, in an experiment with 5-MeV electrons a very small portion of the x-rays reached an energy level of 5 MeV, whereas the highest intensity was observed near 0.3 MeV (11). The x-rays are at least as penetrating as cobalt-60 gamma rays so that food products of about 30 cm thickness can be irradiated without difficulty. The possibility of using either x-rays or electrons in the same facility is an attractive feature of this technology (12-15). A comparison of the theoretical throughput of various irradiators is possible on the basis that 67,578 Ci (or 2.5 TBq) of 60Co or 308,641 Ci (11.4 TBq) of ,37Cs emits 1 kW of gamma radiation. Furthermore, a 1-kW source, assuming 100% efficiency, can process 360 kg of goods with a dose of 10 kGy in 1 h (2). This immediately allows comparison with electron accelerators, the beam power of which is expressed in kilowatts. In well-designed facilites we can assume 50% efficiency for the electron beam, 30% efficiency for a ^C o source, and 20% efficiency for a ,37Cs source (one-third less efficiency for l37Cs than for 60Co because of higher self-absorption). The 1-

1995 ◽  
pp. 41-42
Keyword(s):  
Electron Beam ◽  
Energy Level ◽  
Gamma Radiation ◽  
Gamma Rays ◽  
Food Products ◽  
Beam Power ◽  
X Rays ◽  
Attractive Feature ◽  
Electron Accelerators

Some of these could also be operated in the energy range above lOMeV for experiments designed to determine at which energy level radioactivity can be induced in the irradiated medium. A linac with a maximum energy of 25 MeV was commissioned for the U.S. Army Natick Research and Development Labora­ tories in 1963. Its beam power was 6.5 kW at an electron energy of 10 MeV, 18 kW at 24 MeV. Assuming 100% efficiency, a 1-kW beam can irradiate 360 kg of product with a dose of 10 kGy/h. The efficiency of electron accelerators is higher than that of gamma sources because the electron beam can be directed at the product, whereas the gamma sources emit radiation in all directions. An efficiency of 50% is a realistic assumption for accelerator facilities. With that and 6.5 kW beam power an accelerator of the type built for the Natick laboratories can process about 1.2t/h at 10 kGy. In Odessa in the former Soviet Union, now in the Ukraine, two 20-kW accelerators with an energy of 1.4 MeV installed next to a grain elevator went into operation in 1983. Each accelerator has the capacity to irradiate 200 t of wheat per hour with a dose of 200 Gy for insect disinfestation. This corresponds to a beam utilization of 56% (9). In France, a facility for electron irradiation of frozen deboned chicken meat commenced operation at Berric near Vannes (Brittany) in late 1986. The purpose of irradiation is to improve the hygienic quality of the meat by destroying salmonella and other disease-causing (pathogenic) microorganisms. The electron beam accelerator is a 7 MeV/10 kW Cassitron built by CGR-MeV (10). An irradiation facility of this type is shown in Figure . Because of their relatively low depth of penetration electron beams cannot be used for the irradiation of animal carcasses, large packages, or other thick materials. However, this difficulty can be overcome by converting the electrons to x-rays. As indicated in Figure 9, this can be done by fitting a water-cooled metal plate to the scanner. Whereas in conventional x-ray tubes the conversion of electron energy to x-ray energy occurs only with an efficiency of about %, much higher efficiencies can be achieved in electron accelerators. The conversion efficiency depends on the material of the converter plate (target) and on the electron energy. Copper converts 5-MeV electrons with about 7% efficiency, 10-MeV electrons with 12% efficiency. A tungsten target can convert 5-MeV electrons with about 20%, 10-MeV electrons with 30% efficiency. (Exact values depend on target thickness.) In contrast to the distinct gamma radiation energy emitted from radionuclides and to the monoenergetic electrons produced by accelerators, the energy spectrum of x-rays is continuous from the value equivalent to the energy of the bombarding electrons to zero. The intensity of this spectrum peaks at about one-tenth of the maximum energy value. The exact location of the intensity peak depends on the thickness of the converter plate and on some other factors. As indicated in Figure

1995 ◽  
pp. 40-40
Keyword(s):  
Electron Beam ◽  
Electron Energy ◽  
Maximum Energy ◽  
Metal Plate ◽  
Beam Power ◽  
X Rays ◽  
X Ray ◽  
Emit Radiation ◽  
Electron Accelerators ◽  
Gamma Sources

kW electron beam would thus process 180 kg of food or other materials, the 67,578-Ci 60Co would process 108 kg, and the 308,641-Ci 137Cs would process 72 kg, always with a dose of lOkGy in 1 h. If a 5-MeV electron beam were converted to x-rays with % efficiency and the x-ray beam were absorbed by the irradiated food with 50% efficiency, the electron beam power would have to be about 14.5 kW to process 180 kg with a dose of 10 kGy/h (12). If we recalculate this in each case for a throughput of 1.8t/h, the beam power or source load indicated in Table 2 is obtained. Many 60Co sources of this size exist all over the world, but not a single 137Cs source approaching 7 MCi exists anywhere. Electron accelerators of the capacity indicated in Table 2 are commer­ cially available. The possible throughput is only one of the parameters that influence the choice of a particular type of irradiator. Many other technical, economical, and, increas­ ingly, sociopolitical aspects must be taken into consideration. Technical considerations refer primarily to the different penetrating power of various types of radiation and to differences in dose rate. If large crates of potatoes are to be irradiated, it is obvious that a gamma source rather than an electron irradiator must be chosen. When the two types of gamma sources are compared, it must be considered that the use of Co, due to the higher penetrating

