Spectra, gamma-ray

In terms of what is measured or observed, there are (1) portions of the electromagnetic spectrum gamma-ray, cosmic ray, x-ray, ultraviolet, infrared, far-infrared, microwave, and radiowave instruments (2) regions pertaining to the energies of particles beta ray (electrons), protons, neutrons, and mass associated instruments and (3) instruments dealing with other spectra such as radioactive decay and Mossbauer effects. 

The outside layer is 14 cm of tungsten, which serves both to radiate absorbed x-ray and particle energies at 2000 K and to moderate the neutron spectrum. A layer of high temperature carbon insulation further softens the spectrum. Gamma rays generated in the outer layers are absorbed in a Pb Li layer which melts at 507 K and provides thermal capacity. Aluminized mylar super insulation follows, and a B C and W gamma absorber is added inside the superinsulation. The superconductor is NbTi stabilized with A1 in a Cu matrix. Construction of the superconductor and dewar is shown in Fig. 5. The coil carries 4.8 kA/cm at 8 T. The fractional volumes... 

Gamma rays The highest-energy form of electromagnetic radiation, above the X-ray portion of the spectrum. Gamma rays have energies measured in millions of electron volts and higher. 

Gamma rays of various energy are emitted by potassium-40, thorium, uranium, and the daughter products of these two last elements contained in the earth formations surrounding the borehole. These elements occur primarily in shales. The gamma rays reaching the borehole form a spectrum typical of each formation extending from a few keV to several MeV. 

Spectral Gamma Ray Log. This log makes use of a very efficient tool that records the individual response to the different radioactive minerals. These minerals include potassium-40 and the elements in the uranium family as well as those in the thorium family. The GR spectrum emitted by each element is made up of easily identifiable lines. As the result of the Compton effect, the counter records a continuous spectrum. The presence of potassium, uranium and thorium can be quantitatively evaluated only with the help of a computer that calculates in real time the amounts present. The counter consists of a crystal optically coupled to a photomultiplier. The radiation level is measured in several energy windows. 

X rays comprise that portion of the electromagnetic spectrum which lies between ultraviolet and gamma rays. The range of wavelengths is typically from about 0.01 to 100 A. Because of their very short wavelengths, X rays are powerful probes of atomic structure. 

Gamma spectroscopy is a radiochemistry measurement method that determines the energy and count rate of gamma rays emitted by radioactive substances. Gamma spectroscopy is an extremely important measurement. A detailed analysis of the gamma ray energy spectrum is used to determine the identity and quantity of gamma emitters present in a material. 

Interrogating the light from stars and the absorption features of atoms and molecules in-between requires some fairly complicated optics in the form of a telescope. However, the telescopes are not restricted to the parts of the electromagnetic spectrum that you can see but use radiation from microwaves to gamma rays to observe the Universe. There is too much to learn about the optics or even adaptive optics of telescopes to be discussed here but there are some properties of telescopes that we must know because they are important for the identification of atoms and molecules. We shall discuss three telescope considerations the atmosphere, the spatial resolution and the spectral resolution. 

X-rays are electromagnetic radiation lying between ultraviolet and gamma rays in the electromagnetic spectrum. The wavelength of x-rays is expressed in angstrom units (A) 1 A is equal to 10-8 cm. 

Figure 5.24. Gamma-ray spectrum of preconcentrated river water after short irradiation. Irradiation time 5 min thermal-neutron flux 1 x 1013 n cm 3 s"1 decay time 3 d counting time 1000 s. Source [627]...

Mossbauer spectrum spect A plot of the absorption, by nuclei bound in a crystal lattice, of gamma rays emitted by similar nuclei in a second crystal, as a function of the relative velocity of the two crystals. mus.bau-or. spek-trom mountain blue inorgchem 2CuC03-Cu(0H >2 Ground azurite used as a paint pigment. 

Electromagnetic radiation that has a short wavelength and high frequency, such as gamma rays, is at the high energy end of the electromagnetic spectrum. 

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