1. 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
May 25th, 2007
- Christophe THEISEN - INTAG Workshop GSI

2. 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

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

4. 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

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

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

7. 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

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

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

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

11. 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

12. 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

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

14. 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

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