  The charge read out of a LXe detector via Proportional Scintillation in the
liquid phase was first realized by the Waseda group 40 years ago, but at that
time the technical challenges were overwhelming. Although the tests were
successful, this method was finally discarded and eventually nearly forgotten.
For present day large LXe Dark Matter detectors, this approach was not even
considered. Instead the Dual Phase technology was selected despite many
limitations and challenges. In two independent studies the groups from Columbia
University and Shanghai Jiao Tong University reevaluated Proportional
Scintillation in the liquid phase. Both established the merits for very large
LXe detectors, but the Columbia group also encountered apparent limitations,
namely the shadowing of the light by the anode wires and a dependence of the
pulse shape on the drift path of the electrons in the anode region. The
discrepancies between the two studies, however, are not intrinsic to the
technique, but a direct consequence of the chosen geometry. Taking the
geometrical differences into account the results match without ambiguity. They
also agree with the original results from the Waseda group. With the technical
problems solved, the path is now open to use this method in future large LXe
TPCs.
