Variable Mode High Acceptance Spectrometer Detection and Tracking in VAMOS

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

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

VAMOS in reality

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

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

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

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

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

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

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

Energy loss versus ToF

Recoil Tagging

Recoil Decay Tagging

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

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

Charge versus Proton Number Ca Ar S Si Mg Ne O

Mass versus Mass/Charge All charge states

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

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

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

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

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

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 ?

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)

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

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

MUSETT : Cost and planning 2006 : detector prototype; tests with existing electronics 2007-2008 : full setup (4 det.) with ASICs electronics Cost : ~220 k€

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