The MAGNEX spectrometer, installed at LNS in Catania, is a large acceptance magnetic spectrometer initially proposed and thought for studying reactions performed with radioactive beams but which actually operates with stable nuclei beams accelerated from the K800 Superconducting Cyclotron (CS) or the Tandem Van der Graaf, at LNS.
From the mechanical point of view, MAGNEX is a QD spectrometer composed by two large aperture magnets, a quadrupole magnet (Q) followed by a 55° dipole magnet (D) and a Focal Plane Detector (FPD) for the detection of the emitted ions.
The Focal Plane Detector (FPD) is placed 1.91 m downstream the exit pole face of the dipole and its vessel is mounted on a movable carriage that can translate of ± 0.08 m along to the spectrometer optical axis, in order to match the detector position to different focus conditions. It is installed such that the normal to its entrance surface is rotated of 59.2° with respect to the MAGNEX central trajectory.
The MAGNEX FPD is a gas-filled hybrid detector followed by a wall of 60 silicon detectors. It measures the horizontal and vertical positions of each incident ion at four sequential points along the ions trajectory in four drift chambers separated two by two by a large proportional chamber. It also allows to measure the energy loss in the gas region and the residual energy released in the silicon detectors.
From the measured parameters at the FPD region thanks to the ray-reconstruction procedure - performed with the COSY INFINITY code - it is possible to retrieve the full ion trajectories back to the target thus obtaining the initial phase space parameters. Then the ejectile momentum vector, Q-value and the scattering angle are obtained.
The accepted magnetic rigidities range from 0.2 to 1.8 Tm, corresponding to energies of the detected ions ranging from 0.2 to 40 AMeV, depending on their mass and charge.
Good performances are achieved in terms of mass and energy resolutions, despite the large acceptance both in solid angle - of about 50 msrd - and momentum [-14,3%, +10,3%].
For more details see:
F. Cappuzzello, C. Agodi, D. Carbone and M. Cavallaro Eur. Phys. J. A (2016) 52: 167.
F. Cappuzzello et al. MAGNEX: an innovative large acceptance spectrometer for nuclear reaction studies in: Magnets: Types, Uses and Safety, New York: Nova Publisher Inc., 2011