Varian Linatron High-Energy X-ray Applications 2007

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FIGURE 2-3. Half-value layer for propellant as a function of energy. FIGURE 2-4. Half-value layer for lead as a function of energy. I Z 0 a a I 6 0 0 0 5 10 15 20 25 30 TARGET INCIDENT ELECTRON ENERGY(MeV) FIGURE 2-5. Half-value and tenth-value layer for concrete as a function of energy. page 8 19.8 13.2 6.6 E 0 z a a I- Z w Half-Value Thickness Versus Energy Spectrum The unfiltered X-rays emitted by the Linatron target contain photons varying in energy, with the highest being equal to the incident electron energy. This collection of photons makes up the energy spectrum of the Linatron Xray beam. This continuous spectrum of energies is often termed “white” radiation. The emerging Linatron X-ray beam becomes filtered and modified by the obstacles in its path. If an absorber with a thickness that reduces beam intensity to one-half is placed in the beam, that thickness can be identified as the first HVL. That first layer will be thinner than subsequent HVLs because less material is needed to reduce the intensity of a beam containing large numbers of lower energy photons. The first two layers modify the beam, filter it, and make it “harder”. After about two HVLs, additional absorber material no longer changes the distribution of X-ray energies and a constant value of the HVL results. This is described as the equilibrium state. The values plotted in Figures 2-2 to 2-5 are equilibrium values. Varian Linatron applications
Linatron Radiographic Characteristics General Description The Linatron is an RF-powered electron linear accelerator system that produces a very intense beam of high-energy X-rays for industrial radiography. The system consists of an RF unit, an X-ray head, a modulator and a control console. In addition, an optional temperature control unit is available to provide the required 30° C. liquid coolant supply to the Linatron. Table 3-1 lists the important performance characteristics of Linatron Models M3, M6, M9 and K15. X-ray Quality As noted in Section 2, the most useful measurement of Xray beam quality is the Half-Value Layer (HVL), which is derived from the broadbeam attenuation curve or from the attenuation coefficient. Table 3-2 lists the broadbeam HVL for several common materials for the LINATR0N energies. Linatron Model M3 M3A M6 M6A M9 M9A K15A Table 3-1 Linatron Performance Characteristics Energy (Nominal Peak) (MeV) 3 1 - 3 6 3.5 -6 9 5 - 9 9 - 15 page 9 Field Coverage, Beaming and Field Flatness Field Coverage. X-rays emitted from an X-ray machine create secondary radiation (scatter) that can blur and distort the image on the radiograph when they strike objects located near the item under inspection. Scatter can also fog the film and cause a corresponding loss in image contrast and sensitivity. Therefore, the primary X-ray beam should be restriced to the approximate size and area of the actual inspection. This is accomplished by a device known as a source collimator, which is a shielding device located at the source of the x-ray beam. These vary in geometry and density to control the shape of the beam. Frequently, custom collimators are specified by the customer to meet the needs of a specific application. The standard collimator opening for the Model M9 Linatron is a 30° cone and the standard collimator opening for the K15 Linatron is a 15° x 20° pyramid. Maximum Dose Rate (Gy/min-m) 3.0 0.2 - 3.0 8.0 2.0 - 8.0 30.0 6.0 - 30.0 60.0 - 150.0 Varian Linatron applications Focal Spot Size (mm) ≤2 ≤2 ≤2 ≤2 ≤2 ≤2 ≤2
Page 1: Varian Linatron High-Energy X-ray A
Page 5: Preface This manual presents theory
Page 8 and 9: FIGURE 1-3. Linatron M System Diagr
Page 10 and 11: Linatron targets are specially desi
Page 14 and 15: Beaming and Field Flatness. Electro
Page 16 and 17: FIGURE 3-2. Linatron x-ray intensit
Page 18 and 19: It is most convenient to have expos
Page 20 and 21: Vacuum cassettes are recommended wh
Page 22 and 23: Table 4-3 lists some relative speed
Page 24 and 25: Manufacturers publish density versu
Page 26 and 27: FIGURE 4-5. Plot of density versus
Page 28 and 29: The total unsharpness is reduced to
Page 30 and 31: This wedge block is then radiograph
Page 32 and 33: Increasing Latitude With Multiple F
Page 34 and 35: FIGURE 4-12. Linatron 2 MeV typical
Page 38 and 39: FIGURE 4-16. Linatron typical expos
Page 44 and 45: Radiographic Procedures General Con
Page 46 and 47: When radiographing curved sections,
Page 48 and 49: Radiography of Welds Radiography is
Page 50 and 51: The width of separation required fo
Page 52 and 53: The propellant in large motors is o
Page 54 and 55: Grain Radiography Coverage Requirem
Page 56 and 57: Bibliography Books Practical Radiog
Page 58 and 59: Normally, the light generated in th
Page 60 and 61: FIGURE 6-3. Real-time automated ins
Page 62 and 63:
Real-time image acquisition display
Page 64 and 65:
D/T RATIO Ratio of the distance bet
Page 66 and 67:
LINEAR ATTENUATION COEFFICIENT Cons
Page 68:
Security & Inspection Products 6883
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Varian Linatron High-Energy X-ray Applications 2007

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