or
where formula_63 is the centralizer of formula_19 (i.e., the subgroup of elements that commute with all members of formula_19, also known as the commutant).
Relation between Pauli group and binary vectors.
A simple but useful mapping exists between elements of formula_1 and the binary
vector space formula_67. This mapping gives a
simplification of quantum error correction theory. It represents quantum codes
with binary vectors and binary operations rather than with Pauli operators and
matrix operations respectively.
We first give the mapping for the one-qubit case. Suppose formula_68
is a set of equivalence classes of an operator formula_69 that have the same phase:
Let formula_71 be the set of phase-free Pauli operators where
formula_72.
Define the map formula_73 as
Suppose formula_75. Let us employ the
shorthand formula_76 and formula_77 where formula_78, formula_79, formula_80, formula_81. For
example, suppose formula_82. Then formula_83. The
map formula_84 induces an isomorphism formula_85 because addition of vectors
in formula_67 is equivalent to multiplication of
Pauli operators up to a global phase:
Let formula_88 denote the symplectic product between two elements formula_89:
The symplectic product formula_88 gives the commutation relations of elements of
formula_1:
The symplectic product and the mapping formula_84 thus give a useful way to phrase
Pauli relations in terms of binary algebra.
The extension of the above definitions and mapping formula_84 to multiple qubits is
straightforward. Let formula_96 denote an
arbitrary element of formula_6. We can similarly define the phase-free
formula_7-qubit Pauli group formula_99 where
The group operation formula_101 for the above equivalence class is as follows:
The equivalence class formula_103 forms a commutative group
under operation formula_101. Consider the formula_105-dimensional vector space
It forms the commutative group formula_107 with
operation formula_108 defined as binary vector addition. We employ the notation
formula_109 to represent any vectors
formula_110 respectively. Each
vector formula_111 and formula_112 has elements formula_113 and formula_114 respectively with
similar representations for formula_115 and formula_116.
The "symplectic product" formula_88 of formula_118 and formula_119 is
or
where formula_122 and formula_123. Let us define a map formula_124 as follows:
Let
so that formula_127 and formula_128 belong to the same
equivalence class:
The map formula_130 is an isomorphism for the same
reason given as in the previous case:
where formula_110. The symplectic product
captures the commutation relations of any operators formula_133 and formula_134:
The above binary representation and symplectic algebra are useful in making
the relation between classical linear error correction and quantum error correction more explicit.
By comparing quantum error correcting codes in this language to symplectic vector spaces, we can see the following. A symplectic subspace corresponds to a direct sum of Pauli algebras (i.e., encoded qubits), while an isotropic subspace corresponds to a set of stabilizers.
Example of a stabilizer code.
An example of a stabilizer code is the five qubit
formula_136 stabilizer code. It encodes formula_137 logical qubit
into formula_138 physical qubits and protects against an arbitrary single-qubit
error. It has code distance formula_139. Its stabilizer consists of formula_140 Pauli operators:
The above operators commute. Therefore, the codespace is the simultaneous
+1-eigenspace of the above operators. Suppose a single-qubit error occurs on
the encoded quantum register. A single-qubit error is in the set formula_142 where formula_143 denotes a Pauli error on qubit formula_144.
It is straightforward to verify that any arbitrary single-qubit error has a
unique syndrome. The receiver corrects any single-qubit error by identifying
the syndrome and applying a corrective operation.


Nabeel Kassis

Nabeel Kassis (), also transliterated as Nabil Kassis, Nabil Qasis, Nabeel Qassis, etc., is a Palestinian academic and politician from Ramallah. He was born 1945.
Academic career.
Kassis studied in Germany and Lebanon, earning a master's degree from the University of Mainz, and a PhD from the American University of Beirut, both in nuclear physics. He taught physics at a number of universities in Germany, Italy, France, England, Lebanon, and Jordan before joining Birzeit University in 1980. He served as President of Birzeit University from 2004 to 2010.
Diplomatic career.
Kassis was a member of the Palestinian delegation to the Madrid Peace Conference in 1991, and a deputy head of the negotiation delegation at the Washington talks in 1992 to 1993. He later became the Director-General of the Technical and Advisory Committee to the Palestinian negotiation team, established to do preparatory work for the transition to Palestinian self-government. He was a member of the Palestinian delegation on final status negotiations in 1999.
Political career.
As a proponent of transparency and reform, Kassis was appointed member of the Special Committee for the Investigation of the Auditor's Report in 1997. He later entered government as a political independent, serving as minister of state in 1998, Tourism Minister in 2002, Planning Minister from 2003 to 2005, and Finance Minister from 2012 to 2013.


Eugene Hecht

Eugene Hecht (born 2 December 1938 in New York City) is an American physicist and author of a standard work in optics.
Hecht studied at New York University (B.S. 1960) and Rutgers University (M. Sc. 1963). During his graduate study he worked at Radio Corporation of America.
Adelphi University hired Hecht to teach and he became professor in 1978.
Hecht challenged the notion of potential energy in 2003. The elusive nature of a universal definition of energy was argued by Hecht in a letter to the editor of The Physics Teacher in 2004. Then in 2006 he wrote "There is no really good definition of mass". He continued with the topic in 2011 and 2016.
Eugene Hecht is also widely published authority on George E. Ohr and American art pottery and a founding member of the American Ceramic Arts Society.
Books.
His first textbook on optics was co-authored with Alfred Zajac, a colleague at Adelphi, in 1974
In 1975 Hecht wrote the text "Theory and Problems of Optics" for Schaum's Outlines. In 1977 he began writing about polarization. For the second edition of "Optics" in 1987 Hecht was the sole author. A third edition was published in 1998, and the fourth in 2001.
Brooks/Cole published "Physics:Calculus" in 1996 in which reviewers "found something intriguing on every page".
Celebrated potter George Ohr was discovered after his workshop was consumed in fire.


Gaspar Schott

Gaspar Schott (German: "Kaspar" (or "Caspar") "Schott"; Latin: "Gaspar Schottus"; 5 February 1608 – 22 May 1666) was a German Jesuit and scientist, specializing in the fields of physics, mathematics and natural philosophy, and known for his industry.
Biography.
He was born at Bad Königshofen im Grabfeld. It is probable, but not certain, that his early education was at the Jesuit College at Würzburg. In any case, at the age of 19 he joined the Society of Jesus, entering the novitiate at Trier on 30 October 1627. After two years of novitiate training, he matriculated at the University of Würzburg on 6 November 1629 to begin a three-year study of Philosophy, following the normal academic path prescribed for Jesuit seminarians. Owing to the Swedish invasion of Würzburg in October 1631, the Jesuit community fled the city. Schott went, first to the Jesuit seminary of Tournai in Belgium, and subsequently, in 1633, to Caltagirone in Sicily, where he continued his study of Theology. After two years at Caltagirone, he was transferred to Palermo for his final year study of Theology after which, in 1637, he was ordained a priest. For the next fifteen years he held a range of teaching and pastoral positions in various Jesuit colleges in Sicily. In 1652, following correspondence with his old mathematics teacher at Würzburg, Fr. Athanasius Kircher, now an internationally acclaimed scholar at the Collegio Romano, Schott was transferred to the Collegio to work as Kircher's assistant. He was to spend the next two and a half years assisting Kircher, but also assembling material of his own for which he would later seek a publisher.
In 1655 Schott returned to Germany, first to Mainz, and later the same year to Würzburg where he was to remain until his death. His return to Germany appears to have been partly motivated by the desire of his Jesuit superiors to mollify the Archbishop Elector of Mainz, Johann von Schönborn, with whom relations had been strained.
Works.
Schott was the author of numerous works from the fields of mathematics, physics, and magic. However, those works were mostly compilations of reports, articles or books he read and his own repeated experiments; he did little, if any, original research.
Schott is most widely known for his works on hydraulic and mechanical instruments. His treatise on "chronometric marvels" is the first work describing a universal joint and providing the classification of gear teeth.
Among his most famous works is the book "Magia universalis naturæ et artis" (4 vols., Würtzburg, 1657–1659), filled with many mathematical problems and physical experiments, mostly from the areas of optics and acoustics. His "Mechanica hydraulica-pneumatica" (Würtzburg, 1657) contains the first description of von Guericke's air pump. He also published "Pantometrum Kircherianum" (Würtzburg, 1660); "Physica curiosa" (Würtzburg, 1662), a supplement to the "Magia universalis"; "Anatomia physico-hydrostatica fontium et fluminum" (Würtzburg, 1663), "Technica Curiosa" (1664), "Organum Mathematicum" (1668) and several editions of a "Cursus mathematicus." He was also the editor of the "Itinerarium extacticum" of Athanasius Kircher and the "Amussis Ferdidindea" of Albert Curtz.


