Ch. THEISEN – CEA Saclay Christophe.theisen@cea.fr MUSETT: the segmented Si array for the focal plane of the VAMOS spectrometer Ch. THEISEN – CEA Saclay Christophe.theisen@cea.fr May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

What is MUSETT MUr de Silicium pour l’Etude des Transfermium par Tagging Collaboration Saclay - Ganil Spectroscopy of heavy element with VAMOS and EXOGAM using the RDT technique Motivations : VAMOS : well adapted to asymmetric reactions Large angular acceptance Large transmission Beam rejection with the Wien Filter EXOGAM : high efficiency (single and coincidences). Constrains: Very slow and very heavy ions Optics of Vamos Alpha particle spectroscopy Segmentation for the RDT technique Time stamping Option : energy loss and tracking of heavy ions May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

MUSETT at VAMOS + EXOGAM May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

VAMOS optics Wien Filter tuned on residues; dipole on Beam dispersion  background Wien Filter tuned on beam; dipole off Beam focused Optics optimized on residues in both cases May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

VAMOS optics WF tuned on recoils WF tuned on beam Beam Beam 1+ 5+ 10+ May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Si detectors (Not a MUST II detector, this is a MUSETT one…) May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Si detectors Characteristics 300 μm thick 10 x 10 cm2 128 + 128 strips 3 % Al grid Front side : No Aluminum layer. < 0.25 μm B implantation Depletion ~ 30 V. Nominal voltage ~ 60 V. Provided by Micron Semiconductor 2 evaluation detector + 1 prototype received May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Si detectors May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Si detectors mechanics May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Electronics and DAQ for Si detectors See next presentation… ATHED MUVI CVM May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Gas detectors α Energy loss Escaped radioactivity D IC DSSD 5-10 Torr Iso 16 MeV Bi 150MeV 57 MeV 55 MeV Moreover, Vamos is a dispersive device : musett is installed after a dipole. For a good identification, we have perform a ray-tracing analysis, which means that we have to measure trajectories and position. Measuring the position with the segmented Si wall is not enough : we have also to measure position in a second place, namely with a Drift chamber. With this device, we have also the opportunity to have a much better alpha efficiency. Indeed, only half of the alpha can be detected in the Si det. The other half are leaving the Si as shown here. With the ChIo, we will be able to measure escaped alpha and to have therefore a much better total efficiency and selectivity. α Elect Elect Elect Escaped radioactivity May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Gas detector Constrains Large dynamics : heavy ions + escaped radioactivity Hybrid detector Ionisation Chamber + Drift Chamber Small energy loss of heavy ions Low pressure Small effect on/off Si Wall Coexistence of IC/DC fields Integration in HARPEE mechanics May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Mechanics integration Integration in the HARPEE mechanics : easy installation / maintenance Si Wall module Gas detector module May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

Status 3 Si detectors received ATHED ASICs : ready COFEE Front-end being tested CVM VME readout and DAQ ready. Need to be tested with COFEE. MUVI VXI readout : prototypes OK. Production soon Mechanics for Si : drawing ready, prototype soon Gas detector : R & D phase. Prototype 2007 May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI

SPIRAL2 Perspectives S3 focal plane May 25th, 2007 - Christophe THEISEN - INTAG Workshop GSI