1. Variable Mode High Acceptance Spectrometer
Detection and Tracking in VAMOS

2. Studies with Vamos Measures : - Bρ In dispersive mode
- angular distributions
In dispersive mode
- direct transfer reactions:
24Ne(d,3Heγ…), 26Ne(d,pγ…), 56Ni(d,pγ)
- multi nucleon transfer/deep inelastic reactions:
48Ca + 238U
- fusion reactions: 76Kr + 58Ni
In non-dispersive mode
- fusion reactions: 18O + 208Pb

3. VAMOS Spectrometer Schematic View
QUADRUPOLES
EXOGAM
BEAM
Focal Plane detection at 60°
DIPOLE
Velocity Filter

4. VAMOS in reality

5. VAMOS Measurement (dispersive mode)
Resolution
Θ 0.1°
Φ 0.3°
Bρ 0.5%
M/q 0.5%
q 1/30
M 1/200
Z 1/30 φf θf V Bρ
M/q M q Z φ θ Yf Xf
TOF ΔE E
M/q ~ Bρ x TOF
M ~ E x TOF2
Z2 ~ E x ΔE ~ ΔE/TOF2

6. Light/Fast Ion Detection Dispersive Plane
Drift Chamber
X: charge distribution
2 x 64 pads (6.3x50) mm
XFWHM ~200 μm
Y: drift time
YFWHM ~ 500 μm
Ionisation Chamber
2 x 7 pads (50x50) mm
1 x 7 pads (50x 170)mm
ΔEFWHM ~ 3%
Plastic Detector
EFWHM ~ 4%
Silicon Wall

7. Light/Fast Ion Detection Dispersive Plane
Drift Chamber
Plastic Detector
Ionisation Chamber

8. Heavy/Slow Ion Detection
Ionisation Chamber
Secondary electron Detector
Se-D
XFWHM ~ 1 mm
YFWHM ~ 2 mm
TFWHM ~ 300 ps
Mylar emissive foil

9. Very heavy/slow Ion Detection – non dispersive
Secondary electron Detector
Silicon Wall
QQWFD Mode

10. Examples Recoil Tagging – non dispersive Deep inelastic - dispersive
40Ca at 13.7 MeV/u + natTa
238U at 5.5 MeV/u + 48Ca

11. Very-heavy systems: RT and RDT
Test experiment :
Asymmetric reaction
208Pb(18O,4n)222Th

12. Energy loss versus ToF

13. Recoil Tagging

14. Recoil Decay Tagging

15. Deep Inelastic Collisions measured with VAMOS
40Ca at 13.7 MeV/u + natTa

16. Energy Loss versus EnergyCa Ar S Si Mg Ne O C Be K Cl P Al Na F N B Li

17. Charge versus Proton NumberCa Ar S Si Mg Ne O

18. Mass versus Mass/Charge
All charge states

19. Mass versus Mass/Charge
40Ca
41Ca
42Ca
36Ar
32S
28Si
24Mg
20Ne
160
One electron
Fully stripped
Two electrons

20. Mass Peux faire en redressant
Possible d’améliorer avec mesure de temps de vol

21. Deep Inelastic Collisions (inverse kinematics)
238U at 5.5 MeV/u + 48Ca

22. Online spectra of 50Ca 50Ca 49Ca 48Ca
Tres preliminaire, calib pas faite encore
ONLINE

23. Continuation - Experimentally explore the limits
of the existing setup to fully
identify the nuclei within
the M, Z, Q and E coordinates
- Recoil Decay Tagging
To be obtained by
- Short runs with the deep inelastic
reactions induced by Ni, Ge, Kr … beams
Include ΔE measurement of nuclei stopped in gas
Improve the ToF resolution that
limits the M/Q measurement
Tof : detecteur start (par exemple apres QQ)
Resolution spectro = 1/1000. Limite actuelle = detection

24. How to improve ? M/q ~ Bρ x TOF M ~ E x TOF2 Z2 ~ E x ΔE ~ ΔE/TOF2
Bρ : spectrometer resolution ~1/1000
 Improve algorithm (easy)
ToF : ~ 1/100 (versus HF)
 « start » detector, e.g. in the W.F.
E : Plastic  Silicon
ΔE : silicon detector ?

25. The MUSETT project MUr de Silicium pour l’Etude des
Transfermium par Tagging
(Silicon Wall for Transfermium Studies using Tagging)
Goals:
Detection of very-heavy/slow ions for RDT
Improved detection for light ions (transfer, deep inelastic)

26. MUSETT Configurations
Musett + SeD
RDT
Z,A identification (transfer, deep inelastic)
Musett +
CHIO
CHIO+SeD
40x10cm
4x128x128 strips

27. Specifications Granularity (Decay tagging, ray tracing)
Size (Focal plane coverage)
Energy resolution (Alpha spectroscopy, identification)
Window-less (Slow and heavy ions)
Low noise and compact electronics (ASICs)
Fast readout

28. MUSETT : Cost and planning
2006 : detector prototype; tests with existing electronics
: full setup (4 det.) with ASICs electronics
Cost : ~220 k€

29. Summary Dispersive mode : transfer, deep-inelastic
SeD, Drift chamber, CHIO, SiWall
Non dispersive : very-heavy elements
Asymmetric reactions, SeD, SiWal
Developments :
Improved ToF (dispersive Mode)
MUSETT : RDT; A,Z,Q identification