Johannes Fischer

Johannes Fischer (born 1887) was a German physicist.
Education.
Fischer studied under Arnold Sommerfeld at the Ludwig Maximilian University of Munich. His thesis was on the theory of diffraction, and he was awarded his doctorate in 1922.


Elmarit

The name Elmarit is used by Leica to designate camera lenses that have a maximum aperture of f/2.8.
History.
The Elmarit is a derivation of the Elmar. Confusingly not all f/2.8 lenses are Elmarits. The 50 mm f/2.8 collapsible, manufactured until 2007, was designated an Elmar rather than an Elmarit.
Description.
The Elmarit are popular lenses for extreme focal lengths: 21 mm, 24 mm, 28 mm and 90 mm. The Elmarit has also come in 135mm super-telephoto.
Market positions.
The Elmarit are behind the Summicron and the Summarit lenses. Only the Elmar and most Summaron lenses have a smaller f-number.


Hubert Curien Laboratory

The Hubert Curien Laboratory or "Laboratoire Hubert Curien "is a joint research unit (UMR 5516) of the University of Saint-Etienne, the National Research Centre CNRS, and (since 2016) the Institut d'Optique Graduate School. It is composed of about 90 researchers, professors and assistant professors, 20 engineers and administrative staff, and 130 Ph.D. students and postdoctoral researcher. This makes the Hubert Curien Laboratory with a total of about 240 staff the most important research structure of Saint-Etienne.
The various research activities of the laboratory are organized into two scientific departments: "Optics, photonics and microwave" and "Computer science, telecom and image". The research activity is structured into scientific projects within 6 main teams: "Micro/Nano structuring", "Radiation-matter Interaction", "Image Science & computer vision", "Data Intelligence", "Connected Intelligence" and "Secure Embedded Systems & Hardware Architectures."
The Hubert Curien laboratory coordinates the laboratory of excellence MANUTECH-SISE and the equipment of excellence MANUTECH-USD in partnership with some laboratories of the University of Lyon (LTDS, LDF, LaMCoS) and the company HEF. The partners aim at understanding the surface phenomena such as
wear, friction, wetting, etc. They also aim at creating and controlling the surface functionalities, and at developing advanced manufacturing processes of surfaces and interfaces of different level, in particular processes of ultrafast laser texturation.
In the last few years, the laboratory has paying a special attention to interdisciplinary scientific projects including in materials and surface engineering, in image processing, in Computer vision or in artificial intelligence.


ENGIN-X

ENGIN-X is the dedicated materials engineering beamline at the ISIS Neutron and Muon Source in the UK.
The beamline uses neutron diffraction to determine the spacing between layers of atoms in order to measure elastic strain, and thus residual stress deep within crystalline materials. In other words, it uses the atomic lattice planes as an 'atomic strain gauge'. Internal and residual stress in materials have a considerable effect on material properties, including fatigue resistance, fracture toughness and strength.


