An Imaging Calorimeter for the Linear Collider

1. An Imaging Calorimeter for the Linear Collider Felix Sefkow DESY Seminar at Northern Illinois University August 18, 2003

2. Outline • Precision physics challenges detector R&D • Calorimetry with “energy flow’’ • The CALICE R&D program • Overview • Scintillator tile calorimeter R&D • Alternatives, perspectives Felix Sefkow An Imaging Calorimeter for the Linear Collider

3. Anticipated discoveries • The history of particle physics is full of predicted discoveries: • Positron, neutrino, pions • Quarks, gluons • W, Z bosons • Charm, bottom, • and top • …Mostly made at hadron machines Zooming into the top mass Felix Sefkow An Imaging Calorimeter for the Linear Collider

4. Complemented with precision • A success story to be continued: • e+e- colliders are needed to investigate in detail the hadron machine discoveries • Charm physics at SPEAR • B physics at CESR and factories • Z (and W) boson properties at LEP Closing up to the Higgs Felix Sefkow An Imaging Calorimeter for the Linear Collider

5. The next step • New physics at the origin of electroweak symmetry breaking will be discovered at the next (or even present) generation of hadron collider experiments • A linear e+e- collider is needed to sort these discoveries out • Profile of the Higgs • Precision studies of new phenomena • SUSY particles • Extra dimensions • New interactions e.g. spin Felix Sefkow An Imaging Calorimeter for the Linear Collider

6. The linear collider • There is a world-wide consensus emerging about the scope of the machine • Energy 500 (initially) – 1000 GeV • Luminosity above 1034 cm-2s-1 (500 fb-1 in 4 years) • Options: e+ polarization, Giga-Z, e-e-, gg • Accelerator technology choice by 2004 • Operation concurrent with the LHC 6000x LEP 70 tt /h Felix Sefkow An Imaging Calorimeter for the Linear Collider

7. Detector challenge • The physics potential of precision measurements requires unprecedented detector performance • Excellent resolution, to discriminate rare processes • Small systematics, to mach statistical accuracy • Rates, radiation hardness: • Relaxed conditions (w.r.t. LHC) Felix Sefkow An Imaging Calorimeter for the Linear Collider

8. Vertexing and Tracking • Vertex detector • Charm tagging (!): H  cc • Multi-jet combinatorics • Main tracker • Higgs recoil • Slepton decay momentum endpoint Felix Sefkow An Imaging Calorimeter for the Linear Collider

9. Calorimetry • Excellent photon reconstruction – also non-pointing • Multi-jet final states • E.g. top: • m(top) from ee g tt g 6 j • top Yukawa coupling from ee g ttH • Higgs potential: ZHHg qqbbbb Felix Sefkow An Imaging Calorimeter for the Linear Collider

10. Jet energy resolution • Imagine – there is no Higgs: WW scattering violates unitarity at 1.2 TeV, or new forces appear Felix Sefkow An Imaging Calorimeter for the Linear Collider

11. Energy Flow Algorithms • Best jet energy resolution with minimum calorimetry • tracking detectors to measure energy of charged particles (65% of the typical jet energy) • EM calorimeter for photons (25%) • EM and Had calorimeter for neutral hadrons (10%) Felix Sefkow An Imaging Calorimeter for the Linear Collider

12. Contributions to s(Ejet) • With anticipated resolutions: Ideally realistically (courtesy D.Karlen) Felix Sefkow An Imaging Calorimeter for the Linear Collider

13. Calorimeter concept • Attack the dominant “confusion term”: reconstruct every particle individually • Focus on the imaging capability • Large B field and large calorimeter inner radius • Small Moliere radius, thin gaps • Absolute • Relative to hadronic interaction length • Fine 3D granularity • Calorimeters inside coil, no cracks • Development of energy flow algorithms plays central role Felix Sefkow An Imaging Calorimeter for the Linear Collider

14. E.g. the TESLA detector B = 4T Felix Sefkow An Imaging Calorimeter for the Linear Collider

15. Moliere radius: iron vs. tungsten Iron Tungsten (many images courtesy H.Videau) Felix Sefkow An Imaging Calorimeter for the Linear Collider

16. Hadron calorimeter granularity • From the energy flow algorithm point of view one would like fine segmentation (and tungsten!) in the hadron calorimeter, too: 50’000’000 channels • Cost: (e.g. TESLA) • SiW ECAL 132 M€ • Full detector 286 M€ • Compromise • on granularity: analogue • on resolution: digital (“1 bit ADC”) Felix Sefkow An Imaging Calorimeter for the Linear Collider

17. LC Detector R&D goals • Precision physics dictates detector design goals: • 10x better momentum resolution • 3x better impact parameter resolution with 30x thinner and finer vertexing • 2x better jet energy resolution with 200x higher calorimeter granularity • A formidable challenge for a worldwide R&D efforthttp://blueox.uoregon.edu/~lc/rand.pdf Felix Sefkow An Imaging Calorimeter for the Linear Collider

18. LC Calorimeter R&D • Electromagnetic • Silicon Tungsten • Calice, US • Tile – Fibre • Asia, LCCAL(Italy) • Hadronic • Tile – Fibre • Calice, Asia • Digital HCAL • Calice, US (may need update) Felix Sefkow An Imaging Calorimeter for the Linear Collider

