  We have measured the trapping lifetime of magnetically trapped atoms in a
cryogenic atom-chip experiment. An ultracold atomic cloud is kept at a fixed
distance from a thin gold layer deposited on top of a superconducting trapping
wire. The lifetime is studied as a function of the distances to the surface and
to the wire. Different regimes are observed, where loss rate is determined
either by the technical current noise in the wire or the Johnson-Nyquist noise
in the metallic gold layer, in good agreement with theoretical predictions. Far
from the surface, we observe exceptionally long trapping times for an
atom-chip, in the 10-minutes range.