Mainz Microtron

The Mainz Microtron (German name: "Mainzer Mikrotron"), abbreviated MAMI,
is a microtron (particle accelerator) which provides a continuous wave, high intensity, polarized electron beam with an energy up to 1.6 GeV. MAMI is the core of an experimental facility for particle, nuclear and X-ray radiation physics at the Johannes Gutenberg University in Mainz (Germany). It is one of the largest campus-based accelerator facilities for basic research in Europe. The experiments at MAMI are performed by about 200 physicists of many countries organized in international collaborations.
Research goals.
The scientific research at MAMI focusses on the investigation of the
structure and dynamics of hadrons, particles consisting of quarks and gluons
bound by the strong force.
The most important hadrons
are protons and neutrons, the basic constituents
of atomic nuclei and, therefore, the building blocks of ordinary matter.
Electrons and photons interact with the electric charges
and the magnetization of quarks inside a hadron in a relatively weak and
well understood way providing undistorted information about
basic hadronic properties like (transverse) size, magnetic moments,
distribution of charge and magnetism, flavor structure, polarizabilities and
excitation spectrum.
At MAMI the full potential of electroweak probes is explored in an
energy region characteristic for the first hadronic excitations and with a
spatial resolution in the order of the typical hadron size of about 1 fm.
The MAMI accelerator.
The MAMI accelerator consists of four cascaded
microtrons, an injector linac, a thermal source for unpolarized
electrons and a laser-driven source for electrons with 80% spin polarization.
The operation principle is based on the
continuous wave (cw) microtron technique. There the
beam is recirculated many times
through a normal-conduction linear accelerating structure
with a moderate energy gain per turn. Due to constant, homogenous magnetic bending
fields the length of the beam path is increasing
with energy after each turn. The magnetic fields, the radio-frequency (rf)
used to accelerate the electrons and the energy gain per turn
have to be adjusted to meet the microtron coherence condition, i.e. the
condition that the length of each path is an integer factor of
the rf wavelength.
This microtron scheme makes efficient use of the rf power and
the inherent strong longitudinal phase focussing guarantees
excellent beam quality and stability.
In each of the first 3 stages
the recirculation is archived by two homogeneous 180° bending magnets.
The electron tracks are reminiscent of the race track of an
antique arena which is the origin for the name "race-track-microtron (RTM)".
The third stage, MAMI-B, started operation in 1990 and delivered
a beam for experiments with energies up to 882 MeV and 100 formula_1A cw for more than
97800 h until the end of 2007. The quality of the beam is very high:
an energy spread of 30 keV and an emittance of 25 nm*rad is achieved
routinely. The bending magnets of MAMI-B
are approximately 5 m wide and weigh 450 t. At this
point the mechanical limit of the RTM concept has been reached, leaving
MAMI-B to be the biggest microtron in the world.
At the end of the 1990s, the demand for an energy increase up to about 1500 MeV arose. This was accomplished by adding a fourth accelerator stage. Adding another RTM was not possible because it would have required bending magnets of ~2200 tons each. Therefore, the technique was modified by splitting the 180°-dipoles into a system of symmetric pairs of 90°-dipoles, each forming an achromatic 180°
bending system with magnets of only 250 tons each. To compensate for the strong vertical defocusing due to the 45° pole-face inclination
between the magnets, these dipoles incorporate an appropriate field gradient normal to this pole edge. In this scheme
there are two non-dispersive sections which allow to install two linear accelerators. To meet the microtron coherence condition
within the confined space of existing experimental areas the acceleration frequency of one of these linacs is twice the MAMI-B frequency of 2.45 GHz.
The other linac still operates at 2.45 GHz for enhanced
longitudinal stability.
This special rf scheme gave rise to the name "Harmonic Double-Sided Microtron (HDSM)".
MAMI-C is the worldwide first accelerator
using this concept (Kaiser, K.H. et al., 2000).
The construction work started in 2000.
End of December 2006, within one day,
the first test beam was guided through all 43 recirculations and reached
the design energy of 1508 MeV. After only a few weeks of beam tests,
the first nuclear physics experiment was conducted in February 2007.
About 50% of the MAMI beam time in 2007 (7180 h) was used for 1.5 GeV
operation. All design parameters of the HDSM, including the max. current
of 100 µA (151 kW of beam power), have been verified. End of 2009 an energy
of 1604 MeV was reached.
The mean availability of the beam for experiments (> 80%) is at a very
high level, a clear demonstration that the
HDSM scheme is as reliable and stable as the RTM cascade.
Experimental facilities.
High-resolution electron scattering.
The largest experimental hall of the MAMI accelerator complex houses
three high-resolution, focussing magnetic spectrometers operated by the A1 Collaboration.
The high momentum resolution (formula_2p/p < formula_3) together with the large acceptance in solid angle
(up to 28 msr) and in momentum (up to 25%) makes this setup ideal for
electron scattering in coincidence with hadron detection.
One of the spectrometers can be tilted up to an out-of-plane angle of 10°, allowing for out-of-plane kinematics.
A proton recoil polarimeter gives, in combination with the polarized MAMI beam and
a polarized helium-3 gas target, access to a broad variety of spin observables.
A fourth spectrometer (KAOS/A1, covering high momenta with a moderate path length for the
detection of kaons, is currently in the commissioning phase.
The main physics goals are:
A list of recent publications can be found here.
Photoabsorption experiments.
The A2 Collaboration studies reactions induced by high-energy photons incident
on nucleons or nuclei. A beam of photons with known energy and flux
is produced via bremsstrahlung using a dedicated
tagging spectrometer provided by the University of Glasgow.
A polarized electron beam produces circularly polarized photons. Linearly
polarized photons can be obtained from coherent bremsstrahlung in an oriented crystal radiator.
The central part of the detector system is a hermetic calorimeter consisting
of the Crystal Ball detector (672 NaI crystals) in combination with the TAPS detector (384 BaF2 crystals)
in forward direction. For charged-particle tracking and identification
two layers of coaxial multi-wire proportional chambers and a barrel of 24 scintillation
counters surrounding the target are installed inside the cavity of the Crystal Ball sphere.
A frozen-spin target for polarized protons and deuterons is of particular importance for
studying spin degrees of freedom.
The main physics goals are:
A publication database can be found here.
Single spin asymmetries in elastic electron scattering.
The A4 Collaboration measures small asymmetries in the cross-section of elastic scattering
of polarized electrons off an unpolarized target, basically hydrogen or deuterium.
The momentum transfers achieved either in forward angle- or backward
angle-configuration of the detector vary between 0.1 GeV²/c² and 0.6 GeV²/c².
A high-power liquid hydrogen target of 10 cm or 20 cm length and a polarized electron beam of I = 20 µA lead
to luminosities in the order of formula_6 The scattered electrons are measured by a total
absorbing, segmented lead fluoride calorimeter, which deals with event rates of about 100 MHz.
The degree of polarization of the electron beam is measured by a laser Compton backscatter
polarimeter simultaneously with to the main experiment.
There are two main physics goals:
A list of publications can be found here here.
Brilliant X-ray radiation.
The X1 Collaboration at MAMI develops brilliant novel radiation sources and explores their
potential for applications. The electromagnetic spectrum extends from the far-infrared into the
hard X-ray range. "Brilliant" means that a large number of photons is emitted as a sharp bundle
from a small spot. At MAMI, beam spots with a diameter down to the sub-micron
range are possible. The production mechanisms which have been explored include Smith-Purcell radiation in the
infrared and optical spectral range, undulator radiation in the soft X-ray range as well as
channeling radiation, parametric X-radiation and transition radiation in the hard X-ray range.
A list of publications can be found here.
Further Information and Reading.
Homepage of the Nuclear Physics Institute at the Mainz University.


Claude R. Canizares

Claude R. Canizares is an American physicist who stepped down June 30, 2015 from his post as Vice President of MIT. He remains the Bruno Rossi Professor of Physics at MIT and associate director for MIT of the Chandra X-Ray Observatory Center.
Academic career.
Canizares earned his B.A., M.A. and Ph.D. degrees in Physics from Harvard University. He came to MIT as a postdoctoral fellow in 1971 and joined the physics faculty in 1974. In 1984, he was made a full professor.
From 1990 to 2002, Canizares was the director of MIT's Center for Space Research (now known as the MIT Kavli Institute for Astrophysics and Space Research). In 2002, he was appointed Associate Provost and Vice President for Research. He left the Associate Provostship and VPR positions to become VP in 2013.
Canizares is also the principal investigator for the Chandra X-ray Observatory's High Resolution Transmission Grating Spectrometer instrument.
He was elected a Fellow of the American Physical Society in 1989 for "for pioneering investigations in x-ray astrophysics, particularly in the analysis of astrophysical plasmas by high-resolution x-ray spectroscopy"
Selected publications.
Canizares is the author or co-author of more than 170 scientific papers.
T Fang, GL Bryan, and C.R. Canizares

"ApJ" 564, 604 (2002)
H.L Marshall, C.R. Canizares and N.S. Schulz

"ApJ" 564, 941-952 (2002)
H.L. Marshall, B.P. Miller, D.S. Davis, E.S. Perlman, M. Wise, C.R. Canizares, D.E. Harris, J.A. Biretta

"ApJ" 564, 683-687 (2002)
J.M. Miller, A.C. Fabian, R. Wijnands, R.A. Remillard, P. Wojdowski, N.S. Schulz, T. Di Matteo, H.L. Marshall, C.R. Canizares, D. Pooley, W.H.G. Lewin

"ApJ" submitted, February 2002.
Y.Yao, N.S. Shulz, M.F. Gu, M.A. Nowak and C.R. Canizares
"ApJ" 696, (2) 1418-1430 (2009)
D.P. Huenemoerder, N.S. Schulz, P. Testa, A.Kesich, C.R. Canizares
"ApJ" 707, 942-953 (2009)
T.Fang, D.A. Buote, P.J. Humphrey, C.R. Canizares, L. Zappacosta, R.Maiolino
"ApJ" 714, 1715-1724 (2010)


