Linear accelerators charged particles

Linear accelerator A device used for accelerating charged particles along a straight-line path. 

The experiments went on, however, and in 1968 experiments at the Stanford Linear Accelerator Laboratory showed that quarks were indeed real. When protons were bombarded with high-energy electrons, pointlike charges were discovered inside the proton. These charges could only be charged particles, in other words, quarks. 

Linear accelerator A long straight tube (or series of tubes) in which charged particles (ordinarily electrons or protons) gain in energy by the action of oscillating electromagnetic fields. 

In a looser sense the term radiation also includes energy emitted in the form of particles that possess mass and may or may not be electrically charger, (i.e.. a [positive] and ft [negative] and also neutrons. Beams of such particles may be considered as rays". The charged particles may all be accelerated and the high energy imparted to beams in particle accelerators such as cyclotrons, betatrons, synchrotrons, and linear accelerators. 

Schematic diagram of a linear accelerator, which uses a changing electric field to accelerate a positive ion along a linear path. As the ion leaves the source, the odd-numbered tubes are negatively charged, and the even-numbered tubes are positively charged. The positive ion is thus attracted into tube 1. As the ion leaves tube 1, the tube polarities are reversed. Now tube 1 is positive, repelling the positive ion and tube 2 is negative, attracting the positive ion. This process continues, eventually producing high particle velocity.

The potential value of high-energy electron-producing machines such as the linear accelerator for activation analysis must not be overlooked. Here photonuclear reactions y,n) can be used, either to produce a high neutron flux (as most charged-particle machines can by choice of a suitable reaction), or directly on samples. This may well be valuable, particularly for some light element determinations. 

Figure 23.5 A linear accelerator. A, The voltage of each tubular section is alternated, so that the positively charged particle (a proton here) is repelled from the section it is leaving and attracted to the section it is entering. As a result, the particle s speed is continually increased. B, The linear accelerator operated by Stanford University in California.

Figure 23.6 The cyclotron accelerator. When the positively charged particle reaches the gap between the two D-shaped electrodes ( dees ), it is repelled by one dee and attracted by the other. The particles move in a spiral path, so the cyclotron can be much smaller than a linear accelerator.

Linear accelerator a type of particle accelerator in which a changing electrical field is used to accelerate a beam of charged particles along a linear path. 

Accelerators provide a variety of nuclear reactions for production of neutrons. Cockcroft-Walton accelerators can generate 14.8 MeV neutrons by accelerating deuterons ( H) onto a tritium target to produce 10 -10 neutrons s Cyclotrons and linear accelerators can produce high-energy neutrons with a broad spectrum of energies in spallation reactions that result from the bombardment of heavy elements by charged particles. 

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