Magnetic hyperfine interaction of swift43 K ions recoiling in helium and xenon

The 738 keV 7/2^– isomeric state in⁴³K (=292 ± 5 ns,g=1.266 ± 0.015) was produced in the reaction⁴He(⁴⁰Ar,p) using the 185 MeV pulsed⁴⁰Ar beam of VICKSI and a 2–7 bar helium target cell. The suitability of this isomeric state for hyperfine studies during recoil in gases and after implantation into solids was investigated via the TDPAD technique. The hyperfine deorientation of highly stripped⁴³K ions in He and Xe was investigated and interpreted with the AbragamPound model. When adding up to 15% Xe to the He target gas, a near-exponential loss of alignment with the Xe partial pressure was observed. This effect can be explained by K-hole production in⁴³K in the Xe-K collision for which a cross section of=5 · 10^–18 cm² was estimated.