The proposing team is interested in exploring the low-temperature quantum "rattling" dynamics of helium atom(s) trapped in water-based cages (namely the so-called "clathrate hydrates"). These systems have a relevant scientific and technological importance since they are abundant in nature and could represent new materials suitable for absorbing and storing various gasses (H_2, CO_2 etc.). In a series of previous experiments on TOSCA, the team has studied ternary and binary clathrate hydrates, where the cages were filled with one or two hydrogen molecules, exploiting the neutron rotational spectroscopy to infer unique information on the guest-host potential in the system. Now another technique is proposed: making use of neutron Compton scattering from helium, the guest atom wavefunction can be reconstructed providing new details of the guest-host potential as a function of cage occupancy.