Si D Calorimetry Studies with Simulation Calorimetry RD

Si. D Calorimetry Studies with Simulation Calorimetry R&D Review LCWS 07 May 30, 2007 John Jaros for Tim Barklow and Ron Cassel

Motives for Simulation Studies • Understand physics requirements for jet energy resolution. • Quantify benefits of good jet energy resolution. • Optimize hcal parameters, prepare for technology choice. Complement PFA studies. Build up some intuition Fill up the backs of some envelopes Sample a larger parameter space

What Jet Energy Resolution do we Need? Need clean identification of W’s, Z’s, H’s, tops, … This requires dijet mass resolution few Ge. V. Requiring Z , sets d. M/M = 2. 5/92 = 2. 7 %. This requires d. Ejet/Ejet = 2 (2. 7%) = 3. 8 %, independent of Ejet. This is roughly comparable to the goal often cited, d. Ejet/Ejet = 30%/√E(Ge. V), for Ejet 100 Ge. V.

Mbb (Ge. V) Similar gains for other reactions: H->WW*, HHZ (T. Barklow) Mbb (Ge. V)

Simulation Study Overview • • Topics Studied Single Hadron Response in Infinite HCal Realistic Si. D Ecal/Hcal and Calibrations Jet Energy and Dijet Mass Resolution with Perfect PFA Hadron Shower Sizes in RPC and Scint Hcals • • • Ground Rules Si. D in Geant 4 with LCphysics models “neutral hadron” =. 5 K 0 L +. 25 nbar Detectors: . 12 cm thick RPC; . 5 cm thick scintillator Absorbers: . 75 cm W; 2. 0 cm Fe; . 75 cm detector gap Transverse segmentation: 1 x 1 cm 2 “Resolution Parameter eff” is given implicitly by /E = eff/ E

Resolution vs Energy for Single Neutral Hadrons “infinite” cal RPC eff W Scint Fe Neutral Hadron Energy (Ge. V)

Differential Neutral Energy Fraction (normalized) High Energy Neutral Hadrons Matter d. F/d. E Z pole ZZ at 500 Ge. V Neutral Hadron Energy (Ge. V)

Digital vs Analogue (Scint only) W eff Fe Remaining studies assume Digital Scint d a Neutral Hadron Energy (Ge. V)

Resolution and Absorber Material (RPCs) W Pb Cu eff Fe Neutral Hadron Energy (Ge. V)

Resolution vs Absorber Depth Fe Scint Digital 5 6 eff 7 8 Neutral Hadron Energy (Ge. V)

Si. D Response to Jets • Simulate Si. D Cal with Perfect Pattern Recognition 1 Si/W Ecal + 4 (Fe/W)/(RPC/Scint) Hcal Cross-calibrate Ecal and Hcal Had response Hcal Layers: W 0. 074 ; Fe 0. 12 . (E 0 meas- E 0 act) / E mean=0. 037 (calibration OK) rms= eff=0. 62 Root Energy (Ge. V 1/2) Fe/RPC Z pole

Neutral Energy Resolution at the Z (E 0 meas- E 0 act) / E =. 70 Fe/RPC =. 71 W/RPC =. 55 =. 60 Fe/Scint W/Scint

Jet Energy Resolution vs Jet Energy Perfect Pattern Recogniton, i. e. Assign All Neutral Energy Correctly W/RPC uds jets only W/Scint W Fe/Scint / Fe/RPC 90 eff is rms of 90% of events with optimal resolution Total Jet Energy (Ge. V)

Energy Resolution for Neutrals in Jets ZZ 500 Gev Fe/Scint =. 49 Fe/RPC =. 64 (E 0 meas- E 0 act)/ E

Effect on Dijet Mass Resolution…Small (still assuming perfect pattern reconstruction) Fe/Scint Fe/RPC F e M 12 -MZ gen (Ge. V)

RPC/Scint Differences for PFA for Z pole (qualitative measures only) Purity/Efficiency RPC =E 0 cyl/E 0 tot Scint =E 0 cyl/ Ecy l Neutral Hadron Showers are Bigger in Fe/Scint than in Fe/RPC. Does PFA suffer? Radius of Cylinder about Neutral Hadron Direction (cm)

RPC/Scint Differences for PFA Higher energies 250 Ge. V uds jets Purity/Efficiency 100 Ge. V uds jets Radius of Cylinder about Neutral Hadron Direction (cm)

Conclusions Simulation studies are impacting design of Si. D Calorimeters • Fe/Scint Resolution is better than Fe/RPC for single neutral hadrons, and somewhat better for jets. • Dijet mass resolution comparable with Scint or RPCs with perfect pattern recognition. • Shower sizes, potential confusion, larger in Scint than RPCs. • Fe or Cu give better resolutions than W or Pb in the hcal. • >5 total Hcal thickness desirable. • Digital readout for Fe/Scint, with 1 cm 2 pixels, better than analogue readout. Sim studies will continue. Comparisons and contrasts with PFA studies are next.