The proposed CHAOS instrument needs a fairly large area Solid State Detector (SSD). All Detectors that we can use are spare parts from earlier space missions. For this large area SSD we put our eyes on a couple of recently rediscovered Soho Costep EPHIN F-Detectors, manufactured in the 1980ies.
A quick test revealed that all but one of them have excessive bias currents. The one good detector, unit F2, was subject of a C-V measurement, Capacitance versus bias Voltage. That kind of measurement tells about the impurity concentrations (dopands) and thickness of the detector.
The results confirm that the detector is about 700µm thick, and needs about 150V bias to be fully depleted, which is in range with the expectations. The diameter of the SSD is about 8cm.
This EPHIN F2 detector may become the anticoincidence counter of CHAOS. Currently it is tested in operation with cosmic muons and a gamma ray source.