Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse lengths in the femtosecond range 1-4. This would allow, for example, time-resolved observation of chemical reactions with atomic resolution. Such radiation of extreme intensity, and tunable… (More)
This paper describes an effective frequency doubler scheme for SASE free electron lasers. It consists of an undulator tuned to the first harmonic, a dispersion section, and a tapered undulator tuned to the second harmonic. The first stage is a conventional soft X-ray SASE FEL. Its gain is controlled in such a way that the maximum energy modulation of the… (More)
Wakefields excited in the small aperture collimators may damage the beam. As pointed out by K. Bane and P. Morton the wakefields can be reduced considerably by tapering the steps and using the " step+taper " collimator geometry. The optimisation of this kind of geometry for TTF 2 collimators with different apertures is carried out in the paper. For the… (More)
6 e pick−up − photo− multpl.
In chromatic adapted barnacle median and lateral photoreceptors the two stable states of the photopigment (rhodopsin R and metarhodopsin M) were interconverted with intense, colored light flashes of 1 ms duration. Only after conversion of the red adapted photoreceptor in K+-Ringer solution with an intense flash the negative early receptor potential, ERP (of… (More)