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Mini kappa calibration and maintenance

Mini kappa calibration and maintenance. Translation calibration. use of glass capillary (WPI) phi reconstr. error: 0.0048 – 0.01318 average: 0.00914 (9 calibrations over 8 months) kappa reconstr. error: 0.00335 – 0.01753, average: 0.01077 (9 calibrations over 8 months).

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Mini kappa calibration and maintenance

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  1. Mini kappa calibration and maintenance Translation calibration • use of glass capillary (WPI) • phi reconstr. error: 0.0048 – 0.01318 • average: 0.00914 • (9 calibrations over 8 months) • kappa reconstr. error: 0.00335 – 0.01753, • average: 0.01077 • (9 calibrations over 8 months) Rotation calibration • thaumatin test crystals • kappa angle range: 23.951 deg – 24.038 deg • average kappa angle: 23.9993 deg • (7 calibrations over 7 months)

  2. Improving calibration procedure • different targets • precision pins • capillaries • calibration beads • standard samples • cubic crystals, ferritin, inorganic compounds • systematic studies • dependence on angular distance between sweeps? • taking whole data sets for rotation calibration instead of reference images • refined orientation matrices • image recognition of targets • data processing • physical metrology • automation

  3. Mechanical performance • tested procedure to automate SOC determination • script analysing edges of metal pin (image detection) • fitting routine gives difference in pixel values on screen displacement • not reproducible at kappa angles > 90 deg • visual check required • peak to peak displacement, approx. 3.5 microns (kappa = 0) to 6.5 microns (kappa = 90 deg) • backlash: kappa: 4 deg, phi: 5 deg • sagging effect at higher kappa angles • omega rotation about 180 deg: • kappa = 120 deg : 11 microns • kappa = 150 deg: 12 microns • kappa = 180 deg: 14 microns • kappa = 210 deg: 14 microns long term mechanical stability?

  4. Mechanical performance • inconsistency in nozzle diameter and magnetic base properties • problem with automatic sample unload • Molecular Dimensions SPINE base internal diameter 9.62 mm (+/- 0.02 mm) • Hampton SPINE base internal diameter: 9.54 mm • Standard permanent magnet nozzle external diameter 9.52 mm • Smart magnet nozzle external diameter 9.59 mm • Mini kappa nozzle external diameter 9.59 mm • mechanical reworking of nozzles, reduction from 9.59 mm to 9.52 mm • SPINE standard base internal diameter 9.70 mm

  5. Rotation axis issue • initial reports after mini kappa testing, indexing problems, automatic data processing failing more often • sample problem? beamline problem? • pattern starts to emerge linking problems to mini kappa use • comparison of reference images with corresponding images of shutterless Pilatus data collection revealed problem • omega rotation about 5% slower than demand • investigation into source of problem and clearing • rebooting of motion control rack with ETEL amplifier is clearing fault

  6. Rotation axis issue • work on better diagnostics independent of X-rays • position compare setup, trigger pulse is produced from hardware when goniometer is in certain positions • taking time stamps of two pulses with known required distance between them and check if this corresponds to chosen speed setting from data collection • additionally taking a trigger from the detector every time an image is collected, i.e. we know when data collection is finished, and comparing the actual goniometer encoder count with a precalculated expected count from the position compare system • implementation of diagnostics in EPICS and GDA • systematic test with standard nozzle, smart magnet nozzle and mini kappa • system only showed issue when mini kappa was mounted

  7. Rotation axis issue • omega delay not exactly the same but in the order of 5% • doesn’t scale with speed • exact cause still unclear but a number of theories around • CPU overload problem with Delta Tau • head/device recognition, via Zener diode and collision switch • second mini kappa, no omega rotation • setting of m variables • MD2 tuning parameters • tests with dummy connector • signal processing in ETEL unit? • amplifier gain settings? how determined? change of circuit voltage ... • electrical sanity check of mini kappa devices at supplier • mini kappa devices in use with shutterless data collection?

  8. Discussion • calibration methods • standards • fault finding • documentation • time requirement • automation • mechanical performance • device performance over time • diagnostics • development of methods • development work for second mini kappa on I04 • kappa beamtime scheduling

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