Cherenkov radiation
Cherenkov radiation is electromagnetic radiation emitted when a charged particle
passes through a dielectric medium at a speed greater than the phase velocity of
light in that medium. (Note: I have seen a lot of this radiation looking into spent
fuel pools.)
Creep
A gradual elongation of material when under a constant load at a constant
temperature.
Cosmic Ray Knee
A sudden steepening of the cosmic ray energy spectrum (the knee) is observed at
an energy of about 3 PeV (1 PeV = 10
15
eV). The recent results of extensive air
showers allow scientists to conclude that: (a) the knee has an astrophysical origin;
(b) the ‘sharpness’ and the fine structure of the knee rule out ‘Galactic Modulation’
as the origin of the knee; and (c) most likely the knee is the result of the explosion
of a single, recent, nearby supernova.
Cosmic Dust (rewrite)
1 atom/cm
3
is the density of gas in interstellar space in our galaxy. Cosmic dust
would presumably be grains of condensed atoms bound together. Presolar grains
are individual dust grains that formed around other stars found within meteorites.
Most of the solar system was homogenized rather well in formation, and then
there was fractionation of material with distance from the Sun, proportionately
driving the lighter, more volatile elements and isotopes further out. These presolar
grains are identified by their isotope abundances being starkly different from solar
system abundances. Presolar grains are certainly one sample of what one might
call cosmic dust, but dust in nebula or around other stars would also qualify, and
the cosmic rays we measure with instruments like SuperTIGER have a greater
fraction of material that condenses into dust grains over the volatile elements that
remain as gas. (by Dr. Brian Rauch)
Elastic Limit
The maximum stress which a material can endure without causing permanent
deformation upon complete removal of the load. This is often different from the
proportional limit of stress-strain behavior.
338 Glossary and Terminology
Cherenkov radiation is electromagnetic radiation emitted when a charged particle
passes through a dielectric medium at a speed greater than the phase velocity of
light in that medium. (Note: I have seen a lot of this radiation looking into spent
fuel pools.)
Creep
A gradual elongation of material when under a constant load at a constant
temperature.
Cosmic Ray Knee
A sudden steepening of the cosmic ray energy spectrum (the knee) is observed at
an energy of about 3 PeV (1 PeV = 10
15
eV). The recent results of extensive air
showers allow scientists to conclude that: (a) the knee has an astrophysical origin;
(b) the ‘sharpness’ and the fine structure of the knee rule out ‘Galactic Modulation’
as the origin of the knee; and (c) most likely the knee is the result of the explosion
of a single, recent, nearby supernova.
Cosmic Dust (rewrite)
1 atom/cm
3
is the density of gas in interstellar space in our galaxy. Cosmic dust
would presumably be grains of condensed atoms bound together. Presolar grains
are individual dust grains that formed around other stars found within meteorites.
Most of the solar system was homogenized rather well in formation, and then
there was fractionation of material with distance from the Sun, proportionately
driving the lighter, more volatile elements and isotopes further out. These presolar
grains are identified by their isotope abundances being starkly different from solar
system abundances. Presolar grains are certainly one sample of what one might
call cosmic dust, but dust in nebula or around other stars would also qualify, and
the cosmic rays we measure with instruments like SuperTIGER have a greater
fraction of material that condenses into dust grains over the volatile elements that
remain as gas. (by Dr. Brian Rauch)
Elastic Limit
The maximum stress which a material can endure without causing permanent
deformation upon complete removal of the load. This is often different from the
proportional limit of stress-strain behavior.
338 Glossary and Terminology