Vamos + Exogam Spectrometer

Goals VAMOS was designed for spectroscopy studies using different reaction types in particular induced by low intensity radioactive beams Advantages large acceptance variable mode Coupling with EXOGAM TIARA, DIAMANT INDRA (Neutron Wall) Main working modes magnetic spectrometer separator

VAMOS Spectrometer Schematic View QUADRUPOLES EXOGAM BEAM Focal Plane detection DIPOLE Velocity Filter

VAMOS in reality

Specifications Quadrupoles (850 A) Q1 Q2 Magnetic length [m] 0.6 0.9 Field gradient [T/m] 7.0 2.4 Bρ full(reduced) Ω [Tm] 1.8 (2.2) Dipole (850 A) Magnetic field [T] 1.2 Magnetic length [m] 1.57 Deflection radius [m] 1.5 Bρ at 60° [Tm] 1.8 Wien Filter Length [m] 1 Gap [m] 0.15 E [kV] 300 B [T] 0.2

Specifications Path length 7.3 m Rotation 0°-90° Solid angle 100 msr Translation 0.4-1.2 m Momentum ±7 % Focal Plane Dispersion 2.5 cm/% Angle 0°-60° Example: Θ : -100, +100 [mrad] Bρ : (0.97,1,1.03)BNc

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

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

VAMOS Measurement Resolution Θ 0.1° Φ 0.3° Bρ 0.5% M/q 0.5% q 1/30 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

EXOGAM 12 closely packed Compton suppressed Ge segmented clover detectors Efficiency ~ 12% at 1.33 MeV

Deep Inelastic Collisions measured with VAMOS dE vs E

Deep Inelastic Collisions measured with VAMOS M vs M/Q

Search for 2+ in 54Ca magicity at N=34 -10 -5 f5/2 p1/2 p3/2 f7/2 48Ca 54Ca Large experimental effort to estimate this gap from studies of nearby nuclei. Direct information on this gap is the 2+ energy. Pronounced shell gap in 54Ca

Identification spectra dE vs E dE vs E M vs M/Q

Spectra of 50Ca γ-γ projection γ-γ projection γ-γ gate

Spectra of 52Ca

Recoil (Decay) Tagging Reaction: 18O@95MeV + 208Pb -> 222Th + 4n Time stamping: Time correlations measured using the universal clock CENTRUM SetUp: EXOGAM VAMOS at 0º with focal plane at 10º using WIEN filter focal plane detection: SeD, SiWall

Recoil Decay Tagging