Variable Mode High Acceptance Spectrometer

M. Rejmund/Ch. Theisen INTAG June 2005

Variable Mode High Variable Mode High Acceptance SpectrometerAcceptance Spectrometer

Detection and Tracking in VAMOS


Studies with VamosStudies with Vamos

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

Measures :- Bρ - angular distributions


VAMOS SpectrometerVAMOS SpectrometerSchematic ViewSchematic View

QUADRUPOLES

EXOGAM

BEAM

Focal Plane detection at 60°

DIPOLE

Velocity Filter


VAMOS in realityVAMOS in reality


VAMOS MeasurementVAMOS Measurement(dispersive mode)(dispersive mode)

YfXf

TOF

ΔE

E

φfθf

V

BρM/q

Mq

Z

φθ

M/q ~ Bρ x TOFM ~ E x TOF2

Z2 ~ E x ΔE ~ ΔE/TOF2

ResolutionΘ 0.1°

Φ 0.3°Bρ 0.5%M/q 0.5%q 1/30M 1/200Z 1/30


Light/Fast Ion Light/Fast Ion DetectionDetection Dispersive PlaneDispersive Plane

Drift ChamberX: charge distribution

2 x 64 pads (6.3x50) mmXFWHM ~200 μm

Y: drift timeYFWHM ~ 500 μm

Ionisation Chamber2 x 7 pads (50x50) mm1 x 7 pads (50x 170)mm

ΔEFWHM ~ 3%Plastic Detector

EFWHM ~ 4%

Silicon Wall


Light/Fast Ion Light/Fast Ion DetectionDetection Dispersive PlaneDispersive Plane

Drift Chamber

Plastic Detector

Ionisation Chamber


Heavy/Slow Ion Heavy/Slow Ion DetectionDetection

Ionisation Chamber Secondary electron Detector

Se-DXFWHM ~ 1 mm YFWHM ~ 2 mm TFWHM ~ 300 ps

Mylar emissive foil


Very heavy/slow Ion Very heavy/slow Ion Detection – non dispersiveDetection – non dispersive

Secondary electron DetectorSilicon Wall

QQWFD Mode


ExamplesExamples

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 Very-heavy systems: RT and RDTRDT

Test experiment : Asymmetric reaction

208Pb(18O,4n)222Th


Energy loss versus ToFEnergy loss versus ToF


Recoil TaggingRecoil Tagging


Recoil Decay TaggingRecoil Decay Tagging


Deep Inelastic CollisionsDeep Inelastic Collisionsmeasured with VAMOSmeasured with VAMOS

40Ca at 13.7 MeV/u + natTa


Energy Loss versus Energy Loss versus EnergyEnergy

CaAr

SSi

MgN

eOC

Be

KCl

PAl

NaF

NBLi


Charge versus Proton Charge versus Proton NumberNumber

CaAr

SSi

MgN

eO


Mass versus Mass versus Mass/ChargeMass/Charge

All charge states


Mass versus Mass versus Mass/ChargeMass/Charge

40Ca

41Ca

42Ca

36Ar32S28Si

24Mg20Ne160

Fully stripped

One electron

Two electrons


MassMass


Deep Inelastic CollisionsDeep Inelastic Collisions(inverse kinematics)(inverse kinematics)

238U at 5.5 MeV/u + 48Ca


Online spectra of Online spectra of 5050CaCa

48Ca

49Ca

50Ca


ContinuationContinuation- 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


How to improve ?How to improve ?M/q ~ Bρ x TOF

M ~ E x TOF2

Z2 ~ E x ΔE ~ ΔE/TOF2Bρ : 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 projectThe MUSETT project

MUr de Silicium pour l’Etude desTransfermium 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 ConfigurationsMUSETT ConfigurationsMusett Musett + SeDRDT

Z,A identification (transfer, deep inelastic)

Musett +CHIO

Musett +CHIO+SeD

40x10cm4x128x128 strips


SpecificationsSpecifications

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 planningMUSETT : Cost and planning

2006 : detector prototype; tests with existing electronics

2007-2008 : full setup (4 det.) with ASICs electronics

Cost : ~220 k€


SummarySummary

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

Variable Mode High Acceptance Spectrometer

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