1. M. Gilchriese ATLAS Pixel Upgrade Thoughts on US Role

2. M. Gilchriese 2 History The US had lead or co-lead roles in the fabrication of the current detector in –Integrated circuit electronics –Module design and lab/test beam irradiations and verification of design –Module fabrication coordination, equal role in fabrication –Module hybrid design/fab –Optical readout –Mechanics –Services –Systems integration(such as it was) –Off-detector readout(RODs) Upside – US only country that covered most bases, “vertically integrated” – vital to project Downside – lots of work, take on risk

3. M. Gilchriese 3 Upgrade Considerations SLHC scale currently about x 3 of current detector in area Uncertainty about B-layer replacement (what is it?) likely to add to scope ATLAS not well positioned for relatively early luminosity upgrade to 2-3x10 34 (Phase I, 2013?) => more upgrade pressure? Stated SLHC upgrade schedule (2015-2016) very, very difficult In short, upgrade is a challenge! US involvement in pixels has expanded since construction ….SLAC, Columbia, UT Dallas, OK State… Can imagine some additional expansion for upgrades In what follows, I assume US role in upgrade similar in spirit to previous role in current detector

4. M. Gilchriese 4 Sensors Two, parallel developments? Small radius, very high dose –3D? –Diamond? Larger radius, high dose –Planar that survives. Large areas –Down to what R? –Cheap, compared to 3D or diamond, is critical Fundamental sensor R&D – all But sensors + electronics + irradiation + test beam + lab tests….this was huge amount of work in past, will be again – really will need people! Common tests(3D, planar…) US: New Mexico(3D), OSU(diamond), SLAC?(3D?), Santa Cruz(planar), LBL(only at lab/beam test level)

5. M. Gilchriese 5 ICs and “Off-Detector” FE-I4 –Development launched with Bonn, Genoa, CPPM, Nikhef –LBL hopes to have enough resources to be “core” but overall effort very thin –FE-I4 is only step on the way! System design –MC chip for pixels(not currently) –SMC for pixels(what does this mean?) –Optical drivers/receivers – where are they, what are the specs… –Integration with powering –New RODs Architecture doc (Alex) is start but system design needs vast amount of work. Tightly coupled with FE, modules. Apart from FE-I4, what is appropriate to actually prototype? US: LBL, Santa Cruz(but only overall arch. at moment). Penn? Weak

6. M. Gilchriese 6 Modules Conceptual level(Maurice + minor input from Gil) + Bonn Just started working with Bonn to understand cost/practicalities of high volume, planar? sensors + FE-Ix. How cheap could it be => determines outer radius of pixels(I think) Interconnects(hybrids, microcables) were a miserable experience in current detector Coupled with system design US not involved in key technology – bump bonding. Should we even try? US: LBL. Weak

7. M. Gilchriese 7 Optical Component-level R&D underway VCSELs and PINs survivability under irradiation IC driver/receivers design and prototypes In my view, really needs very much to have system level view imposed to avoid wasting time What are the practical options for location of optical transition? Two extreme models: end of stave(or equivalent) – very hard at low R or outside of ID volume and use cables. Very different R&D for these extremes. Maybe right answer is in middle but focus is lacking so far(I think) US: OSU, OK and OK State. Connection to SMU?

8. M. Gilchriese 8 Mechanics I think I have a clear view of how to develop a “menu” of options for basic mechanical structure for modules over the next some months –Radius dependent –Don’t know cooling yet(not our decision only), so look at both CO2 and C3F8 –Constraints (who holds up what and how) –Thermal FEA for different options –Enough mechanical FEA to estimate material –Materials characterization and small prototypes US: LBL(+ W. Miller), U. of Washington?(contact underway), SLAC?. Interface to CERN-based ID upgrade engineering organization(Catinaccio) – N. Hartman(LBL) stationed at CERN

9. M. Gilchriese 9 Services/Systems Services for current pixels was painful Coupled to electronics system design, modules, optical and mechanics – overall system design Need to make sure any R&D that touches on electrical or cooling services takes into account overall important concepts –Low radiation length but –Reliability! –Easier to make and connect than now –Replacement requirements This is not R&D, it’s engineering Again need interface to CERN-based structure that is developing, for now also Hartman but need electrical side…

10. M. Gilchriese 10 Layout/Simulation Layout –Simplistic view: 4 pixel hits, minimum feasible B-layer radius(determined by radiation damage and practical matters) and maximum outer radius(determined by cost and practicalities eg. disk size) +2 other layers, to give about equal spacing –What is “easily” replaceable and what is not –Strawman layout exists –Alternatives being studied –Needs considerable optimization from a practical point of view and engineering input –A lot of this can be done in the US and soon Simulation –I’m ignorant –Some work(Nevksi, Jason…) –Double-b-layer?

11. M. Gilchriese 11 Practicalities R&D is underway. Keep it going But should we instigate any new ATLAS R&D EoI/projects? There is close connection among many aspects of the R&D Need big picture on regular basis to guide R&D May 22-23 upgrade meeting at LBL first attempt in US Afterwards? Commonality with silicon strips – what is it? Looking towards upgrade project, how organized(depends on ATLAS not just US) –Pixels –Strips –RODs, optical, powering....how much is separate and how much specific to pixels or strips –What part of mechanics/services should be common?