1. Fred Hartjes 1 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Introduction and overview on the Gossip R&D Discussion on the review of the Gossip R&D proposal CERN, February 8, 2010 Harry van der Graaf Fred Hartjes Nigel Hessey

2. Fred Hartjes 2 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Two names for same technology uGridPix lgeneral identification of the technology npixel chip nMicromegas/InGrid mesh ndrift gap uGossip lspeciality of GridPix lThinned pixel chip (50 µm) and narrow drift gap (1 – 1.2 mm) Pixel chip ~ 1 mm Any drift gap

3. Fred Hartjes 3 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Why are we developing Gossip? Three basic advantages 1.Outlook on very high radiation tolerance, by far exceeding any solid state technology 2.Strongly reduced cooling requirements l=> easier operation (+ 20ºC vs - 20ºC for planar silicon) nNo risk on thermal runaway lNo bias current lLower power dissipation frontend electronics nNo DC input current nPractically no external input capacity 3.Lower mass lMassless detecting medium (gas) lNo bump bonds lMajor mass reduction on heat spreaders etc because of relaxed cooling

4. Fred Hartjes 4 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Comparison of four pixel technologies for ATLAS b-layer at sLHC (phase II) uMy personal view (Fred Hartjes)

5. Fred Hartjes 5 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 General considerations on Gossip R&D uPresently four/five technologies are proposed for the ATLAS pixel layers at the sLHC lOnly Gossip has gaseous detection medium, all others use semiconductor u=> many aspects of Gossip are fundamentally different compared to the various solid state technologies lFunctioning lData format lOperation lInteraction with particles lServices lManufacturing uGaseous avalanche detectors exist since many decades lBig, cheap detector structures with position resolution in 70 – 200 µm range lHigh rate gaseous pixel detectors with pixel size < 100 µm are new uVast amount of R&D needed to develop Gossip

6. Fred Hartjes 6 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Eight specific Gossip R&D subjects Ignoring generic subjects like mechanical support, cooling, powering, optical links 1.Photolithography lInGrid lProtection layer against discharges 2.Data structure lInstead of single crossing point Gossip measures a short track from individually detected electrons lData in the form of 3D crossing point and track angles (phi and theta) n4 floating parameters lDedicated frontend electronics needed to fit the local track segment 3.High rate performance more critical because of the amplification by avalanche lRate tolerance lAgeing lRate induced sparking

7. Fred Hartjes 7 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Specific Gossip R&D subjects cntd 4.Different generation of charge signal lPrimary ionization of few electrons lGas avalanche to get sufficient charge signal lTime structure ruled by nElectron drift in drift gap nIonic drift in amplification gap l=> study of fundamental processes of drift, diffusion, gas amplification 5.Performance lPosition resolution including angular dependence nUsing drift time info lReaction on neutrons 6.Engineering super modules lMinimizing edges, enclosing gas volumes, segmenting InGrids lServices: gas supply lines, HV connection

8. Fred Hartjes 8 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Specific Gossip R&D subjects cntd 7.Simulations lDrift velocity, diffusion lOptimizing position resolution lCalculating charge signal development (time structure) 8.Developing tracking algorithms (software) lImplementing local tracking into dedicated ASIC

9. Fred Hartjes 9 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Present status of Gossip R&D 1.Photolithography lPresently going quite well after period of stagnation 2.Dedicated ASIC development (frontend) lDedicated frontends (Gossipo-4) progressing, but no activity yet on local intelligence 3.High rate studies lStagnation, no good prospects (lack of manpower) 4.Study on fundamental processes in gas lOngoing 5.Performance lProgress but lack of manpower 6.Engineering studies lOngoing, but still in premature stage 7.Simulations lProgressing quite well 8.Tracking algorithms lHardly anything done yet

10. Fred Hartjes 10 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Nikhef physicists involved # of personsPositionAvailable (%) 2Senior with permanent contract90; 10 4Temporary contract (postdoc, 65+)90; 90; 20; 70 3PHD student90; 90; 80? 2Graduate student80; 80 5Engineer (mechanical or electronic)10; 10; 10; 60; 50 uAbout 2/3 of the GridPix/Gossip research takes place at Nikhef uR&D projects lGossip in ATLAS lGridPix for TPC in ILC lXENON nGridPix as a single electron detector in bi-phase Xenon filled WIMP search experiments lPolaPix nGridPix as a detector for the measurement of the polarization of X-rays from space Present staff at Nikhef Amsterdam and Nijmegen

11. Fred Hartjes 11 Review of the Gossip R&D proposal for ATLAS at the sLHC CERN, February 8, 2010 Conclusions on Gossip R&D for ATLAS uGossip technology has big potential benefits in terms of reduction of material and price uTechnology differs much from solid state detectors l=> extensive research needed uR&D in early stage of development lNo production prototype yet l=> we do not have an answer on questions on production issues uNot much progress on typical Gossip – b-layer R&D lRate, ageing studies, rate induced sparking uResearch proceeding slowly lCollaboration too small, mainly Nikhef based lExtension urgently needed