Unruh-DeWitt Fermion Detector on a (1+1)-Dimensional Cylindrical   Spacetime: Arbitrary Worldlines and Inequivalent Spin Structures
  We examine an Unruh-DeWitt particle detector which couples linearly to the scalar density of a massless Dirac field on the static cylindrical quotient of the (1+1)-dimensional Minkowski spacetime, allowing the detector's motion to remain arbitrary and working to leading order in perturbation theory. We show that the detector's response distinguishes the periodic and antiperiodic spin structures, and the zero mode that is present for periodic spinors contributes to the response by a state-dependent but well defined and controllable amount. 
Jorma Louko and Vladimir Toussaint
gr-qc hep-th math-ph math.MP