BNL, Upton, New York, USA
Stony Brook University, Stony Brook, New York, USA
Achieving photon beam stability, a critical property of modern synchrotron beamlines, requires a means of high resolution, non-invasive photon beam position measurement. While such measurement techniques exist for hard x-ray beamlines, they have yet to be achieved for soft x-ray beamlines. A new soft X-ray beam position monitor (SXBPM) design based on GaAs detector arrays is being developed and will be installed in the first optical enclosure of the Coherent Soft X-ray Scattering (CSX) beamline at the National Synchrotron Light Source II (NSLS-II). The SXBPM assembly contains four water-cooled blade assemblies, each of which will have a GaAs detector assembly mounted within it, that can be inserted into the outer edges of the CSX undulator beam with sub-micron accuracy and resolution. The primary challenges in design of the SXBPM include: 1) mechanical stability of the assembly, 2) management of the heat load from the undulator x-ray beam to protect GaAs detector assemblies from unwanted illumination, 3) assembly compactness to fit within the first optical enclosure (FOE) of the CSX beamline, and 4) accessibility for modifications. Balancing the unique design requirements of the SXBPM along with their associated constraints has resulted in the design of a non-invasive beam position monitor which will be installed in the CSX FOE as a prototype for testing and iterative improvement. The ultimate goal is development of a widely useful SXBPM instrument for soft X-ray beamlines at high brightness synchrotron storage ring facilities worldwide. The following work seeks to present an overview of the current design of the SXBPM and an analysis of the challenges encountered and the proposed solutions by which they will be addressed.
BNL, Upton, New York, USA
Open Platform and Liquids Scattering (OPLS) is a new experimental station recently built and currently being commissioned at the Soft Matter Interfaces (SMI) beamline 12-ID at NSLS-II. The new instrument expands SMI’s beamline scientific capabilities via the addition of X-ray scattering techniques from liquid surfaces and interfaces. The design of this new instrument, located inside the 12-ID beamline shielding enclosure (hutch B), is based on a single Ge (111) crystal deflector, which bounces the incident x-ray beam downward towards a liquid sample which must be maintained in a horizontal orientation (gravity-driven consideration). The OPLS instrument has a variable deflector-to-sample distance ranging from 0.6 m to 1.5 m. X-ray detectors are mounted on a 2-theta scattering arm located downstream of the sample location. The 2-theta arm is designed to hold up to three X-ray detectors, with fixed 2-theta angular offsets, each dedicated to a different X-ray technique such as X-ray reflectivity, grazing-incidence X-ray scattering, and small- and wide-angle X-ray scattering. Currently, the OPLS experimental station intercepts the SMI beam that otherwise propagates to the experimental endstation located in hutch C and can be retracted to a ’parking’ position laterally out of this beam to allow installation of a removable beam pipe that is needed to support operations in hutch C. The design of OPLS is flexible enough to quickly adapt to a planned future configuration of the SMI beamline in which a OPLS is illuminated separately from the main SMI branch via a second, canted undulator source and a separate photon delivery system. In this future configuration, both branches will be able to operate independently and simultaneously.