Fig. 6From: Fast decay of 23S1 positronium atoms in an MgO lined cavityA scanning electron microscopy (SEM) image of MgO smoke nanocrystals taken by a Karl Zeiss XB1540 microscope with a 3 keV electron beam. The large variation in the edge lengths of the cubic crystals, (10-1000 nm [37]) is visibleBack to article page