Charged-particle accelerator

Bremsstrahlung—X rays that are produced when a charged particle accelerates (speeds up, slows down, or changes direction) in the strong field of a nucleus. 

The transfer or conversion of energy is always associated with the emission of electromagnetic waves. We met this concept in its simplest form in Chapter 2, when we looked at the transfer of infrared radiation (i.e. heat). This emission of photons occurs because all objects contain electrically charged particles and, whenever an electrically charged particles accelerates, it emits electromagnetic waves. 

Humphries Jr., S., Principles of Charged Particles Acceleration, John Wiley Sons, New York (1986). 

Irradiation with charged particles accelerated in a cyclotron, while eliminating the problem of long-lived silver isotopes caused by the different nuclear reactions involved, is not feasible for any large-scale study because of the cost involved. Unlike a nuclear reactor, where numerous different samples can be irradiated simultaneously, only a single sample can be irradiated using a cyclotron beam. 

Commercial neutron generators are compact charged particle accelerators designed to produce a beam of neutrons by an appropriate nuclear reaction. The most com-... 

There will be some practical applications as well, leading to whole new industries, among them advanced electronics and nuclear medicine. Both disciplines have already benefited enormously from the technology of particle accelerators, starting with the invention of the cyclotron, the charged particle accelerator invented in 1931 by Ernest Lawrence, founder of the Lawrence Berkeley Laboratory in California. 

Vojnovic B. (1985) A sensitive single-pulse beam charge monitor for use with charged particle accelerators. Radiat Phys Chem 24 517-522. 

The production, acquisition and distribution of isotopes, and performance of related services, continue long-standing activities conducted by the United States Department of Energy and its predecessor agencies. Materials in inventory or produced in nuclear reactors, charged particle accelerators and separated stable isotopes, DoE offers for sale. The isotopes are mostly in intermediate forms suitable for incorporation in diverse pharmaceuticals, generator kits, irradiation targets, radiation sources, or other finished products. 

The application of ion beam analysis techniques to determine pore size and pore volume or density of thin silica gel layers was first described by Armitage and co-workers [114]. These techniques are non-destructive, sensitive and ideally suited for the analysis of thin porous films such as membrane layers (dense support is needed for backscattering). However, apart from a more recent report on ion-beam analysis of sol-gel films [115] using Rutherford backscattering and forward recoil spectrometry, ion beam techniques have not been developed further despite their potential for membrane characterisation. This is probably due to the limited availability of ion beam sources, such as charged particles accelerators. 

Figure 1 Schematic depictions of electrostatic (a) and oscillating electromagnetic (b) fields for charged particle acceleration.

Humphries, S. Principles of Charged Particle Acceleration John Wiley and Sons New York, 1986. 

With the development of nuclear reactors and charged particle accelerators (commonly referred to as atom smashers ) over the second half of the twentieth century, the transmutation of one element into another has become commonplace. In fact some two dozen synthetic elements with atomic numbers higher than naturally occurring uranium have been produced by nuclear transmutation reactions. Thus, in principle, it is possible to achieve the alchemist s dream of transmuting lead into gold, but the cost of production via nuclear transmutation reactions would far exceed the value of the gold. SEE ALSO Alchemy Nuclear Chemistry Nuclear Fission Radioactivity Transactinides. 

S. Humphries, Principles of Charged Particle Accelerators, Wiley, 1986. 

N.A. Vinokurov and A.N. Skrinsky, Preprint INP77-59, Novosibirsk (1977) N.A. Vinokurov, Proc. 10th Int. Conf. High Energy Charged Particle Accelerators, Serpukhov, vol.2, 454 (1977)... 

Benchtop charged particle accelerators are commercially available for the generation of neutrons. A typi-... 

The main source of transuranium elements is the high-flux reactor, in which or heavier nuclei get transformed into higher-Z elements by multiple neutron capture. In the USA, there is a national program for the production of transuranium elements utilizing the high-flux reactor (HFIR) at Oak Ridge. The heaviest nuclide produced in the reactor is Fm. Neutron-deficient nuclides are synthesized in charged-particle accelerators and very neutron-rich nuclides with short half-lives are produced in reactors. 

An electron volt is the energy acquired by a singly charged particle accelerated through a one-volt electrical potential. The energy is related to the temperature by the Boltzmann equation given by E = 3/2 kT where k is the Boltzmann constant and T is the Kelvin temperature. One eV is equiwilent to about 11300°C. In chemical terms, 1 eV per atom is equivalent to 23 kilocalories per mole. 

A charged-particle accelerator, as the name implies, can produce only beams of charged particles (such as iH ) as projectiles. In many cases, neutrons are most effective as projectiles for nuclear bombardment. The neutrons required can be generated through a nuclear reaction produced by a charged-particle beam. In the following reaction, iH represents a beam of deuterons, the nucleus of a deuterium atom (actually, iH ), from an accelerator. 

Transuranium Elements—Elements beyond Z = 92, commonly referred to as the transuranium elements, have been synthesized by bombarding naturally occurring isotopes with charged particles produced in a charged-particle accelerator (Fig. 25-3). 

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