Ion Chamber Flux Calculator

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

The average ionization enegies are obtained from the SLAC web site.

Standard CHESS chamber lengths: short: 6 cm, long: 27 cm.


A calculator program uses a simple model to calculate the X-ray flux from the ion chamber current data. The model includes single-ionization of the gas, and does not takes into account some of the secondary effects such as charge recombination, or space-charge effect.

The input parameters are:
  • Selection of the gas; the choiches are: Nitrogen, Helium, Argon, Xenon or Krypton;
  • Selection of absorption mechanism responsible for current production;
  • Average ionazation energy in eV (default values from the literature are shown).
  • The density of the selected gas.(default values shown for see level, at 25C)
  • X-ray energy in eV;
  • ion chamber current in Hz (counts/s)
  • The ion chamber current amplifier gain on A/V; and,
  • The length of the ion chamber in cm.
Example 1:

At station A2 with multi-layer optics at 10keV.
The 6cm N2 ion chamber count was 109400 at 1E-6 gain. The calculated flux: 9.6E11 ph/s.

Example 2:

At station A2 with <111> optics at 50keV.
The 6cm N2 ion chamber count was 722000 at 1E-10 gain. The calculated flux: 2.55E9 ph/s.