What Is The Change In Atomic Number Caused By The Emission Of Gamma Radiation?

Gamma Radiation

Quasars

B.Yard. Peterson , ... M. Vestergaard , in Encyclopedia of Physical Science and Technology (Tertiary Edition), 2003

III.A.1 Gamma Rays

Strong γ-ray emission is detected in blazars only. Gamma-ray emission is strongly correlated with radio emission and radio variability. The γ-rays are almost certainly relativistically beamed emission that arises in jets (Department II.C), and therefore are seen only when the jet is directed towards the observer. The γ-ray emission is too highly variable. Gamma rays are probably the result of inverse-Compton upscattering of lower energy photons. The origin of the seed photons is not known, merely might exist either the low-frequency synchrotron photons or photons from the accretion disk.

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Radiation — EFFECTS AND USES

JERRY B. MARION , in Physics in the Modern World (Second Edition), 1981

Gamma Rays and X Rays

Gamma rays are high-free energy electromagnetic radiation and, except for energy, are identical with 10 rays, light photons, and radio waves. For most radiations applications, high energy is required; therefore, in this chapter we discuss just γ rays and Ten rays, and nosotros are not concerned with lower-energy radiation.

The classification of a breakthrough as a γ ray or an X ray depends only on its origin and not on its energy. Any electromagnetic radiation that is emitted from a nucleus is called a γ ray. If the radiation originates in the diminutive electron shells it is chosen an X ray. Thus, a twenty-keV y ray and a 20-keV X ray could be emitted from the same atom and the radiations would be exactly the same.

Gamma rays from radioactive decay processes outcome but in the deexcitation of a nucleus that is left in an excited energy state following α or β disuse (see Fig. 20-four). The emission of γ radiation does not involve a nuclear transmutation. The nuclear isotope does non change during a γ-ray emission process.

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Nuclei and Nuclear Radiation

Ilya Obodovskiy , in Radiations, 2019

2.seven.3 Gamma Radiation of Nuclei

Gamma radiation is a rigid electromagnetic radiations at the short-wave border of the electromagnetic wave spectrum. By tradition, gamma radiation refers to radiations originating in nuclei, and X-ray radiation arises in the electron shells of atoms.

The residue mass, the electrical charge, and the magnetic moment of the gamma quantum equal to nada.

Gamma radiation is emitted, absorbed, and transported as separate quanta. The energy of gamma breakthrough is related to the frequency ν and the wavelength λ by the relation

(2.29) $\mathrm{Eastward}=h\nu =hc/\lambda \text{.}$

Gamma quanta are emitted when the nucleus passes to the ground state from the excited ones, which are formed either in the processes of alpha or beta decay, or in nuclear reactions.

The energy spectrum of gamma radiation is always discrete.

The probabilities of gamma transitions are determined by the pick rules in a style coordinating to that for optical spectra.

For boosted information about gamma radiation and gamma sources see Section 17.2 and about gamma interaction with affair see Chapter 6.

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CHERENKOV COUNTING

MICHAEL F. L'ANNUNZIATA , in Handbook of Radioactivity Assay (Second Edition), 2003

10. GAMMA-RAY DETECTION

Gamma radiation tin can produce Cherenkov photons indirectly through gamma-ray photon-electron interactions as the gamma radiation travels through a transparent medium. The number of photons emitted by a Cherenkov detector is more often than not only approximately 1% of the number emitted by a skilful scintillator for the same gamma-ray energy loss ( Sowerby, 1971). Although the Cherenkov detection efficiencies of gamma radiation are depression, unique applications of the Cherenkov effect for the analysis of gamma radiation exist, and the effect plays an of import role every bit a source of groundwork in various methods of radioactive decay assay. Ane should always be aware of the potential for gamma radiation to produce Cherenkov photons.

