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The free-electron laser, first proposed by Madey in 1971, has significantly reduced laser wavelengths to the vacuum ultraviolet and soft X-ray regions. Recently, an X-ray free-electron laser (XFEL) was operated at 1.2 Å at the Linac Coherent Light Source (LCLS). Here, we report the successful generation of sub-ångström laser light using a compact XFEL source, combining a short-period undulator with an 8 GeV electron beam. The shortest wavelength attained-0.634 Å (63.4 pm)-is four orders of magnitude smaller than the 694 nm generated by Maiman's first laser. The maximum power exceeded 10 GW with a pulse duration of 10?14 s. This achievement will contribute to the widespread use of XFEL sources and provide broad opportunities for exploring new fields in science. [ABSTRACT FROM AUTHOR]

Abstract: A new vacuum seal for a rectangular flange used in r.f. equipments, was developed. The vacuum seal consists of a recess with a flat surface, machined into a rectangular flange, a rectangular metal gasket with a raised projection on one face, and a mating flange with a recess and raised projection. No leak greater than 1 × 10−10 Pa m3/s was found in leak tests, before and after baking cycles (100 °C, 12 h). [Copyright &y& Elsevier]