Conférences et séminaires » Séminaire du Dr A. KHOUAJA (GANIL et LNS, Catane)

Séminaire du Dr A. KHOUAJA (GANIL et LNS, Catane)

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The preliminary results of first Commissioning of MAGNEX large-acceptance spectrometer.

le Jeudi 14 septembre 2006 à 16 h00

Salle de Visioconférences - Bâtiment 25
IPHC, 23 rue du Loess, Strasbourg-Cronenbourg

Abstract :

The large-acceptance MAGNEX magnetic spectrometer, recently commissioned with TANDEM beams at the INFN, Laboratori Nazionali del Sud (LNS), Catania, is an instrument intended for the study of nuclear reactions with both stable and unstable beams from TANDEM and EXCYT facilities, respectively. It has been designed to offer a high energy and mass resolution in a very large accepted phase space. MAGNEX consists of a quadrupole and a multipurpose bending magnet, the former to provide focusing in the vertical plane and the latter both momentum dispersion and a horizontal focus by inclination of the entrance and exit boundaries. The spectrometer relies partly on hardware (especially the shape of the entrance and exit dipole pole tips) and partly on software (ray reconstruction) to compensate the strong aberrations inherent in the 50-msr acceptance. Kinematic correction from 0 to -0.5 rad-1 is achieved partly by moving the focal plane detector (FPD) and partly by means of quadrupolar and sextupolar correction coils mounted on the dipole pole surfaces.

I will briefly present the preliminary results of first commissioning part where the magnetic elements - Quadrupole, Dipole, alpha- and beta-surface coils - and the optics in general, were tested with elastically scattered 16O beams with slit and pepperpot apertures mounted after the target. A demonstration of the particle identification capabilities of the PSD start detector and the focal plane detector was given by a measurement of the 19F(7Li, 7Be)19O charge exchange reaction at 25±5°, using the full acceptance of the spectrometer. The charge state distribution of 48Ti ions scattered at 120 MeV was also measured and found to be in good agreement with the predictions of INTENSITY.

Also, if we have time, I will show preliminary other results about the range (Bragg Curve) measurements of exotic nuclei. This concerns the European RTD Ion-Catcher project at GANIL, which is a development of a new Bragg-Curve detector, called "Maya-Ito". It has strips along the beam path direction and uses the Gassiplex readout system to read the induced charge on each strip. The proportional gas detector allows a measurement of the energy loss and then the stopping power for each incident particle in a buffer of selected noble gases. Therefore, the first experiment of this detector was performed to measure the range distributions (Bragg Curve) of exotic nuclei (48Ca and 78Kr) at intermediate energy (10A MeV) in He, Ne, Ar and Xe at different pressures. The preliminary results showed a small discrepancy with SRIM and Northcliffe and Schilling range data tables.

Contact :

Sandrine COURTIN

Florent HAAS