1. A MAPS-based readout of an electromagnetic calorimeter for the ILC Nigel Watson (Birmingham Univ.) Motivation Physics simulations Sensor simulations Testing Summary For the CALICE MAPS group J.P.Crooks, M.M.Stanitzki, K.D.Stefanov, R.Turchetta, M.Tyndel, E.G.Villani (STFC-RAL) Y.Mikami, O.D.Miller, V.Rajovic, NKW, J.A.Wilson (Birmingham) J.A.Ballin, P.D.Dauncey, A.-M.Magnan, M.Noy (Imperial)

2. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Mass (jet1+jet2) Mass (jet3+jet4) Mass (jet1+jet2) E/E = 60%/ E E/E = 30%/ E Equivalent best LEP detector Goal at ILC Essential to reconstruct jet-jet invariant masses in hadronic final states, e.g. separation of W + W, Z 0 Z 0, tth, Zhh, H ILC: high performance calorimetry LEP/SLD: optimal jet reconstruction by energy flow Explicit association of tracks/clusters Replace poor calorimeter measurements with tracker measurements – no double counting Little benefit from beam energy constraint, cf. LEP

3. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Shower containment in ECAL, X 0 large Small R moliere and X 0 – compact and narrow showers int /X 0 large, EM showers early, hadronic showers late ECAL, HCAL inside coil Lateral separation of neutral/charged particles/particle flow Strong B field to suppresses large beam-related background in detector Compact ECAL (cost of coil) Tungsten passive absorber Silicon pixel readout, minimal interlayer gaps, stability Swap-in alternative to Si diode detector designs, e.g. in LDC, SiD CMOS process, more mainstream: Industry standard, multiple vendors (schedule, cost) (At least) as performant – ongoing studies Simpler assembly Power consumption larger – but better thermal properties ECAL design principles

4. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Basic concept for MAPS How small? EM shower core density at 500GeV is ~100/mm 2 Pixels must be<100 100 m 2 Our baseline is 50 50 m 2 Gives ~10 12 pixels for ECAL – Tera-pixel APS How small? EM shower core density at 500GeV is ~100/mm 2 Pixels must be<100 100 m 2 Our baseline is 50 50 m 2 Gives ~10 12 pixels for ECAL – Tera-pixel APS Swap ~0.5x0.5 cm 2 Si pads with small pixels Small := at most one particle/pixel 1-bit ADC/pixel, i.e. Digital ECAL Effect of pixel size 50 m 100 m >1 particle/ pixel Incoming photon energy (GeV) Weighted no. pixels/event

5. SiD 16mm 2 area cells ZOOM 50 50 μm 2 MAPS pixels Tracking calorimeter

6. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Physics simulation 0.5 GeV MPV = 3.4 keV σ = 0.8 keV 5 GeV MPV = 3.4 keV σ = 0.8 keV 200 GeV MPV = 3.4 keV σ = 0.8 keV Geant4 energy of simulated hits E hit (keV) MAPS geometry implemented in Geant4 detector model (Mokka) for LDC detector concept Peak of MIP Landau stable with energy Definition of energy: E N pixels Artefact of MIPS crossing boundaries Correct by clustering algorithm Optimal threshold (and uniformity/stability) important for binary readout Threshold (keV) (E)/E 20 GeV photons

7. EPS'07, 19-Jul-2007Nigel Watson / Birmingham CALICE INMAPS ASIC1 Architecture-specific analogue circuitry 4 diodes Ø 1.8 m First round, four architectures/chip (common comparator+readout logic) INMAPS process: deep p-well implant 1 μm thick under electronics n-well, improves charge collection 0.18 m feature size

8. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Physics data rate low – noise dominates Optimised diode for Signal over noise ratio Worst case scenario charge collection Collection time Device level simulation Signal/noise 0.9 μm 1.8 μm 3.6 μm Distance to diode (charge injection point) Signal/Noise

9. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Near future plans Work ongoing on the set of PCBs holding, controlling and reading the sensor. Test device-level simulations using laser-based charge diffusion measurements at RAL 1064, 532,355 nm,focusing < 2 μm, pulse 4ns, 50 Hz repetition, fully automated Cosmics and source setup, Birmingham and Imperial, respectively. Potential for beam test at DESY end of 2007 Expand work on physics simulations Test performance of MAPS ECAL in GLDC and SiD detector concepts Emphasis on re-optimisation of particle flow algorithms 3 July: 1 st sensors delivered to RAL 3 July: 1 st sensors delivered to RAL

10. EPS'07, 19-Jul-2007Nigel Watson / Birmingham SummarySummary Concept of CMOS MAPS digital ECAL for ILC Multi-vendors, cost/performance gains New INMAPS deep p-well process (optimise charge collection) Four architectures for sensor on first chips, delivered to RAL Jul 2007 Tests of sensor performance, charge diffusion to start in August Physics benchmark studies with MAPS ECAL to evaluate performance relative to standard analogue Si-W designs, for both SiD and LDC detector concepts

11. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Backup slides…

12. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Architectures on ASIC1 PresamplerPreshaper Type dependant area: capacitors, and big resistor or monostable

13. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Beam background studies Beam-Beam interaction by GuineaPig Detector: LDC01sc 2 scenarios studied : 500 GeV baseline, 1 TeV high luminosity purple = innermost endcap radius 500 ns reset time ~ 2 inactive pixels

14. EPS'07, 19-Jul-2007Nigel Watson / Birmingham The sensor test setup 5 dead pixels for logic : -hits buffering (SRAM) - time stamp = BX (13 bits) - only part with clock lines. 84 pixels 42 pixels Data format 3 + 6 + 13 + 9 = 31 bits per hit 7 * 6 bits pattern per row Row index 1*1 cm² in total 2 capacitor arrangements 2 architectures 6 million transistors, 28224 pixels

15. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Neighbouring hit: hit ? Neighbours contribution no hit ? Creation of hit from charge spread only All contributions added per pixel + noise σ = 100 eV Impact of digitisation E initial : geant4 deposit What remains in the cell after charge spread assuming perfect P- well + noise σ = 100 eV, minus dead areas : 5 pixels every 42 pixels in one direction

16. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Physics data rate low – noise dominates Optimised diode for Signal over noise ratio Worst case scenario charge collection Collection time. Device level simulation Using Centaurus TCAD for sensor simulation + CADENCE GDS file for pixel description Signal/noiseCollected charge 0.9 μm 1.8 μm 3.6 μm Distance to diode

17. EPS'07, 19-Jul-2007Nigel Watson / Birmingham Digitisation procedure Geant4 E init in 5x5 μm² cells Sum energy in 50x50 μm² cells E sum Apply charge spread E after charge spread Add noise to signal hits with σ = 100 eV (1 e- ~ 3 eV 30 e- noise) + noise only hits : proba 10 -6 ~ 10 6 hits in the whole detector BUT in a 1.5*1.5 cm² tower : ~3 hits. %E init E init Register the position and the number of hits above threshold Importance of the charge spread :