The BI-XDC X-Ray disc centrifuge from Testa Analytical Solutions e.K allows scientists to make accurate, high-resolution particle size distribution measurements, from nanometers to tens of micrometers, without time-consuming calibration or absorption correction. Based on the principle of photosedimentation, the instrument measures the size of particles according to the time the particle takes to sediment in the detector according to Stokes’ law. The system combines centrifugal and gravitational sedimentation in a single instrument. There are no optical corrections and no optical properties, just a simple mass sensitive response based on X-ray absorption. The centrifuge features reproducible, digitally controlled disk speed to ensure high performance and accuracy. Its proprietary scanning X-ray head typically allows measurements to be made in 8 minutes.