ray (redirected from ß-rays)

ray (ra)

1. a line emanating from a center.

2. a more or less distinct portion of radiant energy (light or heat), proceeding in a specific direction.

---

a-rays , alpha rays high-speed helium nuclei ejected from radioactive substances; they have less penetrating power than beta rays.

ß-rays , beta rays electrons ejected from radioactive substances with velocities as high as 0.98 of the velocity of light; they have more penetrating power than alpha rays, but less than gamma rays.

digital ray 

1. a digit of the hand or foot and the corresponding portion of the metacarpus or metatarsus, considered as a continuous structural unit.

2. in the embryo, a mesenchymal condensation of the hand or foot plate that outlines the pattern of a future digit.

?-rays , gamma rays electromagnetic radiation of short wavelengths emitted by an atomic nucleus during a nuclear reaction, consisting of high-energy photons, having no mass and no electric charge, and traveling with the speed of light and with great penetrating power.

grenz rays  very soft x-rays having wavelengths about 20 nm, lying between x-rays and ultraviolet rays.

medullary rays  the intracortical prolongations of the renal pyramids.

roentgen rays  x-r's.

x-rays  electromagnetic vibrations of short wavelengths (approximately 0.01 to 10 nm) or corresponding quanta that are produced when electrons moving at high velocity impinge on various substances; they are commonly generated by passing high-voltage current (approximately 10,000 volts) through a Coolidge tube. They are able to penetrate most substances to some extent, to affect a photographic plate, to cause certain substances to fluoresce, and to strongly ionize tissue.

---

Ray, John 1627-1705.

English naturalist who was the first to use anatomy to distinguish between specific plants and animals. He established the species as the basic classification of living things.

---

ray (r)

n.

1. A narrow beam of light or other electromagnetic radiation.

2. A narrow beam of particles, as a cathode.

3. A structure or part having the form of a straight line extending from a point.

---

ray(s),

n a line of light, heat, or other form of radiant energy. A ray is a more or less distinct or isolated portion of radiant energy, whereas the word
rays is a very general term for any form of radiant energy, whether vibratory or particulate.

ray, alpha,

n See particle, alpha.

ray, beta,

n See particle, beta.

ray, cathode,

n See electron stream.

ray, central,

n the center of a radiographic beam.

ray, cosmic,

n radiation that originates outside the earth's atmosphere. Cosmic rays have extremely short wavelengths. They are able to produce ionization as they pass through the air and other matter and are capable of penetrating many feet of material such as lead and rock. The primary cosmic rays probably consist of atomic nuclei (mainly protons), some of which may have energies of the order of 1010 to 1015 eV. Secondary cosmic rays are produced when the primary cosmic rays interact with nuclei and electrons (e.g., in the earth's atmosphere). Secondary cosmic rays consist mainly of mesons, protons, neutrons, electrons, and photons that have less energy than the primary rays. Practically all the primary cosmic rays are absorbed in the upper atmosphere. Almost all cosmic radiation observed at the earth's surface is of the secondary type.

ray, gamma,

n photons with a shorter wavelength than those ordinarily used in diagnostic medical and dental radiography and that originate in the nuclei of atoms. A quantum of electromagnetic radiation emitted by a nucleus as a result of a quantum transition between two energy levels of the nucleus; e.g., as a radioisotope decays, it gives off energy, some of which may be in the form of gamma radiation.

ray, grenz

n roentgen rays that are greater in length than 1 Å; used in radiography of soft tissues, insects, flowers, and microscopic sections of teeth and surrounding tissues. These rays are the result of using approximately 10 to 20 kV in a specially constructed radiation-generating device. They have a wavelength of about 2 Å.

ray, neutron,

n particulate ionizing radiation consisting of neutrons. On impact with nuclei or atoms, neutrons possess enough kinetic energy to set the nuclei or atoms in motion with sufficient velocity to ionize matter or enter into nuclear reactions that result in the emission of ionizing radiation. The former variety is usually called the fast neutron, and the latter the thermoneutron, with gradations of epithermal and slow neutrons between them.

ray, roentgen (r)

n an international unit based on the ability of radiation to ionize air. The exposure to x- or gamma radiation such that the associated corpuscular emission per 0.001293 g of air produces, in air, ions carrying 1 esu of quantity of electricity of either sign (2.083 billion ion pairs).

---

ray

a line emanating from a center, as a more or less distinct portion of radiant energy (light or heat), proceeding in a specific direction.

---

alpha r's,

a-r's high-speed helium nuclei ejected from radioactive substances; they have less penetrating power than beta rays. See also alpha particles.

beta r's,

ß-r's, beta particles electrons ejected from radioactive substances with velocities as high as 0.98 of the velocity of light; they have more penetrating power than alpha rays, but less than gamma rays.

digital ray

a digit of the hand or foot and corresponding metacarpal or metatarsal bone, regarded as a continuous unit.

ray fungus

branched filamentous appearance of Actinomyces bovis in granules in pus.

gamma r's,

?-r's electromagnetic radiation of short wavelengths emitted by an atomic nucleus during a nuclear reaction, consisting of high-energy photons, having no mass and no electric charge, and traveling with the speed of light and with great penetrating power.

They have very great range in penetrating tissues and cytotoxic effects, especially on nuclei and on tissues which are replicating rapidly. The fetus, bone marrow, blood, liver and gonads are particularly susceptible. See also radiation injury, radiation therapy.

medullary ray

a cortical extension of a bundle of tubules from a renal pyramid.

roentgen r's

x-rays.

x-r's

see x-ray.