Beam line front end

THE MACHINE, BEAM LINE FRONT ENDS, BEAM POSITION MONITORING AND STABILITY... 

Figure 4.8 A scheme proposed for an undulator beam line front end. From the ESRF Red Book (1987) with permission. 

Water-cooled absorbers and masks are placed in the beam line front end. There are fixed and movable masks. A fixed mask is located next to the bending magnet vacuum chamber it constrains the opening fan of bending magnet radiation. The movable masks are the personnel safety... 

Problem 3.4 Positrons in a 5mm-diameter beam are detected in two different ways (a) directly by a channeltron (lOmm-diameter mouth) placed at the end of an evacuated beam line, and (b) indirectly via annihilation radiation from the channeltron by a 75mm-diameter, 75mm-long Nal(Tl) crystal on a PM detector mounted outside the vacuum system directly to one side of the channeltron. The distance from the channeltron to the front face of the scintillator is 100mm, and the intrinsic detection efficiency of the... 

A schematic diagram of the front end of the beam line is shown in figure 4.8. The machine vacuum has to be protected. Hence, the beam lines emanating from the ring are separated from the main ring vacuum chamber. For an X-ray beam line this is by using a beryllium window at the front end of the beam line. For a soft X-ray or vacuum ultra-violet (VUV) line such a window would completely absorb the radiation of... 

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