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Burkhard Schmidt May 11, 2012

Muon detector requirements at upgrade luminosities Again some general reflections about the Muon system upgrade; a follow up of my presentation of March 26, 2012. Burkhard Schmidt May 11, 2012. Detector Requirements. Purpose of the Muon Detector:

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Burkhard Schmidt May 11, 2012

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  1. Muon detector requirements at upgrade luminositiesAgain some general reflections about the Muon system upgrade; a follow up of my presentation of March 26, 2012 Burkhard Schmidt May 11, 2012

  2. Detector Requirements • Purpose of the Muon Detector: The main purpose for the Muon system remains the same for the upgraded detector as for the present detector: • Provide a PT selective muon trigger • Provide high quality Muon ID offline • Muon ID offline: • The performance requirements for Muon ID remain in 1st order unchanged. It seems they can be maintained even with higher pileup. See talk Fatima Soomro on March 26, 2012

  3. Detector Requirements (cont.) • PT selective muon trigger: • Since M1 will not be there, the PT –resolution (based on the M2-M3 track segment) will be worse. • With the present granularity the PT –resolution would deteriorate from ~21% to ~34%. • This should be ok, as the LLT muon trigger output rate will be anyhow larger than the present L0 muon trigger output rate (LLT: 10MHz vs. L0: 1MHz). • The impact on physics has to be understood if the granularity of M2R1/R2 gets worse. Reminder: • One should keep in mind that about 12% of the interactions contain a muon. • With an average pile-up of 4 at L = 2x1033/cm2/s this becomes nearly 50%, hence the requirement for a PT selective trigger. • The fraction of muons in R1 with a PT above threshold is 15%.

  4. Work plan for the coming year • We will get a Technical student for 1 year, starting in July, to study the muon system granularity for the inner part of M2/M3 (where the rate is a problem at high lumi) for the upgrade. • The student will also investigate how much background rejection can be obtained with improved beam-plugs under the Calorimeters and improved shielding.

  5. Possible scenario • The outcome of simulations is crucial to define the layout for M2R1 and maybe other inner regions. • A muon detector where M2R1 is replaced by shielding • Implies a non PT-selective muon trigger for R1.  Looks unrealistic for the LLT. • A ‘minimal solution’: • Keep the same (or very similar) number of FE-channels for M2/M3 R1, but change wire-readout channels to cathode readout channels. • It worsens the granularity in x by a factor 3 and hence the PT resolution significantly.  Is it enough for the LLT ? • Keep the same CARDIAC FE-boards. No new board design. • Keep the same gas-system, hence the same chamber technology. • A real upgrade: • Increase the number of FE-channels to maintain the same granularity as we have at present: • Increase the number of logical channels from 112 to 384 per chamber. • This implies the design of a new CARDIAC board housing more FE-chips.  See presentation of Paolo C. et al. and BS at the meeting we had on March 26, 2012.  It would be a safe solution for the LLT, but has huge implications in terms of modifications to the system – and cost/manpower.

  6. Comments • In the present cost estimate for the upgrade, as put in the FTDR, only a ‘minimal solution’ can be accommodated. • Any more ambitious upgrade will immediately blow up the cost: • New FE-boards, new chambers, partial re-cabling, cooling • Using GEM technology requires significant modifications to the gas system. • Designing a new FE-chip has the cost overhead for the development (MPWs), engineering run, production and testing, etc. • A more ambitious upgrade needs first of all to be well motivated / justified by a significantly improved muon detector performance, which is not easy! • It requires in-depth studies, for which the time is short (we have only 1 year). • A more ambitious upgrade might therefore be rather considered for a later time (LS3).

  7. An option for minimal solution • Re-build MWPCs with wire only cathode readout for M2R1 and the same number of FE-boards. • 12 (16 including spares) chambers cost <50kCHF • For M2R2 (26 chambers) the cost is already about twice as high • Keep in mind that we have anyhow to build some additional MWPCs to have more spares, in particular for M5R2, so a production side has to be re-activated. • Discussion on the construction of new/spare chambers have started with our PNPI colleagues and will be pursued. Reminder: • Space-charge is not the concern for MWPCs in the inner part of M2/M3 (up to particle densities of nearly 1MHz/cm2) • Ageing effects are not seen so far and are being monitored.

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