Village: Soft Condensed Matter
Main Research Techniques:
Small Angle Scattering & Diffraction, ASAXS, USAXS, microfocus SAXS
Two beamstop upgrades are in development. The first will replace the old main beam beamstop with a new better shielded design still including a diode for transmission measurement. Trials of the replacement diode will take place in January 2013 with replacement beamstop assemblies being available for AP13.
A beamstop for the microfocus endstation is also under evaluation which could provide drain current values for transmission corrections.
The beam conditioning section for I22, just upstream of the sample, has grown organically since first designed. This I22 BCO upgrade Project planned to improve the performance and usability of the experimental hutch beamline components to deliver quality, versatile beam to the sample area has now started. The upgrade will move I22's microfocus capability from a drop-in endstation to a permanently installed solution that can be driven in and out of the beam dramatically reducing swap-over time between these two modes of operation (days to minutes).
We have identified a number of additional or improved components that will enhance the capability of this section of the beamline.
1: A quad beam position monitor, which in combination with feedback to piezo positioners on the primary KB mirrors will ensure that the photon beam always enters the BCO section at the same position. This will alleviate a long standing problem on I22, namely that almost any motion of the beam caused by the machine or upstream optics has a definite detrimental effect on the instrument background, since collimation and guard slits must be so close to the primary beam to deliver good background for SAXS.
2: Upgrade of the final gate valve on the beamline to include an X-ray transparent insert will allow some use of the beamline even if the vacuum in the final section is not good enough to be exposed to the machine vacuum (I22 has only the final beamline window separating machine vacuum from atmosphere during data collection). A beryllium window in this gate valve would allow alignments to proceed even if data collection could not.
3: Creation of a secondary source point in the transfer tube in CIA2 should allow greater flexibility in selection of beam sizes. A combination of a variable number of CRLs in the beam, variable focus from the primary KB mirrors and tuning of the secondary source point size should allow us to offer beam sizes from millimetres down to microns, although not necessarily continuously variable. An optical concept design will form the first stage of this project.
4: I22 does not currently have a usable in-vacuum fast shutter. Because of this we are damaging samples and sample environments. New designs are now available on the market that will accommodate the beam sizes we are expecting to cover.
5. A laser alignment system that is collinear with the X-ray beam would be invaluable for aligning samples and sample environments without exposure to X-rays. Some options also allow for distance measuring which would give additional options for beamline calibration.
6. One of the major reasons for this upgrade is to provide a permanent installation for our microfocussing optics in the beamline which will reduce changeover time between modes from 2 days to, potentially, minutes. The exact solution will be identified during the concept design phase.
7. Upgrading our collimation and guard slits (S4 and S5 in current designation) to a scatterless design will improve instrument background. We have instigated collaboration with MaxLab to investigate solutions.
8. Inclusion of a diagnostic stick with a diode will simplify alignment of upstream components. Calibration of this diode periodically will allow for an accurate measure of incident photon flux onto the sample. Delicate reference samples could be included here to protect them and in combination with a laser measuring system could improve beamline calibration procedures.
9. An inline viewer, in concert with laser alignment, will improve sample alignment. This will also allow for optical images to be collected synchronously with X-ray data.
10. A larger beamline window will be needed to accommodate the inline viewer. Trials to determine the optimum design will form part of the concept design phase.
11. A larger beamline window will be a greater failure risk for the beamline. A protective shutter, interlocked to the hutch door, will ameliorate most of this risk as the most likely breakage is when users are in the vicinity.
We propose to design and build automated sample delivery systems for I22 for the materials science communities. In order to do this we need to establish a test facility for developing this automation. As a secondary benefit the lab developemnt will also give us a facility for integrating User equipment into EPICS/GDA and for carrying out experimental protocol trials. This infrastructure capability will include fitting out the development room with a cut down mock-up of the essential beamline equipment including breadboards, motorised stages, geobricks and some of the data acquisition infrastructure as well as a dedicated, fully featured, GDA and EPICS environment.
While this is an urgent need for I22 a facility of this type would also benefit other beamline groups around Diamond and time will be taken during the development phase to gather user requirements from these teams so ultimately we have a sample environment development lab capable of supporting all users of Diamond.
This project, to sequentially repolish the two bimorph mirrors of I22 while keeping the beamline operational with Diamond’s spare bimorph mirror, is now complete.
I22’s bimorph mirrors were in the first batch of bimorph mirrors received by Diamond. They appear to have suffered from surface damage at the piezo ceramic junctions during their early life cycle. As such it was initially impossible to fully optimise the performance of the I22 beamline to deliver the variable focus expected. It also prevented full exploitation of the Micro Focus end station on I22. Repolishing of the two I22 mirrors has seen significant improvements for I22 with this modest upgrade.
Both mirrors have now been repolished and have lead to significantly improved focusing capability. The results for the VFM are shown below
This upgrade enables I22 to work in grazing incidence mode for thin film materials and includes a hexapod sample platform and environmental chamber together with a remodelled SAXS detector platform with multiple beamstops for direct, reflected and specular beams.
This project has now delivered a replacment Silicon pixel based system for the final gas based detector on I22, HOTWAXS. I22 has purchased a 21 module device in L shaped geometry with P3 technology from Dectris. This gives I22 some 2D capability in simultaneous 2D SAXS/WAXS measurements.
The project has included the purchase of the detector and infrastructural changes to I22 to accommodate the new in vacuum detector shape.
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