Musumeci, P.

Paper	Title	Page
TUPPH018	Development of Ultra-short Pulse, Single Coherent Spike for SASE X-ray FELs
	P. Musumeci, C. Pellegrini, S. Reiche, J. B. Rosenzweig UCLA, Los Angeles, California
	There is a large interest in the production of high power, ultra-short, one femtoseconds or less, coherent X-ray pulses, for atomic physics and other applications. However the present design of X-ray SASE FELs leads to an X-ray pulse about 100 times longer. Several methods to reduce the bunch length to the 10-1 fs region have been proposed. These methods are based on electron bunch manipulation to cut the lasing part of the bunch to a fraction of the total length, thus reducing the X-ray pulse length. We are considering here a different method, using ultra-short, very low charge electron bunches, with a length of the order or shorter than the FEL cooperation length. In this case the X-ray pulse length after amplification in the undulator is a few times the electron bunch length. Our simulations show that in an LCLS-like case we can obtain coherent, Fourier transform limited, X-ray pulses, consisting of a single spike, with a FWHM of about 0.1 um, corresponding to about 300 as, a peak power of about 5 GW, and an intensity of about 10 uJ.
WEPPH041	7th Harmonic Buncher Experiment at Neptune Laboratory	441
	R. Tikhoplav, S. Tochitsky, P. Musumeci UCLA, Los Angeles, California
	Since typically FEL undulator magnets have period length in the cm range, and the normalized magnetic field strength K is maintained close to unity to guarantee a good coupling, a very high energy electron beam is needed to access the far UV and x-ray region of the electromagnetic spectrum. One way to reduce the beam energy necessary for short wavelength light sources consists of exploiting the FEL harmonic interaction. An experiment aimed at demonstrating the efficiency of harmonically coupled schemes is proposed for the Neptune Laboratory at UCLA. We plan to inject the 12.4 MeV beam from the split photoinjector in an already available undulator with period = 3.3 cm and K = 1.8. The FEL resonant wavelength with these parameters is 74.2 um. A copropagating high power 10.6 um CO2 laser bunches the beam via 7th harmonic FEL/IFEL interaction. Preliminary calculations show that even though the interaction is weakened by the high harmonic number, it is required to use only 5 -10 MW of power in order to induce full bunching on the beam in the 10 period long undulator.
WEAAU02	Direct Measurement of Phase Space Evolution in the SPARC High Brightness Photoinjector	284
	D. Alesini, M. Bellaveglia, M. Boscolo, M. Castellano, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, M. Incurvati, C. Ligi, L. Pellegrino, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, F. Tazzioli, S. Tomassini, C. Vaccarezza, M. Vescovi, C. Vicario, E. Chiadroni INFN/LNF, Frascati (Roma) A. Bacci INFN/LASA, Segrate (MI) L. Catani, A. Cianchi INFN-Roma II, Roma S. Cialdi, A. R. Rossi, L. Serafini INFN-Milano, Milano L. Giannessi, M. Quattromini, C. Ronsivalle ENEA C. R. Frascati, Frascati (Roma) M. Migliorati, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma P. Musumeci, J. B. Rosenzweig UCLA, Los Angeles, California M. Petrarca INFN-Roma, Roma
	The characterization of the transverse phase space for high charge density relativistic electron beams is a fundamental requirement in many particle accelerator facilities, in particular those devoted to fourth-generation synchrotron radiation sources, such as SASE FEL. The main purpose of the SPARC initial phase was the commissioning of the RF photoinjector. At this regard, the evolution of the phase space has been fully characterized by means of the emittance meter diagnostics tool, placed in the drift after the gun exit. The large amount of collected data has shown not only that we can achieve the SPARC nominal parameters, but has also allowed for the first time a detailed reconstruction of the transverse phase space evolution along the drift, giving evidences of the emittance compensation process to occur as predicted by theory and simulations. In particular the peculiar behavior of a flat top longitudinal electron distribution compared to a gaussian distribution has been studied giving important insights for the correct matching with the following linac based on the double emittance minimum effect.
	Slides