Tracking of low energy heavy ions

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Tracking of low energy heavy ions . Two applications in nuclear physics. Upstream beam tracking at medium energy (>10MeV/u) Downstream reaction product tracking at low energy (<1MeV/u ) Event by event detection. Application : Upstream Tracking. unknown distribution. With a perfect beam
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Trackingoflow energyheavy ions Two applications in nuclear physics
  • Upstream beam tracking at medium energy (>10MeV/u)
  • Downstream reaction product tracking at low energy (<1MeV/u)
  • Event by event detection
  • Application : Upstream Trackingunknown distributionWith a perfect beam track only the outgoing particlesIncomingbeamv0(x0,y0)θ0perfect beamθ1θ1Incident anglePosition of vertexVelocityScattering angleTarget Large Beam emittance ~10π mm.mrad (hor+vert)On target0.5m upstream1.5m upstreamEffects on kinematics reconstruction11C+p  11C+p’ 40.6 MeV/uC. JOUANNE (SPHN) PHD 200211C11CE*ΘpProtonEpWithoutBeam TrackingWithBeam TrackingBEAM2nd tracking detectorTargetExperimental set-up: CATS + MUST2MUST 2 : light particle detector (p, d, t, He, Li) (ΔE,E) or (E,t) : identification(x,y) : scatering angle7cmThe CATS Beam Tracking DetectorsLow Pressure gas detectorAnodeThin windowMylar 1.5µmcathodes600mV (after gain x200)incoming ionCharge distribution positioni+ i+ i+ i+Xe- e- e- e-10nsconducting StripsLow pressure (P=4-10 Torr)gas: CF4, C3F8, iC4H10EIf E/P high enough  avalanche(>100V/cm/Torr)  amplificationcharge movement  induced signalelectrons are rapid  fast signalBasic CATS/BTD mechanicsActive area: 7x7cm2iC4H10 @ 6Torr2x28 strips on cathodes1 fast anode signalOttini & al., NIM A, 431(1999) p. 476-484. Virtues & Flaws of Low pressure detectors - fast signal  good time resolution σ = 100ps- good position resolutionσ = 100µm- highdetectionefficiency (~100%)- large size available (>100cm2)- cheap and canberepaired- Thin : ~5µm of Mylar (fromwindows and cathodes) - vulnerable to discharge : rate < 106pps- 1.5µm windows required  Eion > 10MeV/u- fragile and delicate to useApplication : Downstream TrackingThe Super Separator Spectrometer S3- Selection and transmission of low energy fusion-evaporation residues In flight mass measurementBeamMass spectrometerMomentum achromatElectric dipoleMagnetic dipoleFinal focal planeVery low Energy regime <1MeV/uMass Dispersive Focal plane 99Sn100Sn101Sn10cmQ=26+Q=25+Q=24+Q=23+Q=22+Distribution FWHM ~ 1.3 mmShashikant Manikonda, ANLMass SeparatorMomentum Achromat10cmSecondaryelectronsEmissive foil detectorVery low thickness< 1µm foilEmissive foil(Mylar+Al, Carbon)IonsBESecondary emission- low energy electrons (few eV)- depends on the material (CsI…)- surface process- proportional to dE/dxElectron detector = gaseous detectorThe Se-D : Secondaryelectron DetectorThe Se-D : Secondaryelectron DetectorExistingSe-DDetector
  • <1µm of Mylar
  • σtime ~ 100ps
  • σspace ~ 600µm
  • VAMOS Spectometer Focal plane size : 10 x 40 cm2Se-Dwith one 2D cathodeX+Y 2D cathode (strips)X cathode(strips)anode (wires)anode (wires)Y cathode(wires)
  • similar time resolution σtime ~ 100ps
  • more robust
  • higher counting rate : up to 2.106pps
  • New Prototype for S3
  • SED2D sym. chamber of 201x138 mm2 or 68x47 1D strips
  • Mounted since sept 2011, time resolution on-going
  • AFTER-SED ASIC to connect
  • Spatial resolution to be done
  • Conclusions & PerspectivesUpstream Beam Detectors: MWPC good time and position resolutionBUTLimited counting rate + not so thin (5µm of Mylar)Downstream reaction product detectors: emissive foil MWPC as 1st generation  2D cathode placegood time resolution, very thin, high couting rate BUTpoor position resolution σspace ~ 600µm
  • To come
  • improve position resolution of emissive foil detector
  • test of other secondary electron detector : Micromegas
  •  use emissive foil detectors for upstream applications
  • CollaborationPeople involved at CNA, GANIL and CEA/IRFUTechnical support & Engineering: T. Chaminade, F. Druillole, E. Monmarthe (IRFU) M. Kebbiri (IRFU), S. Damoy (GANIL), M. Riallot (IRFU), G. Fremont (GANIL)Scientific coordinator : M. Alvarez (CNA), H. Savajols, E. Clement, F. Farget(GANIL), A. Drouart, D. Doré, T. Materna (IRFU)Technical coordinator and analysis : B. Fernandez (CNA) , J. Pancin (GANIL), T. Papaevangleou (IRFU)And the othersThank youfor yourAttention
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