Radio-quiet neutron star ten bodies have been proposed as rotation-powered neutron stars that are not visible as radio sources, but are visible as x–ray and gamma ray sources. Indicators that they are indeed neutron stars include them having a high x-ray to lower frequencies emission ratio, a constant x-ray emission profile, and coincidence with a gamma ray source. Quark stars, theoretical neutron star-like objects composed of quark matter, may be radio quiet, according to some theories. More plausibly, however, radio-quiet neutron stars may simply be pulsars which do not pulse in our direction. As pulsars spin, it is theorized they emit radiation from
Beam dump beams to be absorbed can run into the megajoules. Materials used for such beam dumps include blocks of copper, aluminium, carbon, beryllium, and tungsten. The block often has a long conical hole, where the beam hits it, so as to spread the heating over a larger region of the block. If the beam to be absorbed is high-powered, these blocks may be up to several meters long and water-cooled. Pools of mercury have also been used. If the particles in the beam are energetic enough, induced radioactivity, production of neutrons by spalling, radiation embrittlement, and production of secondary particles can