The transfer of gamma-ray photon free energy to an atomic electron via a Compton interaction produces a Compton electron with energy, E _e, within the range between nix and a maximum divers by

(9.34) $0<E_e\le E_{\gamma }-\frac{E_{\gamma }}{1+\mathrm{ii}{\mathrm{East}}_{\gamma }/0.511}$

where E _γ is the gamma-ray photon energy in MeV and the term E _γ –(E _γ/(1 + 2 E _γ/0.511)) defines the Compton-electron energy at 180° Compton scatter according to equations previously defined in Chapter ane. To produce Cherenkov photons the Compton electron must possess energy in excess of the threshold free energy, Eth, defined by Eq. 9.5 previously in this chapter. For example, the threshold energy for electrons in water (n = 1.332) according to Eq. 9.5 is calculated to be 263 keV. A Compton electron must possess, therefore, energy in excess of 263 keV to produce Cherenkov photons in water. In this example, however, the gamma-ray photon must possess an energy in backlog of 422 keV calculated according to the inverse of Eq. 1.109 or

(9.35) ${\mathrm{Due\; east}}_{\gamma }={\mathrm{Due\; east}}_{\text{due east}}+{\mathrm{Due\; east}}_{\gamma }^{\text{'}}+\phi$

where E _east is the Compton electron energy, E′_γ is the energy of the Compton-scattered photon, and ϕ is the electron bounden energy. The electron binding energy is negligible and tin can exist ignored. Thus, Eq. 9.35 can becomes

(9.36) $E_{\gamma }=E_{\text{eastward}}+\frac{E_{\gamma }}{\mathrm{i}+2{\mathrm{Eastward}}_{\gamma }/0.511}$

For example, if we accept E _e to be 0.263 MeV, the threshold electron free energy for Cherenkov production in h2o, and E′_γ as the scattered-photon energy at 180° Compton scatter, Eq. 9.36 becomes

(9.37) $E_{\gamma }=0.263\text{MeV+}\frac{{\mathrm{East}}_{\gamma }}{\mathrm{one}+2{\mathrm{Due\; east}}_{\gamma }/0.511}$

where Eastward _γ = 0.422 MeV is the threshold gamma-ray energy for the production of Cherenkov photons in water. Threshold energies will vary co-ordinate to the alphabetize of refraction of the medium, and these are provided graphically in Fig. 9.13 for gamma radiation and electrons or beta particles.

FIGURE ix.thirteen. Threshold free energy for Cherenkov radiations as a office of index of refraction of the detector medium for gamma rays and electrons or beta particles. The threshold energies for electrons or beta particles are calculated co-ordinate to Eq. 9.5, and the gamma-ray threshold energies are calculated according to Eq. 9.36 equally the gamma rays that yield electrons of the threshold energy via 180° Compton besprinkle.

Although Cherenkov detection efficiencies for gamma radiations are low, the phenomenon is applied to create threshold detectors. A multifariousness of media, which vary significantly in refractive index, can exist selected to discriminate against gamma radiation of specific energy. For example, silica aerogels of depression refractive index (n = i.026) tin can exist used to discriminate confronting gamma rays of relatively loftier free energy (two.0 MeV) while a transparent medium of high refractive index such as flint glass (n = 1.72) can serve to discriminate against relatively low-energy gamma radiation (0.25 MeV). Figure 9.thirteen illustrates the potential for gamma-ray energy discrimination according to refractive index of the detector medium.

Another awarding of gamma-ray detection is the Cherenkov verification technique used in nuclear safeguards to verify the authenticity of irradiated nuclear fuel, which is one of the of import tasks performed past the International Diminutive Energy Agency (IAEA). The IAEA nuclear safeguards plan audits the national declarations of fuel inventories to insure that no illicit diversion of nuclear material has occurred. High levels of gamma radiation are emitted by fission products in irradiated nuclear fuel. The irradiated fuel stored nether water will produce Cherenkov light as a result of Compton handful in the water surrounding the fuel. A Cherenkov Viewing Device containing a UV-transmitting lens coupled to a UV-sensitive charge-coupled device (CCD) and image monitor enables the real-time imaging of the UV low-cal portion of the Cherenkov radiations in the presence of normal room lighting (Attas et al., 1990, 1992, 1997; Attas and Abushady, 1997; Kuribara, 1994; Kuribara and Nemeto, 1994, Lindsey et al., 1999). The presence of fission products and the nature of their distribution, every bit indicated past the Cherenkov glow, is used as evidence of fuel verification.

