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Calorimeter Status and Possible Next Steps
Ray Frey, U. of Oregon

I. Where we are (I think) - Overall Picture - up dates from Snowmass

I I. What R&D is needed (I b elieve) - Simulations and physics - Software - Hardware

I I I. Towards a plan of future action (I hop e) Who is going to do this in the US ?


Current Scene

Ç EFlow represents a paradigm shift of sorts Ç No existing templates Ç Intrinsically complex Sp eedy evaluation not easy Ç On the other hand: Potentially quite p owerful Interesting and fun! Ç Prop osed by NLC group, Snowmass 96 Ç Pushed hard by TESLA Ç Requires dense, highly segmented ECal and highly segmented HCal


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(contd) Ç Primary EFlow asset: Jet Reconstruction and Resolution Ç What comes along for free: Excellent Lepton id. (HCal is also muon tracker) Isolated and non-p ointing photons/neutrals Ç Typical single-particle resolutions: eÁ, : (10 to 20%)/ h0 : (40 to 50%)/ hÁ : tracker Ç Jet resolution: (20 to 30%)/ EJ (using e+e- q q ) ? Alternative p ov: Vertexing requires large B , for which traditional calorimetry do esn't work well. So we might as well make the b est of it! E

E




Resolution, e-

Snowmass 2001

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Resolution, pi-

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LCD SD Detector Ultimate" Jet Energy Resolution, e+e, ! qq
E_jet (GeV)
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Ej Nent = 1438 Mean = 93.45 RMS = 11.4 Chi2 / ndf = 28.52 / 7 Constant = 203.4 Á 8.942 Mean = 99.01 Á 0.07008 Sigma = 1.892 Á 0.0632

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Compare perfect EFlow with perfect calorimeteronly jet reconstruction "bp hand" compensation, y SD detector, e+e, ! qq, s =200 GeV EFlow:
JJ Mass (GeV)

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JJM Nent = 692 Mean = 191 RMS = 14.82 Chi2 / ndf = 12.55 / 10 Constant = 70.09 Á 4.324 Mean = 198.4 Á 0.1926 Sigma = 2.578 Á 0.151

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Mj j = 2:6 GeV c2

Calorimeter Only:
JJ Mass (GeV)

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JJM Nent = 525 Mean = 187.3 RMS = 15.39 Chi2 / ndf = 40.96 / 41 Constant = 17.89 Á 1.196 Mean = 192.4 Á 0.5162 Sigma = 9.246 Á 0.4695

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Current Approaches

Ç Europ e ECal: Si/W layers: 40 20 (15 ç 0.8X0 +5 ç 3.2X0) 3500 m2 Si 1700 m2 segmentation: 1 cm2 1.5 cm2 ECal alternative: Shaslik HCal: "digital" vs scint. tile digital: 1 cm2 seg. (RPCs? fib ers?) tiles: > 25 cm2 Making go o d progress with software dev. Ç Asia Pb/scint. tile ECal and HCal with presampler going route of "traditional" comp ensating cal.




'
photon reconstruction efficiency
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5

$
Hadronic events at the Z peak

energy

(GeV)

The fake rate is about 1.61.7 fake photon event with a mean energy of 0.40.4GeV for the 4020 layers

&

July 2001 - Snowmass

-11-

J.C.Brient LPNHE-X




'
E( component in jet) GeV
1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2

The jet energy resolution
hadronic events at the Z peak

$

The jet resolution at Z peak if neutral hadron reconstruction

doesn't depend on W-Si number of layers
W-Si type Evis GeV 40 layers - PFD04 2.9 GeV 20 layers - PFD04 3.0 GeV

The resolution is dominated by the neutral hadron reconstruction, therefore

&

HCAL granularity is of ma jor importance

July 2001 - Snowmass

-8-

J.C.Brient LPNHE-X







US Scene Ç SD: TESLA sup erficially Many major design elements still under review (should remain that way for awhile!) ECal seg and layering (0.25 cm2, 30 ç 0.7X0) gap thickness (0.25 cm/ly) HCal absorb er, seg., and active elements Ç LD: What is it? Large BR2 EFlow ? But marginal transverse seg with scint tile/Pb 4.2 cm ç 4.2 cm is sp ec... . Is this realistic? 4:1 ratio Pb:scint comp ensating ? 1 mm scint layers: insufficient light gang? What do we want for LD ? Start over ? Ç Ignore PD for now


