radiation(redirected from pyramidal radiation)
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The emission and propagation of energy; also, the emitted energy itself. The etymology of the word implies that the energy propagates rectilinearly, and in a limited sense, this holds for the many different types of radiation encountered.
The major types of radiation may be described as electromagnetic, acoustic, and particle, and within these major divisions there are many subdivisions. Electromagnetic radiation is classified roughly in order of decreasing wavelength as radio, microwave, visible, ultraviolet, x-rays, and γ-rays. Acoustic or sound radiation may be classified by frequency as infrasonic, sonic, or ultrasonic in order of increasing frequency, with sonic being between about 16 and 20,000 Hz. The traditional examples of particle radiation are the α‒ and β-rays of radioactivity. See Electromagnetic radiation, Radioactivity, Sound
radiation(ray-dee-ay -shŏn) See electromagnetic radiation; energy transport.
ii. The transfer of energy in the form of electromagnetic waves through either a vacuum or air.
electromagnetic radiationThe energy that radiates from all things in nature and from man-made electrical and electronic systems. Electromagnetic radiation includes cosmic rays, gamma rays, x-rays, ultraviolet light, visible light, infrared light, radar, microwaves, TV, radio, cellphones and all electronic transmission systems. Electromagnetic radiation is made up of an electromagnetic field (EMF), which comprises an electric field and a magnetic field that move at right angles to each other at the speed of light. See spectrum, microwave and electromagnetic hypersensitivity.
radiation hardenedRefers to electronic products used in space, satellite, nuclear plant and military applications. Radiation hardened devices are built to withstand cosmic rays and other natural electromagnetic radiation, as well as nuclear explosions. The effects of such radiation can be a temporary alteration or a slow degradation of the semiconductor elements in memory cells and transistors. If either a cell or transistor is induced to change its state, it can cause a program to crash (see abend). As the elements in a chip are made smaller, radiation has an increasingly greater and harmful influence.
"Rad hard" products are highly insulated from the outside world. In addition, devices may be built with redundant components at the system level or at the circuit level, and error-correcting memories can detect and correct a memory failure. See electromagnetic radiation.
|A Wide Resistance Difference|
|This C-RAM phase change 4MB memory chip is shown without the cover and before the leads are cut. When the bit is 0, the memory cell resistance is 5,000 ohms, but 100,000 ohms when a 1. Due to the huge resistance difference between a 0 and 1, the chip is inherently radiation hardened (see phase change memory). (Image courtesy of BAE Systems, www.baesystems.com)|