  Cherenkov-type particle detectors or scintillators use as a fundamental
element photomultiplier tubes, whose efficiency decreases when subjected to the
Earth's magnetic field. This work develops a geomagnetic field compensation
system based on coils for large scale cylindrical detectors. The effect of
different parameters such as the size of the detector, the distance between
coils or the magnetic field strength on the compensation using a basic coil
system composed of circular and rectangular coils is studied. The addition of
coils of very specific geometry and position to the basic configuration is
proposed in order to address the compensation in the areas of the detector
where it is more difficult to influence, in order to minimize the loss of
efficiency. With such improvement, in the considered simulated system, more
than 99.5% of the photomultiplier tubes in the detector experience an
efficiency loss of less than 1% due to the effect of the magnetic fields.
