Speaker
Description
We propose a new type of astronomical X-ray interferometer without using mirrors. The structure is very simple, consisting of an X-ray absorption grating and an X-ray spectral imaging detector. Quasi-parallel light from a celestial object passing through the grating makes a self-image of the grating by the Talbot effect. Stacking the image with the grating pitch in the analysis provide the profile of the X-ray object. The angular resolution of the system can be arcseconds or sub-arcseconds, which are difficult to be achieved X-ray mirror systems for satellites. We call this interferometer system Multi Image X-ray Interferometer Module (MIXIM).
We started an experiment using a micro-focus X-ray source, and 4.8 $\rm{\mu m}$ pitch 17 $\rm{\mu m}$ thick Au X-ray absorption grating, and an XRPIX2b detector with a pixel size of 30 $\rm{\mu m}$. We employed charge sharing analysis to achieve finer positional resolution than the pixel size and detected the interference fringes with a magnification factor of 4.4. Our final goal is, however, parallel X-rays from celestial objects, and thus detectors with finer or comparable position resolution as the grating pitch is required. To meet this requirement, we have recently introduced a CMOS sensor developed by Gpix inc. with a small pixel size of 4.25 $\rm{\mu m}$. This device is designed for visible light application, but we irradiated X-rays and find sensitivity for them. We present the current status of these preliminary experiments for MIXIM.
