RADIATION PROTECTION - ILEA

8 | Some Interesting Energy Values 17
8 Some Interesting Energy Values
The residual radiation from the Big Bang, the cosmic background radiation
that permeates all space, has a temperature of 2.7 K. The most probable
energy of the radiation photons is kT = 0.00023 eV. The wavelength is
0.538 cm and the frequency is 56 GHz.
The energy of 100 MHz photons from an FM radio station is 4.14 ×
10 −7 eV.
Photons of infrared radiation have energies ranging from 0.004 to
1.6 eV.
Photons of visible light have energies between 1.6 and 3.3 eV. The corresponding
wavelengths are from 760 nm (red) to 380 nm (violet).
Ultraviolet light photons UV-B (radiation in the skin-burn region)
range from 3.9 eV to 4.4 eV (320–280 nanometers)
The initial temperature in an H-bomb explosion is 100,000,000 K, so
the most probable energy of the photons of thermal radiation, kT, equals
8600 eV, classified as low-energy x rays. These x rays are absorbed in a
short distance (within meters) in air, heating the air to very high temperatures
and producing the characteristic fireball.
A chest x ray is produced by photons with maximum energies between
75 and 120 keV.
Cobalt-60 emits gamma rays of two energies, 1.18 MeV and 1.33 MeV.
Linear electron accelerators used in radiation therapy typically produce
x rays with maximum energies in the range of 18 to 25 MeV.
The Stanford linear accelerator accelerates electrons over a distance of 3
km to achieve energies of 50 GeV for research in high-energy physics.
The Tevatron, located at Fermi National Accelerator Laboratory, is currently
the world’s most powerful accelerator, producing protons with energies
of 1.8 TeV (1.8 × 10 12 eV).
The highest energy ever recorded was that of a cosmic ray, at 3 × 10 8
TeV.