Cutting-Edge Cosmic Calibration & Particle Trigger: R&D Insights

1. EMC SuperModule Cosmic Calibration, VHMPiD R&D status, and A High Pt Charged Particle Trigger. N. Smirnov Physics Department, Yale University, Oct, 06. ALICE-USA collaboration meeting at Yale U.

2. EMC SM cosmic calibration; possible set-up. • We need a simple set-up to select a “single MIP through a tower” • Must be: compact, easy to move ( many strips), reliable (low rate). ~ 10 cm ~ 0.1 s-1 rate  ~10000 tracks / 24 hours / Module  ~ 1 Month / SuperModule

3. One EMC Module ( top view ) Triple GEM Detector (“active” surface ) 10 cm 12 cm 4 read-out pads to cover each tower 10 cm 12 cm Possible Set-up 4 Scintillation Counters ( ~ 75x14 cm2 ) 4 + 2 x { 12 x 4 } = 100 Read-out channels / EMC strip 10 cm 12 triple GEM detectors with pad read-out

4. Triple GEM Detector • Simple in construction ( NO: strong frame, wires, high precision parts ) • Reliable (discharge-free, but high gain in “all” gas mixtures ) • Efficient as a track detector 98% mip efficiency, ~20 ns response COMPASS experience • R&D, test and “production” Lab at Yale “Tech-Etch” (MA) mass-production ~ 1 cm One EMC Module ( top view ) Triple GEM Detector (“active” surface ) 10 cm 12 cm 4 read-out pads to cover each tower It needs: 2 x 12 x 3 = 72 GEM foils 2 x 12 x 4 = 96 FEE channels 10 cm 12 cm

5. VHMPiD R&D and Simulation Status • Group inside of ALICE ( >10 people) • CERN, Hungary, Italy, Mexico, USA (Yale U, BNL(?)) first HI collision ? start of LHC yesterday HMPID 3σ p/K limit HMPID TDR ALICE Club - May 2, 2005 Paolo Martinengo

6. GEANT Simulation Double sided Read-out plane Triple GEM foils with CsI UV Mirror, spherical shape in ZY AeroGel, 10cm 50 cm CF4 gas Detector response: GEANT hits(π+, Pt~10. GeV/c; local coordinate system, cm) Y 50 cm UV photoelectrons from “CF4 + Mirror” side C4F10 gas X Z R position: ~450 cm. Bz: 0.5 T CaF2 Window Particle track & UV photons MIP For all materials; n, transmission, absorption, reflection, Qw.Eff, - F(E = 5.5 – 11. eV) UV photoelectrons from “C4F10 + Window” side

7. Simulation for high Pt π+ Flat mirror Spherical mirror AeroGel, 10cm UV Mirror, spherical shape in ZY Double sided Read-out plane Triple GEM foils with CsI CF4 gas CaF2 Window C4F10 gas R Z In saturation: <N ph.e.>  25. (C4F10); 30. (CF4)

8. Detector response: GEANT hits(π+, Pt~10. GeV/c; local coordinate system, cm) UV photoelectrons from CF4 + Mirror MIP z x UV photoelectrons from C4F10 + Window

9. PiD table • Radiators: thickness L, refractive index n, angle θc, UV-light threshold AeroGel C4F10 CF4 L 10 50 50 cm n 1.008 1.0014 1.0005 θc ~100. 53. 32. mrad π 1.2 2.6 4.4 GeV/c K 4.2 9.3 15.6 GeV/c p 8.3 19.5 31.3 GeV/c P, GeV/c π/μ/e K p 5. – 9.3 ArG Y YN Ch1 YN N Ch2 YN N 9.3 - 15.6 ArG Y Y Y Ch1 Y Y N Ch2 YN N 15.6 – 20. ArG Y Y Y Ch1 Y Y N Ch2 Y Y N >20. ArG Y Y Y Ch1 Y Y Y Ch2 Y YN UV photoelectrons ring for CF4 + Mirror,Circle Fit, Nhits > 5. R, cm π K π/K PiD – ring radius P, GeV/c

10. ~ 2m ALICE Club - May 2, 2005 Paolo Martinengo

11. One detector response on “standard central ALICE event”. X - MIP position - Track “reflection” from mirror; “circle center” - Photo-electrons from “bottom” gas UV light + window. Red circle – track has hits in TPC - Photo-electrons from “top” gas UV light + mirror green means Sc. Light from CF4

12. GEANT Simulation, ALICE set-up VBHC Realistic material budget and position for: Si Vertex, TPC*, TRD, ToF + 100 modules of HMPiD (100 x 100 x 100 cm3 ) GEM D. AeroGel, 10cm UV Mirror, spherical shape in ZY CF4 gas Double sided Read-out plane Triple GEM foils with CsI CaF2 Window C4F10 gas *For TPC all “read-out” stuff is as realistic as possible to simulate dE/dX performance GEM D. 30 x 30 cm2 COMPAS read-out strip structure R Z

13. High Pt trigger using “fast” tracking data (?!) “R2D” Does not need primary Vertex position Sigma (cm): 0.02 0.2 0.02 0.9 “ALICE” Needs primary Vertex with ~n cm resolution ~1 m ToF hit R fit, DCA to Vertex in XY SLFtoBLine Straight Line Fit in RZ “Z” DCA to Vertex cut ~4 m Y Y SLDtoV X X

14. Track finding and selection for HMPiD only(plus Primary Vertex) SLDtoV, cm With cuts selected: (~ > 6. GeV/c ) I. 32 π+ /event; Pt = (8. – 10.) GeV/c  80% efficiency II. 32 π+ & Central PbPb HJ event ( ~ 2200 particles / rapidity)  70% efficiency (the SAME tracks that were found in step I ) III. “Standard Central ALICE” event ( ~ 8000 particles / rapidity )  1 track was found, Pt = 5.6 GeV/c Pt, GeV/c This “high Pt trigger approach” can be checked / tested with “available” equipments and in reasonable short period of time

15. ALICE TPC: 159 pad-rows; 63x (0.75x0.4) + 64x(1.x0.6) + 32x(1.5x0.6)Ne+CO2 (10%), B=0.5 T, Dl = Dt = 220 μm/cm-1Drift <= 250 cm. Vdr = 2.84 cm/μs (88 μs max) Simulation approach:N inter./cm; N el. / cluster; For each e- : (Ekin, range, Drift, wire position, timing, gas amplification, charge on pads); FEE shaping and noise; Hit position and Q reconstruction. dE/dX dE/dX Cluster efficiency – 85%, Truncated – 60% π, K, p P, Gev/c P, Gev/c “Perfect” in simulation: gas amplification calibration, P – reconstruction, one particle / event, |η| < 0.9; No “tail subtraction” problem; FADC approach.