Scattering experiments

Scattering experiments (atoms and molecules)

Experiments in which a beam of incident electrons, atoms, or molecules is deflected by collisions with an atom or molecule. Such experiments provide tests of the theory of scattering as well as information about atomic and molecular forces. Scattering experiments can be designed to simulate conditions in planetary atmospheres, electrical discharges, gas lasers, fusion reactors, stars, and planetary nebulae. See Electrical conduction in gases, Gas discharge, Laser, Nuclear fusion

In general, in any type of collision, scattering occurs, which causes the direction of relative motion of the two systems to be rotated to a new direction after the collision. More than two systems may also result from such an impact. A complete description of a collision event requires measurement of the directions, speeds, and internal states of all the products. See Collision (physics)

There are two basic types of scattering experiments. The simpler involves passing a collimated beam of particles (electrons, atoms, molecules, or ions) through a dilute target gas (in a cell or a jet) and measuring the fraction of incident particles that are deflected into a certain angle relative to the incident beam direction. In the second method, a collimated beam of particles intersects a second beam. The scattering events are usually registered by measuring the deflection or internal-state change of the beam particles. See Molecular beams

Scattering in a particular type of collision is specified in terms of a differential cross section. The probability that, in a particular type of collision, the direction of motion of the electron is turned through a specified scattering angle into a specified solid angle is proportional to the corresponding differential scattering cross section. Collision cross sections can be measured with appropriately designed experimental apparatus. Depending on the type of collision process, that apparatus may measure the scattering angle, energy, charge, or mass of the scattered systems.

For the simplest case, the scattering of a beam of structureless particles of specified mass and speed by a structureless scattering center, the differential cross section may be calculated exactly by using the quantum theory. In the special case where the Coulomb force fully describes the interaction, both the quantum and classical theory give the same exact value for the differential cross section at all values of the scattering angle.

For scattering of systems with internal structure (for example, molecules, and their ions), no exact theoretical calculation of the cross section is possible. Methods of approximation specific to different types of collisions have been developed. The power of modern high-speed computers has greatly increased their scope and effectiveness, with scattering experiments serving as benchmarks. See Atomic structure and spectra


Scattering experiments (nuclei)

Experiments in which beams of particles such as electrons, nucleons, alpha particles and other atomic nuclei, and mesons are deflected by elastic collisions with atomic nuclei. Much is learned from such experiments about the nature of the scattered particle, the scattering center, and the forces acting between them. Scattering experiments, made possible by the construction of high-energy particle accelerators and the development of specialized techniques for detecting the scattered particles, are one of the main sources of information regarding the structure of matter. See Nuclear structure, Particle accelerator, Particle detector, Scattering matrix

References in periodicals archive ?
For example, Dynamical spin correlation functions, Measured in neutron scattering experiments, Provide signatures of topologically ordered spin liquids.
X-ray scattering experiments are performed at Beamline 1W2A of Beijing Synchrotron Radiation Facility (Beijing, China).
The 14 papers consider such topics as Swiss light sources: the next 20 years, accelerator projects in Korea: current status and perspectives, challenges and opportunities of high-intensity X/gamma photon beams for nuclear photonics and photon-photon scattering experiments, advances and perspectives of synchrotron-based techniques for cultural heritage, and energy catalysis research with advanced X-ray techniques in the Shanghai Synchrotron Radiation Facility: present and future challenges.
Using results from simulations and X-ray scattering experiments, scientists at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and at the University of California, Berkeley, found the electrons in vanadium dioxide are able to conduct electricity without conducting heat at a rate of thermal conductivity which was "ten times smaller than what would be expected from the Wiedemann-Franz Law.
The Compact Dynamic Beamstop (CDBS) design is simple, compact, easily commercialized, customizable for a wide variety of X-ray scattering experiments and unique in its capabilities to provide information about X-ray beams in real time without interfering with the collection of data on precious samples.
Experienced researchers introduce students to the capabilities and the limits of conducting X-ray scattering experiments using nanobeams--X-ray beams focused to sub-micron spot size.
Scattering experiments are used as a primary tool for investigating the structure of physical objects.
The team of scientists has found evidence for the confinement idea by neutron scattering experiments on magnetic crystals of calcium cuprate.
Provision of easy-to-use software is a key factor in enabling non-experts to carry out successful neutron scattering experiments.
His topics include the quest for a theory of everything, Rutherford's scattering experiments, the first accelerators, the Tevatron and the Super Proton Synchrotron, building the Large Hadron Collider, looking for portals to higher dimensions, and microscopic black holes.
This preliminary result indicated that the onset of a visible scratch can be determined from optical scattering experiments.
There is simply no way to generate valid scientific data that can be compared with each other by scattering experiments over 50 different jurisdictions without consistent testing or reporting requirements, as this proposal would permit.