• F.H. O'Shea, G. Marcus, J.B. Rosenzweig
  UCLA, Los Angeles, California
• J. Bahrdt, A. Gaupp
  BESSY GmbH, Berlin
• F.J. Grüner, R. Weingartner
  LMU, Garching

The fundamentals of insertion device physics demand that to have access to ever higher photon energies either the beam energy must increase or the undulator period must decrease. Recent advances in accelerator technology have increased beam energies and at the same time insertion device technology has developed creative ways of producing light of the desired energy, characteristics and quality. This paper describes the simulation work for the design of a 9 mm period in-vacuum planar undulator using a new rare-earth magnetic material.

• M. Ferrario, D. Alesini, M. Bellaveglia, R. Boni, M. Boscolo, M. Castellano, E. Chiadroni, L. Cultrera, G. Di Pirro, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, C. Marrelli, M. Migliorati, A. Mostacci, E. Pace, L. Palumbo, B. Spataro, C. Vaccarezza, C. Vicario
  INFN/LNF, Frascati (Roma)
• G. Andonian, G. Marcus, J.B. Rosenzweig
  UCLA, Los Angeles, California
• A. Bacci, V. Petrillo, A.R. Rossi, L. Serafini
  Istituto Nazionale di Fisica Nucleare, Milano
• A. Cianchi, B. Marchetti
  INFN-Roma II, Roma
• L. Giannessi, M. Labat, M. Quattromini, C. Ronsivalle
  ENEA C.R. Frascati, Frascati (Roma)
• M. Rezvani Jalal
  University of Tehran, Tehran
• M. Serluca
  INFN-Roma, Roma

One of the main goals of the SPARC high brightness photoinjector is the experimental demonstration of the emittance compensation process while compressing the beam with the velocity bunching technique, also named RF compressor. For this reason, the first two S-band travelling wave accelerating structures downstream of the RF gun are embedded in a long solenoid, in order to control the space charge induced emittace oscillations during the compression process. An RF deflecting cavity placed at the exit of the third accelerating structure allows bunch length measurements with a resolution of 50 μm. During the current SPARC run a parametric experimental study of the velocity bunching technique has been performed. The beam bunch length and projected emittance have been measured at 120 MeV as a function of the injection phase in the first linac, and for different solenoid field values. In this paper we describe the experimental layout and the results obtained thus far. Comparisons with simulations are also reported.

• G. Marcus, G. Andonian, A. Fukasawa, P. Musumeci, S. Reiche, J.B. Rosenzweig
  UCLA, Los Angeles, California
• M. Ferrario, L. Palumbo
  INFN/LNF, Frascati (Roma)
• L. Giannessi
  ENEA C.R. Frascati, Frascati (Roma)

It has been suggested that an ultra-short, very low charge beam be used to drive short wavelength single-spike operation at the SPARC FEL. This paper explores the development and construction of a longitudinal diagnostic capable of completely characterizing the radiation based on the Frequency-Resolved Optical Gating (FROG) technique. In particular, this paper explores a new geometry based on a Transient-Grating (TG) nonlinear interaction and includes studies of start to end simulations for pulses at the SPARC facility using GENESIS and reconstructed using the FROG algorithm. The experimental design, construction and initial testing of the diagnostic are also discussed.