We construct a kink solution on a non-BPS D-brane using Berkovits' formulation of superstring field theory in the level truncation scheme. The tension of the kink reproduces 95% of the expected BPS D-brane tension. We also find a lump-like solution which is interpreted as a kink-antikink pair, and investigate some of its properties. These results may be considered as successful tests of Berkovits' superstring field theory combined with the modified level truncation scheme.

X-ray generation by a thermally heated LiNbO3 crystal and effect of ultraviolet (UV) laser light irradiation to a LiNbO3 crystal on pyroelectric electron emission were investigated. The x ray was detected with a gap distance of 15 mm between the surface of the crystal and the anode, whereas it was not detected with a gap distance of ∼200 μm. The dependence of the electron emission excited by UV laser irradiation on the vacuum pressure, laser power density, and gap distance between the crystal and the anode was measured. The electron emission showed a fast response with a rise time of 1 μs to the laser irradiation. The emission current was 45 nA with a laser power density of 6.6 MW/cm2 with a gap distance of 125 μm between the surface of the crystal and the anode.

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Ions ejected from a liquid metal ion source of an Li-Mg (10 atom %) alloy have been investigated by using a magnetic mass analyzer. In addition to singly charged homonuclear Li n (+) (n ≤ 9) and Mg n (+) (n ≤ 4) and heteronuclear MgmLi n (+) (m, n ≤ 2) clusters, doubly charged diatomic and triatomic Mg clusters are observed. Discussion is focused on the observability and the formation mechanism of the doubly charged small Mg clusters. A postionization process is suggested for the formation of the doubly charged clusters.