ADA collider

ADA (short for Anello Di Accumulazione, also stylized as AdA) was one of the first Italian particle accelerator and the first-ever electron–positron particle collider measuring around in diameter which was designed to store beams of 250 MeV.
History.
The AdA collider was built at the LNF (Frascati National Laboratory) in Frascati in the year of 1961 with the help of a group of Italian physicists guided by the Austrian physicist Bruno Touschek (the individual to propose the idea of its development)"." During the time of ADA's proposal, many American physicists were distancing themselves from using accelerators that sent a beam of particles into a fixed target to experiment with colliding two beams of particles instead"." ADA was a great extension of this idea as it replaced one of the beams of particles (electrons) with a beam of antiparticles (positrons), a modification that was new and never before tested by physicists.
After the machines construction, it was operated from 1961 to 1964, by the National Institute of Nuclear Physics, in Frascati, Italy.
However, in 1962, the machine was relocated to the Laboratoire de l’Accelerateur Lineaire in Orsay, France, where it was used for an additional four years alongside the laboratory's powerful particle injector.
Towards the end of 1963, AdA's first electron-positron collisions were recorded. Then, the machine was operated a few more years for further successful and decisive tests before dismantling. AdA was never used to collect physics data. Instead, it was a testing ground for a breed of machines that was to change the course of particle physics in the following decades.
The collider is no longer operational but the legacy of the machine still lives on today. On 5 December 2013, the Italian National Institute of Nuclear Physics (INFN) Frascati National Laboratory (LNF) was given the great honour of becoming an EPS Historic Site for the realization of the Storage Ring AdA, the first official particle-antiparticle collider. Today, the European Physical Society recognized machines grand importance to particle physics, marking it as a historic site in its original home of the Frascati National Laboratory, that is part of Italy's National Institute of Nuclear Physics.
Impact of the ADA collider.
The ADA collider had a large impact on accelerator physics. The machine was the first particle-antiparticle collider and the first electron-positron storage ring. It also proved the possibility of accelerating and colliding a beam of particles and antiparticles in the same machine. The ADA collider opened the possibility for a long line of particle and antiparticle colliders and storage rings long after its lifespan. These include the Frascati National Laboratory's ADONE (big AdA or Higher energy collider) and CERN’s Large Electron-Positron collider. ADA's success was also instrumental to discovering the Touschek effect in the year of 1963 that explains how the length of time a beam lasts is effected by the scattering of particles inside a beam. It also allowed scientists to witness the interaction and annihilation of particles and antiparticles during energetic collisions alongside allowing physicists to understand better several aspects of accelerator physics that would not have been possible if not for the machines existence.


Calorescence

Calorescence is when matter absorbs infrared radiant energy and emits visible radiant energy in its place. For example, some kinds of flammable gas give off large amounts of radiant heat and very little visible light when burning, and if a piece of metal is placed into such a flame, the metal will become bright red-hot—which is to say the metal absorbs invisible infrared and emits visible radiation. The word "calorescence" was coined in 1864 on the model of the word "fluorescence" which had been coined in 1852. At that time, fluorescence was defined as absorption in the ultraviolet part of the spectrum followed by emission in the visible part of the spectrum. Calorescence was defined complementarily as absorption in the infrared followed by emission in the visible.
The following is a laboratory demonstration of calorescence. An ordinary lightbulb emits much infrared light. Carbon disulfide is a colorless liquid transparent to both infrared and visible. Iodine readily dissolves in this liquid and causes the liquid to turn a black color and to become completely opaque to visible light, given enough iodine. At the same time, however, the iodine has essentially no effect on the transparency of the liquid with respect to infrared light. Hence when light from an ordinary lightbulb is passed through a body of this solution, much infrared and only infrared emerges out at the other side. This infrared light can be brought to a focus with a concave mirror (or an optical lens made from rock-salt, but not a lens made from glass because glass is a poor transmitter of infrared). At the point of focus, with a good focusing tool, the infrared beam is strong enough to set paper on fire. If a little piece of non-combustible solid material is placed at the focus, it will glow visibly in the heat; i.e. the material will absorb infrared and emit visible light.
The following is another laboratory illustration of calorescence. In a flame of pure hydrogen burning in oxygen, the hydrogen chemically combines with the oxygen to form water (H2O) plus a lot of heat is produced. This heat is a radiant emission from the newly formed water molecules. That is, the heat is thermal radiation whose particular set of radiant frequencies is uniquely characteristic of water molecules, as determined by emission spectroscopy. Water molecules have very little emission in the visible portion of the spectrum at any temperature (c.f. spectral absorption of water). The temperature of the hydrogen flame is more than 2000 degrees Celsius. If a piece of platinum is placed in the flame, the platinum will become "white hot" and give out a bright light. The platinum thus absorbs radiation having the spectral profile of water, and emits radiation having the spectral profile of platinum. (The platinum also picks up heat from collisions with moving gas molecules).
The term calorescence is rarely seen in use today, whereas the term fluorescence is common. One reason is that there isn't a physical explanation for calorescence that's specific to calorescence. Relatedly, the physical explanations for some types of fluorescence behavior are also explanations for calorescence and the word fluorescence has been preferred and expanded in customary usage to include calorescence. Another reason is that there isn't a widely used practical application attached to the word calorescence, whereas there is for fluorescence. A related item of physics terminology today is the so-called "Anti-Stokes Shift". A Stokes shift refers to molecular absorptions of radiant energy of higher frequencies followed by emissions of lower frequencies; and an anti-Stokes shift refers to absorptions of lower frequencies followed by emissions of higher frequencies. With this terminology, practical applications are attached to the term "anti-Stokes photoluminescence" in materials science including semiconductors (see examples). Equal terminology in use in laser science is "infrared upconversion", "upconversion luminescence", or simply "upconversion" (see examples). This terminology is usually contemplating luminescence, as opposed to incandescence, whereas the word Calorescence belongs to the 19th century when the only known upconversion methods were of the incandescent kind.
References and external links.
The word calorescence was coined by John Tyndall and the two laboratory demonstrations described above appear in Tyndall's 1872 book "Contributions to Molecular Physics in the Domain of Radiant Heat" (format DjVu, 17 megabytes).


