The GRANIT spectrometer

The existence of quantum states of matter in a gravitational field was demonstrated recently in the Institut Laue-Langevin (ILL), Grenoble, in a series of experiments with ultra cold neutrons (UCN). UCN in low quantum states is an excellent probe for fundamental physics, in particular for constraining extra short-range forces; as well as a tool in quantum optics and surface physics. The GRANIT is a follow-up project based on a second-generation spectrometer with ultra-high energy resolution, permanently installed in ILL. It will become operational in 2011. The spectrometer consists of several neutron-optics elements and UCN detectors installed on a massive granite table in an aluminium vacuum chamber with a volume of about 1.5 m3. 3 types of detectors will be used at the first stage of the GRANIT experiment: 3He gaseous proportional counters with extremely low background, position-sensitive nuclear-track UCN detectors will be used to study the spatial distribution in quantum states, and real-time position-sensitive detectors with a resolution of a few hundred microns to measure velocity distributions of neutrons in quantum states. The key elements of the GRANIT spectrometer is a set of mirrors to shape/analyze neutron spectra and to store neutrons in quantum states