<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>L</mml:mi></mml:math>-Subshell Resolved Photon Angular Distribution of Radiative Electron Capture into He-like Uranium

Abstract

The photon angular distributions for radiative electron capture (REC) into the $j=\frac{1}{2}$ and $j=\frac{3}{2}$ $L$ subshell levels were measured and calculated for ${\mathrm{U}}^{90+}$ \ensuremath{\rightarrow} C collisions at 89 MeV/u. The experiment provides the first study of the photon angular distribution of REC into a projectile $p$ state ($j=\frac{3}{2}$) which was found to exhibit a slight backward peaking in the laboratory frame. For radiative capture to the $j=\frac{1}{2}$ states, the measured angular distribution deviates considerably from symmetry around 90\ifmmode^\circ\else\textdegree\fi{}. The results demonstrate that the usual ${sin}^{2}{\ensuremath{\theta}}_{\mathrm{lab}}$ distribution is not valid in the high-$Z$ regime.