On photoionization in the hard $X$-ray region

It is demonstrated that the results of recent experiments on ionization of $3p$- and $3s$-electrons in Ni film and solid body [1] cannot be reproduced in the frames either Hartree–Fock or the random phase approximation with exchange. The difference between experimental data and calculation results is so big that from the theoretical side it requires inclusion of huge and yet not understood effects. Perhaps, it requires also experimental efforts in order to clarify the prominent difference obtained for films and crystal samples.