1. Abstract: We present on overview of the STAR project (Southern european Thomson source for Applied Research), in progress at the Univ. of Calabria (Italy) aimed at the construction of an advanced Thomson source of monochromatic tunable, ps-long, polarized X-ray beams, ranging from 20 to 140 keV. The project is pursued in collaboration among: Univ. della Calabria, CNISM, INFN and Sincrotrone Trieste. The X-rays will be devoted to experiments of matter science, cultural heritage, advanced radiological imaging with micro-tomography capabilities. One S-band RF Gun at 100 Hz will produce electron bunches boosted up to 60 MeV by a 3m long S-band TW cavity. A dogleg will bring the beam on a parallel line, shielding the X-ray line from the background radiation due to Linac dark current. The peculiarity of the machine is the ability to produce high quality electron beams, with low emittance and high stability, allowing to reach spot sizes around 15-20 microns, with a pointing jitter of the order of a few microns. The collision laser will be based on a Yb:Yag 100 Hz high quality laser system, synchronized to an external photo-cathode laser and to the RF system to better than 1 ps time jitter. Beam Dynamics Analysis, two WPs at 0.5 nC The Thomson Scattering process, laser e-beam interaction has been simulated by using the TSST (Thomson Scattering Simulation Tools) code, which is based on analytical results of [P.Tomassini, et al., Appl. Phys. B80 (2005) 419] but is suitable also for gaussian shaped pulses. TSST is able to treat each macroparticle of the bunch as an independent relativistic and nonlinear oscillator, avoiding the use of any superimposed statistical average on particles distribution. The spectrum of the collected photons depends on geometry and laser photons/bunch phase space distributions. The peak energy (Emax=4γ2E ph where E ph is the laser photons energy) is achieved by a full head-on collision with emission of a backscattered photon. In a cylindric reference frame (θ,φ) pointing through the beam direction (i.e 180° of scattering angle) this is obtained on axis (θ=0). Relativistic and nonlinear effects generate a reduction of the photons energy (see Fig. A) when either multiphotons absorption (nonlinearities) or non-perfect backscattering occur. Electron Laser interaction Scattering Thomson at SPARC_lab The final focus sistem. This year, febrary/march, we made the first collisions as reporte on poster/proceeding MOPRO078 Hangar and Linac Bunker Q4=3.95 T/MQ6=3.95 T/M Q4=3.75 T/MQ6=3.75 T/M Amittance degradation from space- charge (<0.1 mm-mrad) sig_z=1mm, =43 A Trace3d Astra Dispersion region space charge on a narrow vertical envolope in a quite long path 200 microns z [mm] x [mm] y [mm] x [mm] y [mm] z [mm] pz[eV/c] z [mm] 85MeV at IP (18.736m)60MeV at IP (18.736m) 240 microns Astra tracking with sp on: comparison between envelope computed by Astra and my post-processor with beam rotation IP ~20 mic. at 18.73 m Relevant variation into the dipoles tracking X,Y norm. emittances for t_step=2ps,1ps,0.5ps Space Charge on/off, 0.5ps case Ɛ x -2ps Ɛ y -2ps Ɛ x -1ps Ɛ x -0.5ps Ɛ y -1ps Ɛ y -0.5ps 0.5ps_sc-off 2.0 mm-mrad 1.5 mm-mrad z [mm] x [mm] y [mm] x [mm] y [mm] z [mm] pz[eV/c] z [mm] x [mm] y [mm] Jitters analysis Dark Current at IP Local energy spectrum for a given scattering angle, 60MeV WP with waist of 18 µm The TS optimization involves collimation angle θc, laser pulse waist size w0, bunch focusing size and pulse-bunch spatial jitter. The increase of the photon flux within the max. bandwith of 5% rms is linked to the acceptance angle (Fig. B) Rel. E_spread (blue) and spect. dens. of collected photons [phot./eV] (green) vs accept. angle. 60MeV WP Photons Flux VS waste VS e-bunch Pointing Instabilities