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X8A External Homepage
Beamline X8A
General Information
Source Type
Bending Magnet Status
Operational General User Beamtime
25% Energy Range Category
Hard X-Ray (1-50 keV) Energy Range
1.0-5.9 keV
Beamline Type
Participating Research Team (PRT) Technique(s)
Metrology
Institution(s)
Lawrence Livermore National Laboratory
Los Alamos National Laboratory
National Security Technologies
Sandia National Laboratory
Research Types
Calibration of x-ray instruments, detector systems, mirrors and filters and the measurement of material optical constants and spectrometric properties.
Contact Information
Spokesperson 
Kenneth Moy, National Security Technologies, moykj@nv.doe.gov, 805/681-2284
Local Contact
Bin Dong, SFA, Inc., bdong01@bnl.gov, 6313447015
Beamtime Scheduler
Bin Dong, SFA, Inc., bdong01@bnl.gov, 6313447015
Beamline Phone
631-344-5708
Instrumentation
Beamline Characteristics
| Energy Range |
Mono Crystal or Grating |
Resolution (ΔE/E) |
Flux |
Spot Size (mm) |
Total Angular Acceptance (mrad) |
| 2.1 – 5.9 keV |
Si(111) |
5 x 10-4 |
1.7 x 1010 ph/sec (@ 3.1 keV) (1) |
2H x 3V |
4 |
| 0.8 – 2.8 keV |
Beryl(1010) |
8 x 10-4 |
< 1010 ph/sec (2) |
< (2H x 3V) |
4 |
| 0.26 – 2.0 keV |
W/Si multilayers |
2 x 10-2 |
.3 x 1010 ph/sec (@ 1.4 keV) (3) |
> (5H x 15V) |
4 |
1. Flux measured thru a 1/16" aperture with detuned crystal 2 rock, as typically used (peak flux of 1011 ph/sec available at 4 keV). Flux falls off at the lower end of the energy range, and there is some useable flux up to 6.0 keV.
2. The beryl crystals are difficult to use because they crack under full beam power. At least 90% of the beam must be apertured off the crystals to prevent this. Measured flux is not available.
3. W/Si multilayers produce a very diffuse, high (total) flux, low resolution beam. Flux measured thru a 1/16" aperture. Flux drops off steadily below 1 keV.
Source Type
Bending magnet Optical System
Mirror: The single beamline focusing mirror is a nickel coated fused quartz bent cylindrical mirror, 50 mm wide x 900 mm long, located 7.5 m from the source. It focuses horizontally and vertically at the nominal sample position 21.4 m from the source. The incidence angle is 10 mrad, resulting in a nominal energy cutoff of 5.9 keV. The horizontal and vertical acceptances are approximately 4 and 0.7 milliradians, respectively.
Monochromator: The monochromator is located 19 m from the source and has a simple double flat crystal design. A water-cooled tray holds three separate crystal pairs which can be translated into the beam in situ. The available Bragg angle range is from 75o to 15o for 1.25" long crystals, down to 7o for 3" long crystals. The exit beam height changes with Bragg angle by up to18 mm. A stepping motor driven differential screw on the second crystal enables tuning (detuning) of the crystal on the rocking curve.
Because the monochromator geometry involves simple double reflection from two flat crystals, the beam is displaced upward at the monochromator by approximately 1" times the cosine of the Bragg angle. The resulting beam movement with energy at the end station is tracked using a lift table. Experimental Apparatus
Lift Table: Full 6-motor alignment capability. Software control for alignment and photon energy tracking.
"Standard" End Station: Selectable pinhole apertures from 1/8" to 1/128" size. Calibrated monitor diode. "Back" diode for transmission measurements. Calibrated Keithley electrometers for diode/detector signal measurement. Detector/Filter "stalk" ("Standard" detector holder (6 positions) with vacuum feedthroughs; "Standard" filter holder (5 positions)). Endstation isolation valve; vent and pump capability. Software for scanning and data collection.
Other setups require: Full interlocks for all vacuum valves (if extensions are used, contiguous valveless vacuum with endstation is preferred). Vacuum tight to 10-6 Torr or lower. For details on holders please consult beamline staff. Computer System Hardware & Software
The beamline is operated from a 1.8 GHz Pentium Dell PC with Windows XP OS, LabVIEW beamline control software, and a combination GPIB/PXI communications interface. The monochromator and lift table motors are controlled with CAMAC E500 indexers via a cc-488 GPIB CAMAC crate controller, and Centent CN0142 and CN0162 x10 microstepping motor drivers. The beamline software includes experimental data acquisition and control programs written in LabVIEW, enabling programmatic beam line control from within such programs.
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