High performance cross-strip detector technologies for space astrophysics

We describe a novel MCP imaging detector scheme using the Cross Strip (XS) anode. This anode uses charge division, and centroiding, of microchannel plate charge signals detected on two orthogonal layers of sense strips to encode event X-Y position, event time and signal amplitude. We have developed novel XS anode structures that will, in combination with a new generation of small pore MCP´s (< 4 mum pores), perform at the highest resolution levels (<10 mum) with self triggered ~1 ns timing accuracy and encode photons at greater than 1 MHz rates. Our development the XS charge division scheme has been demonstrated with formats up to 32 mm². They show excellent resolution (better than 7 mum FWHM, actually imaging the MCP pores) using low MCP gain (5 times 10⁵). We have investigated XS anode structures that will accommodate a wide variety of forms (circular, square, rectangular). We are using this concept to produce open face and sealed tube detectors for imaging a wide range of photon and particle events. To encode event positions we have designed and built a parallel channel encoding electronics. The front end boards utilize two RD-20, 32 channel preamplifier ASICs. The pre- amplified signal is post-amplified on the same board in order to match the dynamic range of downstream 60 Msps ADCs that constantly digitize the signal for subsequent digital peak detection. Tests with eight 60 Msps ADC channels and a software Finite Impulse Response algorithm demonstrate < 5 mum electronic resolution and <10 mum resolution with a 32 mm XS anode detector. A full 64 channel 60 Msps ADC circuit has been constructed along with a Xilinx Virtex 5 FPGA event processing board. In combination with firmware based Xilinx centroiding algorithms, encoding the event positions at more than 1 MHz rates over large areas should also be possible. Such detector system may be used for a variety of future missions, in solar, solar system and astronomical applicat- ions.