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The target D is a thin layer of W/Bi epoxied on to a Al foil that is irradiated by energetic electrons from crystal B on cooling. This gives rise to x rays and bremsstrahlung. This radiation fluoresces a target at E. The detector outside the chamber records the resulting x-ray spectra. A is a resistor epoxied to the base of the crystal. C represents the thermocouple and heater wires. F is the gas output/inlet.
(a) Bremsstrahlung-fluoresced spectrum of Ta when the geometry is as shown in Fig. 1 and the crystal is . Note the background-free nature of the spectrum. Only one thermal cycle was used and the x-ray detector was only activated when the incident electron energy exceeded the Ta edge, . (b) Ta x rays superimposed on a bremsstrahlung background when the Ta is irradiated directly by electrons rather than by photons.
(a) Bremsstrahlung fluoresced Sn x rays superimposed on attenuated bremsstrahlung spectrum arising from electron bombardment of Pt. The crystal was ( long) with its base exposed. Note Pt electron excited x rays. The geometry is collinear as shown above in the inset. The logarithmic spectrum in (b) is multiplied by an arbitrary number for display purposes. The gas amplification effect is demonstrated since the “cooling” bremsstrahlung maximum energy end point is twice as high as the “heating” end point energy.
X-ray spectrum of bremsstrahlung fluoresced Pb combined with Bi x rays from the target. The geometry was that of Fig. 1. The crystal provided higher energy electrons than the crystal. This spectrum shows that the electron energy was , the Bi -shell ionization energy.
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