A Two-dimensional event-counting detector for HV-CSA electrostatic analyzer at SpLine the Spanish CRG beamline at the ESRF

A novel 2D-detector has been designed, manufactured and installed on the high voltage cylindrical sector electrostatic analyzer (HV-CSA300/15) of the HAXPES station of SpLine the Spanish CRG beamline at the ESRF. This original 2D-detector constitutes an important improvement of the HAXPES station. A drawback of electrostatic analyzer in HAXPES, is that the electron counter must be raised to high voltages (up to 15 kV). Hence the development of a 2D detector system compatible with a high voltage electrostatic analyzer is a scientific instrumentation challenge. The developed two-dimensional event-counting detector consists of a 2D image intensifier (combination of scintillating screen and MCP) optically coupled with a CMOS-camera and a data processing system. The accumulated event image is transferred to the image processing software on the PC, where the events are classified by their position to give single detector readout. The energy window accepted by the area detector ranges from 100 meV to 50 eV, depending on the analyzer pass energy. Hence, for single shot measurements, i.e, without sweeping the pre-retarding lens voltages up to 200 detector channels can be used compared to a single channel. This results in a gain of the analyser transmission of at least a factor of 20. Thus we overcome the limitations imposed by the low count rate when dealing with high excitation energies and high kinetic-energy electrons.