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laboratory notes
A cold finger attached to the second refrigeration stage of a DE-201 Displex closed-cycle helium refrigerator has been equipped with a miniature DC motor. The device allows reorientation of the crystal at low temperature, without remounting or warming to ambient temperature. The axis around which the crystal is rotated is inclined by 45° to the cryostat axis, which gives a 90° change in orientation of the crystal upon 180° rotation.