A SiW EM Calorimeter for the Silicon Detector Santa Fe, NM June 8, 2012 Norman Graf (for the SiW ECal group)

Overview Motivation (LC physics) and goals Applications: ILC (SiD) A Higgs factory LC ? CLIC ? Muon Collider ? Other ? Project R&D status Sensors KPiX readout Interconnects Integrated ! Plans

SiW R&D Team KPiX readout chip detector development interconnects M. Breidenbach, D. Freytag, N. Graf, R. Herbst, G. Haller, J. Jaros, T. Nelson SLAC National Accelerator Laboratory J. Brau, R. Frey, D. Strom, Craig Gallagher (tech), D. Meade, P. Radloff (grad students), (undergrads) U. Oregon B. Holbrook, R. Lander, M. Tripathi, M. Woods (grad student) UC Davis KPiX readout chip downstream readout mechanical design and integration detector development readout electronics testing and integration interconnects

“Imaging Ecal”: Motivated by LC Physics Guiding principles: Measure all final states and measure with precision Multi-jet final states (t-chan, missing E, combinatorics)  measurement should not limit jet resolution id and measure h and h± showers track charged particles Tau id and analysis Unique window on BSM Photons Energy resolution, e.g. h Vertexing of photons ( b1 cm ), e.g. for GMSB Electron ID Bhabhas and Bhabha acollinearity Hermiticity  Imaging (E)Calorimetry can do all this (“particle flow”)

ILC Application Drives Design ILC bunch train structure Power pulsing  passive cooling using the tungsten (average heat load is <1% of max) Readout cadence Beam energy Electronics dynamic range and noise: single MIPs (tracking) to 500 GeV EM showers (up to 2000 MIPs/pixel). Physics pixel area (particle flow -- jets, taus) longitudinal structure (energy resolution)

R&D Goals Design a practical ECal which meets (or exceeds) the LC physics requirements with a technology that would actually work at a LC… Physics  A highly-segmented imaging Si-W ECal Very collimated EM showers and MIP tracking; Modest EM energy resolution OK Key to making this practical is a highly integrated electronic readout ~1000 pixels per readout chip (KPiX) with power pulsing Readily segmented silicon: 13 mm2 is current default Interconnects give small readout gap (1 mm): 13 mm eff. Moliere radius Bump-bond KPiX directly to Si sensor Flex cables to outside

Segmentation Requirement Resolve individual photons from jets, tau decays, … Resolving power depends on shower radius and segmentation. Want transverse segmentation significantly smaller than RMoliere = ~10 mm Dense absorber, thin readout, lateral segmentation Two EM-shower separability in LEP data with the OPAL Si-W LumCal (David Strom)

Silicon Sensor Transverse Segmentation Silicon is easily segmented KPiX readout chip is designed for 13 mm2 pixels (1024 pixels for 6 inch wafer) Cost nearly independent of seg. Limit on segmentation comes from chip power (minimum  2 mm2 ) KPiX ASIC and sample trace Fully functional prototype (Hamamatsu)

Silicon Sensor Longitudinal Segmentation Critical parameter for RM is the gap between layers

ECal schematic cross section Metallization on detector from KPix to cable Bump Bonds Tungsten Gap ~1 mm Kapton Data Cable KPix Si Detector Kapton Tungsten Heat Flow Thermal conduction adhesive

KPiX Circuit Schematic Storage until end of train. Pipeline depth presently is 4 13 bit A/D Si pixel Dynamic gain select Leakage current subtraction Event trigger calibration

Bump-bonding X-ray of Kpix bumps to sensor

Flex-cable Attachment

SiD Ecal Sensors KPiX bump-bonded to sensor Cable bump-bonded to sensor Assembly 1mm high Contract IZM to bump-bond 30-40 sensors Sufficient for full longitudinal testbeam stack

Cross-Talk Study Red: Pulse 4 random pixels with 500 fC, Blue: No pixels pulsed. Plot residuals for all pixels. <1 fC level for a total injected charge of 2 pC. Crosstalk in this test is thus <0.1%.

Cosmic Ray Bench Tests First silicon sensor with bump-bonded 1024 KPiX chip (Red) cosmic-ray triggered: hit pixel + noise (Blue) sensor removed: noise only Signal distribution as expected for MIPs (~4 fC) Good separation from noise No measurable crosstalk to non-hit channels Low leakage current (as expected) Will do battery of tests with MIPs, sources, IR laser

Cosmic Ray Self-trigger Test

Longitudinal Sampling Compare two tungsten configurations: 30 layers x 5/7 X0 (20 x 5/7 X0) + (10 x 10/7 X0) Resolution is 17% / √E , nearly the same for low energy (photons in jets) Better for the 20+10 config. at the highest energies (leakage)  adopt as baseline

Testbeam Assembly

SiD Baseline Configuration Transverse segmentation 13 mm2 pixels Longitudinal: (20 x 5/7 X0) + (10 x 10/7 X0)  17% / E  1 mm readout gaps  13mm effective Moliere radius ~3.5x3.5 mm2 Cooling (~20mW/KPiX) hex Digital signals & power

ECal schematic readout Data Concentrator “Longitudinal” Data Cable “Transverse” Data Cable Readout Chip “KPix” Detectors Locating Pins Tungsten Radiator ~ 1m

ECal Cooling Electronics operated in pulsed mode  20mW per chip Active cooling required (each sub detector must remove the heat produced) Cold plate with water pipes routed laterally of the wedge Total heat load per wedge module 115 Watt Max DT ~ 1.35oC 8 x 20mW R1= DT/Q=1.35/0.16 =8.43oC/W Max DT ~ 1.35oC

Timeline for R&D Complete contract & bump-bond KpiX chips and cables to Hamamatsu sensors. Assemble test module Secondary End Station test beam at SLAC, which is now scheduled to be ready for use in late 2012 Construct full scale prototype, full width & thickness, short z length Stainless steel in place of Tungsten Perfect Test bed for the small screws design The integration of the electrical interconnections the cooling cold plates

Summary A narrow gap silicon-tungsten detector is an attractive solution for a highly-segmented (transverse and longitudinal), compact (rMoliere, X0) detector for ILC physics requiring individual particle reconstruction. A highly integrated electronic readout can provide a practical realization of such an ECal. The development of such a readout chip is well underway. Prototypes of sensors, chips and cables are in hand, beam tests of full stack awaited. Physics studies to characterize and optimize the performance of the ECal as part of the combined SiD concept continue.