Torque wrench

A torque wrench is a tool used to apply a specific torque to a fastener such as a nut, bolt, or lag screw. It is usually in the form of a socket wrench with special internal mechanisms.
A torque wrench is used where the tightness of screws and bolts is crucial. It allows the operator to set the torque applied to the fastener so it can be matched to the specifications for a particular application. This permits proper tension and loading of all parts. A torque wrench uses torque as a proxy for bolt tension. The technique suffers from inaccuracy due to inconsistent or uncalibrated friction between the fastener and its mating hole. Measuring bolt tension (indirectly via bolt stretch) is actually what is desired, but often torque is the only practical measurement which can be made.
Torque screwdrivers and torque wrenches have similar purposes and mechanisms.
History.
The first patent for a torque wrench was filed by John H. Sharp of Chicago in 1931. This wrench was referred to as a "torque measuring wrench" and would be classified today as an indicating torque wrench.
In 1935, Conrad Bahr and George Pfefferle patented an adjustable ratcheting torque wrench. The tool featured audible feedback and restriction of back-ratcheting movement when the desired torque was reached. Bahr, who worked for the New York City Water Department, was frustrated at the inconsistent tightness of flange bolts he found while attending to his work. He claimed to have invented the first torque limiting tool in 1918 to alleviate these problems. Bahr's partner, Pfefferle, was an engineer for S.R. Dresser Manufacturing Co and held several patents.
Types.
Beam.
The most basic form of torque wrench consists of two beams. The first is a lever used to apply the torque to the fastener being tightened and serves also as the handle of the tool. When force is applied to the handle it will deflect predictably and proportionally with said force in accordance with Hooke's law. The second beam is only attached at one end to the wrench head and free on its other, this serves as the indicator beam. Both of these beams run parallel to each other when the tool is at rest, with the indicator beam usually on top. The indicator beam's free end is free to travel over a calibrated scale attached to the lever or handle, marked in units of torque. When the wrench is used to apply torque, the lever bends and the indicating beam stays straight. Thus, the end of the indicating beam points to the magnitude of the torque that is currently being applied. This type of wrench is simple, inherently accurate, and inexpensive.
The beam type torque wrench was developed in between late 1920s and early 1930s by Walter Percy Chrysler for the Chrysler Corporation and a company known as Micromatic Hone. Paul Allen Sturtevant—a sales representative for the Cedar Rapids Engineering Company at that time—was licensed by Chrysler to manufacture his invention. Sturtevant patented the torque wrench in 1938 and became the first individual to sell torque wrenches.
A more sophisticated variation of the beam type torque wrench has a dial gauge indicator on its body that can be configured to give a visual indication, or electrical indication, or both when a preset torque is reached.
Deflecting beam.
The dual-signal deflecting beam torque wrench was patented by the Australian Warren and Brown company in 1948. It employs the principle of applying torque to a deflecting beam rather than a coil spring. This is claimed to help prolong the accuracy of the wrench throughout its working life, with a greater safety margin on maximum loading and provides more consistent and accurate readings throughout the range of each wrench. The operator can both hear the signal click and see a visible indicator when the desired torque is reached.
The wrench functions in the same general way as an ordinary beam torque wrench. There are two beams both connected to the head end but only one through which torque is applied. The load carrying beam is straight and runs from head to handle, it deflects when torque is applied. The other beam (indicating beam) runs directly above the deflecting beam for about half of the length then bends away to the side at an angle from the deflecting beam. The indicating beam retains its orientation and shape during operation. Because of this, there is relative displacement between the two beams. The deflecting beam torque wrench differs from the ordinary beam torque wrench in how it utilizes this relative displacement. Attached to the deflecting beam is a scale and onto that is fitted a wedge which can be slid along the length of the scale parallel to the flexing beam. This wedge is used to set the desired torque. Directly facing this wedge is the side of the angled indicating beam. From this side protrudes a pin, which acts as a trigger for another pin, the latter pin is spring loaded, and fires out of the end of the indicating beam once the trigger pin contacts the adjustable wedge. This firing makes a loud click and gives a visual indication that the desired torque has been met. The indicator pin can be reset by simply pressing it back into the indicating beam.
Slipper.
A slipper type torque wrench consists of a roller and cam (or similar) mechanism. The cam is attached to the driving head, the roller pushes against the cam locking it in place with a specific force which is provided by a spring (which is in many cases adjustable). If a torque which is able to defeat the holding force of the roller and spring is applied, the wrench will slip and no more torque will be applied to the bolt. A slipper torque wrench will not overtighten the fastener by continuing to apply torque beyond a predetermined limit.
Click.
A more sophisticated method of presetting torque is with a calibrated clutch mechanism. One common form uses a ball detent and spring, with the spring preloaded by an adjustable screw thread, calibrated in torque units. The ball detent transmits force until the preset torque is reached, at which point the force exerted by the spring is overcome and the ball "clicks" out of its socket. This design yields greater precision as well as giving tactile and audible feedback. The wrench will not start slipping once the desired torque is reached, it will only click and bend slightly at the head; the operator can continue to apply torque to the wrench without any additional action or warnings from the wrench.
A number of variations of this design exist for different applications and different torque ranges. A modification of this design is used in some drills to prevent gouging the heads of screws while tightening them. The drill will start slipping once the desired torque is reached.
"No-hub" wrench.
These are specialized torque wrenches used by plumbers to tighten the clamping bands on hubless soil pipe couplings. They are usually T-handled wrenches with a one-way combination ratchet and clutch. They are preset to a fixed torque designed to secure the coupling adequately but insufficient to damage it.
Electronic torque wrenches.
With electronic (indicating) torque wrenches, measurement is by means of a strain gauge attached to the torsion rod. The signal generated by the transducer is converted to the required unit of torque (e.g. N·m or lbf·ft) and shown on the digital display. A number of different joints (measurement details or limit values) can be stored. These programmed limit values are then permanently displayed during the tightening process by means of LEDs or the display. At the same time, this generation of torque wrenches can store all the measurements made in an internal readings memory. This readings memory can then be easily transferred to a PC via the interface (RS232) or printed straight to a printer. A popular application of this kind of torque wrench is for in-process documentation or quality assurance purposes. Typical accuracy level would be ±0.5% to 4%.
Programmable electronic torque / angle wrenches.
Torque measurement is conducted in the same way as with an electronic torque wrench but the tightening angle from the snug point or threshold is also measured. The angle is measured by an angle sensor or electronic gyroscope. The angle measurement process enables joints which have already been tightened to be recognized. The inbuilt readings memory enables measurements to be statistically evaluated. Tightening curves can be analyzed using the software via the integrated tightening-curve system (force/path graph). This type of torque wrench can also be used to determine breakaway torque, prevail torque and the final torque of a tightening job. Thanks to a special measuring process, it is also possible to display the yield point (yield controlled tightening). This design of torque wrench is highly popular with automotive manufacturers for documenting tightening processes requiring both torque and angle control because, in these cases, a defined angle has to be applied to the fastener on top of the prescribed torque (e.g. + 90° – here the means the snug point/threshold and +90° indicates that an additional angle has to be applied after the threshold).
In 1995, Saltus-Werk Max Forst GmbH applied for an international patent for the first electronic torque wrench with angle measurement which did not require a reference arm.
Mechatronic torque wrenches.
Torque measurement is achieved in the same way as with a click-type torque wrench but, at the same time, the torque is measured as a digital reading (click and final torque) as with an electronic torque wrench. This is, therefore, a combination of electronic and mechanical measurements. All the measurements are transferred and documented via wireless data transmission. Users will know they have achieved the desired torque setting when the wrench "beeps".
Hydraulic torque wrenches.
Hydraulic torque wrenches are used for tightening large torques with high accuracy. They are used for aviation and heavy machinery assembly and are specialized tools. Their general construction varies depending on manufacturer and torque requirement. Generally, they consist of at least one hydraulic cylinder operating a drive head ratchet. The cylinder extends, pushing the drive head round via the pawls, and then retracts freely over the ratcheting teeth. The process is repeated until the desired torque is met. Smaller hydraulic torque wrenches have a reaction arm built into the tool, which rests against another fastener or part of the assembly to prevent rotation when torque is being applied. Larger models require other fixing arrangements in order to prevent rotation.
Pneumatic torque wrench.
A pneumatic torque wrench is a planetary torque multiplier or gearbox that is mated to a pneumatic air motor. At the end of the gearbox, a reaction device absorbs the torque and allows the tool operator to use it with very little effort. The torque output is adjusted by controlling the air pressure.
These planetary torque multiplier gearboxes have multiplication ratios up to 125:1 and are primarily used where accurate torque is required on a nut and bolt, or where a stubborn nut needs to be removed. For critical applications, the "final" torque is often applied with a high-accuracy tool.
Unlike a standard impact wrench, which it resembles, a pneumatic torque wrench is driven by continuous gearing, and not by the hammers of an impacting wrench, so it has very little vibration.
The pneumatic torque wrench was invented in Germany in the early 1980s.
Torque capabilities of pneumatic torque wrenches range from 118 Nm, up to a maximum of 47,600 Nm.
A pneumatic motor using compressed air is the most common source of power for pneumatic torque wrenches, which typically require 20–25 CFM.
Torque wrench standardization.
ISO.
The International Organization for Standardization maintains standard ISO 6789. This standard covers the construction and calibration of hand-operated torque tools. They define two types of torque tool encompassing twelve classes, these are given by the table below. Also given is the percentage allowable deviation from the desired torque.
The ISO standard also states that even when overloaded by 25% of the maximum rating, the tool should remain reliably usable after being re-calibrated. Re-calibration for tools used within their specified limits should occur after 5000 cycles of torquing or 12 months, whichever is soonest. In cases where the tool is in use in an organization which has its own quality control procedures, then the calibration schedule can be arranged according to company standards.
Tools should be marked with their torque range and the unit of torque as well as the direction of operation for unidirectional tools and the maker's mark. If a calibration certificate is provided, the tool must be marked with a serial number that matches the certificate or a calibration laboratory should give the tool a reference number corresponding with the tool's calibration certificate.
ASME.
The American Society of Mechanical Engineers maintains standard ASME B107.300. This standard has the same type designation as the ISO standard with the addition of the type 3, (limiting) torque tool. This type will release the drive once the desired torque is met so that no more torque can be applied. This standard, however, uses different class designations within each type as well as additional style and design variants within each class. The standard also separates manual and electronic tools into different sections and designations. The ASME and ISO standards cannot be considered compatible. The table below gives some of the types and tolerances specified by the standard for manual torque tools.
Tools should be marked with the model number of the tool, the unit of torque and the maker's mark. For unidirectional tools, the word "TORQUES" or "TORQUE" and the direction of operation must also be marked.
Using torque wrenches.
Precision.
Click type torque wrenches are precise when properly calibrated—however the more complex mechanism can result in loss of calibration sooner than the beam type, where there is little to no malfunction, (however the thin indicator rod can be accidentally bent out of true). Beam type torque wrenches are impossible to use in situations where the scale cannot be directly read—and these situations are common in automotive applications. The scale on a beam type wrench is prone to parallax error, as a result of the large distance between indicator arm and scale (on some older designs). There is also the issue of increased user error with the beam type—the torque has to be read at every use and the operator must use caution to apply loads only at the floating handle's pivot point. Dual-beam or "flat" beam versions reduce the tendency for the pointer to rub, as do low-friction pointers.
Extensions.
The use of cheater bars that extend from the handle end can damage the wrench, so only manufacturer specified equipment should be used.
Using handle or socket extensions requires no adjustment of the torque setting.
Using a crow's foot or similar extension requires the use of the following equation:
formula_1
using a combination of handle and crow's foot extensions requires the use of the following equation:
formula_2
where:
These equations only apply if the extension is colinear with the length of the torque wrench. In other cases, the distance from the torque wrench's head to the bolt's head, as if it were in line, should be used. If the extension is set at 90° then no adjustment is required. These methods are not recommended except for extreme circumstances.
Storage.
For click (or other micrometer) types, when not in use, the force acting on the spring should be removed by setting the scale to its minimum rated value in order to prevent permanent set in the spring. Never set a micrometer style torque wrench to zero as the internal mechanism requires a small amount of tension in order to prevent components shifting and reduction of accuracy.
Calibration.
As with any precision tool, torque wrenches should be periodically re-calibrated. As previously stated, according to ISO standards calibration should happen every 5000 operations or every year, whichever comes first. It is possible that torque wrenches can fall up to 10% out of calibration in the first year of use.
Calibration, when performed by a specialist service which follows ISO standards, follows a specific process and constraints. The operation requires specialist torque wrench calibration equipment with an accuracy of ±1% or better. The temperature of the area where calibration is being performed should be between 18 °C and 28 °C with no more than a 1 °C fluctuation and the relative humidity should not exceed 90%.
Before any calibration work can be done, the tool should be preloaded and torqued without measure according to its type. The tool is then connected to the tester and force is applied to the handle (at no more than 10° from perpendicular) for values of 20%, 60% and 100% of the maximum torque and repeated according to their class. The force should be applied slowly and without jerky or irregular motion. The table below gives more specifics regarding the pattern of testing for each class of torque wrench.
While professional calibration is recommended, for some people it would be out of their means. It is possible to calibrate a torque wrench in the home shop or garage. The process generally requires that a certain mass is attached to a lever arm and the torque wrench is set to the appropriate torque to lift said mass. The error within the tool can be calculated and the tool may be able to be altered or any work done adjusted for this error.


