• a supporting body of ceramic material
• a specially formulated lead silicate glass
• a conductive layer of silver deposited onto both ends of the CEM

Fig. 1 Semitransparent view of the ceramic body (KBL 15 RS)

The special ceramic material was chosen for its ability to maintain the lead glass under a compressive force thus preventing the appearance of fine cracks that may result from sudden fluctuations in temperature. The ceramic material also has a porosity of zero permitting utilization of the detectors in an ultrahigh vacuum. The ceramic material is first processed and then sintered. Both halves of the rectangular models and both halves and the funnel of the circular models are fused together without the use of adhesives. The procedure is followed by the final processing of the ceramic body.

Fig.2 KBL 15 RS

The lead glass is hydrogen reduced thereby producing the active surface of the CEM and the secondary emissive characteristics critical to CEM performance. The glass coats the entire surface of the inner wall so that a continuous dynode is formed (Fig. 3 and 4).

Fig.3 Cross-sectional view (see Fig. 4)

A silver layer is deposited onto both ends of the CEM for electrical contacting of the CEM input and output to the applied voltage. This layer is deposited with a thick-film process and cannot be interrupted inadvertently. In addition, the electrical contacts are applied on both sides of the standard CEM models.

The channel extending from the funnel is curved as shown in Fig. 1. This curvature is necessary in order to prevent ion feedback that would cause spurious output pulses and an unstable gain.