Pulsar star. The neutron star retains most of its angular momentum, and since it has only a tiny fraction of its progenitor's radius (and therefore its moment of inertia is sharply reduced), it is formed with very high rotation speed. A beam of radiation is emitted along the magnetic axis of the pulsar, which spins along with the rotation of the neutron star. The magnetic axis of the pulsar determines the direction of the electromagnetic beam, with the magnetic axis not necessarily being the same as its rotational axis. This misalignment causes the beam to be seen once for every rotation
Beam spoiler Beam spoiler A beam spoiler is a piece of material, placed into the path of the photon beam in radiotherapy. The purpose of the spoiler is to reduce the depth of the maximum radiation dosage. The beam spoiler is composed of a sheet of material which has a low atomic number, typically lucite, the thickness of which is varied according to the beam energy and the distance by which the radiation dose must be shifted. As the primary photon beam passes through the plate, secondary electrons are generated. The beam exiting the spoiler is a combination of the spoiler-attenuated photons