Jack Goldman

Jacob E. "Jack" Goldman (July 18, 1921 – December 20, 2011) was an American physicist and former chief scientist of Xerox Corporation. He was also a faculty member at Carnegie Tech and directed the Ford Scientific Laboratory. He is especially notable for hiring physicist Dr. George Pake to create the Xerox Palo Alto Research Center, which produced many seminal ideas in modern computing.
Goldman was born in Brooklyn, New York, and died in Westport, Connecticut.
Among the projects that Goldman worked on at Ford in the 1960s was the sodium–sulfur battery for electric cars.
After narrowly surviving a fiery crash of his gasoline-powered Lincoln, Goldman quipped "I guess I proved gasoline is more dangerous than a sodium–sulfur battery."
Jack Goldman died from congestive heart failure on December 20, 2011.


Hou Xun

Hou Xun (; ; born 6 December 1936) is a Chinese optical physicist, specializing in optoelectronics. He is a research professor and former director (1986–1995) of the Xi'an Institute of Optics and Precision Mechanics. He won the State Science and Technology Progress Award three times and was elected an academician of the Chinese Academy of Sciences in 1991.
Early life and education.
Hou was born 6 December 1936 in Lingbao, Henan, China, with his ancestral home in Xianyang, Shaanxi.
He graduated from the Department of Physics of Northwest University in Xi'an in 1959, and conducted research under Wang Chengshu at the Institute of Nuclear Energy of the Chinese Academy of Sciences (now China Institute of Atomic Energy) from 1960 to 1961. In March 1962, he began working at the Xi'an Institute of Optics and Precision Mechanics (XIOPM). From 1979 to 1981 he was a visiting scholar at the Physics Department of Imperial College London and conducted research in optics.
Career.
In 1982, he became Deputy Director of XIOPM, and was promoted to Director in June 1986, serving until March 1995. He was a professor at Northwest University and an adjunct professor at Xi'an Jiaotong University, the University of Science and Technology of China (USTC), and South China Normal University.
Hou's main research area is transient optics. He led or participated in the development of eight types of high-speed cameras, which have been used in nuclear tests. He served as chief scientist of the "Femtosecond Laser Technology and Ultrafast Process of the Climbing Project A", a large-scale research project on ultrafast phenomena. He also invented the Pd-Ag-O-Cs (Palladium-Silver-Oxygen-Caesium) photocathode and published more than 200 research papers.
Hou won the State Science and Technology Progress Award three times, and was awarded the Ho Leung Ho Lee Prize for Technological Sciences. He was elected an academician of the Chinese Academy of Sciences in 1991.


Massimo Porrati

Massimo Porrati (born 1961 in Genova, Italy) is a professor of physics and a member of the Center for Cosmology and Particle Physics at New York University. He graduated from the Scuola Normale Superiore di Pisa, Italy with a "Diploma di Scienze" degree in 1985. Later he worked as a postdoctoral fellow at UCLA and UC Berkeley in the USA. He was a research scientist at the INFN section in Pisa, Italy, in collaboration with CERN, where he over the years has spent several periods, before joining NYU in 1992. His major research interests are string theory, supersymmetry and supergravity, nonperturbative aspects of strings and quantum field theory, and cosmology.
Among other things, Porrati is known for his work on the large-distance modification of gravity and its application to the cosmological constant problem. With Gia Dvali and Gregory Gabadadze he co-pioneered and advanced this direction by proposing a generally covariant model of infrared modification of gravity (the so-called DGP model), and studying many novel and subtle features of this class of models.
Porrati held the Marie Curie Chair (2005–2007) at the Theoretical Physics Group in the Scuola Normale Superiore di Pisa, Italy.


