Specification for goniometer mount for radiators

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The planned Hall-D goniometer is a 6-axis device with 3 translational and 3 rotational degrees of freedom:

Short description of the stages (from bottom to radiator mount):

  • horizontal translational stage (x-stage) to move the into/out-of beam (range ~20 cm)
  • vertical translational stage (y-stage) to adjust the height of the radiator (range ~5 cm)
  • rotation about the vertical axis (yaw) to ±15 deg.
  • rotation about the horizontal, perpendicular to the beam direction (pitch) to ±15 deg.
  • craddle: rotation about the beam direction (roll) to +120 deg. and -30 deg.
  • horizontal translational stage (target ladder), positioned in the center of the craddle and range of ≥ 8 cm (space for mounts of 5 diamonds and thin foil for normalization run).

The listed accuracy is based on the existing Huber goniometer in Hall B.

  • accuracy of translational motion:
      vertical:                     200 μm
      horizontal (bottom axis):     200 μm
      target ladder (fine tuning):   25 μm
  • accuracy of rotational motion:
      yaw (about vert.axis):                   1.5 μrad
      pitch (about horizontal, perp. to beam): 1.5 μrad
      roll (about beam direction):             3.0 μrad

End switches required for all axes, additional home switches for rotations.

The device is operated under vacuum (~10-6).