CDR

Paper	Title	Other Keywords	Page
TUYPA01	Femtosecond Bunch Length Measurements	radiation, diagnostics, laser, electron	915
	S.P. Jamison CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Berden FOM Rijnhuizen, Nieuwegein W.A. Gillespie, P.J. Phillips University of Dundee, Nethergate, Dundee, Scotland A. MacLeod UAD, Dundee B. Steffen DESY, Hamburg
	The measurement of ultrashort longitudinal bunch profiles is of growing importance to accelerator development and operation. With requirements of ~10fs time resolution, and a desire for non-destructive and real time diagnostics, the challenges for diagnostic development are significant. Alongside more established transverse deflecting cavity and CTR measurement techniques, new approaches arriving from the field of ultrafast lasers offer significant potential; Ultrafast electro-optic detection has now been demonstrated on several accelerators, and in many distinct forms, although challenges remain in getting to the desired time resolution. Proposed schemes combining ultrafast laser diagnostics with FEL interactions, such as the "optical replica" scheme also have considerable potential. Here, an overview of the current status of femtosecond scale longitudinal profile diagnostics will be given, together with an outlook to the future expectations.
	Transparencies
TUPCH053	Bunch Length Characterization Downstream from the Second Bunch Compressor at FLASH DESY, Hamburg	electron, radiation, FEL, SASE	1127
	E. Chiadroni INFN-Roma II, Roma
	The characterization of the longitudinal density profile of picosecond and sub-picosecond relativistic particle bunches is a fundamental requirement in many particle accelerator facilities, since knowledge of the characteristics of the accelerated beams is of utmost importance for the successful development of the next generation light sources and linear colliders. The development of non-intercepting beam diagnostics is thus necessary to produce and control such beams. First experimental evidences of the non-intercepting nature of diffraction radiation diagnostics are given. The longitudinal bunch distribution downstream of the second bunch compressor of the DESY TTF VUV-FEL has been reconstructed using a frequency-domain technique based on the autocorrelation of coherent diffraction radiation. Due to the low and high frequency suppression, introduced by the experimental apparatus, only a portion of the CDR spectrum participates to the reconstruction of the longitudinal bunch profile. The knowledge of the system frequency response is then crucial in order to correct the results and extrapolate a bunch shape as close as possible to the real one.