  Through a combination of spin-exchange collisions in a magnetic field and
optical pumping, it is possible to cool a gas of atoms without requiring the
loss of atoms from the gas. We investigated this technique, Collision Assisted
Zeeman Cooling, using 85Rb and 87Rb. We experimentally confirmed that our
measured two isotope CAZ cooling rate agreed with a cooling rate predicted
though a simple analytic model. As part of the measured cooling rate, we
quantitatively characterized the heating rates associated with our actual
implementation of this cooling technique and found hyperfine-changing
collisions to be a significant limitation for the 85/87Rb gas mixture. We
comment on the prospects for improving the cooling performance beyond that
presented in this work.