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Gamma-Ray Astronomy

J.Gregory Stacy , W.Thomas Vestrand , in Encyclopedia of Physical Scientific discipline and Applied science (Third Edition), 2003

III.B.1 Atmospheric Gamma Rays

Gamma rays are produced in copious quantities in the upper atmosphere of the Earth every bit a consequence of cosmic-ray interactions. Balloon experiments rely typically on the "growth curve" technique to judge the contribution of atmospheric gamma rays to the observed event count charge per unit. In this method, the total count rate of the detector is determined every bit a function of the residual atmosphere remaining above the balloon-borne instrument every bit it rises to float altitude. Since the downward vertical atmospheric gamma-ray flux is causeless to exist zero at the top of the atmosphere, all remaining result counts are assumed to be truly cosmic in nature (or locally produced within the experiment itself, meet following). Both Monte Carlo calculations and semiempirical models are employed to test the reliability of such measurements.

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THE COINCIDENCE METHOD

A.H. WAPSTRA , in Alpha-, Beta- and Gamma-Ray Spectroscopy, 1968

§ 7 Geometries in γ-γ coincidences

Difficulties similar to those in the preceding paragraph arise when the two detectors 'see' i some other, now due to Compton handful processes. Consider two γ-ray counters arranged as in Fig. 15a and intended to measure a sample with the disuse scheme of Fig. 14. We will then certainly discover too many coincidences: there will be a quite considerable probability that 1300 keV γ-rays will be backscattered at 1 detector, loosing at that place about 300 keV, and causing the remainder of its energy to be detected in the other detector. Once again, an system as in Fig. 15b can prevent this trouble merely information technology will requite much lower efficiencies; and for favorable energies the geometry of Fig. 15c can help without reducing the efficiencies too much. In cases where one wants to mensurate coincidences between two γ-rays both in the region of backscattered radiation, the arrangement of Fig. 17b offers some other possibility.

Fig. 17. Geometries for measuring γ-γ coincidences; (a) applies to sources where positons are present. The source is mounted betwixt absorbers in order to obtain that all annihilations accept place virtually the source

A special disadvantage is present in the geometries of Fig. 15a and c and Fig. 17b if the source emits positons stopped well-nigh the source. The fact that one annihilation quantum is registered in one detector entails here a strongly enhanced probability that the other detector absorbs the other one, due to the very stiff angular correlation in the preponderant case of ii quanta annihilation. If this is objectionable, e.k. in order to avoid strong piling up, ane may identify the source a picayune aside as shown in Fig. 17a.

Gamma-rays above 1 MeV may have considerable pair germination cross sections ¹² , so that anything radiation may accompany their absorption. Therefore, also in their detection the system of Fig. sixteen can be used. (The optimum diameter of a central NaI(Tl) crystal in such an arrangement is about 4 cm, since for larger thicknesses, at least one of the anything quanta has too big a probability for absorption.) The γ-rays volition and so be detected as relatively narrow single lines at 1022 keV lower energies, which may be a considerable advantage. ^*

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Gamma-Ray Spectroscopy

R.F. Casten , C.W. Beausang , in Encyclopedia of Physical Science and Engineering (Third Edition), 2003

Two.B.iii Ultra-High Energy Resolution Spectroscopy: Crystal Diffraction

Gamma-rays are, after all, electromagnetic photons, and under certain circumstances their wave properties may exist used in their detection and measurement. Indeed, the ultimate in current gamma-ray energy resolution and measurement precision is obtained by the utilise of crystal diffraction. With such techniques it is routine to measure a 1-MeV gamma-ray with an free energy resolution of ∼3   eV and an energy precision of better than one   eV. The cost, all the same, is low efficiency and the demand to scan the free energy spectrum one small-scale energy bite at a time.

