  A lateral array of ferromagnetic tunnel junctions is used to inject and
detect non-equilibrium quasi-particle spin distribution in a superconducting
strip made of Al. The strip width and thickness is kept below the quasi
particle spin diffusion length in Al. Non-local measurements in multiple
parallel and antiparallel magnetic states of the detectors are used to in-situ
determine the quasi-particle spin diffusion length. A very large increase in
the spin accumulation in the superconducting state compared to that in the
normal state is observed and is attributed to a diminishing of the
quasi-particle population by opening of the gap below the transition
temperature.
