X-Ray Calibration Facility (XRCF)

The X-ray Source and Detection System

The X-ray Source and Detection System (XSDS) consists of two subsystems; the X-ray Source System (XSS) and the X-ray Detection System (XDS). The XDS has two different detector systems for monitoring the X-ray beam during setup and operation. The XSS utilizes four different X-ray generators producing a well-calibrated parallel beam of X-rays.

The X-ray generators comprising the XSDS are:

• The Electron Impact Point Source
• The Penning Gas Discharge Source
• The Rotating Anode Source (used with 4 and 5)
• The High Resolution Erect Field Spectrometer
• The Double Crystal Monochromator

The Electron Impact Point Source
Data

The Electron Impact Point Source (EIPS) is a Henke-type source which produces X-rays by focusing an electron beam onto a pure or composite metal target.  The EIPS operates over the energy range of 0.09-10keV and is designed to project the source as a spot measuring 0.5mm in diameter. The EIPS is capable of producing X-ray flux intensities in the approximate range of 1 to 500 photons/sec per square-cm, depending on the target.

The Penning Gas Discharge Source

The Penning Gas Discharge Source uses ionized argon gas interacting with aluminum cathodes to produce radiation at 95 and 500eV.  X-ray flux intensity up to approximately TBD photons/sec per square-cm at the IC entry are possible.

The Rotating Anode Source
The Rotating Anode Source (RAS) is an 18 kW Rigaku electron impact x-ray generator and operates between 6 to 40 kV and 10 to 450 mA.  Three Different anode materials and three different cathode configurations are available.  Two 18 kW generators are attached to the two monochromators described below.

The High Resolution Erect Field Spectrometer

The High Resolution Erect Field Spectrometer (HIREFS) is a Model SXR- 1.75 grating monochromator designed and built by Hettrick Scientific in 1996. The HIREFS utilizes grazing angle mirrors and gratings to select a calibrated energy between 0.09 to 1.5keV.   The four gratings are manually selected but the motion during a scan of the grating is computer controlled and logged to a database. 

The Double Crystal Monochromator

The Double Crystal Monochromator (DCM) was manufactured for NASA by the National Institute of Standards and Technology (NIST) in 1996.  The DCM utilizes one pair of crystals mounted on two turrets to maintain an optimal alignment for the selected energy.   The calibrated operational range of the DCM is presently 1 to 10 keV.  Both turrets are computer controlled and all the positions are logged to a computer database.  

Included in the X-ray Source and Detection System is the X-ray Filter Chamber which allows researchers to limit the bandwidth (the maximum and minimum wavelengths) of the source being used. The Filter Chamber houses two filter wheels, each of which provides positions for 31 filters, for a total of 62 filters and two open positions. The filter wheels are driven by stepper-motors which are capable of 101,000 steps per revolution, allowing accurate positioning of the filters.

Also included in the XSDS is the Mounting, Alignment and Transportation System (MATS) which provides easy movement of the X-ray sources into and out of the test position. The sources are secured to carts that travel upon a set of Thompson rails mounted to a 3x3 meter (10x10ft.) Newport optical table. The sources travel at right angles to the optical axis of the facility and are fixed by rigid stands when placed in the test position. The system allows the sources to be repositioned to within 0.025mm (0.001in.).

The X-ray Detection System consists of two different detector systems.  One is located approximately 125 feet from the source and consists of a non-imaging flat field detector mounted on a 2-axis translation stage and a solid state detector.  The other is located at the entrance of the instrument chamber over 1700 feet from the source and consists of three fixed flat field detectors and one flat field detector mounted on a 2-axis translation stage.  All the flat field detectors are flow proportional counters and use a computer controlled gas supply system to maintain an accurate flow and pressure in each counter.  The solid state detector is a Canberra 30mm ultra low energy Germanium detector and offer non-imaging, high energy photometry with excellent spectral resolution.