for the Transition region G. Aielli for the RPC collaboration BIS 7-8 RPCs for the Transition region Project updates G. Aielli for the RPC collaboration ATLAS Italia meeting 09/05/2014 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Introduction It has been proposed by the ATLAS muon community to assess the performance stability of the muon system in the long term It has been pointed out that the trigger system in the barrel needs for the Phase II are >> than what it can be offered by the present system (both LVL1 electronics and detector). It was conceived basing on the standard requirement of L=10^34 cm^-2s^-1, working for 10 years The new requirements are to run to up to 7x luminosity and for a very extended period, up to 2030 To reinforce the Muon barrel it has been proposed to build the inner RPC layer as proposed originally, before the “down scoping” 09/05/2014 G. Aielli for the RPC collaboration

The ATLAS RPC Muon System completed New BI RPCs Request by ATLAS to anticipate to Phase 1 the BIS 7-8 installation to reduce the LVL1 rate to an acceptable level The BIS extreme chambers (BIS7-8) represent less than 10% of the total BI coverage They are crucial to strengthen the trigger in the 1<|h|<1.3 region 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Yasuyuki Horii Nagoya University, Japan 09/05/2014 G. Aielli for the RPC collaboration

Larger fake trigger rate @ 25 ns Large contamination with 25 ns bunch spacing  Consistent with late protons Estimated rate of present (run-I) trigger in phase-1 (TDAQ upgrade TDR):L1_MU20 = 57 kHz @ L=3x1034 cm-2 s-1 and 13 TeV 70% of the rate from |η|>1.3 will be reduced by the NSW upgrade 22% of the rate comes from 1<|η|<1.3 To be reduced to safely stay within the muon trigger total budget (25 kHz) K.Nagano L1_MU20: rate 25ns / rate 50ns Barrel 8.7% Endcap (total) 69.2% Endcap 1<|η|<1.3 21.9% Forward 22.1% Fraction of L1_MU20 triggers @25 ns 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Present situation IN THE LARGE SECTORS The EIL4 are doublets of TGCs usable to provide a point like measurement but are not sufficiently redundant to suppress the fakes. Cabled to the SL but unused. The recent TILE muon proposal offer the missing robustness and can complement the EIL4, also providing coverage of the acceptance holes IN THE SMALL SECTORS No instrumentation present able to provide granularity. The TILE can provide a large area coincidence to reduce the fakes Proposal: new RPCs to complete the system Projection on the BW ROIs The transition region is the external part. The red areas are the projection of the EIL4 while the blu areas are not instrumented 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration PROPOSAL Two main advantages: For the BIS 7-8 location: Small detector area is needed This area is upstream of the criostats where most of the fake muons are generated For the RPC technology: Excellent timing (0.5ns)  more than enough to suppress the photon and neutron background High granularity trigger possible New generation of high performance RPC now available! 1.33 40.31 deg eta 1.03 11430 at BW 33.67 1.19 9400 at BW 31.06 1.28 8400 at BW 29.60 1.33 1.03 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration System Layout Replace BIS7 and BIS8 MDTs with half width tubes sMDT chamber A whole piece structure allowing to fit in the old MDT envelope a new integrated s(MDT+RPC) chamber: Much bigger space to host the RPCs  no space concern Standard installation in one go by means of crane as for any other ATLAS chamber  no installation concern Enable a good alignment scheme for both chambers Solving performance problem in the hottest region of the barrel Positive impact on the already established RPC layout Enabled the “optimal” scenario  enhanced coverage Avoid interferences with the NSW 09/05/2014 G. Aielli for the RPC collaboration

Enhanced envelope for the BIS8 EIL4 NSW cables Approximate new BIS8 envelope shape (depending on NSW envelope) BIS8 RPC can be extended within the envelope to enhance the coverage 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration BIS 6 MDT BIS 7 RPC BIS 8 RPC Using BIS 7 & 8 sMDTs with only 15 mm drift tube diameter: sufficient space for additional RPCs in all sectors. MPI Munich G. Aielli for the RPC collaboration 09/05/2014

G. Aielli for the RPC collaboration MPI Munich 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration BIS 7+8 sMDT BIS 6 MDT Praxial alignment sensors connecting BIS 6 MDT and BIS 7+8 sMDT A single BIS 7+8 sMDT chamber optically aligned to both endcaps (Small Wheel) and barrel (BIS 6). MPI Munich 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Baseline Layout BIS 7+8 sMDT BIS 8 RPC BIS 7 RPC MPI Munich Independent support and (if desired) Independent installation of RPCs and sMDTs on the rails. 09/05/2014 G. Aielli for the RPC collaboration

