Abstract: A detection apparatus for fine particles in a fluid includes: a flow cell which passes the fluid therein; an X-ray source which irradiates a side face of the flow cell with X-rays; an X-ray detector that detects the intensity of transmission X-rays that the X-rays which have been emitted from the X-ray source have been attenuated by due to the fine particles in the fluid; a fluorescent X-ray detector which detects fluorescent X-rays that are emitted by the fine particles in the fluid due to the X-rays which have been emitted from the X-ray source; and a data processing device which discriminates between fine particles and air bubbles in the fluid based on the fluctuation amount from each reference variable of the intensity of the transmission X-rays and the intensity of the fluorescent X-rays, and calculates the number and the particle diameter of the fine particles.

Abstract: An object of the present invention is to provide a method and an apparatus which solve problems such as a measurement error due to air bubbles in a scattering method and a light-shielding method, count loss due to different elements and impossible measurement due to emulsification, and can easily and accurately measure the number, the particle size and the like of fine particles in a fluid at a low cost.