Trapped Bose condensate in a gravitational field

The Bose condensation of atoms in finite 1D and 2D parabolic traps placed i n a gravitational field is considered. The distortion of the trap potential in this field is modeled by a combination of two rectangular 1D and 2D tra ps. The change in the critical temperature T-c is found with regard to the cutoff and renormalization of the spectrum of these model potentials. The s hift of the critical temperature T-c in the gravitational field is calculat ed. The shift sign and magnitude depend on the way of introducing the gravi tational field. For a certain choice, three critical temperatures can be se quentially observed. These temperatures can be attributed to three Bose con densations that occur in the cyclic motion of the trap along the Earth (I)- space (II)-Earth (III) route. (C) 2000 MAIK "Nauka/ Interperiodica".