The technique uses Bragg diffraction from a nearly perfect crystal, unremarkably of Si. As for optical and X-ray transitions, the gamma-ray wavelength λ and diffraction angle θ are related by the Bragg police: northwardλ   =   iid sin θ, where the lattice spacing d is known to an accuracy of 1 role in 10¹⁰ and due north is the order of diffraction. Clearly, the resolution scales with n. Higher order diffraction gives greater dispersion and, hence, energy precision, although the efficiency generally falls off with northward. The accurateness depends on the precision of the angle measurement. In the realization of this technique at the Institut Laue Langevin in Grenoble, in the GAMS (GAMma-ray Spectrometer) family of instruments, accuracies of the latter are typically in the milli-arc seconds range(Koch et al., 1980). Given the nature of the technique, the gamma-ray energy spectrum is stored energy interval past interval rather than sampled fully at each betoken in time. An example of a crystal diffraction spectrum compared to the corresponding Ge detector spectrum is shown inFig. 3b. Generally speaking, crystal spectrometers offer the greatest advantages over Ge detectors for gamma-ray energies below ∼i   MeV. At higher energies their efficiency drops quickly, and hence, lower orders of diffraction are used with poorer free energy resolution.

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Gamma- and X-Radiations — Photons

Michael F. L'Annunziata , in Radioactivity, 2007

3.1 INTRODUCTION

Gamma radiations is electromagnetic radiation that is emitted by an unstable nucleus of an cantlet during radioactive decay. A nucleus in an unstable state may fall to a more stable state by the emission of energy as gamma radiation. The radiations has a dual nature, that of a wave and a particle with zero mass at rest. Information technology was Albert Einstein who showtime demonstrated the dual nature of electromagnetic radiation when he explained the photoelectric outcome. He thus discovered the uncomplicated particle known every bit the photon, which is electromagnetic radiation with its particulate nature. Another origin of gamma radiations is via the miracle referred to as annihilation whereby a positron coming to residuum encounters an electron, its antiparticle, and the two particles are annihilated. Their annihilation results in the conversion of their mass into energy equally gamma radiation. The amount of free energy produced by this process is equivalent to the mass of the two electrons annihilated according to Einstein's equation of equivalence of mass and free energy ( E = mc ²). ten-radiation is electromagnetic radiation with a dual nature of moving ridge and particle, like gamma radiation; still, x-radiation may originate from electron free energy level transitions in an unstable cantlet. The transition of electrons from higher to lower energy states may result in the emission of x-radiations. Also ten-radiation may be emitted when a charged particle decelerates in a serial of collisions with atomic particles. For case, when a high-free energy electron or beta particle traveling through matter approaches a nucleus, the electron may be deflected and caused to decelerate with the emission of x-radiation referred to as Bremmstrahlung or "braking radiation". This affiliate deals with the origins and properties of gamma- and 10-radiation and their mechanisms of interaction with matter.

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Planets and Moons

P. Falkner , ... R. Schulz , in Treatise on Geophysics, 2007

10.18.iv.vii Gamma-Ray Spectrometer

Gamma-ray spectroscopy (GRS) is a well-established technique for determining the elemental composition of the surface of planetary bodies. Measurements can exist performed either from orbit or straight on planetary surfaces. In situ measurements on surfaces are important since they provide direct analysis without the demand to compensate for atmospheric effects or other contributions. Thus, surface measurements tin can verify and extend the interpretation of orbital measurements and provide a better approximate of the elemental composition, but are in nigh cases limited to local measurements merely.

