Beamline X-18B: The Characteristics

Beamline X-18B is for high energy X-ray absorption spectroscopy, in the range 4.8 - 40.0 KeV. A channel cut Si(111) crystal is used as monochromator with upstream vertical slits of size 0.1, 0.2, 0.3, 0.5, 1.0 and 1.5 mm. The horizontal size could be up to 20 mm. The monochromator crystal is about 18 m and the sample position about 20 m from the bending magnet X-ray source. The entire beamline is under 10E-8 - 10E-9 Torr vacuum with three 10 mil Be windows in between. Separation between the channel cut crystals is small (2.5 mm) therefore the vertical beam movement during a typical scan is minimized. The higher harmonics are rejected by tilting the second crystal through a piezo-driven picomotor. Another motor turns the monochromator in chi direction to reduce and displace the glitches. The beamline hardware is controlled by a 1 GHz Dell Pentium computer using the Lab View program developed at the Light Source by Meyer, Furenlid and Kirkland. Ban, WINXAS, FEFFIT Athena and Artemis programs developed by Tolmar Industries, Thorston, Ravel, Newville and many in Washington Group are available on a separate Pentium with Windows 2000 operating system machine. The data analysis, data collection and the X-19A computers are inter linked through the network. Data transfer within the computers and back home is done through the network. CD burners are available on both the computers. The beamline also has a LaserJet 4L printer hooked up to both computers. Three sealed Oxford Instrument ion chambers with filling station to choose the gases and their ratios are available at the beamline. Two 27 cm and one 17 cm long gas flowing ion chambers with kepton window and two sealed ion chambers with Be windows are also available. A PIPS and a Lytle detector is also available for fluorescent X-ray absorption spectroscopy. Argon helium and nitrogen gases will also be provided for ion chambers. In addition, a close circuit video camera and monitor and a laser for alignment purpose is also available at the beamline. 13 element energy dispersive Ge detector can be reserved to use at beamline X18B or X19A. The general and contributing users data will be archived for one year, however it is users responsibility to transfer and take their data with them.

Beamline X19A: The Characteristics

The X18B-X19A beamlines are facility beamlines where 50% of the operational time is given to general users and the 25% is now being used by the newly formed Synchrotron Catalysis Consortium. The NSLS is in charge of the management and operation of this beamline. To get time on this beamline as a general user please contact the User Administration Office or contact:Contact Person: Syed Khalid 631-344-7496, khalid@bnl.gov or the Spokesperson: Steve Ehrlich, 631-344-7862,ehrlich@bnl.gov.