Hello, Speaking not from a physicist perspective, but from being in the business for over 20 years...
The mechanism depends somewhat on the amount of flux that has been traveling through the CBT, which determines if the cesium becomes exhausted before the electron multiplier first dynoe "wears out". In general with the HP/Agilent/Symmetricom CBT there is enough getter material inside to trap contaminants well beyond the time that the cesium should run out in the oven. As long as the Ion Pump is working, internal contamination should be the minimal contributor to EOL. Whether the cesium runs out or the Electron Multiplier first dynode loses its coating is largely dependent on the amount of flux. The High-Performance CBT run at a hotter oven temperature to gain better S/N and thereby exhaust the available cesium at a faster rate. In these CBT the EOL mechanism is more likely due to that. As the cesium runs out the S/N degrades. Increasing the EM voltage can help, but eventually you're amplifying more and more noise. In the standard-performance or long-life CBT the EOL mechanism is more likely due to the first dynode of the EM becoming depleted of its coating, than buildup of internal contaminants. Dave ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <time-nuts@febo.com> Sent: Monday, February 04, 2008 6:39 AM Subject: [time-nuts] CBT EOL When a CBT reaches end-of-life, is it because the source of Cs is used up? Or is it due to contamination of the electron multiplier? I've heard both as causes but wanted more info. I have a CBT with very low beam current and it keeps falling. I'm wondering if running a higher than normal EM voltage might help keep it on life-support. -Brain, WA1ZMS/4 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.