Measurements of B-dependent effects




To asses B-field dependent effects in the electron optics of the Pad HPD, a Helmholtz coil magnet has been designed and built.

helmholtz setup 2.gif (26846 bytes)

The coils have a radius of 15 cm and a distance of 15 cm. Each of the coils consists of 65 windings of 1.5 mm diameter copper wire. Due to temperature limitations the magnet can be continuously operated at a maximum current of 9 A.Higher currents should be applied only for short time periods (few minutes).

The relation between the magnetic field (longitudinal and transverse) in the centre of the magnet and the current is shown below. The magnet provides an essentially purely longitudinal feld of 3.7 Gauss/A.

Helmholtz_B_I.gif (5561 bytes)

The B-field of the magnet has been mapped with a Hall probe. The length of the shown vectors are proportional to the magnitude of the field, the direction of the vector is identical to the direction of the field vectors at the tail of the arrow. 

Helmholtz_map.gif (14260 bytes)

This page was last updated by C. Joram, 04/08/09