EDS detectors works like a thermos bottle that slow liquid nitrogen evaporation. When the vacuum in the detector deteriorates the liquid nitrogen that cools the detector evaporates quicker. That is happening in the ESEM detector. We refill the detector twice each week but depending on the timing you might hear an alarm signaling that the liquid nitrogen is low. The alarm is a beep signal every few seconds. Here is the important part of this message – if you hear the alarm let me, Aleister or Liz know so we can refill it.
I will have the vacuum replenished in the summer when ESEM use drops.