Universal empirical and theoretical for an updated compilation of K x-ray production cross sections by protons Gregory Lapicki, Department of Physics, East Carolina University, Greenville NC 27858, USA

     The relevance of x-ray production cross sections (XRPCS) and the related ionization cross sections (ISC) in many research areas has been described at length and analyzed in detail [1].  X-ray emission cross sections by ion impact are a relevant input in many areas such as studies of track structure in biological matter. Particle Induced X-ray Emission (PIXE) strongly requires trustworthy databases for XRPCS and/or reliable predictions of inner-shell ionization theories as periodically evaluated in Monte Carlo Geant4 simulations [2]. To check if theories are accurate across the periodic table of elements and a large range of projectile energies, equally comprehensive databases are essential and a universal fit for them is desired.    

     For each target element, the compiled XRPCS [1] follow a single curve when plotted versus the ratio of the proton velocity v₁ to the orbital velocity of v_2L=Z_2L//n of the inner-shell electron. Furthermore, for all elements XRPCS peak at σ_LX^max(Z_2L) when v₁ = v_2L. With v≡ v₁/v_2L, a universal fit to all compiled data σ_LX= σ_LX^max(Z_2L)·exp[-(1+a₁Z_2L)v²+a₂v⁷] is made with just two adjustable parameters a₁=0.00484 and a₂=0.005. The predictions of the ECUSAR theory [3] can be also fitted in a similar fashion as done recently based on recently updated data and the revised universal empirical fit [4].  With a standard deviation of 29%,  97% of these ratios are within a factor of 2 from the ideal ratio of 1.00.

      For this meeting, 1) universal empirical and theoretical fits to the updated database from [5,6] will be reviewed as it was done the L shell [4], and 2) similar fits will be presented for the K shell.

[1] J. Miranda and G. Lapicki 2014 ADNDT 100 651.

[2] S. Incerti et al. 2015 NIM.B 358 210.

[3] G. Lapicki 2001 NIM.B 189 6.

[4] G. Lapicki 2020 NIM B 467 123.

[5] G. Lapicki 1989 JPCRD 18 111.

[6] H Paul and J. Sacher 1989 ADNDT 42 105.