“…The absolute 2s population was also in fairly good agreement between the experiment and calculation, although some disagreements can be found in levels 2 and 4. Note that the coherence zone chosen in this analysis is consistent with that in earlier studies [18,19,24], and a change of the coherence zone within a reasonable range does not essentially affect the resonance shape and absolute 2s population at the resonance maximum. The discrepancy of the relative intensity of the levels between the calculation and the experiment might be attributed to the beam divergence and the misalignment of the crystal from the channeling condition, which is not included in the current calculation.…”