I have a question regarding characteristic peaks in a X-ray spectrum. A Finnish textbook shows a typical figure on intensity against wavelength with a continuous part and characteristic peaks. There is one peculiarity, however: the intensity of the K(alpha) peak is smaller than K(beta) and K(gamma) peaks. I have thought that the intensity of a characteristic peak is related to the probability at which a certain transition takes place and that the transition from the L-shell (n = 2) into the K-shell (n = 1) would be more probable than the transition, say, from the M-shell (n =3).
Is it possible that for some elements the K(beta) peak would indeed be greater than the K(alpha) peak? Or is there simply a mistake in the textbook?