Institut des Sciences Moléculaires d'Orsay




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Home > Research Teams > Molecular systems, Astrophysics and Environment > Experimental tools > AGAT


Experiments are conducted at the Tandem accelerator in Orsay, at IPNO, using the AGAT set-up. Collisions between molecular projectiles (Cn+, CnHm+, CnN+) delivered by the accelerator and rare gas atoms occur in a gaseous jet of known thickness allowing absolute cross sections to be derived. The thickness is varied by changing the flow rate through the jet’s capillary. Fragments produced by dissociation of molecular projectiles in the collision are deflected, according to their charge over mass ratios, by an intense electric field (10 kV/cm) produced between two parallel plates situated 325 mm after the jet. After electrostatic deflection, the fragments impinge on solid-state silicon detectors suitably positioned, of 100% efficiency and operating in coincidence (see the figure below). The analysis of the transient current delivered by the detector (shape analysis method) allowed the mass and the charge identification of all fragments impinging on it to be realized in the case of homonuclear projectiles. For heteronuclear projectiles, the shape analysis method does not work and we used an original pixelated solid-state silicon detector (CCD camera) for resolving the fragmentation of neutrals.

With this set-up, all electronic processes such as single and double electron capture, electronic excitation, single and multiple ionization and their subsequent fragmentation, were studied

View of the inside of the detection chamber with suitably positioned fragments detectors

Vue des différents détecteurs de fragments du montage AGAT installé auprès de l'accélérateur TANDEM