Quantum optical time-of-arrival model in three dimensions
  We investigate the three-dimensional formulation of a recently proposed operational arrival-time model. It is shown that within typical conditions for optical transitions the results of the simple one-dimensional version are generally valid. Differences that may occur are consequences of Doppler and momentum-transfer effects. Ways to minimize these are discussed. 
V. Hannstein, G.C. Hegerfeldt, J.G. Muga