CEMs were developed and used as particle and/or UV and soft X-ray pulse counters onboard early satellite missions owing to their low mass of a few grams and a high gain of 108 with almost no power consumption.
For example, the Russian INTERBALL satellite is using ~ 70 SCEMs. CEMs are still frequently used on many balloon missions. In recent space missions, the microchannel plate has slowly superseded SCEM arrays.