Range Measurements in Oriented Tungsten Single Crystals (0.1-1.0 MeV). II. A Detailed Study of the Channeling ofK42Ions

Abstract

In this paper the mechanism of channeling of ${\mathrm{K}}^{42}$ ions in monocrystalline tungsten is investigated. The influence of various parameters—ion energy, crystal direction, surface oxide thickness, misorientation, lattice temperature, and bombardment dose—has been studied. It is found that: (i) the over-all range distribution is rather sensitive to all these parameters; (ii) the maximum range $R_{max}$ depends only on the ion energy and crystal direction; (iii) planar channeling exists down to the lowest energy studied (70 keV); (iv) the critical angle for channeling is about 3° at 500 keV and decreases slowly with increasing energy. In all cases, the crystals have been oriented with respect to the ion beam to ±0.1°, by means of wide-angle scattering of protons. An attempt is made to correlate the results for these fairly slow heavy ions with Lindhard's theoretical treatment of the motion of charged particles in a crystal lattice, and with the experimental studies on fast light ions.