The LHCb Muon System Upgrade Alessandro Cardini on

The LHCb Muon System Upgrade Alessandro Cardini on behalf of The LHCb Muon Upgrade Group

Outline • The LHCb muon system • The upgrade project • The new electronics • Performance studies • Project organization • Conclusions LHCC, 03 December 2013 A. Cardini for the Muon Group 2

The LHCb Muon system • 5 muon stations (interleaved with iron walls), 2 independent layers/station increased redundancy • Layers are logically OR-ed increased efficiency • 435 m 2 of detector active area, 1380 chambers • MWPC and triple-GEM in inner region of M 1 • It provides: – robust muon identification – high pt muon trigger at L 0 LHCC, 03 December 2013 A. Cardini for the Muon Group 3

Current muon electronics LHCC, 03 December 2013 A. Cardini for the Muon Group • • • 7536 front-end boards 125 k front-end channels 26 k readout (logical) channels • • 152 ODE (12 crates) 152 IB (12 crates) • 10 TELL 1 • 144 SB + 12 PDM (12 crates) 4

The Muon upgrade in brief • Get ready for the 40 MHz readout @ LS 2 – New muon readout boards (n. ODE, with n. SYNC ASIC) for an efficient detector readout by TELL 40 – New boards for an efficient chamber pulsing (n. PDM) and control (n. SB) via GBT protocol – IB removal in M 5 outermost region – Additional shielding around beam pipe behind HCAL to reduce particle rates in M 2 inner regions – Spare MWPC construction LHCC, 03 December 2013 A. Cardini for the Muon Group 5

Considerations • At the upgrade luminosities particles rates are tolerable except in M 1 removed • Particle fluxes very high in M 2 inner regions additional shielding behind HCAL • Occupancies very high in M 5 R 4 due to backsplashes from a corrector magnet and because logical readout (~0. 5 m 2) channels are an OR of 24 physical channels remove IB in this region (this solution could also be implemented elsewhere if needed) • The new electronics will be installed in existing crates without re-cabling • Ageing of detectors is a concern after LS 3, especially in innermost regions of M 2 an R&D program for new more radiation tolerant detectors is ongoing (these new detectors could be built with higher readout granularity to deal with the increased occupancies) • The proposed new electronics architecture is able to accommodate all the changes described above LHCC, 03 December 2013 A. Cardini for the Muon Group 6

LHCC, 03 December 2013 A. Cardini for the Muon Group 7

New off detector board n. ODE board LHCC, 03 December 2013 A. Cardini for the Muon Group n. SYNC ASIC 8

New control and pulsing system n. PDM board LHCC, 03 December 2013 n. SB board A. Cardini for the Muon Group 9

Additional HCAL shielding • In present detector 6. 8 λI behind M 2, not sufficient for upgrade luminosities, rates on M 2 inner stations will be very high • Replace PMT and bases of innermost cells of HCAL with W (or Fe) absorber • Simulations show a 26% average rate reduction on M 2 R 1 LHCC, 03 December 2013 A. Cardini for the Muon Group 10

Spare MWPCs • Very low replacement rate up to now • No correlation with MWPC location on detector no evidence of damage induced by radiation • Foreseen replacement rates similar to the ones currently observed • Spare MWPCs will be identical to the ones currently installed LHCC, 03 December 2013 A. Cardini for the Muon Group 11

Performance studies • • Rates in the upgrade conditions were estimated from current measurements – Rates scale very well with luminosity – Include spill-over effect for 25 ns bunch spacing – Conservative scaling with energy (from 7 Te. V and 8 Te. V data comparison) – Effect of HCAL additional shielding included (-26% average rate reduction in most irradiated detectors of M 2 R 1) Estimated rates at 2 x 1033/cm 2/s Errors on rates: – – – Uncertainty of pp cross section (± 10%) Increase in hit multiplicity with energy Uncertainty of additional shielding effect LHCC, 03 December 2013 A. Cardini for the Muon Group 12

Inefficiency estimate • No space charge effects seen in a high luminosity test (1 x 1033/cm 2/s) performed in Dec. 2012 • Efficiency decreases because of dead time due to large occupancies • Dead time computation takes into account the in-time occupancy, the hit time profile, the analogue and digital dead time of the front-end electronics • Method validated using special runs at 25 ns bunch spacing (it allows to disentangle dead time effect from other contributions) • Extra O(1%) MWPC-related inefficiencies included LHCC, 03 December 2013 A. Cardini for the Muon Group 13

Muon identification efficiency • Inefficiencies impact on physics are very analysis dependent show Muon. ID as the figure of merit • Muon. ID – Is. Muon: matching track to muon hits – Additional criteria: DLL (hit distance from extrapolated track + RICH/CALO info) • Use simulated Bs μμ events, with random hit removal according to estimated efficiencies • Small efficiency losses (-5%) at 2 x 1033/cm 2/s with respect to 2012 conditions LHCC, 03 December 2013 A. Cardini for the Muon Group 14

Pion misidentification probability • Muon misidentification (Mis. ID) measured directly on data using D 0 K-π+ sample • Events are divided in various samples according to number of reconstructed tracks (ntrk) in each sample average number of primary vertices <n. PV> is estimated • Mis. ID found to scale linearly with <n. PV> used to for the extrapolation at the upgrade conditions • Mis. ID increases due to higher occupancies - can be partially recovered with additional particle identification criteria (DLL-cut) • Further improvements expected by optimizing current Muon. ID algorithm to upgrade conditions and by including additional shielding LHCC, 03 December 2013 A. Cardini for the Muon Group 15

Project organization • Tasks have been allocated to the participating institutes, matching their experience • Project planning clearly defined • Simplified installation of the new equipment at LS 2 • Important ECS reorganization planned to occur significantly in advance of LS 2 to reduce software commissioning time after hardware installation LHCC, 03 December 2013 A. Cardini for the Muon Group 16

Conclusions • High performance muon system is a key element of the particle identification system of LHCb • The upgraded electronics is compliant with the 40 MHz LHCb readout system • The new control boards take advantage of the fast GBT protocol to improve system configuration and monitoring capabilities • Muon system performance at high luminosity appears to be adequate and studies are ongoing to improve muon misidentification • The new electronics architecture allows to better exploit the intrinsic granularity of the detector (also permits additional IB removal and possible new higher granularity detectors for most irradiated regions) LHCC, 03 December 2013 A. Cardini for the Muon Group 17

Backup slides LHCC, 03 December 2013 A. Cardini for the Muon Group

Costs • Costs not changed much from FTDR, but project has evolved substantially • Much better use of resources with the new proposed electronics • New architecture allows other possible modifications to deal with high rates (further IB removal, new higher granularity detectors in M 2/M 3 inner regions) LHCC, 03 December 2013 A. Cardini for the Muon Group 19

LHCC, 03 December 2013 A. Cardini for the Muon Group 20