ICE:: a transportable atomic inertial sensor for test in microgravity

We present the construction of an atom interferometer for inertial sensing in microgravity, as part of the I.C.E. (Interferometrie Coherente pour l'Espace) collaboration. On-board laser systems have been developed based on fibre-optic components, which are insensitive to mechanical vibrations and acoustic noise, have sub-MHz line width, and remain frequency stabilised for weeks at a time. A compact, transportable vacuum system has been built, and used for laser cooling and magneto-optical trapping. We will use a mixture of quantum degenerate gases, bosonic Rb-87 and fermionic K-40, in order to find the optimal conditions for precision and sensitivity of inertial measurements. Microgravity will be realised in parabolic flights lasting up to 20 s in an Airbus. We investigate the experimental limits of our apparatus, and show that the factors limiting the sensitivity of a long-interrogation-time atomic inertial sensor are the phase noise in reference-frequency generation for Raman-pulse atomic beam splitters and acceleration fluctuations during free fall.