TY  - JOUR
AU  - Mitzner, R.
AU  - Sorokin, A. A.
AU  - Siemer, B.
AU  - Roling, S.
AU  - Rutkowski, M.
AU  - Zacharias, H.
AU  - Neeb, M.
AU  - Noll, T.
AU  - Siewert, F.
AU  - Eberhardt, W.
AU  - Richter, M.
AU  - Juranic, P.
AU  - Tiedtke, K.
AU  - Feldhaus, J.
AU  - DESY
TI  - Direct autocorrelation of soft-x-ray free-electron-laser pulses by time-resolved two-photon double ionization of He
JO  - Physical review / A
VL  - 80
IS  - 2
SN  - 1050-2947
CY  - College Park, Md.
PB  - APS
M1  - PHPPUBDB-10798
SP  - 025402
PY  - 2009
N1  - © The American Physical Society
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:00
DO  - DOI:10.1103/PhysRevA.80.025402
UR  - https://bib-pubdb1.desy.de/record/88145
ER  -