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. [1] In 1921 he received his PhD from the University of Chicago with his thesis Multiple valency in the ionization by alpha rays. [2] 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. [1]
In modern physics, antimatter is defined as matter composed of the antiparticles of the corresponding particles in "ordinary" matter, and can be thought of as matter with reversed charge, parity, and time, known as CPT reversal. Antimatter occurs 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. Minuscule numbers of antiparticles can be generated at particle accelerators; however, total artificial production has been only a few nanograms. No macroscopic amount of antimatter has ever been assembled due to the extreme cost and difficulty of production and handling. Nonetheless, antimatter is an essential component of widely-available applications related to beta decay, such as positron emission tomography, radiation therapy, and industrial imaging.
The neutron is a subatomic particle, symbol
n
or
n0
, 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 dalton, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics. Protons and neutrons are not elementary particles; each is composed of three quarks.
The positron or antielectron is the particle with an electric charge of +1e, a spin of 1/2, and the same mass as an electron. It is the antiparticle of the electron. When a positron collides with an electron, annihilation occurs. If this collision occurs at low energies, it results in the production of two or more photons.
Cosmic rays or astroparticles are high-energy particles or clusters of particles 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 are deflected off into space 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.
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 an American physicist who, with Burton Richter, received the Nobel Prize in 1976 for discovering the subatomic J/ψ particle.
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.
Robert Henry Dicke was an American astronomer and physicist who made important contributions to the fields of astrophysics, atomic physics, cosmology and gravity. He was the Albert Einstein Professor in Science at Princeton University (1975–1984).
Pierre Victor Auger was a French physicist, born in Paris. He worked in the fields of atomic physics, nuclear physics, and cosmic ray physics. He is famous for being one of the discoverers of the Auger effect, named after him.
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 high energy astrophysics, and SETI.
Silicon (14Si) has 23 known isotopes, with mass numbers ranging from 22 to 44. 28Si, 29Si (4.67%), and 30Si (3.1%) are stable. The longest-lived radioisotope is 32Si, which is produced by cosmic ray spallation of argon. Its half-life has been determined to be approximately 150 years, and it decays by beta emission to 32P and then to 32S. After 32Si, 31Si has the second longest half-life at 157.3 minutes. All others have half-lives under 7 seconds.
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 modified form of photographic plate that can be used to record and investigate fast charged particles like alpha-particles, nucleons, leptons or mesons. After exposing and developing the emulsion, single particle tracks can be observed and measured using a microscope.
Wang Ganchang was a Chinese nuclear physicist. He was one of the founding fathers of Chinese nuclear physics, cosmic rays and particle physics. Wang was also a leader in the fields of detonation physics experiments, anti-electromagnetic pulse technology, nuclear explosion detection, anti-nuclear radiation technology, and laser stimulated nuclear explosion technologies.
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+
or 4
2He2+
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
2He.
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 also holds academic positions at Texas A&M University and the University of New Mexico. Corkum is both a theorist and an experimentalist.
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.
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.
Thorfin Rusten Hogness was a physical chemist, director of plutonium research for the Manhattan Project, and, after WW II, an advocate of "international control of nuclear energy".