Backgrounds Constrain on the Torsion Detection

The sources of torsion, macroscopic rotation and aligned spin are discussed. In the case of Dirac spin particle as a direct sensor for torsion, the detection of torsion-spin effect is constrained by the larger backgrounds strongly, which are magnetic-spin and rotation-spin. Increasing the source of the torsion is equivalent to increasing the background itself. So, the conclusion is that Dirac particle spectra experiments have no hope to give the evidence for torsion directly in some special torsion gravity theory.