Pixelated-anode for direct MCP readout in imaging applications

The novel IonCCDTM, a charged-particle-sensitive pixelated detector, was used as an anode to directly read out the electrons exiting from the back of a micro-channel plate (MCP). The IonCCD chip is a 51-mm-long linear array of 2126 pixels, each of 21-μm width and 1.5-mm height, resulting in a 24-μm pitch. Both simulations and experiments were performed to assess MCP-IonCCD performance. The assembled MCP-IonCCD test apparatus consisted of a standard, off-the-shelf, 25-mm-diameter circular MCP. The IonCCD was mounted at proximity focus. The IonCCD eliminates the requirement for a phosphorus screen (after glow and electrons-to-photons conversion), as well as the need for a transformer lens or fiber coupling, as commonly used in imaging devices such as electro-optical ion detector systems (EOIDs). Another advantage is the elimination of the rather high voltages (~5-kV) that are typically needed for effective electron-to-photon conversion. Finally, the IonCCD should preclude any photon-scattering-induced spatial resolution degradation. Our early MCP-IonCCD tests showed that the MCP permits an immediate 103-104 gain, with virtually no additional noise beyond that attributed to the IonCCD alone. The high gain allows the use of lower IonCCD integration times, which will motivate the development of faster IonCCD readout speeds (currently at 2.7 ms) to match the 2-kHz 1D chip. The presented detector system exhibits a clear potential not only as a trace analysis detector in scan-free mass spectrometry, ion mobility and electron spectroscopy but more importantly as a means to achieve simpler, more compact and robust 2D imaging detectors for photon and particle imaging applications.

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