• A. Fukasawa, J.B. Rosenzweig, D. Schiller
  UCLA, Los Angeles, California
• D. Alesini, L. Ficcadenti, B. Spataro
  INFN/LNF, Frascati (Roma)
• L. Faillace, L. Palumbo
  Rome University La Sapienza, Roma

A unique SW/TW hybrid photoinjector are being developed under the collaboration of UCLA, LNF/INFN, and University of Rome. It can produce 240-fs (rms) bunch with 500 pC at 21 MeV. The bunch distribution has a strong spike (54 fs FWHM) and the peak current is over 2kA. As the bunch form factor at 1 THz is 0.43, it can produce coherent radiation at 1 THz. We are considering three types of way to generate it; coherent Cherenkov radiation (CCR), superradiant FEL, and coherent transition/edge radiation (CTR/CER). CCR used hollow dielectric with the outer surface metallic-coated. OOPIC simulation showed 21 MW of the peak power (5 mJ) at 1 THz. For FEL and CTR/CER simulation, QUINDI, which was written at UCLA to solve the Lienard-Wiechert potential, was used to calculate the radiation properties. In the contrast to CCR, their spectra were broad and their pulse lengths were short. They will be useful for fast pumping.

• L. Palumbo
  Rome University La Sapienza, Roma
• C. Vaccarezza
  INFN/LNF, Frascati (Roma)

The SPARX-FEL project is meant to provide ultra high peak brightness electron beams, with the energy ranging between 1.5 - 2.4 GeV, in order to generate FEL radiation in the 0.6-40 nm range. The construction will start with a 1.5 GeV Linac; besides the basic S-band technology the C-band option is also presently under study. Both RF-compression and magnetic chicane techniques are foreseen to provide the suitable electron beam to each one of the three undulator systems which will generate VUV-EUV, Soft X-Rays and Hard X-rays radiation respectively. Dedicated beamlines will distribute the beam to the downstream undulators for applications in basic science and technology. In this paper we present the status of the project funded by the Italian Department of Research, MIUR, and by the local regional government, Regione Lazio, that foresees the construction of a user facility inside the Tor Vergata campus by collaboration among CNR, ENEA, INFN and the Università di Tor Vergata itself.

• L. Faillace, L. Palumbo
  Rome University La Sapienza, Roma
• P. Frigola
  RadiaBeam, Marina del Rey
• A. Fukasawa, B.D. O'Shea, J.B. Rosenzweig
  UCLA, Los Angeles, California
• B. Spataro
  INFN/LNF, Frascati (Roma)

The quest for high brightness beams is a crucial key for the SPARX-FEL Project. In this paper, we present the design (including RF modeling, cooling, thermal and stress analyses as well as frequency detuning) of a single feed S-Band RF Gun capable of running near 500 Hz. An alternative design with dual feed has already been designed. Also, experimental results from the RF characterization of the prototype, including field measurements, are presented. The RF design follows the guidelines of the LCLS Gun, but the approach diverges significantly as far as the management of the cooling and mechanical stress is concerned. Finally, we examine the new proprietary approach of RadiaBeam Technologies for fabricating copper structures with intricate internal cooling geometries that may enable very high repetition rate.

* C.Limborg et al., "RF Design of the LCLS Gun".
** P. Frigola et al., "Development of solid freeform fabrication (SFF) for the production of RF Photoinjectors".

• A. Mostacci, M. Migliorati, L. Palumbo
  Rome University La Sapienza, Roma
• D. Alesini, P. Antici
  INFN/LNF, Frascati (Roma)
• L. Picardi, C. Ronsivalle
  ENEA C.R. Frascati, Frascati (Roma)

Protons generated by the irradiation of a thin metal foil by a high-intensity short-pulse laser have shown to posses interesting characteristics in terms of energy, emittance, current and pulse duration. They might therefore become in the next future a competitive source to conventional proton sources. Previous theoretical and numerical studies already demonstrated the possibility of an efficient coupling between laser-plasma acceleration of protons with traditional RF based beam-line accelerator techniques. This hybrid proton accelerator would therefore benefit from the good properties of the laser-based source and from the flexibility and know-how of beam handling as given from RF based accelerator structure. The proton beam parameters of the source have been obtained from published laser interaction experimental results and are given as input to the numerical study by conventional accelerator design tools. In this paper we discuss recent results in the optimization and design of the such hybrid schemes in the context of proton accelerators for medical treatments.

• P. Antici, A. Mostacci
  INFN/LNF, Frascati (Roma)
• C. Benedetti
  Bologna University, Bologna
• M. Migliorati, L. Palumbo
  Rome University La Sapienza, Roma

Electron beams produced by laser-plasma interaction are attracting the interest of the conventional accelerator community. In particular Laser-accelerated electrons are particularly interesting as source, considering their high initial energy and their strong beam current. Moreover, the advantages of using laser-plasma electron beam can be expressed in terms of size and cost of the global accelerating infrastructure. However, improvements are still necessary since, currently, the many laser-accelerated beams are characterized by a large energy spread and a high beam divergence that degrades quickly the electron beam properties and makes those sources not suitable as a replacement of conventional accelerators. In this paper, we report on the progress of the study related to capture, shape and transport of laser generated electrons by means of tracking codes. Our study has focused on laser-generated electrons obtained nowadays by conventional multi hundred TW laser systems and on numerical predictions. We analyze different lattice structures, working on the optimization of the capture and transport of laser-accelerated electrons. Results and open problems are shown and discussed.

• R. Boni, D. Alesini, M. Bellaveglia, G. Di Pirro, M. Ferrario, L. Ficcadenti, A. Gallo, F. Marcellini, E. Pace, B. Spataro, C. Vaccarezza
  INFN/LNF, Frascati (Roma)
• A. Bacci
  Istituto Nazionale di Fisica Nucleare, Milano
• A. Mostacci, L. Palumbo, V. Spizzo
  Rome University La Sapienza, Roma
• C. Ronsivalle
  ENEA C.R. Frascati, Frascati (Roma)

In the frame of the SPARC-X project, the energy of the Photo-Injector SPARC, in operation at INFN-LNF, will be upgraded from 180 to 250 MeV by replacing a low gradient S-band traveling wave accelerating section with two C-band units, designed and developed at LNF. The new system will consist of a 50 MW klystron, supplied by a pulsed modulator, to feed the high gradient C-band structures through a RF pulse compressor. This paper deals with the design of the full system, the C-band R&D activity and study of the related beam dynamics.