%0 Journal Article
%A Mitzner, R.
%A Sorokin, A. A.
%A Siemer, B.
%A Roling, S.
%A Rutkowski, M.
%A Zacharias, H.
%A Neeb, M.
%A Noll, T.
%A Siewert, F.
%A Eberhardt, W.
%A Richter, M.
%A Juranic, P.
%A Tiedtke, K.
%A Feldhaus, J.
%A DESY
%T Direct autocorrelation of soft-x-ray free-electron-laser pulses by time-resolved two-photon double ionization of He
%J Physical review / A
%V 80
%N 2
%@ 1050-2947
%C College Park, Md.
%I APS
%M PHPPUBDB-10798
%P 025402
%D 2009
%Z © The American Physical Society
%X The pulse duration of soft x-ray free-electron laser (FEL) radiation is directly measured by time-resolved observation of doubly charged helium ions at 51.8 eV. A wave front splitting autocorrelator produces two correlated FEL pulses with a resolution of better than a femtosecond. In the interesting intensity range from 10<sub>13</sub> to 10 W/cm direct and sequential double ionization contribute to the ion yield which has significant influence on the correlation width, being a general feature at high photon energies. Here, a duration of τL=(29±5) fs is derived for the soft x-ray pulses at FLASH.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:00
%R 10.1103/PhysRevA.80.025402
%U https://bib-pubdb1.desy.de/record/88145