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X-RAY RUNS: Apply for Beamtime

2017  March 15 - April 24

2017  May 17 - June 29
2017  BTR deadline: 04/17/17

2017  October 11 - December 21
2017  Proposal deadline: 08/01/17
2017  BTR deadline: 09/10/17

Ion Chambers:

X-ray fluxes are routinely monitored by ion chambers in the hatches. These devices are simple, reliable, requiring almost no maintenance and they are non-interfering with the experiments downstream. The construction of the ion chambers is simple: it consists of a vessel with thin Kapton entrance and exit windows, filled with gas (usually nitrogen) and inside have pair of electrode plates that create an drift-field perpendicular to the X-ray beam.

As X-rays pass through the ion chamber, as a result of the absorption process in the gas, electron/ion pairs are created. These are pulled apart by the electric field and as a result electric current is created in the outer circuitry. The ion chamber current or the ion chamber counts can be used to calculate the corresponding X-ray flux.

Please click here to launch the Ion Chamber Flux Web Calculator

 

Silicon Diodes:

At higher energies and fluxes the ion chambers may have difficulties duel to space charge effects and multiple ionizations.

Semiconductor diodes are excellent alternatives in many ways. The have the advantage of wider dynamic flux range and excellent linearity. On the down-side diodes obstruct the X-ray beam therefore, while using diodes for flux measurement the experiment downstream cannot go on. Exceptions are the so-called fully depleted diodes that are so thin that they can be used during measurements.

Please click here to launch the Diode Flux Web Calculator

For absolute flux measurement in 8000-25000eV range using the XPD100 flux meter use this calculator.