1995 ◽  
pp. 43-43
Keyword(s):  
Electron Beam ◽  
Dose Rate ◽  
Beam Power ◽  
X Rays ◽  
137Cs Source ◽  
Gamma Source ◽  
Electron Accelerators ◽  
The World ◽  
Gamma Sources ◽  
Technical Considerations

food was presented by McLaughlin and collaborators (29). Glover’s review (30) is less detailed but more recent. Dosimetry for food irradiation processing has reached a high level of perfec­ tion. Many standards for this purpose have been issued by the American Society for Testing and Materials (31,32). The role of dosimetry in good radiation processing practice is described in the Recommended International Code of Practice for the Operation of Irradiation Facilities Used for the Treatment of Foods (see Appendix II) and in a series of Codes of Good Irradiation Practice issued by ICGFI (International Consultative Group on Food Irradiation) (see Appendix III). With some food items, such as whole eggs (33) and ground com (34), it may be possible to use the food itself as a dose meter. This will be discussed in more detail in Chapter 5. As mentioned earlier, electron beams, on the one hand, and gamma rays and x-rays, on the other hand, differ greatly in their ability to penetrate matter. This has important consequences for the dose distribution in the irradiated medium. Since many foods consist mostly of water, the penetration of radiation in water is shown in Figure 14. When an electron beam penetrates an aqueous medium the dose somewhat below the surface is higher than at the surface. This is due to the formation of secondary electrons which, because of their lower energy, are more effectively absorbed than the primary electrons. Also, scattering causes some secondary electrons to escape from the surface in the direction opposite to that of the beam of primary electrons. Thus a 10-MeV electron beam giving a dose of 10 kGy at the surface will deposit about 12.5 kGy at 2 cm below the surface. As more and more primary electrons lose their energy by interacting with water molecules, the absorbed dose decreases with increasing depth and at about 5 cm the limit of penetration is reached. In contrast, the dose delivered by gamma rays decreases continuously. The rate of decrease is faster with 137Cs gamma radiation than with 60Co gamma radiation. With x-rays it depends on the energy of the x-ray-producing electrons. For practical purposes the penetration of 5-MeV x-rays is comparable to that of 60Co gamma rays. Two-sided irradiation permits processing of thicker packages with more uni­ form dose distribution, as indicated in Figure 15. If the density of the irradiated medium is less than that of water, e.g., in fatty foods or in dehydrated or porous foods, the depth of penetration is correspondingly greater. The 10-MeV electron beam, which barely reaches a depth of 5 cm in water, will reach approximately 10 cm at a density of 0.5g/cm3. From Figures 14 and 15 it is clear that an absolutely uniform dose distribution cannot be obtained, even if a material of uniform density is irradiated. If dose

1995 ◽  
pp. 52-52
Keyword(s):  
Electron Beam ◽  
Gamma Radiation ◽  
Gamma Rays ◽  
Dose Distribution ◽  
Food Irradiation ◽  
X Rays ◽  
Secondary Electrons ◽  
60Co Gamma ◽  
American Society ◽  
Primary Electrons

scholarly journals NEEDLE DETECTOR OF X-RAY AND GAMMA RADIATION

2017 ◽  
Vol 7 (1) ◽  
pp. 121-124
Author(s):  
Grzegorz Domański ◽  
Roman Szabatin ◽  
Piotr Brzeski ◽  
Bogumił Konarzewski
Keyword(s):  
Energy Spectrum ◽  
Gamma Radiation ◽  
Gamma Rays ◽  
Proportional Counter ◽  
Incident Radiation ◽  
X Rays ◽  
The Novel ◽  
Direction Parallel ◽  
X Ray ◽  
Gas Detector

The article presents the developed structure of the novel needle proportional gas detector (NPC – Needle Proportional Counter) used for the detection of X-rays and gamma rays. The advantage of the detector is its simple mechanical construction and the possibility of detection of incident radiation in a direction parallel to the needle. The measured energy spectrum of the isotope Fe-55 by means of the developed detector is presented.

