Author: Prince, K.C.
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MOP013 The Fermi Seeded FEL Facility: Operational Experience and Future Perspectives 57
  • L. Giannessi, E. Allaria, L. Badano, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, M. Coreno, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, F. Iazzourene, M. Kiskinova, S. Krecic, M. Lonza, N. Mahne, M. Manfredda, C. Masciovecchio, M. Milloch, F. Parmigiani, E. Pedersoli, G. Penco, L. Pivetta, O. Plekan, M. Predonzani, K.C. Prince, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, E. Roussel, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  FERMI is the seeded FEL user facility in Trieste, Italy, producing photons from the VUV to the soft X-rays with a high degree of coherence and spectral stability. Both FEL lines, FEL-1 and FEL-2, are available for users, down to the shortest wavelength of 4 nm. We report on the completion of the commissioning of the high energy FEL line, FEL-2, on the most recent progress obtained on FEL-1 and on the operational experience for users, in particular those requiring specific FEL configurations, such as two-colour experiments. We will also give a perspective on the improvements and upgrades which have been triggered based on our experience, aiming to maintain as well as to constantly improve the performance of the facility for our user community.  
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Measurements and Future Prospects for Coherent Control with FEL Radiation  
  • K.C. Prince
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  FELs produce ultrafast, intense, polarised and coherent pulses of light, similar to optical lasers, and these properties have been exploited in FEL experiments, with one exception, namely longitudinal coherence. There have been few if any FEL applications of this property. The FERMI FEL is longitudinally coherent, and can be configured to produce simultaneous, different wavelengths which are mutually coherent, with a well-defined phase relationship. We have exploited this in recent experiments to produce overlapping pulses of first and second harmonic light with a tunable phase delay, and perform an experiment on neon atoms. The first harmonic was set to about 63 nm and high intensity, and the second harmonic to lower intensity and half of this wavelength. The first harmonic gave rise to two-photon photoemission, while the second harmonic caused single photon emission. At appropriate relative intensities of the two beams, the emitted photoelectrons interfered to give asymmetric angular distributions (Brumer-Shapiro type experiment.) The asymmetry depended on the value of the phase difference between the two wavelengths, thus demonstrating their correlation in phase. The relative phase was controlled with a precision of 3 attoseconds. This result opens the way to coherent control experiments in the short wavelength region, and some planned applications will be illustrated.  
slides icon Slides FRA04 [4.216 MB]  
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