RADIATION DAMAGE IN TUNGSTEN TARGET OF THE “KIPT NEUTRON SOURCE”

In this work, mathematical modeling of a complex of processes occurring in a tungsten target under irradiation with high-energy electrons with an energy of 100 MeV: an electromagnetic shower, the production of photo-neutrons, and particle transport along the target, damage from neutrons of the subcritical assembly. It was found that the greatest contribution to the rate of damage formation in a tungsten target give the elastic scattering of high-energy electrons on nuclei.

Complex emission patterns: fluctuations and bistability of polar-cap potentials

ABSTRACT Development of the ion-proton pulsar model extends it to the limit of large unscreened polar-cap potentials, for example, as in the Vela pulsar, in which ion charges differ only by small increments from their complete screening values. It is shown that the atomic number Z of an ion following its passage from the canonical Z0 = 26 value through the electromagnetic shower region to the surface is not necessarily time-independent but can vary between fixed limits in an irregular or quasi-periodic way in a characteristic time of the order of 104 s. Thus, at a certain Z the system may transition to an unstable state of higher electric potential and it is argued that this is the physical basis for mode-changes, long-term nulls, periodic or otherwise. The model requires an orientation of magnetic dipole moment relative to rotational spin giving a positive corotational charge density. Success of the model would fix the particle composition of the remaining parts of the magnetosphere, including the Y-point and is therefore relevant to X-ray and γ-ray emission processes.