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

2. Agnieszka Kowal ECFA 2003, Montpellier2 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

3. Agnieszka Kowal ECFA 2003, Montpellier3 Forward Calorimeter Layout 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 TDR design (postponed) New mask design

4. Agnieszka Kowal ECFA 2003, Montpellier4 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

5. Agnieszka Kowal ECFA 2003, Montpellier5 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 LAT Design Simulation beam pipe Tungsten mask

6. Agnieszka Kowal ECFA 2003, Montpellier6 LAT –  reconstruction and resolution 24 sectors48 sectors  Resolution as function of the number of cylinders readout from odd rings only reduction of the # of channels Angle reconstruction with simple energy weighting

7. Agnieszka Kowal ECFA 2003, Montpellier7 LAT –  reconstruction and resolution 48 sectors 24 sectors  Resolution as function of the number of cylinders 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 artificial shift

8. Agnieszka Kowal ECFA 2003, Montpellier8 LAT – performance with energy  E=40%√E E beam = 62.32 * E det + 0.36 0.2E-03 0.035 ()() ()() Energy Resolution & CalibrationAngular Resolution vs Energy R. Ingbir (TAU)

9. Agnieszka Kowal ECFA 2003, Montpellier9 LAT – angle reconstruction methods 15 cylinders / 24sectors / 30 rings Bhabha scattering with BHWIDE Simple weighting Logarythmic weighting R. Ingbir (TAU) 250 GeV

10. Agnieszka Kowal ECFA 2003, Montpellier10 LAT – design optimization # of active rings around the shower maximum logarythmic weighting in angle reconstruction  (  ) ~ 70  rad feasible  resolution as function of the depth # of cylinders R. Ingbir (TAU)

11. Agnieszka Kowal ECFA 2003, Montpellier11 LAT – Stripped design 30 tungsten rings every second ring has either 120 radial or 64 concentric Si strips 2960 readout channels B.Pawlik (INP-PAN, Cracow)

12. Agnieszka Kowal ECFA 2003, Montpellier12 Stripped LAT reconstruction results 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.) B.Pawlik (INP-PAN, Cracow)

13. Agnieszka Kowal ECFA 2003, Montpellier13 Laser measurement of the LAT detector displacement reconstruction of He-Ne laser spot on CCD camera Requirements on alignment: Inner Radius of LAT < 4 μm Axial LAT position < 60 μm possible resolution of ~1  m if the center of the light spot is determined with accuracy better than 0.1 pixel J.Zachorowski (UJ), W.Wierba (INP-PAN) Cracow work has just started

14. Agnieszka Kowal ECFA 2003, Montpellier14 LCAL performance with Real Beam simulation Included in the simulation: ground motion, feedback system delay, emittance growth, lumi optimisation V.Drugakov (BSU, Minsk)

15. Agnieszka Kowal ECFA 2003, Montpellier15 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 100 GeV V.Drugakov (BSU, Minsk)

16. Agnieszka Kowal ECFA 2003, Montpellier16 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