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Status of straw-tube tracker

Status of straw-tube tracker. V.Peshekhonov, D.Peshekhonov, A.Zinchenko JINR, Dubna V.Tikhomirov P.N.Lebedev Physics Institute, Moscow Presented on the 10 th CBM Collaboration Meeting, 25-28 September 2007, Dresden.

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Status of straw-tube tracker

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  1. Status of straw-tube tracker V.Peshekhonov, D.Peshekhonov, A.Zinchenko JINR, Dubna V.Tikhomirov P.N.Lebedev Physics Institute, Moscow Presented on the 10th CBM Collaboration Meeting, 25-28 September 2007, Dresden

  2. Straw tube detectors are widely used for accelerators and astrophysics experiments. • Straw transition radiation detectors for the balloon investigation • ATLAS TRT • COMPASS straw tracker • (straw length – up to 3.6 m) • CBM straw TRD: • in the angle range 50 mrad – 200 mrad hit rate per 1 cm.sq. of the straw – from 1.2 MHz to ~200 kHz (central AuAu collisions, CBM detector setup with RICH) • To reduce the occupancy we propose to use segmented straws Status of straw-tube tracker

  3. What the segmented straws are: Anode consists of some independent part of the anode wires (segments) Each segment has own HV and readout channel Length of segments may be from few cm up to ~70cm Readout: low-mass transmission line (TL) from segment to FEE length of the TL up to 2m; drop of the signals - ~3% for TL 1.5m long and ~30% for 2m long Energy resolution ~24% Signal amplitude non-uniformity between segments – below ~5% Two segmented straw prototypes have been built and tested in JINR (results have been presented to the CBM Collaboration on March-2007 Meeting) Status of straw-tube tracker

  4. New prototype is now under development: It will be two-layer chamber with size 40 x 40 cm.sq. ~200 straws (4mm) Segmentation of straw: 4-5 segments with length from ~5 to 10 cm Should be ready for testing before spring-2008 Now: simulation and tests of transmission lines samples Problems: FEE, purchase of XC160 kapton film,……. Status of straw-tube tracker

  5. TOF M3 M2 M1 MD Straw Tracker: Distance – 4 m, 6 m and 8 m for 1-st, 2-d and 3-d module Each module consist of three double layers: one for X coordinate measurement and two inclined at ±10 degrees (U and V) layers. Status of straw-tube tracker

  6. To estimate the possibility of straw tube detectors using in the CBM muon detector setup, some Monte Carlo simulation has been performed. • AuAu central collisions at 25 GeV • “Compact” muon system and the system with additional absorbers have been considered • Hit rate has been estimated • Track reconstruction efficiency is evaluated • Accuracy of straw tracker and TOF matching is estimated Status of straw-tube tracker

  7. HIT RATE Here – for version of muon system with additional absorbers Status of straw-tube tracker

  8. HIT RATE Slices of occupancy map at Y=0 and X=0 Maximum expected rate ~0.005 hits/cm2 or ~2% occupancy for 10 cm straw with 4 mm diameter Status of straw-tube tracker

  9. HIT RATE “Compact” version of muon system Version with additional absorbers Status of straw-tube tracker

  10. General straw tracker layout (1-st module; muon system with additional absorbers) S:320 x 170 m2 (X,Y) 0.005÷0.003 cm-2 0.003÷0.002 cm-2 Ch.1 0.002÷0.001 cm-2 0.001÷0.0005 cm-2 < 0.0005 cm-2 S: 270 x 220 m2 (X,Y) Segmented straws, both side readout Ch.2 Terminated straws, readout – from outside ends Status of straw-tube tracker

  11. GRANULARITY (configuration of the muon detector with additional absorbers) ª)3-d module - 6 mm in diameter straws can be used ªª) Far periphery – long terminated straws ( 2÷4 m) can be used Status of straw-tube tracker

  12. Rate: 0.05÷0.02 1/cm2 Rate: 0.02÷0.005 1/cm2 Rate: 0.005÷0.002 1/cm2 Rate: < 0.002 1/cm2 600 500 450 300 1-1 300 1-2 400 500 GRANULARITY (1-st module, compact version of muon system) Granularity and occupancy of the central area Rate for the nearest area to the beam pipe Status of straw-tube tracker

  13. TRACKING EFFICIENCY • Very simple tracking procedure: • at least one hit in each of three tracker modules with the same track ID • hit smearing with coordinate resolution – 200 µm on X, 200 µm/sin(10o) on Y • straight line fit with χ2/NDF<10 Without multiple scattering With multiple scattering Status of straw-tube tracker

  14. STRAW TRACKER – TOF MATCHING X: σ = 1.7 mm 14 Y: σ = 2.3 mm Status of straw-tube tracker

  15. Conclusions • The concept of straw tube tracker for the CBM experiment with muon detector system is observed • Preliminary estimation of expected hit rate is obtained • To reduce the occupancy of the tracker in the central region, the segmented straws can be used • The preliminary estimation of tracker efficiency and coordinate matching with TOF is obtained • The straw tube tracker can be used in the CBM experiment with muon system option Status of straw-tube tracker

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