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Tracking of low energy heavy ions

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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Tracking of low energy heavy ions

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  1. Trackingof 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

  2. Application : Upstream Tracking unknown distribution With a perfect beam  track only the outgoing particles Incoming beam v0 (x0,y0) θ0 perfect beam θ1 θ1 Incident angle Position of vertex Velocity Scattering angle Target Large Beam emittance ~10π mm.mrad (hor+vert) On target 0.5m upstream 1.5m upstream

  3. Effects on kinematics reconstruction 11C+p  11C+p’ 40.6 MeV/u C. JOUANNE (SPHN) PHD 2002 11C 11C E* Θp Proton Ep Without Beam Tracking With Beam Tracking

  4. BEAM 2nd tracking detector Target Experimental set-up: CATS + MUST2 MUST 2 : light particle detector (p, d, t, He, Li) (ΔE,E) or (E,t) : identification (x,y) : scatering angle 7cm

  5. The CATS Beam Tracking Detectors Low Pressure gas detector Anode Thin window Mylar 1.5µm cathodes 600mV (after gain x200) incoming ion Charge distribution  position i+ i+ i+ i+ X e- e- e- e- 10ns conducting Strips Low pressure (P=4-10 Torr) gas: CF4, C3F8, iC4H10 E If E/P high enough  avalanche (>100V/cm/Torr)  amplification charge movement  induced signal electrons are rapid  fast signal

  6. Basic CATS/BTD mechanics Active area: 7x7cm2 iC4H10 @ 6Torr 2x28 strips on cathodes 1 fast anode signal Ottini & al., NIM A, 431(1999) p. 476-484.

  7. 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 use

  8. Application : Downstream Tracking The Super Separator Spectrometer S3 - Selection and transmission of low energy fusion-evaporation residues  In flight mass measurement Beam Mass spectrometer Momentum achromat Electric dipole Magnetic dipole Final focal plane Very low Energy regime <1MeV/u

  9. Mass Dispersive Focal plane 99Sn 100Sn 101Sn 10cm Q=26+ Q=25+ Q=24+ Q=23+ Q=22+ Distribution FWHM ~ 1.3 mm Shashikant Manikonda, ANL Mass Separator Momentum Achromat 10cm

  10. Secondary electrons Emissive foil detector Very low thickness < 1µm foil Emissive foil (Mylar+Al, Carbon) Ions B E Secondary emission - low energy electrons (few eV) - depends on the material (CsI…) - surface process - proportional to dE/dx Electron detector = gaseous detector

  11. The Se-D : Secondaryelectron Detector

  12. The Se-D : Secondaryelectron Detector

  13. ExistingSe-DDetector • <1µm of Mylar • σtime ~ 100ps • σspace ~ 600µm VAMOS Spectometer Focal plane size : 10 x 40 cm2

  14. Se-Dwith one 2D cathode X+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

  15. 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

  16. Conclusions & Perspectives Upstream Beam Detectors: MWPC good time and position resolution BUT Limited counting rate + not so thin (5µm of Mylar) Downstream reaction product detectors: emissive foil MWPC as 1st generation  2D cathode place good time resolution, very thin, high couting rate BUT poor 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

  17. Collaboration People involved at CNA, GANIL and CEA/IRFU Technical 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 others Thank you for your Attention

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