1. Joerg Dubert’s Questions as you all aware we currently do not yet know how the final mechanical design of the new Small Wheel will look like. Nevertheless, in the end the available space for detectors will be quite similar: - in the x-y plane the maximum size will be approximately that of the current CSCs or MDT chambers. Of course, in the radial direction the new chambers could be smaller and their number increased. In the phi-direction the size is more or less fixed as we want to keep the arrangemnt in 16 sectors. - in the z-direction the space will be about 25-40 cm, depending whether we can profit from an additional wall of neutron shielding. If possible we still envision the new Small Wheel to use only one single type of chamber (which could of course consist of a mechanically integrated sandwich of technologies if needed), i.e. we want to avoid regions with different technologies like the current CSC and MDT/TGCs. 1

2. Mmegas-based Strawman Detector Toy Detector just to get a rough idea what could be possible and approximate channel count Two basic criteria: 1. At least one dimension of the chamber must be <= 1100 mm 2. Channels/plane give a sensible chip count with strip width ~0.5 mm 2

3. The resulting “Parameter Table” 3

4. Total width easily within 40 cm  Generate track at a given angle  Track crosses a strip at a random position  Generate primary ionization clusters Poisson distributed  Generate number of electrons for each cluster  Take strip with earliest time and charge over a certain threshold as the track’s coordinate Strip pitch = 0.5 mm Reconstruct track and compare slope with the generated one No transverse diffusion considered but effect is negligible for the first arriving cluster 4

5. Questions (cont) if your technology is chosen for the new Small Wheel provide a time line on how would you proceed from beginning of 2012 to the installation in 2016 (or 2017/18). Please comment on your plans concerning chamber construction and production/availability of the electronics, as well as the chamber commissioning before the Small Wheel assembly (a full commissioning of the assembled wheels is planned in any case, regardless of the technology) Please give an update on existing prototypes and test beam plans for 2011 as well. At the Oxford ATLAS upgrade week (muon session on Tuesday March 29 th ) updates and follow-up discussions will take place. 5

6. New Small Wheel Construction Timeline (Based on 1018 Shutdown) Project encouraged and strongly supported by CERN/ATLAS Recent developments in LHC schedule contribute to increase in uncertainty as to when things need to be done Current thinking as follows: Formal proposals for Detector Technology: Fall 2011 Decision on Technology: Spring - Summer of 2012 Technical Design Report: Early 2013 Construction: 2013 – late 2016 Installation on Surface, commissioning: 2017 –early 2018 Installation in Cavern, Integration: 2018 Shutdown 6

7. Questions (cont) 2) by the next muon week (starting April 11th): please provide information on the estimated the mimimum and maximum number of services and the power consumption for you detectors. This will allow us to proceed with the design of the flexible chains and the cooling. 7

8. Complete digitized parameters per hit: 32 bits 10 mW/channel 8

9. Interface to GBT For more details see talk at 2011 ACES meeting http://indico.cern.ch/conferenceOtherViews.py?view=standard&confId=47853 9

10. Rough Bandwidth Calculation BC (nsec)2.50E-08 ADC conversion5.00E-07 width 0.5 mm0.05 Rate Hz/sq.cm200060001000020000 Strip length(cm)Occupancy per BC 501.25E-043.75E-046.25E-041.25E-03 1002.50E-047.50E-041.25E-032.50E-03 1503.75E-041.13E-031.88E-033.75E-03 2005.00E-041.50E-032.50E-035.00E-03 Occupancy /strip/BC, Take as average (actually overestimate), 1 m x 0.5 mm @6 kHz/cm 2 For 2048 channels/plane on the average we expect 1.5 hits/plane/BC Then: Record 5 BC Assume on the average 4 strips/hit 40 bits per hit 10 5 Level 1 Accepts 8 planes per chamber Comes to ~1 Gbps In Principle 3-5 Chambers/GBT! But probably more of a problem to gang 3 chambers. In any case even if on-detector boards consume, e.g. 30 W, we add ~1 mW/channel Total power then for 2 M Channels is 22 kW. 10

11. Services Power needed 22 kW (Have 18 kW presently for CSC) Existing cooling more than adequate (only use ~15 l/min/loop, 4 loops) Existing MDT Gas Infrastructure adequate Optical fibers assuming 1 link/Chamber 128-256 (depending on max size) Already have 320 for CSCs HV needs further studies to devise a distribution strategy 11