The detected gamma rays arise from two sources: gamma rays emitted spontaneously by naturally occurring radioactive elements like Chiliad, Th, and U and catholic-ray induced gamma rays emitted by elements like H, C, O, Si, and Fe. The nucleus of each chemical element produces a unique gear up of gamma-ray lines, and the technique of gamma spectroscopy allows the unique identification of these lines and therefore the specific chemical element and its relative abundance. The ambient cosmic-ray flux produces neutron-induced reactions on elements in the planetary surface, which in turn produce the characteristic γ-rays that are used to determine the elemental concentration. A scintillator (eastward.g., cesium iodide (CsI), LuAP, or LaBr3) is used to catechumen the γ-ray into low-cal emission, which is detected by sensitive big photodiodes. The background provided by cosmic rays and by the spacecraft is a source of dissonance. Mars Odyssey GRS, for example, was mounted on a 6   m boom to reduce the S/C groundwork for the measurements (Boynton et al., 2004). The utilise of anti-Compton shielding, of the same or unlike detector material, is often used to meliorate the quality of the received spectra by rejection of γ-rays that practice non come from the planetary surface, or are resulting from cosmic-ray interactions with the spacecraft material. Of import musical instrument factors are the relative precision of the scintillator material, sensitivity to radiation damage, breakthrough efficiency of the readout photo diodes, and the capability to suppress groundwork counts. Since the gamma-ray spectrometer sensitivity increases with the square root of the integration time, the expected integration times range from several orbits for the natural radio nuclides to several months for the cosmic-ray induced events. Of course, the sensitivity is also a stiff role of the efficiency and free energy resolution of the instrument.

Surface compositions finally are deduced from a comparison between the γ-ray spectra emitted by an area of the planetary surface with simulations based on calculated fluxes of causeless surface composition. By applying an iterative procedure, it is possible to derive a chemical limerick that best fits the measured in-orbit fluxes.

Examples of gamma-ray spectrometers based on either Ge-detectors or scintillators are the gamma-ray and neutron spectrometer (GNRS) on Messenger (Burks et al., 2004) or the Mercury Gamma-ray and Neutron Spectrometer (MGNS) (Kozyrev et al., 2006) on the BepiColombo Mission to Mercury.

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Nuclear Physics

Christopher R. Gould , ... Philip J. Siemens , in Encyclopedia of Physical Scientific discipline and Technology (3rd Edition), 2003

7.B Other Particles

Gamma rays, electrons and positrons, muons, pions and other mesons, and antiprotons accept been used as projectiles to bombard nuclei. Each is unique in probing unlike aspects of nuclear structure: Electrons and muons, as discussed in Section 3.A, can be used to explore nuclear charge distributions considering they interact as signal particles and only through the electromagnetic field. Photons, of course, also interact merely electromagnetically, and eolith a discrete amount of free energy and momentum upon absorption. Pions interact with nuclei through the strong force; they tin be absorbed (depositing the large rest mass of the pion as energy of excitation), scattered (with target excitation), or undergo accuse exchange ( ${\pi }^{+}{+}_{\text{Z}}{\text{X}}_{\text{N}}\to {\pi }^0{+}_{\text{Z}+\mathrm{i}}{\text{X}}_{\text{N}-1},$ and similarly for the other charged pions) or, more rarely, double charge exchange ( ${\pi }^{+}{+}_{\text{Z}}{\text{Ten}}_{\text{N}}\to {\pi }^{\mathrm{-}}{+}_{\text{Z}+\mathrm{two}}{\text{10}}_{\text{N}-2},$ etc.).

Antiprotons collaborate strongly with nuclei and also annihilate hands. Therefore, they explore the periphery of nuclei. Like other negatively charged particles, they can also course hydrogen-like atoms with nuclei. From the spectrum of gamma rays produced through diminutive transitions, data on their interaction with nuclei can be deduced.

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