FIG. 2.

Probability distributions for k photons being detected by the energy-resolved x-ray detector for different average fluxes. Grey symbols represent experimental results, while blue and red symbols represent simulated values based on the same average flux, assuming an x-ray source with purely Poissonian or chaotic characteristics. (a) Results for the (111) Bragg reflection of a thin Bi film with an average flux of 0.4 photons/shot. The three distributions are very similar, in this case with a photon flux less than one. The results in panels (b)–(d) were obtained on the (123), (110), and (126) Bragg reflections of an X-cut LiNbO₃ single crystal. Here, the differences between the three distributions become apparent, as the flux is significantly larger than in the case of the Bi (111) Bragg reflection. The experimentally observed distribution is neither purely chaotic nor purely Poissonian. It shows characteristics of both distributions, i.e., the non-vanishing probability at low photon numbers as in chaotic light and a clear maximum as in a Poisson distribution.