Design and realisation of a Thomson Spectrometer for Laser Plasma Facilities

A research project, LILIA (Laser Induced Light Ion Acceleration), has been funded at INFN (Italian Institute for Nuclear Physics) with the aim to study the mechanisms of charged particles acceleration by high power lasers. In Italy, at LNF INFN of Frascati, a high power laser (intensity in the range 1020 - 1021 W/cm2, 10 Hz repetition rate and high contrast, of the order of 1010, between main pulse and pre-pulse) named FLAME will be operative within 2010. The activities related to this project, along with the FLAME peculiarities, would result in a signicant synergy to improve the research on plasma ac- celeration in Italy. In this frame our group is involved in the design and construction of a spectrometer based on the Thomsons conguration in order to diagnostic the ion ejection from the laser-generated plasma. This kind of analyzer allows to get most of information about energy and species of beams produced from a single laser shot. The main goal is to realize a compact system which is both very practical and optimized with regard to the mass and energy resolution of particles obtained by laser-plasma interactions. The preliminary design has to be able to analyze and resolve beams of protons and ions up the total energy of 10 MeV. However, the technical choices adopted in this prototype have to be applied for the nal device concerning a challenging spectrograph able to analyze beams of 150 MeV of total energy. An intensive study by means of 3D electromagnetic FEM code and beam dynamics were accomplished out and the results will be shown. The rst prototype of the spectrometer is being realized and tested at LNS-INFN of Catania. After the magnetic and electric measurements the device will be calibrated as well as the detectors will be tested with proton and carbon beams delivered by the accelerators operating at LNS-INFN of Catania (Italy) within the expected energy range (0.1-10 MeV) and for dierent charge to mass ratios (Q=+1 to +6). The results of these tests will be also presented and discussed.