1. Sensitivity of HO to Muons Shashi Dugad for HO group India-CMS Meeting 6-7 Oct.-2003

2. Sensitivity of HO to Muons Shashi Dugad India-CMS Meeting 6-7 Oct.-2003

3. HO Setup 1 Sector (6 Trays) of Ring-1, Ring-2 and 5- Trays of Ring-0 hooked up in the testbeam 2 Readout Box (RBX) of HB configuration containing 4 HPD each were provided for optical readout of HO towers –20,30,30 towers each in Ring-0,1,2 respectively –Eta-tower=5 (Ring-1) cannot be connected due to constraints from RBX

4. HO Readout Only 4-HPD (18 towers each) could be connected to DAQ system at any time Depending on the beam direction, following configuration chosen; RBX-2 RBX-1 Ring-0 Ring-1 HPD 1,2 RBX-1 Ring-1 Ring-2 HPD 1,2 HPD 3,4 RBX-2 Ring-0 HPD 1,2 HPD 3

5. HO Read Out Signal Flow: –Tile  Pigtail  Optical Cable  HPD  QIE  Transducer  Optical fiber communication cable  HTR Charge data from each tile is readout at every 25 nSec and stored on trigger –Data from 20 time slices (500 nSec) is stored for each event RBX-1RBX-2 Ring # Tray # HPD4 HPD3 HPD2 HPD1 1 1 2 2 4,5,6 1,2,3 HPD4 HPD3 HPD2 HPD1 0 0 0 6 4,5 2,3

6. Muon Runs Muons of 225 GeV shooted in each tower 10 K events taken for each tower Data is stored in root-tuple – Data read through HTBDAQ library All HB towers upto Phi_tower = 6 scanned All HO towers from Phi=2-6 scanned except one tower in each phi-strip

7. Analysis Average charge/slice distribution obtained Latency: Distribution of Slice# giving max. charge obtained Signal contained in 5-time slice for HO and 7-time slices for HB detector –Higher signal width as compared to last year data Signal charge obtained by summing 10-14 time slices in HO Signal charge obtained by summing 0-4 time slices in HO S/B Ratio = Signal Peak/Ped. RMS

8. S/B Ratio Study Charge readout by 4 different capacitor banks –Each of them may have different ped. peak and RMS Obtain noise distribution as per Cap-ID S/B does not change with Cap-ID correction Signal charge is dominantly coming from 3-time slices –Obtain S/B for 3- time slices –Obtain S/B by choosing slice with max. charge and then summing in 3- slices Signal increases with HV –Obtain S/B at diff. HV

9. Summary of S/B Ratio Study Signal Strength and S/B Ratio for HO Detector –3d  Dynamic selection of 3-slices Ring # #of SlicesAvg.Peak (fC) S/B using Peak Avg. Mean (fC) S/B using Mean 033.74.55.46.6 03d3.94.85.87.0 054.34.56.26.5 131.92.22.63.1 13d1.72.02.52.9 152.1 2.9 232.53.03.44.1 23d2.42.93.23.9 252.82.93.73.8

10. HO for Muon Trigger Important to see effect of noise on trigger efficiency –Signal Eff.(Q) = Fractional area beyond Q for signal run –Purity(Q) = 1. – Fractional area beyond Q for pedestal run –Signal Eff. And Purity obtained at different values of Q for each tile Ring-1 has low purity at moderate efficiency, need to enhance signal strength –Sort HPD’s by QE –Enhance HV to HPD

11. Summary Clean muon signal seen in all HO towers –No dead channels S/B Ratio: –4.5 for Ring-0, 2.2 Ring-1 and 3 for Ring-2 No significant improvement with 3-time slice signal size or CapID criteria Latency: Signal Peak Charge has a spread in 3-slices Ring0, Ring2 has reasonable purity at high efficiency, Ring-1 needs improvement –30% improvement in S/B @10 KV –Pre-selection of HPD expected to improve S/B by another 20-30%

12. LASER CALIBRATION SETUP Only 1 of the RBX (HO-1, located behind Ring-2) was lighted with laser light pulses Data from Spigot=11,12,13 used for analysis –Spigot-14 had problem with 3-channels in the readout Run#EventsAttenuation 9535 9537 9538 9539 9540 4000 0.85 0.75 0.65 0.55 0.45

13. High Intensity LASER Runs Light Intensity correction using PIN is important and depends upon the accuracy with which PIN signal is measured? –Should be much better than statistical accuracy of HPD pixel signal (~1% at high intensity) Light intensity correction can be obtained by summing of normalized HPD pixel signal –Statistical accuracy of this would be 1/Sqrt(N) better than the pixel (N=3*18 for this dataset) –This will work provided systematic effects are much smaller than statistical accuracy Usage of high intensity runs depends on deeper understanding of these issues –LOW intensity runs (9535, 9537) are used in the current analysis

14. Analysis Get ped. and signal distribution for each HPD pixel and PIN diode at different LASER intensity. – 7-time used for obtaining signal charge (7-13 for HPD and 3-9 for PIN) Get intensity correction using normalized PIN and HPD signal distribution Apply intensity correction and re-obtain signal distribution –Get peak and sigma using gaussian fit Tails seen signal distribution –Using these parameters, obtain # of p.e. and calibration factor (#of p.e./fC) for each pixel at each intensity

15. Results Low intensity runs gives calibration factors of 3.6  0.2 p.e./fC Variation of calib factors among different pixels are not very high Intensity corrections can be obtained form HPD itself Bright intensity runs could not be used for obtaining calibration factors