Leonardo Senatore (physicist)

Leonardo Senatore is an Italian theoretical physicist and professor at the Stanford Institute for Theoretical Physics, the Kavli Institute for Particle Astrophysics and Cosmology, and SLAC. He was recently appointed professor at ETH Zurich.
Biography.
Senatore initially studied aerospace engineering, before earning a Laurea in Theoretical Physics from the Scuola Normale Superiore di Pisa in 2003. He continued his studies at the MIT Center for Theoretical Physics, earning a Ph.D. in 2006 under the supervision of Nima Arkani-Hamed and Alan Guth. He then held joint postdoctoral positions at Harvard and the Institute for Advanced Study.
Senatore's research focuses on theoretical cosmology. Some of his contributions have included work applying effective field theory techniques to cosmology, theoretical insights regarding inflation, and his studies of large-scale structure in the universe. He has also worked on analysis of data from experiments like WMAP, which studied the cosmic microwave background, and connections of string theory to cosmology.
Senatore won an Early Career Award from the U.S. Department of Energy in 2012 for his work, as well as a New Horizons in Physics Prize in 2016 "for outstanding contributions to theoretical cosmology."


Bernice Durand

Bernice Black Durand (born 28 December 1942) is an American particle physicist and emeritus Professor at the University of Wisconsin–Madison. She is the emeritus Vice Provost for Diversity and Climate.
Early life and education.
Durand was born in Clarion, Iowa. Her father studied mechanical engineering at Iowa State University and Harvard University, and joined the United States Army Corps of Engineers. She grew up in Ames and attended Radcliffe College, but never finished her course. She eventually completed her Bachelor's degree from Iowa State University in 1965. She earned her PhD with a dissertation titled "A point and local position operator," in 1971. She was a member of Sigma Delta Epsilon. From 1992 she has endowed an undergraduate research scholarship at Iowa State University, which provides financial support for a member of an under-represented group to complete a summer project.
Research and career.
Durand was appointed to the University of Wisconsin–Madison in 1970. She was a much celebrated teacher, teaching all levels at University of Wisconsin–Madison. She appeared in the Aspen Center for Physics video series. She worked on the SVZ method to calculate hadronic masses as well as heavy-quark systems. During her career she was a visiting scientist in several national facilities. She worked at the Fermi National Accelerator Laboratory in 1973, 1982 and 1984. She also worked at Los Alamos National Laboratory, the Institute for Advanced Study and California Institute of Technology. In 1994, Iowa State University endowed a brick in the Iowa State University "Plaza of Heroines".
Durand has been involved in several initiatives to improve diversity amongst the faculty and student population at University of Wisconsin–Madison. She directed an Alfred P. Sloan Foundation grant that promoted equity and career flexibility for all academic staff. She was a founder of the National Science Foundation Women in Science and Engineering Leadership Institute. She served on the Committee on the Status of Women in Physics. Her efforts were widely appreciated; in 2002 she received the Chancellor's Recognition Award for Outstanding Leadership and the Faculty and Staff Recognition Award from the Wisconsin Alumni Association's Cabinet 99.
Durand endorsed Barack Obama in the United States elections, 2008. She campaigned for the democratic candidate, working with over thirty scientists to get articles and letters in newspapers across the country.


Haze (optics)

