In3He-B at temperatures of the order of 0.1Tc, where the meanfree path of the excitations measures several hundreds of metres, we are able to perform experiments on fully ballistic quasiparticle beams. We describe the first direct production and detection of a quasiparticle beam in superfluid3He with the use of a black-body radiator. The radiator may be used as a smoothly controllable continuous source and also as a bolometric detector, sensitive to a quasiparticle energy flux of order 100 fW mm−2.