Random-loss cooling of a Bose-Einstein condensate ($T\propto N^{2/5}$)

For a partially condensed equilibrium ideal Bose gas in a fixed three-dimensional box, the energy scales as $T^{5/2}$. Unbiased random particle removal keeps mean energy per particle fixed, so re-equilibration gives $T\propto N^{2/5}$ until condensation disappears. Removal of an excited particle can be followed by partial replenishment from the zero-energy condensate. This differs from selective evaporative cooling of atoms, which preferentially removes high-energy atoms and reduces mean energy per particle.