Some Open Questions/Issues for LCD Calorimetry Feb 2001
Develop means for evaluating energy flow performance Full simulations parameterizations of full sim. clustering techniques charged pion rejection neutral hadron rejection Figures of merit Jet-jet Mass Mjj vs cost Missing energy Lepton id. non-pointing track/shower recon. Particularly relevant physics processes HZ vs WW vs ZZ HHH coupling (see talk by P. Gay at LCWS2000) WW -> jets full recon from sqrt(s)=180 to 1500 GeV top full recon. non-pointing photons SUSY: selectron t-channel? Others? How to compare various detector designs Do Fast Sim. comparisons have any meaning? Are single-particle resolutions meaningful? How to evaluate full sim without good reconstruction? What do we do, short of exhaustive full sim. and recons studies? Track finding in the EM Cal. Luminosity spectrum role of endcap What spatial resolution is required? What is role of small-angle cal., if any, for this Other issues related to EFlow designs: optimization of EM layer config. for cost & performance Silicon gap reduction and mechanical design Alternatives to Si/W for EM Cal EFlow Is the L EM scintillator design feasible? What about a hybrid scint/Si design? Inserting Silicon layers in a LAr or scint design Hadron calorimeter Inside or outside the coil: Figures of merit Absorber digital detectors? integrated muon id. Timing Do we need to resolve bunches? What does the physics require?


What the technologies could deliver Forward Tagger 2-photon vs SUSY: what are the requirements? What would this look like? Does it fit the interaction region design? electron/photon energy resolution Is very good resolution required for any physics? Optimization of silicon thickness Readout Issues Required dynamic range in EM cal How to implement: overlapped ADCs? How much overlap? How to get light out of small scint. tiles Getting beyond sky hooks and non-supporting structures module designs integrating readout heat loads? endcaps and long barrels Cost of silicon What should we expect? Can electronics be integrated with the detectors? Other component costing issues HPDs absorbers Uniform costing criteria for L,SD, and P What EM energy resolution is required at v. high energy (ie what constat term) ? Parameterization of performance for non-full simulations E res shower position res How to parameterize EFlow performance? Updated March 2001 Ray Frey


R&D Items (EFlow-related)

A. Physics and (fast) simulations 1. Further develop case for excellent EFlow cal. (or not)

- General argument of complementarity and hadronic final states - Sp ecific pro cesses: Higgs self coupling (Gay) WW/ZZ at high energy (Videau) Recon of top and W for anom. couplings ? (Masako) Many others to b e explored: SUSY decays; Br(H), MH > 160, ... 2. Integration of EFlow with flavor tagging 3. Parameterizations of EFlow p erformance for fast 0 sim. (e.g. and KL effic as fn of separation) 4. What is required for forward tagger?





Reconstructed W with 2 jets
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B. Software development 1. Clustering recognition of EM vs HAD showers vs MIPs optimization for p osition optimization for energy optimization for angle (extrap. to IP) 2. Tracking in cal. merge tracks with showers (hÁ id) muons integrated tracker/cal tracking 3. Digital Cal.: Pattern recog. and resolution 4. Geant4 (e.g. do esn't require towers) 5. Detector parameter tradeoffs (R, seg, layering, coil in/out, etc.) 6. Extract parametrizations for fast sim.


C1. Hardware (Si/W) 1. Integration of electronics with Si detectors b eating straight channel counts (Marty) 2. Si detector cost reduction apparently not dominated by cost of Si wafers 3. Gap reduction (Rm reduction) 4. Mechanical/assembly issues 5. B = 5 T ?

C2. Hardware (HCal) - digital design technology choice - low cost and 1 cm transverse seg


C3. Hardware (non-Si ECal) - Scint. tile < 1. Is 2 cm seg p ossible? light yield? fib er coupling? gap thickness? resp onse uniformity? 2. Readout (HPD/APD ?) 3. Is it really cheap er than Si ? - Other technologies?


What Next? Ç Extreme EFlow is something which requires a thorough understanding - we're not close Ç US manp ower effort presently b elow threshold Ç Need several p eople working consistently and talking to each other (i.e. similar to TESLA recon/sim efforts) Ç We should start doing some hardware R&D in parallel with sw/sim Ç TESLA group strength is presently in EFlow recon development Ç Everything wide op en for new p eople Ç I'd like to see a framework for co op erative international R&D b e develop ed ASAP (Krakow?) (as simple as a list to start with)