Radiation particle

Thermoluminescence. Thermoluminescence is a property of some solids in which excitation by light or particle radiation is frozen in as trapped electrons and holes or a crystal defect. Subsequent heating allows relaxation of the excited state and emission... 

Human Cytogenetic Dosimetry A Dose-Response Relationship for Alpha Particle Radiation from Am-241, Health Physics 37 279-289 (1979). 

Figure 3.1 shows the stopping power of water toward some typical charged particle radiations. For others, similar curves can be drawn using the procedure... 

Beta particle Radiation in the form of an energetic electron emitted from the nucleus of an atom. Negatively charged (-1) radiation particle consisting of an energetic electron emitted from the nucleus of an atom. 

Beryllium is an excellent source of alpha particles, which are the nuclei of helium atoms. Alpha particles (radiation) are not very penetrating. These particles travel only a few inches in air and can be stopped by a sheet of cardboard. Alpha particles are produced in cyclotrons (atom smashers) and are used to bombard the nuclei of other elements to study their characteristics. 

Cancer is a disease present in people and animals in which the stracture and normal function of body tissues are disrupted. The exact etiology of most types of cancer is unknown. However, it is well known that infections, environmental factors (chemical substances, foreign particles, radiation), and genetic factors can induce transformation of normal cells to neoplastic cells, i.e. those that multiply and function abnormally. 

We begin with the simplest case. A vacancy flux j° (driven, for example, by inhomogeneous particle radiation) flows across a multicomponent crystal (k = 1,2,.., n) and the component fluxes are restricted to one sublattice. We assume no other coupling between the fluxes except the lattice site conservation, which means that we neglect cross terms in the formulation of SE fluxes. (An example of coupling by cross terms is analyzed in Section 8.4.) The steady state condition requires then that the velocities of all the components are the same, independent of which frame of reference has been chosen, that is,... 

If high temperatures eventually lead to an almost equal population of the ground and excited states of spectroscopically active structure elements, their absorption and emission may be quite weak, particularly if relaxation processes between these states are slow. The spectroscopic methods covered in Table 16-1 are numerous and not equally suited for the study of solid state kinetics. The number of methods increases considerably if we include particle radiation (electrons, neutrons, protons, atoms, or ions). We note that the output radiation is not necessarily of the same type as the input radiation (e.g., in photoelectron spectroscopy). Therefore, we have to restrict this discussion to some relevant methods and examples which demonstrate the applicability of in-situ spectroscopy to kinetic investigations at high temperature. Let us begin with nuclear spectroscopies in which nuclear energy levels are probed. Later we will turn to those methods in which electronic states are involved (e.g., UV, VIS, and IR spectroscopies). 

Almost all radioactive nuclides that emit alpha particles are in the upper end of the periodic table, with atomic numbers greater than 82 (lead), but a few alpha-particle emitting nuclides are scattered through lower atomic numbers. The reason why alpha-particle emitters are limited to nuclides with larger mass numbers is that generally only in this region is alpha-particle emission energetically possible. Most radioactive nuclides with smaller mass numbers emit beta-particle radiation. 

Kleinknecht, K. Detectors for Particle Radiation, 2nd ed., Cambridge, 1998. An excellent discussion from a high-energy physics perspective. 

This chapter describes the fundamental principles of heat and mass transfer in gas-solid flows. For most gas-solid flow situations, the temperature inside the solid particle can be approximated to be uniform. The theoretical basis and relevant restrictions of this approximation are briefly presented. The conductive heat transfer due to an elastic collision is introduced. A simple convective heat transfer model, based on the pseudocontinuum assumption for the gas-solid mixture, as well as the limitations of the model applications are discussed. The chapter also describes heat transfer due to radiation of the particulate phase. Specifically, thermal radiation from a single particle, radiation from a particle cloud with multiple scattering effects, and the basic governing equation for general multiparticle radiations are discussed. The discussion of gas phase radiation is, however, excluded because of its complexity, as it is affected by the type of gas components, concentrations, and gas temperatures. Interested readers may refer to Ozisik (1973) for the absorption (or emission) of radiation by gases. The last part of this chapter presents the fundamental principles of mass transfer in gas-solid flows. 

For particle heating with Tw Tp, it is reasonable to neglect particle radiation to the surroundings. Thus, Eq. (4.62) becomes... 

Takahashi S, Patrick G. 1987. Long-term retention of Ba in the rat trachea following local administration as barium sulfate particles. Radiat Res 110 321-328. 

Antenna-coupled bolometers (Schwarz and Ulrich, 1977) offer another way to achieve a small heat capacity and a small area sensitive to charged particles. Radiation is absorbed by an antenna and then coupled into a transmission line which brings it to a very small absorbing thermometer. 

The Hamiltonian of the particle + radiation system now assumes the form... 

Furthermore, multiple ionization, which has been postulated as being able to bring about displacements of interior atoms (30), might be extremely effective in leading to surface migrations and thermal patches, in which case surface properties could be more sensitive to electromagnetic radiation than to particle radiation. it was hoped that the present studies would shed some light on what actually happens. 

The depth of introduction can be varied by technical tools as well. Transmission techniques can be applied for bulk analysis, while reflection techniques are appropriate to the study of the interfaces. Transmission and reflection techniques can be applied using a wide range of electromagnetic radiation, from infrared to x-ray ranges. Moreover, particle radiation (e.g., the neutron scattering technique) can also be used for the study of the structure of interfaces. 

Line-width broadening may also be caused by other fast relaxation mechanisms in addition to a small particle size. For example, it is well known that, for spherical particles, radiation losses become more pronounced with increasing radius. In some metals, these relaxation mechanisms are so strong that a well-defined plasmon resonance is not observed, as in Fe, Pd, and Pt. Nanosized particles are interesting because the optical resonance can be designed in. For example, in a nanoshell consisting of a dielectric core surrounded by a metallic outer layer, the relative dimensions of these components can be varied. This, in turn, varies the optical resonance, possibly over several-hundred nanometers in wavelength. 

---