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Optimization of the Design of the Forward Calorimeters

This workshop focuses on the optimization of the design and performance of the forward calorimeters in the ECFA project. Topics include layout and functions of the forward calorimeters, LAT design and angle reconstruction algorithms, laser alignment system for LAT, and performance of LCAL with real beam simulation.

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Optimization of the Design of the Forward Calorimeters

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  1. ECFA LC Workshop Optimization of the Design of the Forward Calorimeters Montpellier, 15 November 2003 Agnieszka Kowal * University of Science and Technology, Cracow *FC Collaboration: Colorado, Cracow, DESY(Zeuthen), JINR Dubna, London (UC),Minsk (BSU), Prague, Protvino (IHEP), Tel Aviv Collaboration

  2. Agenda • Layout and functions of the forward calorimeters • Optimization of LAT design and angle reconstruction algorithms • Stripped LAT design as an alternative • Laser alignment system for LAT • Performance of LCAL with real beam simulation Agnieszka Kowal ECFA 2003, Montpellier

  3. Forward Calorimeter Layout TDR design (postponed) • LAT • z = 305-325 cm • R= 8-28 cm • 26.2<<82 mrad • 0<<360 deg • LCAL • z = 365-385 cm • R = 1.2-8 cm • 5<<28 mrad • 0<<360 deg New mask design Agnieszka Kowal ECFA 2003, Montpellier

  4. Functions of the very forward calorimeters • Measurement of luminosity (LAT) • Fast beam diagnostics (LCAL) • Detection of electrons and photons at very small angles • Shielding of the tracking detectors Agnieszka Kowal ECFA 2003, Montpellier

  5. LAT Design Simulation • Si/W calorimeters on both sides of the IP • 8-128 concentric cylinders (in r) • 30 rings (in z) • 24/48 sectors (in ) • Detector simulation with Barbie–Geant3.21 (L.Suszycki) • Single 250 GeV electrons Tungsten mask beam pipe Agnieszka Kowal ECFA 2003, Montpellier

  6. LAT –  reconstruction and resolution  Resolution as function of the number of cylinders 24 sectors 48 sectors Angle reconstruction with simple energy weighting readout from odd rings only reduction of the # of channels Agnieszka Kowal ECFA 2003, Montpellier

  7. LAT –  reconstruction and resolution  Resolution as function of the number of cylinders artificial shift resolution better for 48 sectors Optimum LAT segmentation: 32 cylinders in R 48 sectors in  30 rings in z (readout from every 2nd) 23040 channels 24 sectors 48 sectors Agnieszka Kowal ECFA 2003, Montpellier

  8. LAT – performance with energy R. Ingbir (TAU) Energy Resolution & Calibration Angular Resolution vs Energy E=40%√E () 0.2E-03 Ebeam = 62.32 * Edet + 0.36 () 0.035 Agnieszka Kowal ECFA 2003, Montpellier

  9. LAT – angle reconstruction methods 15 cylinders / 24sectors / 30 rings Bhabha scattering with BHWIDE R. Ingbir (TAU) 250 GeV Simple weighting Logarythmic weighting Agnieszka Kowal ECFA 2003, Montpellier

  10. LAT – design optimization R. Ingbir (TAU) resolution as function of thedepth • # of active rings around the shower maximum • logarythmic weighting in angle reconstruction • () ~ 70 rad feasible # of cylinders Agnieszka Kowal ECFA 2003, Montpellier

  11. LAT – Stripped design B.Pawlik (INP-PAN, Cracow) • 30 tungsten rings • every second ring has either 120 radial or 64 concentric Si strips • 2960 readout channels Agnieszka Kowal ECFA 2003, Montpellier

  12. Stripped LAT reconstruction results B.Pawlik (INP-PAN, Cracow) • Accuracy in measuring  is 0.5x10-4 rad • Energy measurement with accuracy of 5 GeV (E~0.31√E) • low segmentation level seems to be sufficient (~3000 read-out chan.) Agnieszka Kowal ECFA 2003, Montpellier

  13. Laser measurement of the LAT detector displacement J.Zachorowski (UJ), W.Wierba (INP-PAN) Cracow Requirements on alignment: Inner Radius of LAT < 4 μm Axial LAT position < 60 μm reconstruction of He-Ne laser spot on CCD camera work has just started possible resolution of ~1m if the center of the light spot is determined with accuracy better than 0.1 pixel Agnieszka Kowal ECFA 2003, Montpellier

  14. LCAL performance with Real Beam simulation V.Drugakov (BSU, Minsk) Included in the simulation: ground motion, feedback system delay, emittance growth, lumi optimisation Agnieszka Kowal ECFA 2003, Montpellier

  15. Real Beam vs. Ideal Beam LCAL particle recognition performance • the identification efficiency of electrons close to the beam is nearly the same for RB and IB • fake rate resulting from BG fluctuation is on the same level V.Drugakov (BSU, Minsk) 100 GeV Agnieszka Kowal ECFA 2003, Montpellier

  16. Summary • optimization of LAT structure and angle reconstruction algorithms is ongoing (so far () ~ 70rad achieved) • room for improvement in angular reconstruction algorithms (reduction of the bias in ) • LAT sensor geometry (pad/strip) is still discussed • for the goal L/L precision a laser alignment system is being developed for LAT • LCAL registration efficiency good for electrons with energy above 100 GeV Agnieszka Kowal ECFA 2003, Montpellier

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