Thomas Russell Wilkins (6 June 1891, Toronto – 10 December 1940, Rochester, New York) was a Canadian physicist.
Wilkins received in 1912 his bachelor's degree in physics from McMaster University (which was then located in Toronto). He began graduate study in physics at the University of Chicago and taught at Brandon College, where he was head of the department of mathematics and physics from 1918 to 1925.In 1921 he received his PhD from the University of Chicago with his thesis Multiple valency in the ionization by alpha rays. In 1924 he was an Invited Speaker at the ICM in 1924 in Toronto.
He spent one year, 1925–1926, at the Cavendish Laboratory at Cambridge, England. In 1926 he joined the Physics Department of the University of Rochester in New York. In 1928 he was appointed director of the Institute of Optics. He died in Rochester on 10 December 1940. Wilkins secured photographic recordings of cosmic rays and the disintegration of radium atoms.
In modern physics, antimatter is defined as matter composed of the antiparticles of the corresponding particles in "ordinary" matter. Minuscule numbers of antiparticles are generated daily at particle accelerators—total artificial production has been only a few nanograms—and in natural processes like cosmic ray collisions and some types of radioactive decay, but only a tiny fraction of these have successfully been bound together in experiments to form antiatoms. No macroscopic amount of antimatter has ever been assembled due to the extreme cost and difficulty of production and handling.
The neutron is a subatomic particle, symbol
, which has a neutral charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics.
A proton is a subatomic particle, symbol
, with a positive electric charge of +1e elementary charge and a mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are jointly referred to as "nucleons".
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 e, a spin of 1/2, and the same mass as an electron. When a positron collides with an electron, annihilation occurs. If this collision occurs at low energies, it results in the production of two or more photons.
Cosmic rays are high-energy protons and atomic nuclei that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own galaxy, and from distant galaxies. Upon impact with Earth's atmosphere, cosmic rays produce showers of secondary particles, some of which reach the surface; although the bulk is intercepted by the magnetosphere or the heliosphere.
Antihydrogen is the antimatter counterpart of hydrogen. Whereas the common hydrogen atom is composed of an electron and proton, the antihydrogen atom is made up of a positron and antiproton. Scientists hope that studying antihydrogen may shed light on the question of why there is more matter than antimatter in the observable universe, known as the baryon asymmetry problem. Antihydrogen is produced artificially in particle accelerators.
Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule is called an ion. Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with electromagnetic radiation. Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs. Ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner-shell electrons causing it to be ejected.
Masatoshi Koshiba was a Japanese physicist and one of the founders of neutrino astronomy. His work with the neutrino detectors Kamiokande and Super-Kamiokande was instrumental in detecting solar neutrinos, providing experimental evidence for the solar neutrino problem.
Willard Frank Libby was an American physical chemist noted for his role in the 1949 development of radiocarbon dating, a process which revolutionized archaeology and palaeontology. For his contributions to the team that developed this process, Libby was awarded the Nobel Prize in Chemistry in 1960.
Samuel Chao Chung Ting is a Chinese-American physicist who, with Burton Richter, received the Nobel Prize in 1976 for discovering the subatomic J/ψ particle. More recently he has been the principal investigator in research conducted with the Alpha Magnetic Spectrometer, a device installed on the International Space Station in 2011.
Bruno Benedetto Rossi was an Italian experimental physicist. He made major contributions to particle physics and the study of cosmic rays. A 1927 graduate of the University of Bologna, he became interested in cosmic rays. To study them, he invented an improved electronic coincidence circuit, and travelled to Eritrea to conduct experiments that showed that cosmic ray intensity from the West was significantly larger than that from the East.
Philip Morrison was a professor of physics at the Massachusetts Institute of Technology (MIT). He is known for his work on the Manhattan Project during World War II, and for his later work in quantum physics, nuclear physics and high energy astrophysics.
A Nuclear Emulsion plate is a type of particle detector first used in Nuclear and Particle physics experiments in the early decades of the 20th century. It is a type of photographic plate, but coated with a thicker photographic emulsion of gelatine containing a higher concentration of very fine silver halide grains; the exact composition of the emulsion being optimised for particle detection. Nuclear emulsion can be used to record and investigate fast charged particles like alpha-particles, nucleons or mesons. After exposing and developing the emulsion, single particle tracks can be observed and measured using a microscope.
The dihydrogen cation or hydrogen molecular ion is a cation with formula H+
2. It consists of two hydrogen nuclei (protons) sharing a single electron. It is the simplest molecular ion.
Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways. Alpha particles are named after the first letter in the Greek alphabet, α. The symbol for the alpha particle is α or α2+. Because they are identical to helium nuclei, they are also sometimes written as He2+
indicating a helium ion with a +2 charge. Once the ion gains electrons from its environment, the alpha particle becomes a normal helium atom 4
Paul Bruce Corkum is a Canadian physicist specializing in attosecond physics and laser science. He holds a joint University of Ottawa–NRC chair in Attosecond Photonics. He is one of the students of strong field atomic physics, i.e. atoms and plasmas in super-intense laser fields.
Philip H. Bucksbaum is an American atomic physicist, the Marguerite Blake Wilbur Professor in Natural Science in the Departments of Physics, Applied Physics, and Photon Science at Stanford University and the SLAC National Accelerator Laboratory. He also directs the Stanford PULSE Institute.
The Antihydrogen Laser Physics Apparatus (ALPHA), also known as AD-5, is an experiment at the Antiproton Decelerator at CERN, designed to trap neutral antihydrogen in a magnetic trap, and conduct experiments on them. The ultimate goal of this experiment is to test CPT symmetry through comparison of the atomic spectra of hydrogen and antihydrogen. The ALPHA collaboration consists of some former members of the ATHENA collaboration or AD-1 experiment, as well as a number of new members.
Helen Sarah Freedhoff was a Canadian theoretical physicist who studied the interaction of light with atoms. She gained her doctorate at the University of Toronto in 1965 and completed a postdoctoral fellowship at Imperial College in London. Freedhoff was the first woman appointed as a physics professor at York University in Toronto, and is believed to have been the only woman professor of theoretical physics in Canada at the time.
Linda Young is a distinguished fellow at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and a professor at the University of Chicago’s Department of Physics and James Franck Institute. Young is also the former director of Argonne’s X-ray Science Division.