Detector

Somewhat similar to FIES, we also had problems with maintaining the StanCam detector cold. After some investigation it was concluded that this was the common feature of the CryoTiger cooler for unknown reasons loosing cooling capacity. For StanCam it is only possible to see if the CryoTiger is functioning properly by looking at the detector temperature which is 0.1 degree below its set temperature of -95.0 degrees Celsius.

One of the potential causes for the CryoTiger loosing cooling capacity is the dewar loosing vacuum. Ever since StanCam was mounted we have been unable to obtain its pressure without having to go in to the dome and read it off a digital display. It was found that the pressure sensor display is actually a complete controller unit, and has an RS-232 port through which it is possible to obtain the pressure reading. Via a system using an Ethernet/RS-232 (Moxa box) interface it is now possible to see the pressure in the data base. The main limitation is that the sensor only goes down to $10^-5$ millibar which implies that under normal circumstances it will only provide an upper limit, but at least we have now a way of automatically detecting any major loss of vacuum such that any corrective action can be taken in a timely manner.