Precise Study of the Resonance at Q0 = (1,0,0) in URu2Si2

New inelastic neutron scattering experiments have been performed on URu2Si2 with special focus on the response at Q(0) = (1, 0, 0), which is a clear signature of the hidden order (HO) phase of the compound. With polarized inelastic neutron experiments, it is clearly shown that below the HO temperature (T-0 = 17.8 K) a collective excitation (the magnetic resonance at E-0 similar or equal to 1.7 meV) as well as a magnetic continuum co-exist. Careful measurements of the temperature dependence of the resonance lead to the observation that its position shifts abruptly in temperature with an activation law governed by the partial gap opening and that its integrated intensity has a BCS-type temperature dependence. Discussion with respect to recent theoretical development is made.