64- and 128-pixel Si-APD linear array x-ray detectors with 0.5 ns time resolution

We developed a silicon avalanche photodiode (Si-APD) linear-array detector to be used for nuclear resonant scattering experiments using synchrotron X-rays. The detector has a 64-pixel or 128-pixel linear array (pixel size: 100 × 200 μm²). Each pixel pitch is 150 μm, and the depletion depth is 10 μm. The multichannel scaling (MCS) system for the detector counted X-ray pulses over 2048 continuous time bins with minimum time resolution of 0.5 ns. The detector system can record a time spectrum of the nuclear radiation simultaneously with an intensity distribution at each pixel. We investigated its performance using synchrotron X-rays and the 128-pixel linear array exhibited a time resolution of 0.5 ns (full width at half maximum, FWHM) at 14.4 keV. A vacuum feedthrough for the 64-pixel linear array system was fabricated to detect low-energy electrons of <10 keV using internal conversion electrons. The feedthrough consists of a fast-transmission flexible flat cable, multi-electrode micro connectors and a build-up printed circuit board. The energy spectra of ~6 keV M-photoelectrons emitted from Tm foil were successively measured in vacuum with one pixel from the 64-pixel linear array using the vacuum feedthrough. The time spectrum was also recorded using the electron signal.