  We report on the first storage of ion beams in the Double ElectroStatic Ion
Ring ExpEriment; DESIREE, at Stockholm University. We have produced beams of
atomic carbon anions and small carbon anion molecules (C$_n^-$, $n=1,2,3,4$) in
a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy
and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at
13 K. For 10 keV C$_2^-$ molecular anions we measure the residual-gas limited
beam storage lifetime to be 448 s $\pm$ 18 s with two independent detector
systems. Using the measured storage lifetimes we estimate that the residual gas
pressure is in the 10$^{-14}$ mbar range. When high current ion beams are
injected, the number of stored particles does not follow a single exponential
decay law as would be expected for stored particles lost solely due to electron
detachment in collision with the residual-gas. Instead, we observe a faster
initial decay rate, which we ascribe to the effect of the space charge of the
ion beam on the storage capacity. %The latter effect becomes insignificant
after longer storage times of typically 100-150 seconds and we then observe a
constant decay rate due to residual-gas collisions.
