1. GEM DHCAL Simulation Studies J. Yu* Univ. of Texas at Arlington ALCW, July 15, 2003 Cornell University (*on behalf of the UTA team; S. Habib, V. Kaushik, J. Li, M. Sosebee, A. White) Introduction Analog Studies: TDR vs GEM Preliminary GEM Digital Studies Initial EFA studies with GEM Summary

2. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 2 Introduction DHCAL a solution for keeping the cost manageable for EFA Finer cell sizes are needed for effective calorimeter cluster association with tracks and subsequent energy subtraction UTA Has been working on DHCAL using GEM for –Flexible geometrical design, using printed circuit readout –Cell sizes can be as fine a readout as GEM tracking chamber!! –High gains, above 10 3~4,with spark probabilities per incident  less than 10 -10 –Fast response 40ns drift time for 3mm gap with ArCO 2 –Relatively low HV A few 100V per each GEM gap –Reasonable cost Foils are basically copper-clad kapton ~$400 for a specially prepared and framed 10cmx10cm foil

3. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 3 UTA GEM Simulation Use Mokka as the primary tool –Kept the same detector dimensions as TESLA TDR –Replaced the HCAL scintillation counters with GEM ( 18mm SS + 6.5mm GEM, 1cmx1cm cells ) Single Pions used for initial studies –3 – 100 GeV single pions –Analyzed them using ROOT Compared the results to TDR analog as the benchmark –GEM Analog and Digital (w/ and w/o threshold)

4. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 4 Resolution curve – TESLA TDR I know this is about 10% higher than others. Estimate of 2.5% systematic uncertainties included

5. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 5 Double GEM schematic S.Bachmann et al. CERN-EP/2000-151

6. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 6 UTA Double GEM Geometry 3.4 mm ArCO 2 GEM 3.1 mm Simple GEM Detailed GEM 0. 00 5 1. 0 Cu Kapton ArCO 2 G10 0. 00 5 6.5mm

7. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 7 Comparison of Detailed and Simple GEM Geometries Detailed GEM 75GeV  25.2sec/event for Simple GEM v/s 43.7 sec/event for Detailed GEM Responses look similar for detailed and simple GEM geometry Simple GEM sufficient =0.80  0.007MeV =0.81  0.008MeV Simple GEM 75GeV 

8. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 8 Energy Deposit for 10 GeV Pions (GEM) f EM >=0.85 Remaining Total f HC >=0.85

9. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 9 EM-HAD Relative Weighting Factor To compensate the response differences between ECAL and GEM HCAL responses a procedure to normalize them had to be introduced –E Live =  E EM + W  gE HAD (g:GEM Intrinsic gain) –Obtained the relative weight W using two Gaussian fits to EM only v/s HAD only events –Perform linear fit to Mean values as a function of incident pion energy –Extract ratio of the slopes  Weight factor W –E = C* E Live

10. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 10 GEM GEM Response (Analog) Estimate of 2.5% systematic uncertainties included Sampling fractions are as expected for both TDR and GEM TESLA TDR

11. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 11 GEM GEM Resolution (analog) Systematic uncertainties for GEM amplified by 50% to reflect unconsidered sources We just cannot make the resolution as good as our French colleagues saw. TESLA TDR

12. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 12 GEM Digital Response

13. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 13 GEM Cell Occupancies ~85% single hit ~15% >1 hit ~74% single hit ~26% >1 hit Number of cells with higher number of hits increase w/ E

14. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 14 N vs Layer Energy Deposit/Ncells vs Layers for 50 GeV Pions E vs Layer

15. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 15 Extraction of of dE/dN

16. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 16 GEM Digital Response Estimate of 2.5% systematic uncertainties added to analog. Digital analysis w/ syst. in progress. GEM Digital Sampling fractions are consistent between digital and analog. GEM Analog

17. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 17 GEM MIP Digital Threshold Efficiency Energy Deposited (MeV) Efficiency 95% efficiency At 0.23MeV Energy Deposit MIP Efficiency

18. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 18 Discharge Study: N Pairs for Muons in GEM

19. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 19 Single GEM gain/discharge probability A.Bressan et al, NIM A424, 321 (1998) Single pion study almost completed Understand average total charge deposit in a cell of various sizes Study fake signal from spiraling charged particle in the gap

20. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 20 Single Pion EFA Study Track-cluster association is the first step for a good EFA Must work for simplest cases Start with single pion in analog and digital cases Fit the centroid of shower using energy weighted (analog) and numerically averaged (digital) center in each layer Measure the distance between fit shower position and the particle incident position E  =50 GeV

21. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 21  E weighted vs Numerical Mean) E  = 50 GeV 1cm x 1 cm cells E weighted =-3.1x10 -5  =1.1x10 -2 Numerical Mean =-1.2x10 -3  =2.5x10 -2 Analog seems to be better than digital but not by significant factor

22. July 15, 2003Jae Yu: UTA GEM DHCAL ALCW, Cornell 22 Summary UTA’s GEM based DHCAL simulation has made significant progress in the past year First pass single particle studies completed with a M.S. thesis, using Mokka: –GEM analog resolution comparable to TDR –GEM digital seems to be comparable to GEM analog –GEM digital with threshold will complete soon –Fit method refinement in progress EFA studies began –Single particle study seems to show reasonable performance in E weighted vs numerical means –Jet final state studies will come next Funding for ½ student for this effort available