After first testing with a simple CCD, a custom designed Proxitronic image intensified camera system #18804 was used for further investigation of OTR. The system is specified as follows:
Bialkali photocathode (200 - 600 nm)
V-stack double Multichannelplate (diam. 25mm)
P46 Phosphor (decay 90%-10% in 300ns)
Relay-Optic coupling (β 0.6)
AVT Marlin CCD, monochrome, vga resolution
This setup enables single photon counting and fast triggering. A timing window of 100 ns could be used even for low currents, still achieving reasonable signal. The following was investigated:
Shifted 50µs time-window to measure the change of OTR signal before/ during/ after the beam pulse » thermal afterglow could be for sure excluded !
OTR signal comparison for polished stainless steel and for aluminium foil (10µm Al on Kapton)
Current variation between 0,2µA and 10µA (1,4 E+07 - 7 E+08 ppp)
OTR signal for different thicknesses of stripping foils (carbon: 370 µg/cm² ; 571 µg/cm² ; 563 µg/cm²)