There are two different types of haze that can occur in materials:
The measurement and control of both types during manufacture is essential to ensure optimum quality, acceptability and suitability for purpose of the product.
For instance, in automotive manufacturing, a high quality reflective appearance is desirable with low reflection haze and high contrast whilst in packaging clear, low haze, highly transmissive films are required so that the contents, foods etc., can be clearly observed.
Reflection Haze.
Reflection Haze is an optical phenomenon usually associated with high gloss surfaces, it is a common surface problem that can affect appearance quality. The reflection from an ideal high gloss surface should be clear and radiant, however, due to scattering at imperfections in the surface caused by microscopic structures or textures (≈ 0.01 mm wavelength) the reflection can appear milky or hazy reducing the quality of its overall visual appearance.
Causes of this could be due to a number of factors –
A high gloss surface with haze exhibits a milky finish with low reflective contrast- reflected highlights and lowlights are less pronounced.
On surfaces with haze, halos are visible around the reflections of strong light sources.
Measurement.
Measurement of reflection haze is primarily defined under three International test standards:
ASTM E430.
ASTM E430 comprises three test methods:
Test method A specifies a 30° angle for specular gloss measurement, 28° or 32° for narrow-angle reflection haze measurement and 25° or 35° for wide-angle reflection haze measurement.
Test method B specifies a 20° angle for specular gloss measurement and 18.1° and 21.9° for narrow-angle reflection haze measurement.
Test method C specifies a 30° angle for specular gloss measurement, 28° or 32° for narrow-angle reflection haze measurement and 15° wide-angle reflection haze measurement.
ASTM D4039.
Test method specifies gloss measurements to be made at 20° and 60°, the haze index is then calculated as the difference between the 60° and 20° measurements.
ISO 13803.
Test method specifies a 20° angle for specular gloss measurement and 18.1° and 21.9° for narrow-angle reflection haze measurement.
All test methods specify that measurements should be made with visible light according to CIE spectral luminous efficiency function V(λ) in the CIE 1931 standard observer and CIE standard illuminant C.
As most commercially available glossmeters have gloss measurement angles of 20°, 60° and 85° haze measurement is incorporated at either 20° (ISO 13803 / ASTM E430 method B) or at 20° and 60° ( ASTM D4039). There are however some manufacturers that offer glossmeters with measurement angles of 30° and haze measurement in accordance with ASTM E430 Method A and C but are fewer in number, therefore for the purposes of detailing haze measurement theory only the first three methods will be included.
ISO 13803 / ASTM E430 method B.
Both test methods measure specular gloss and haze together at 20° that means light is transmitted and received at an equal but opposite angle of 20°.
Specular gloss is measured over an angular range that is limited by aperture dimensions as defined in ASTM Test Method D523. The angular measurement range for this at 20° is ±0.9° (19.1° - 20.9°). For haze measurement additional sensors are used either side of this range at 18.1° and 21.9° to measure the intensity of the scattered light. Both solid colours and those containing metallics can be measured using this method provided haze compensation is used (as detailed later).
ASTM D4039.
This method can only be used on nonmetallic materials having a 60° specular gloss value greater than 70 in accordance with ASTM Test Method D523 / ISO 2813. Haze Index is calculated from gloss measurements made at 20 and 60 degrees as the difference between the two measurements (HI = G60-G20).
As measurements of specular gloss depend largely on the refractive index of the material being measured 20° gloss will change more noticeably than 60° gloss, therefore as haze index is calculated using these two measurements it too will be affected by the refractive index of the material. Evaluations of reflection haze using this test method are therefore confined to samples of roughly the same refractive index.
Haze compensation.
It is important to note that the colour (luminous reflectance) of a material can greatly influence the measurement of reflection haze. As colour and haze are both components of scattered light (diffuse reflectance) they must be separated so that only the haze value is quantified; this is also true for metallics or coatings containing metallic pigments where a higher scattering exists.
As test method ASTM D4039 is only suitable for nonmetallic materials of more or less the same refractive index separation of the colour and haze components is not detailed. Haze index calculations and measurements using this test method will therefore produce higher haze results on brighter coloured materials than darker with the same level of haze present. The chart below shows these differences for various colours:-
Both ISO 13803 and ASTM E430 method B require a separate measurement of luminous reflectance, Y, to calculate compensated haze. The tri-stimulus value Y gives a measure of the lightness of the material as defined in ISO 7724-2 requiring a 45°/0° geometry to be used with standard illuminant C and 2° observer (although it is mentioned that slightly different conditions will not result in significant errors). Luminous reflectance measurements, Y, are required on both the sample material and a reference white; ISO 13803 details the use of a BaSO4 standard - Barium sulphate, a white crystalline solid having a white opaque appearance and high density as this material is a good substitute for a perfectly reflecting diffusor as defined under ISO 7724-2.
Compensated haze can then be calculated as -
H Comp = H Linear – Y Sample / Y BaSO4
Using the ISO / ASTM method therefore to measure luminous reflectance produces a reliable measurement of Y for non-metallic surfaces as the diffuse component is lambertian, i.e. it is equal in amplitude at all angles in relation to the sample surface.
However, for metallic coatings and those containing speciality pigments, as the particles within the coating reflect the light directionally around the specular angle, little or no metallic reflection is present at the angle at which the luminosity is measured, therefore these types of coatings have an unexpectedly high haze reading. Using a measurement angle which is closer to the region adjacent to the haze angle has proven successful in providing compatible readings on solid colours and also compensating for directional reflection from metallic coatings and speciality pigments
Applications.
Generally measurement of reflection haze is confined to high gloss paints and coatings and highly polished metals. Although there has been some degree of success using this measurement method for films it has proven unreliable due to variability caused by changes in the film thickness (internal refraction variations) and the background colour on which the film sample is placed. Generally haze measurement of films is performed using a transmission type hazemeter as described hereafter.
Transmission Haze.
Light and transparent materials.
When light strikes the surface of a transparent material the following interactions occur –
• Light is reflected from the front surface of the material
• Some light is refracted within the material (depending on thickness) and reflected from the second surface
• Light passes through the material at an angle which is determined by the refractive index of the material and the angle of illumination.
The light that passes through the transparent material can be affected by irregularities within it; these can include poorly dispersed particles, contaminants (i.e. dust particles) and/or air spaces. This causes the light to scatter in different directions from the normal the degree of which being related to the size and number of irregularities present. Small irregularities cause the light to scatter, or diffuse, in all directions whilst large ones cause the light to be scattered forward in a narrow cone shape. These two types of scattering behaviour are known as Wide Angle Scattering, which causes haze due to the loss of transmissive contrast, and Narrow Angle Scattering a measure of clarity or the "see through quality" of the material based on a reduction of sharpness.
These factors are therefore important for defining the transmitting properties of a transparent material-
Transmission – The amount of light that passes through the material without being scattered
Haze – The amount of light that is subject to Wide Angle Scattering (At an angle greater than 2.5° from normal (ASTM D1003))
Clarity – The amount of light that is subject to Narrow Area Scattering (At an angle less than 2.5° from normal)
Measurement.
Measurement of these factors is defined in two International test standards-
ASTM D1003.
ASTM D1003 comprises two test methods:
Procedure A – using a Hazemeter
Procedure B – using a Spectrophotometer
BS EN ISO 13468 Parts 1 and 2.
Part 1 – Using a single beam Hazemeter
Part 2 – Using a dual beam Hazemeter
The test methods specify the use of a Hazemeter as shown below -
A collimated beam of light from a light source (ASTM D1003 - Illuminant C, BS EN ISO 13468 Parts 1 and 2 - Illuminant D65 ) passes through a sample mounted on the entrance port of an integrating sphere.
The light, which is uniformly distributed by a matte white highly reflective coating on the sphere walls, is measured by a photodetector positioned at 90° from the entrance port. A baffle mounted between the photodetector and the entrance port prevents direct exposure from the port.
The exit port immediately opposite the entrance port contains a light trap to absorb all light from the light source when no sample is present. A shutter in this exit port coated with the same coating as the sphere walls allows the port to be opened and closed as required.
Total transmittance is measured with the exit port closed.
Transmittance haze is measured with the exit port open.
Commercially available Hazemeters of this type perform both measurements automatically, the only operator interaction being the placement of the sample material on the measurement (entrance) port of the device.


Kinsey Anderson

Kinsey Amor Anderson (September 18, 1926 – June 11, 2012) was professor emeritus of physics at the University of California at Berkeley (UCB) and an internationally known pioneer of space physics during the early years of rocket, balloon, and satellite exploration of the upper atmosphere, cosmic rays, solar-terrestrial environment, and solar physics.
Anderson was born in Preston, Minnesota. He was the son of Malvin Anderson and Allene (Michener) Anderson. He received his BA in physics from Carleton College in 1949, his PhD from the University of Minnesota under Prof. John Winckler in 1955, and joined the UC Berkeley physics department in 1960. He served in the U. S. Navy in 1945-1946. Anderson was a Guggenheim Fellow in 1959-1960.
During the following decade at UCB he and his students flew instruments on many of the early generation of space science missions, including the Interplanetary Monitoring Platforms (IMP) 1-6, OGO 5, Explorer 33 and 35, and Apollo 15 and 16 lunar sub-satellites. He was an author on about 200 scientific papers, and trained 24 graduate students at Berkeley.
He was director of the Space Sciences Laboratory (SSL) at UCB, and a member of the National Academy of Sciences.


Ilham Al-Qaradawi

Ilham Al-Qaradawi is a qatari professor of positron and radiation physics at Qatar University and adjunct professor of physics at Texas A&M University at Qatar. She was born on September 19, 1959, and is the daughter of the Egyptian Muslim scholar, Yusuf Al-Qaradawi.
She is known for her work in positron physics, establishing the first slow positron beam facilities in the Middle East region. She has appeared on Al-Jazeera news network to address several nuclear energy problems in the world.
Education and early career.
Al-Qaradawi received her Bachelor of Science degree in physics in 1981 from Qatar University in Doha, Qatar. She then attended Bedford College, University of London for her Master of Science degree in nuclear physics in 1984. She obtained her PhD in positron physics from the Royal Holloway College, University of London in 1991. She then worked as an Assistant Professor at Qatar University until 2009, when she was promoted to professor. She held a research fellowship at the University of London working on positron physics from 1998 to 1999.
Research.
Al-Qaradawi's research centers on positron and radiation physics and its applications. She led the efforts in establishing the first slow positron beam facility in the Middle East region, known as the "Qatar Positron Beam". The positron beam facility incorporates a Na-22 source and Tungsten mesh moderator, and is a magnetically guided beam with energies of 0-30 keV. has established an environmental radiation measurement laboratory in Qatar University due to her interests in nuclear and radiation physics.
In 2016, she founded the first scientific societies in Qatar, the Qatar Physics Society. She is currently the president, and holds training workshops for physics teachers and other activities in an effort to spread physics knowledge and improve physics education in the region.


Chinese Journal of Physics

The Chinese Journal of Physics is a peer reviewed journal of physics. It is published by "The Physical Society of Republic of China" in Taiwan. The journal publishes reviews, articles, and refereed conference papers in all the major areas of physics.
The current editor-in-chief is Shin Nan Yang. There is an international advisory board with seven members mainly from institutions in the USA.