Neutron star concluded that the radiation comes from a neutron star at the stage of accretion. In 1967, Jocelyn Bell Burnell and Antony Hewish discovered regular radio pulses from PSR B1919+21. This pulsar was later interpreted as an isolated, rotating neutron star. The energy source of the pulsar is the rotational energy of the neutron star. The majority of known neutron stars (about 2000, as of 2010) have been discovered as pulsars, emitting regular radio pulses. In 1971, Riccardo Giacconi, Herbert Gursky, Ed Kellogg, R. Levinson, E. Schreier, and H. Tananbaum discovered 4.8 second pulsations in an X-ray source in the constellation
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