Small angle x-ray scattering with photon counting spectral detectors and their novel applications in biophysics and imaging*

Small angle x-ray scattering (SAXS) techniques measure elastic x-ray scattering, which provide microstructural information and unique signatures of biomaterials and samples. However this technique is often limited by the need for high flux (often found in synchrotrons) and the need for high collimation of beam and small samples. Recent advances of direct conversion semiconductor detectors with photon counting capabilities offer new avenues in SAXS. We will show the benefits and describe applications of a cutting edge photon counting detector (PCD) developed by the CERN Medipix collaboration. This detector processes up to 40M hits/cm2/s when operated in data-driven mode. It allows readout of pixel coordinate, time-over-threshold(TOT) and time of arrival (TOA) immediately after a photon hits a pixel, while the other pixels remain sensitive. The detector efficiency, enhanced spatial resolution and true spectroscopic capabilities of this family of detectors provide unique features that make it ideal for SAXS applications. 

We will show the utility of our new methods for SAXS for interrogating bio-samples of various sizes and at very low flux. Applications of these novel advances are in the fields of biophysics, bioimaging, material and chemical spectroscopy and imaging.