Speaker
Description
Recently, a new three-axes Hall probe mapper system was commissioned at CERN. Its performance has been improved in several aspects, which we will be discussed in this presentation.
(1) A 3D calibration setup is presented. Two piezoelectric turntables are used to manipulate the orientation of an incident reference dipole field. This enables the calibration of planar and 3D Hall effects.
(2) A cone quadrupole magnet was built for the fiducialization of the sensor position. We exploit its high gradient field to calibrate the positions of the three Hall elements within the Hall cube.
(3) To improve the overall measurement duration, the mapper system is taking measurements on-the-fly while moving the stages. However, small imperfections in the stage motion cause vibrations in the mapper's arm, which are harmful to the sensor positioning. We have therefore derived a sensor noise model which includes the effect of mechanical vibrations, using the Euler-Bernoulli beam theory.
(4) Mapping only the boundary of a three-dimensional domain, we can reduce the number of mapper moves from O(1/h^2) to only O(1/h), where h is the measurement resolution. We present an approach to reconstructing the field in the enclosed domain by using a boundary element method.