Figure 11
Helium box: the new design. The maximum polar angles are ±63°. A double window filled with warm helium replaces the Mylar window shown in Fig. 1, in order to avoid the formation of frost at the outer surface of this window. The second Mylar window, of thickness 6 µm, would decrease the transmission by almost 30% at wavelengths near the K-edge of phosphorus. |