Gamma sources

Irradiation Conditions. The gamma (cobalt-60) radiation facility and the source calibration are described by Holm and Jarrett (4). Irradiation doses were 3-4 Mrad and 6-7.5 Mrad at 9 X 102 rads per second for the screening study. Irradiation temperatures were 5, —30, and — 90°C. The gamma source was calibrated with the ferrous sulfate-cupric sulfate dosimeter. 

Milham, R. C. The Preparation of an Americium Gamma Source. Report... 

Protection Against Radiations from Sealed Gamma Sources (1960). [Superseded by NCRP Reports Nos. 33, 34, and 40] 26 Medical X-Ray Protection Up to Three Million Volts (1961). [Superseded by NCRP Reports Nos. 33, 34, 35, and 36]... 

As gamma rays pay no heed to lenses and mirrors, INTEGRAL is a rather special telescope, resembhng rather a nuclear physics installation than an astronomical instrument. As a result, its resolving power will be much lower than that of an optical, UV or X-ray telescope. The identification of gamma sources will thus require support from more conventional forms of astronomy. INTEGRAL is an ESA project. 

Protection Against Radiations from Sealed Gamma Sources (1960). [Superseded by NCRP Report Nos. 33, 34, and 40]... 

For the measurement of thickness and coverage (coatings) of very thin materials, the absorption of alpha radiation may be used as a measure of weight/unit area. For moderately thick materials, the beta radiation emitted by °Sr (strontium-90),35Kr (kryplon-85), or 14C (carbon-14) is used. For greater thicknesses, bremsstrahlung or gamma sources are used. 

If a gamma source is placed on one side of the welded metal, and a photographic film on the other side, weak points or air bubbles will show up on the film, like an X-ray. 

Apparatu8 constructed of the metals indicated y field indicates experiments carried out in the presence of a Co-60 gamma source ... 

Ey is the energy of the photon emitted by the gamma source at rest... 

The most commonly used sources of radiation are the 60 Co gamma source for continuous irradiation and pulsed high-energy (>1 MeV) electron beams for fast kinetic studies. Detailed descriptions of several such sources and accelerators are given in numerous books, as are the various methods used by radiation chemists for dosimetry, sample preparation and irradiation, and common product analysis. Several new developments in the analytical procedures, both in the determination of final products and in the direct observation of transient species, will be discussed below. 

Banford et al. studied the radiation effects on electrical properties of low-density polyethylene (LDPE) at 5 K with the use of a 60Co gamma source and a thermal nuclear reactor [86]. They reported that both the electrical conductivity and the dielectric breakdown strength of LDPE at 5 K were not significantly affected by radiation absorbed doses up to 10s Gy, but an erratic pulse activity under high applied fields was observed in the sample irradiated at 106 Gy. 

The standard sources have been designed in order to allow the calibration of all the classical detectors of a, p, e, y, n, X radiation (ionisation chambers, Geiger-Miiller or proportional counters, scintillation or solid-state counters, etc.). They are classified as alpha sources, electron sources, beta sources, gamma sources, neutron sources. X-ray sources, heat flux sources, and sources for radiation protection dose meters. 

Tl. Takahashi, I. T., and Blanchard, F. A., Counting quenched liquid scintillation samples by using an outside-the-instrument gamma source and an external-standard channels-ratio method. Anal. Biochem. 35, 411-423 (1970). 

The contemporary observation of the full sky with at least two neutrino telescopes in opposite Earth Hemispheres is an important issue for the study of transient phenomena. Moreover v events detection from the Northern Hemisphere is required to observe the Galactic Centre region (not seen by ICECUBE), already observed by HESS as an intense TeV gamma source. In the Norther Hemisphere a favourable region is offered by the Mediterranean Sea, where several abyssal sites (> 3000 m) close to the coast are present and where it is possible to install the detector near scientific and industrial infrastructures. 

AMS will search for dark matter through antimatter from these annihilation channels. Electron and positron fluxes will be detected up to 300 GeV and antiproton flux up to 400 GeV. After 3 years, AMS-02 will collect 107 e with E < 10 GeV, 106 e+ with E < 5 GeV and 106 p with E < 5 GeV (Figure 3). AMS will also contribute to the study of gamma diffuse background, both galactic and extragalactic and gamma source location [4],... 

A dose of 10 R Co gamma rays reduced the diamagnetic susceptibility of a-lead azide more than threefold [53]. Colloidal lead azide, irradiated with a Co gamma source with exposures of 2.5, 7.5, and 22.5 X lO R, had its impact sensitivity increased from 12 to 6 in. with the Picatinny impact test [57,58]. 

Irradiation. All irradiations were performed at the University of Maryland with a 25,000 curie cobalt 60 gamma source. The absorbed dose rate of 1.2 Mrad per hr was determined by ferrous sulfate dosimetry. All samples were irradiated under secondary electron equilibrium conditions. Following irradiation, all samples irradiated in vacuum were annealed in vacuum at 380 K for 24 hours this treatment reduces the long-lived radical concentration to undetectable levels. 

The samples were irradiated in a 60Co gamma source at a dose rate of 0.9 X 1017 e.v./ml. min. The electrical conductivity of the samples was measured either during or after irradiation. In the latter case the conductivity (or the optical) measurements were begun about 1 minute after termination of the irradiation. The samples were protected from the incidence of light when transported from irradiation to measurement. 

Certain radioactive decay processes can be used to provide a source of gamma radiation for radiolysis. One particularly useful isotope is Co, which is produced by thermal neutron bombardment of Co. Co has a half-life of 5.27 yr and emits gamma radiation with an average energy of 1.2 MeV. Another commonly used gamma source is Cs (half-life 30.17 yr, 0.66 MeV). 

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