An electromagnetic gamma-ray free electron laser

2013 ◽  
Vol 79 (6) ◽  
pp. 995-998 ◽  
Author(s):  
BENGT ELIASSON ◽  
CHUAN SHENG LIU
Keyword(s):  
Electron Beam ◽  
Theoretical Model ◽  
Gamma Rays ◽  
Free Electron ◽  
Free Electron Laser ◽  
Gamma Ray ◽  
High Energy ◽  
X Rays ◽  
High Energy Electron ◽  
Coherent Light

AbstractWe present a theoretical model for the generation of coherent gamma rays by a free electron laser, where a high-energy electron beam interacts with an electromagnetic wiggler. By replacing the static undulator with a 1-μm laser wiggler, the resulting radiation would go from X-rays currently observed in experiments, to gamma rays. Coherent light in the gamma-ray range would have wide-ranging applications in the probing of matter on sub-atomic scales.

scholarly journals Comparative study of radio-sensitivity and relative biological effectiveness of gamma rays, x-rays, electron beam and proton beam in short grain aromatic rice

2020 ◽  
Vol 80 (04) ◽  
Author(s):  
Deepak Sharma ◽  
Richa Sao ◽  
Parmeshwar K. Sahu ◽  
Gautam Vishwakarma ◽  
J. P. Nair ◽  
...  
Keyword(s):  
Electron Beam ◽  
Proton Beam ◽  
Gamma Rays ◽  
Relative Biological Effectiveness ◽  
Germination Percentage ◽  
Mutation Breeding ◽  
X Rays ◽  
X Ray ◽  
Biological Effectiveness ◽  
Radio Sensitivity

Knowledge about the type of mutagen used and its optimized dose are of paramount importance to design and implement any plant mutation breeding programme. Present study was first time carried out to evaluate the comparative effectiveness, radio-sensitivity behavior and relative biological effectiveness of four physical mutagens viz., gamma rays, X-rays, electron beam and proton beam on two short grain aromatic rice landraces viz., Samundchini and Vishnubhog. The seeds of these two varieties were treated with 15 different doses of all four mutagens, ranging from 50Gy to 750Gy with an interval of 50Gy. Germination percentage and seedling growth parameters were recorded at seven and 15 days after sowing, respectively in two replications. It was observed that germination percentage, shoot and root length of the seedling gradually declined with the increase in doses of all the physical mutagens. On the basis of these observations, LD50 and GR50 doses were calculated. The present study reports the optimum range of doses for gamma ray (280 to 350 Gy); electron beam (290 to 330Gy); X-ray (200 to 250 Gy) and proton beam (150 to 200Gy). GR50 doses were observed higher than LD50 doses for all the mutagens in both landraces. However, Samundchini showed higher LD50 and GR50 doses than Vishnubhog indicating later to be more radio-sensitive. Furthermore, both the genotypes were highly radio-sensitive for proton beam and least for gamma rays. Similarly, high relative biological effectiveness was observed for proton beam followed by X-ray, electron beam and gamma rays indicating their decreasing trend of penetration capacity and lethality. Results of present study will be useful for plant breeders to use the above mutagens in an appropriate dose for mutation breeding in rice.

scholarly journals Economical evaluation of radiation processing with high-intensity X-rays

Nukleonika ◽  
2020 ◽  
Vol 65 (3) ◽  
pp. 167-172
Author(s):  
Zbigniew Zimek
Keyword(s):  
Electron Beam ◽  
Electron Energy ◽  
High Power ◽  
High Intensity ◽  
Power Level ◽  
Unit Cost ◽  
Utilization Efficiency ◽  
Beam Power ◽  
X Rays ◽  
Radiation Processing

AbstractX-rays application for radiation processing was introduced to the industrial practice, and in some circumstances is found to be more economically competitive, and offer more flexibility than gamma sources. Recent progress in high-power accelerators development gives opportunity to construct and apply reliable high-power electron beam to X-rays converters for the industrial application. The efficiency of the conversion process depends mainly on electron energy and atomic number of the target material, as it was determined in theoretical predictions and confirmed experimentally. However, the lower price of low-energy direct accelerators and their higher electrical efficiency may also have certain influence on process economy. There are number of auxiliary parameters that can effectively change the economical results of the process. The most important ones are as follows: average beam power level, spare part cost, and optimal shape of electron beam and electron beam utilization efficiency. All these parameters and related expenses may affect the unit cost of radiation facility operation and have a significant influence on X-ray process economy. The optimization of X-rays converter construction is also important, but it does not depend on the type of accelerator. The article discusses the economy of radiation processing with high-intensity of X-rays stream emitted by conversion of electron beams accelerated in direct accelerator (electron energy 2.5 MeV) and resonant accelerators (electron energy 5 MeV and 7.5 MeV). The evaluation and comparison of the costs of alternative technical solutions were included to estimate the unit cost of X-rays facility operation for average beam power 100 kW.

scholarly journals Durability of Radiation-Sterilized Polymers XV : Comparison of Damage on Polypropylene Irradiatated by Converted X-rays with Those by Gamma-rays and Electron Beam

1991 ◽  
Vol 61 (9) ◽  
pp. 387-392
Author(s):  
Fumio Yosii ◽  
Hiromi Sunaga ◽  
Kiezo Makuuchi ◽  
Isao Ishigaki ◽  
Kamarudim BAHARI
Keyword(s):  
Electron Beam ◽  
Gamma Rays ◽  
X Rays

X-ray micro tomography in the scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 106-107 ◽  
Author(s):  
W. Brünger
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Target Surface ◽  
The Body ◽  
X Rays ◽  
Cross Sectional ◽  
X Ray ◽  
Micro Tomography ◽  
Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

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