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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) ILC: high performance calorimetry Mass (jet3+jet4) Mass (jet3+jet4) Essential to reconstruct jet-jet invariant masses in hadronic final states, e.g. separation of W+W, Z0Z0, tth, Zhh, H E/E =optimal 60%/E E/E =flow 30%/E LEP/SLD: jet reconstruction by energy Explicit association of tracks/clusters Replace poor calorimeter measurements with tracker measurements – no “double counting” Equivalent best LEP detector Goal ILC Little benefit from beam energy constraint, cf. at LEP Mass (jet1+jet2) Nigel Watson / Birmingham Mass (jet1+jet2) EPS'07, 19-Jul-2007 ECAL design principles Shower containment in ECAL, X0 large Small Rmoliere and X0 – compact and narrow showers int/X0 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 Nigel Watson / Birmingham EPS'07, 19-Jul-2007 Basic concept for MAPS • How small? • EM shower core density at 500GeV is ~100/mm2 • Pixels must be<100100mm2 • Our baseline is 5050mm2 • Gives ~1012 pixels for ECAL – “Tera-pixel APS” Nigel Watson / Birmingham Weighted no. pixels/event • Swap ~0.5x0.5 cm2 Si pads with small pixels • “Small” := at most one particle/pixel • 1-bit ADC/pixel, i.e. Digital ECAL Effect of pixel size 50mm 100mm >1 particle/ pixel Incoming photon energy (GeV) EPS'07, 19-Jul-2007 Tracking calorimeter 5050 μm2 MAPS pixels ZOOM SiD 16mm2 area cells Physics simulation MAPS geometry implemented in Geant4 detector model (Mokka) for LDC detector concept Peak of MIP Landau stable with energy Geant4 energy of simulated hits 0.5 GeV MPV = 3.4 keV σ = 0.8 keV Definition of energy: E a Npixels Artefact of MIPS crossing boundaries Correct by clustering algorithm s(E)/E Optimal threshold (and uniformity/stability) important for binary readout Ehit (keV) 5 GeV MPV = 3.4 keV σ = 0.8 keV 20 GeV photons Ehit (keV) 200 GeV MPV = 3.4 keV σ = 0.8 keV Nigel Watson / Birmingham Threshold (keV) Ehit (keV) EPS'07, 19-Jul-2007 CALICE INMAPS ASIC1 First round, four architectures/chip (common comparator+readout logic) 0.18mm feature size INMAPS process: deep p-well implant 1 μm thick under electronics n-well, improves charge collection 4 diodes Ø 1.8 mm Architecture-specific analogue circuitry Nigel Watson / Birmingham EPS'07, 19-Jul-2007 Device level simulation Physics data rate low – noise dominates Optimised diode for Signal over noise ratio Worst case scenario charge collection Collection time Nigel Watson / Birmingham Signal/Noise 0.9 μm 1.8 μm 3.6 μm Signal/noise Distance to diode (chargeEPS'07, injection point) 19-Jul-2007 Near future plans 3 July: 1st sensors delivered to RAL 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 Nigel Watson / Birmingham EPS'07, 19-Jul-2007 Summary 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 Nigel Watson / Birmingham EPS'07, 19-Jul-2007 Backup slides… Nigel Watson / Birmingham EPS'07, 19-Jul-2007 Architectures on ASIC1 Presampler Preshaper Type dependant area: capacitors, and big resistor or monostable Nigel Watson / Birmingham EPS'07, 19-Jul-2007 Beam background studies Beam-Beam interaction by GuineaPig purple = innermost endcap radius 500 ns reset time ~ 2‰ inactive pixels Detector: LDC01sc 2 scenarios studied : 500 GeV baseline, 1 TeV high luminosity Nigel Watson / Birmingham EPS'07, 19-Jul-2007 The sensor test setup 1*1 cm² in total 2 capacitor arrangements 2 architectures 6 million transistors, 28224 pixels 7 * 6 bits pattern per row 5 dead pixels for logic : -hits buffering (SRAM) - time stamp = BX (13 bits) - only part with clock lines. 84 pixels 42 pixels Nigel Watson / Birmingham Row index Data format 3 + 6 + 13 + 9 = 31 bits per hit EPS'07, 19-Jul-2007 Impact of digitisation E initial : geant4 deposit •What remains in the cell after charge spread assuming perfect Pwell •Neighbouring hit: •hit ? Neighbour’s contribution •no hit ? Creation of hit from charge spread only •All contributions added per pixel •+ noise σ = 100 eV •+ noise σ = 100 eV, minus dead areas : 5 pixels every 42 pixels in one direction Nigel Watson / Birmingham EPS'07, 19-Jul-2007 Device level simulation Physics data rate low – noise dominates Optimised diode for Signal over noise ratio Worst case scenario charge collection Collection time. Using Centaurus TCAD for sensor simulation + CADENCE GDS file for pixel description Collected charge Signal/noise 0.9 μm 1.8 μm 3.6 μm Distance to diode Nigel Watson / Birmingham Distance to diode EPS'07, 19-Jul-2007 Digitisation procedure Geant4 Einit in 5x5 μm² cells Apply charge spread Eafter charge spread %Einit Einit Register the position and the number of hits above threshold %Einit + noise only hits : %Einit proba 10-6 ~ 106 hits in the whole detector BUT in a 1.5*1.5 cm² tower : ~3 hits. Add noise to signal hits with σ = 100 eV (1 e- ~ 3 eV 30 e- noise) Nigel Watson / Birmingham %Einit %Einit %Einit %Einit %Einit Importance of the charge spread : Eneighbours ~ (50% 80%) Einit Sum energy in 50x50 μm² cells Esum EPS'07, 19-Jul-2007
