Can anyone explain why there are the discontinuities in proximity of the electron energies? I was thinking : every time the photon gains enough energy to ionize a new and a more bounded electron there is a "new" way to interact, and there is an increase of the probability interaction.
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In the image photon attenuation $ \mu/ \rho $ in lead(from https://physics.nist.gov/PhysRefData/Xcom/html/xcom1.html).


1 Answer 1


Yes, they're absorption edges. From this documentation:

4.10. The Output Table The atomic numbers and fractions by weight of the atomic constituents are given above the table. The main body of the table is supplied with enough headings to be self-explanatory. The left-most column gives the designations of the absorption edges (K, L1, L2, L3, M1, M2, ...) as well as the atomic number of the pertinent atomic constituent. Data for energies immediately below and above each edge, are given on two lines. It should be noted that the standard energy grid automatically includes at least one other energy between any two successive absorption edges. For materials of atomic number Z ≤ 10, there are no absorption edges above the minimum energy, 1 keV.


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