Gamma rays were discovered by Villard more than a hundred years ago. Rutherford
gave the name -rays to the electrically neutral radiation emitted by the naturally
occurring radioactive materials.
Gamma rays are electromagnetic radiation, photons, which arises due to energy
changes in the nucleus. It does not appear as an independent form of radiation, but it
follows and β decay, in those cases when the newly created core of the offspring is
found in the excited state.
Introduction to LEDs: How LEDs work + some points. Comparison with other sources of light. LED in communication. Blue &White LED technologies. How they are made? Their application? Brief about blue laser? Stands for light emitting diode.
emits incoherent narrow spectrum light
(due to recombination in transition region near the junction.)
Color of the emitted light depends on the chemical of the semiconducting material used.
(Near-ultraviolet, visible or infrared.)...
All of the types of automatic pyrometers, listed in Section 8.1 and shown in Figure 8 .2 are considered in this chapter. To reach a sufficiently high measurement precision, the radiation emitted by the body under measurement is concentrated on the radiation detector by lenses, light-guides or mirrors . Thus, they also reduce the pyrometer viewing angle and consequently the necessary object diameter . It its also essential that the pyrometer optical system should be able to aim properly at the target .
This report of the National Council on Radiation Protection and
Measurements (NCRP) , successor to the National Committee on Radiation
Protection and hleasurements, is concerned with the spccification
of sealed sources of nuclides which emit gamma rays-sources
useful in brachytherapy. The report resulted from the Council's belief
that a single well-defined method for specifying the radionuclide in an
encapsulated source would be advantageous for both the users and the
suppliers of such sources....
In 1961 the NCRP issued NCRP Report No. 28, A Manual of
Radioactivity Procedures, which was published as the National Bureau
of Standards Handbook 80. The report came to be one of the definitive
works in the area of radioactivity measurements. As the development
of new techniques, procedures, and equipment made parts of the
Report obsolescent, the NCRP recognized the need to update and
extend the document.
Benzene is a colourless, liquid, flammable, aromatic hydrocarbon that is a component of
petrol, or may result from incomplete combustion of fuels.
Benzene, a natural component of crude oil, is emitted from a range of industrial and
combustion sources. The major source of benzene is motor vehicles—both vehicle
exhaust (contributing approximately 75% to 80% of emissions) and evaporative
emissions (including evaporation losses from motor vehicles and evaporation losses
during the handling, distribution and storage of petrol).
Computed tomography is the process of reconstructing the interiors of objects from data collected based on transmitted or emitted radiation. The problem occurs in a wide range of application areas. Here we discuss the computer algorithms used for achieving the reconstructions.
The Reconstruction Problem
We want to solve the following general problem. There is a three-dimensional structure whose internal composition is unknown to us. We subject this structure to some kind of
Greenhouse gases, such as carbon dioxide, nitrous oxide, methane, and ozone, play an
important role in balancing the temperature of the Earth’s surface by absorbing and
emitting radiation within the thermal infrared range from the source. However, with
the enormous burning of fossil fuels from the industrial revolution, the concentration
of greenhouse gases in the atmosphere has greatly increased.
A laser, an acronym lor light amplification by stimulated
emission of radiation, is a device for generating a high-intensity,
ostensibly parallel beam of monochromatic (single
wavelength) electromagnetic radiation. The possibility of
stimulated emission was predicted by Einstein in I9I7;
based on the work of Gordon in 1955 and Schawlow and
Townes in 1958, Maiman created the first operational laser
in 1960, a ruby laser emitting a brilliant red beam of light.
In recent years, possible health hazards due to radiofrequency radiation
(RFR) emitted by mobile phones have been investigated. Because several
publications have suggested that RFR is stressful, we explored the potential
biological effects of Global System for Mobile phone communication at
900 MHz (GSM-900) exposure on cultures of isolated human skin cells
and human reconstructed epidermis (hRE) using human keratinocytes.