[en] Intrinsic efficiencies of the multilayer boron detectors have been examined both theoretically and experimentally. It is shown that due to the charge loss in the boron layers, the practical efficiencies of most multi-layer ¹⁰B detectors are limited up to about 42%, much less than 77% of the 2 bar 2-inch diameter ³He detectors. It is suggested that the same charge loss mechanism will prevent essentially all substrate-based boron detectors from ever reaching the efficiencies of high-pressure ³He tubes, independent of the substrate geometry and material composition (including silicon). Meanwhile, the experimental data indicate that the multi-layer approach can increase the efficiencies up to the theoretical limit. Good n/γ discrimination has also achieved using the ionization charnber technique.