  Recently, we developed a method for calculating the lifetime of a particle
inside a magnetic trap with respect to spin flips, as a first step in our
efforts to understand the quantum-mechanics of magnetic traps. The 1D toy model
that was used in this study was physically unrealistic because the magnetic
field was not curl-free. Here, we study, both classically and
quantum-mechanically, the problem of a neutral particle with spin S, mass m and
magnetic moment mu, moving in 3D in an inhomogeneous magnetic field
corresponding to traps of the Ioffe-Pritchard, `clover-leaf' and `baseball'
type. Defining by omega_p, omega_z and omega_r the precessional, the axial and
the lateral vibrational frequencies, respectively, of the particle in the
adiabatic potential, we find classically the region in the $(\omega_{r}%
(omega_r -- omega_z) plane where the particle is trapped.
  Quantum-mechanically, we study the problem of a spin-one particle in the same
field. Treating omega_r / omega_p and omega_z / omega_p as small parameters for
the perturbation from the adiabatic Hamiltonian, we derive a closed-form
expression for the transition rate 1/T_{esc} of the particle from its trapped
ground-state. We find that in the extreme cases, the expression for 1/T_{esc}
is dominated by the largest of the two frequencies omega_r and omega_z.
