Diode Flux Calculator

X-ray attenuation/absorption data are from the NIST database.


A calculator program uses a simple model to calculate the X-ray flux from the diode current data. It includes an accepted model for electron-hole pair creation by X-rays in Silicon requiring 3.66eV energy per charge-pair. The model does not takes into account some of the seconary effects such as charge recombination and multiplication. The calculations are based on the one-dimensional model of the p-n junction working in photovoltaic mode (no-bias) taking into account photo-current generation originating from the depletion region and minority minority carrier diffusion from the space-charge-neutral region.

The input parameters are:
  • Selection of absorption mechanism responsible for current production;
  • The depletion layer thickness in microns.
  • The minority carrier diffusion length in microns.
  • X-ray energy in eV;
  • Counter for diode current in Hz (counts/s)
  • The diode current amplifier gain in A/V;

At station B2 with Ge <111> optics at 12keV.
The depletion layer was 53 microns, diffusion length: 0, count was 163909 cts at 1E-6 gain. The calculated flux: 1.47E10 ph/s.