19. Inter-regionally joint efforts on sub-detector level Matching both accelerator schemes Following different technologies Goal: prepare basic technology decisions to be taken soon after LC approval R&D Proto-collaborations Felix Sefkow An Imaging Calorimeter for the Linear Collider

20. CALICE collaboration • 164 Physicists, 26 Institutes, 9 Countries: 3 Regions • Si W ECAL: • France, UK, Czech, Russia • Analogue tile scintillator HCAL: • Germany, Czech, Russia • Digital HCAL options: • RPCs: US, Russia • GEMs: US • Scintillator: US EFLOW, software: “all” Felix Sefkow An Imaging Calorimeter for the Linear Collider

21. Energy resolution (due to trunc. Landau) S.Magill (ANL) DigitalAnalog Slope = 23 hits/GeV HCAL simulations • Shower size L.Xia, ANL, A.Sokolov, Paris Depends on thresholds • Do we buy it? Felix Sefkow An Imaging Calorimeter for the Linear Collider

22. The Calice R&D programme • Imaging calorimetry is sensitive to the low energy (de)tails • Goals: • Develop and establish the technologies (ECAL, RPCs) • Verify (and improve) the simulations • Refine the energy flow algorithms • Steps: • Table-top R&D • Pre-prototyping (e.g. MiniCAL): ongoing • Electron and hadron test beam studies with a 1m3 ECAL+HCAL physics prototype: mainly 2005-06 • Obtain high resolution data on hadronic showers Felix Sefkow An Imaging Calorimeter for the Linear Collider

23. Calice 1m3 physics prototype • Combined ECAL and HCAL approach • # channels: • ECAL 10k • aHCAL ~ 5k • dHCAL ~ 400k • Task-sharing • Common use of • Test beam infrastructure • Mechanics (stack) • DAQ • software Felix Sefkow An Imaging Calorimeter for the Linear Collider

24. Calice ECAL Structure 2.8 (2×1.4mm of W plates) Structure 4.6 (3×1.4mm of W plates) Fine granularity tracking calorimeter Silicon – Tungsten sandwich 1 x 1 cm2 pads 40 layers Simulated energy resolution Prototype for test beams 30 layers Active area 18 x 18 cm2 9720 channels Goal: first tests in 2004 Structure 1.4 (1.4mm of W plates) Metal insert Detector slabs ACTIVE ZONE 10×10 mm2 60 mm Si Wafer with 6×6 pads 60 mm (courtesy J.Repond) Felix Sefkow An Imaging Calorimeter for the Linear Collider

25. HCAL • TESLA TDR: • Analog: Thickness 4.5 λ … Barrel 6.2 λ … Endcap Cell structure Iron 20 mm Active medium 6.5 – 10.0 mm Scintillator tiles Area 5 x 5 → 25 x 25 cm2 Thickness 5 mm Longitudinal segmentation 9 … Barrel 12 … Endcap Felix Sefkow An Imaging Calorimeter for the Linear Collider

26. Analogue HCAL R&D • See M.Danilov’s talk last week • and V.Korbel’s note • Scintillator development • Tile fibre system optimization • Photodetector studies: Avalanche photodiodes: stability, low noise electronics Silicon Photomultiplier development Matrix APD Felix Sefkow An Imaging Calorimeter for the Linear Collider

27. MiniCAL • 27 layers x 3x3 tiles • 5x5x0.5 cm3 each • Different scintillators • SiPMs and APDs • Cosmics and DESY electrons (1…6GeV) • Gain experinece with larger # of channels • Understand hardware in simulations • Study calibration & resolution Felix Sefkow An Imaging Calorimeter for the Linear Collider

28. 42m 20m pixel h Resistor Rn=400 k Al R 50 Depletion Region 2 m substrate Ubias The Silicon Photomultiplier • A pixilated solid state Geiger counter • 1000 pixels on 1mm2 • Gain few x 10**6, efficiency 10..15% • At 50..60 V bias voltage Felix Sefkow An Imaging Calorimeter for the Linear Collider

29. 25 detected photoelectrons Fig.27 Recent progress • Efficiency vs noise Felix Sefkow An Imaging Calorimeter for the Linear Collider

30. Saturation effects • Finite dynamic range: Felix Sefkow An Imaging Calorimeter for the Linear Collider

31. New possibilities • One SiPM per tile • No fibre readout Felix Sefkow An Imaging Calorimeter for the Linear Collider 2 Fig.22

32. Which granularity? One out of a large variety Many showers Felix Sefkow An Imaging Calorimeter for the Linear Collider

33. Shower substructure resolution Felix Sefkow An Imaging Calorimeter for the Linear Collider

34. Analog meets digital • Smaller analog tiles • More digital thresholds Felix Sefkow An Imaging Calorimeter for the Linear Collider

35. Conclusions • The excellent linear collider physics potential needs the best possible detector • There are exciting ideas how to make significant steps ahead in precision calorimetry • New photo-detectors open new possibilities for scintillator based calorimeters • We are preparing to try them out – now! Felix Sefkow An Imaging Calorimeter for the Linear Collider