  A well-adapted spectrograph concept has been developed for the SNAP
(SuperNova/Acceleration Probe) experiment. The goal is to ensure proper
identification of Type Ia supernovae and to standardize the magnitude of each
candidate by determining explosion parameters. An instrument based on an
integral field method with the powerful concept of imager slicing has been
designed and is presented in this paper. The spectrograph concept is optimized
to have very high efficiency and low spectral resolution (R~100), constant
through the wavelength range (0.35-1.7 microns), adapted to the scientific
goals of the mission.