Project participation COLLABORATION INFN 10 FTE out of 26 Physicists and technicians Bologna (simulation; performance study; production drawings; DCS) Roma1 and Napoli trigger electronics integration (PAD) Roma2 (front-end-electronics and gas volume and chamber design) MPI approx. 10 FTE (including the sMDT construction) exact number awaited (system layout, mechanics, integration, station assembly and test) UMICH 2.5 FTE out of 4 Physicists and Engineers trigger simulation, serializer, Readout and DAQ USTC 2 FTE out of 4 Physicists funds available for construction; expressed interest for RPC R&D 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Project overview RPC CORE COST ESTIMATE (for the BIS RPCs)  440 kCHF 32 x (3-layer detector + strip panels + supports) = 240 kCHF 6 k front-end-electronics channels = 80 kCHF Cabling and services = 60 kCHF Trigger: 16 PAD boxes + fibers 60 kCHF This cost estimate is based on the construction cost of the BME chambers (4 units) extrapolated to a larger system. It is reasonable to expect scale factor for producing larger system (32 units) RPC CORE COST sharing: INFN (apply for ~150 keuro) MPI (cover the chamber mechanics: ~150 keuro) USTC (~150 k$ available for CORE and R&D finalization) UM (participation in kind as American DOE can not be involved in the barrel) 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Project schedule Activity 2013/12 2014/03 2014/06 2014/09 2014/12 2015/03 2015/06 2015/09 2015/12 2016/03 2016/06 2016/09 2016/12 2017/03 2017/06 2017/09 2017/12 2018/03 2018/06 2018/09 2018/12 2019/03 2019/06 2019/09 Approval   Production Design Module-0 prod. and test Production Assembly and test Installation A single trimester to be defined by TC Commissioning INFN funding request  30 K euro 100 K  20 K 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Atlas schedule Project reviewed positively by ATLAS referees in 2013 ATLAS TC assessed the project compatibility 04/2014 Final formal discussion on 8/5/2015 USC Awaiting for approval by the EB FA awaited by ATLAS to give a sign of “likely” funding assignment Possible approval by CB on 20/6/2014 ATLAS week in Sibiu Installation scheduled on 2018 (LS2) Run in 2020 (RUN 3) 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Backup 09/05/2014 G. Aielli for the RPC collaboration

RPC BIS and overall ATLAS perspective The New Small Wheels will cover the region 1.3< |η| < 2.5 and will address the problem of the large fake rate in the end-cap region TILE  very good coverage + good rejection against fakes but very broad granularity: No muon momentum selection Sensitive to high pileup due to broad coincidence RPC BIS SYSTEM (plus the existing EIL4) complete the trigger in the transition region robust against fakes insensitive to the high pileup due to higher granularity coincidence (ROI matching) provide finer granularity pT selectivity Extends to the transition region NSW-like performance In Phase1 we propose the following scenario: Small sectors  RPC BIS triplet  stand-alone capabilities and failure tolerance Large Sectors EIL4 doublets. The TILE coincidence needed for robustness (being a OR-ed doublet) Residual uncovered area (17%) TILE stand alone with reduced performance 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Geometrical Coverage Making a raw calculation estimating the holes with the green rectangles shown in the pictures, the geometrical coverage results to be ~83.5%. With bigger BIS8 chambers the geometrical coverage would increase to ~87.3%. Adding RPCs to the cryoline the geometrical coverage would increase to ~89.2%. Blue: segment on EI chambers Orange: segment on BIS6 Red: segment on BIS7 Pink: segment on BIS8 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Extrapolation to high pile-up - Probability to find Tile energy (offline) above threshold Measured in ZeroBias triggers : 0.36% - Extrapolation assuming that the probability to find a RPC doublet (or Tile) scales with μ - Probability to find a random coincidence, extrapolated to μ=140 : ~5.2% for Tile - Negligible for RPCs after Δη and Δφ cuts. These estimates have large Uncertainties due principally to: Tile estimation from offline  optimistic Linear extrapolation with μ Uncertainty on the final Tile threshold The effect is LARGE Tile ZeroBias@25 ns (μ=9.7) 0.36% Probability to find a RPC doublet / Tile above threshold .μ = 9.7 .μ=140 (extrapolated) RPC doublet 0.003-0.005 ~0.03-0.06 Δη<0.04, ΔΦ<0.04 ~<0.0001 ~<0.001 Tile (E>500 MeV) 0.0036 ~0.052 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Geometrical Coverage 50ns physics_Muons stream Reconstructed muons pt > 20 GeV h-f of reconstructed muons (staco) associated to EC triggers: BIS 6,7,8 cover small sectors Coverage of EIL4(+5) chambers in large sectors limited by holes due to rails, cryo-lines etc. Total BIS+EI coverage (1<|η|<1.3) -without large BIS8: 83.5% -with large BIS8: 87.3% BIS (with large BIS8) cover 40% of the region (1.04<|η|<1.24) Blue: segment on EI chambers Orange: segment on BIS6 Red: segment on BIS7 Pink: segment on BIS8 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Performance study using real data Study done using MDT segments to emulate RPC/EI hits Correlation between EndCap RoIs and MDT segments (Muonboy) on BIS 7+8 L. Massa BIS7 BIS7 Reconstructed muons (Staco CB pT>20 GeV) all RoIs L1_MU20 reconstructed muons (staco) (pT>20 GeV) Δη = ηRoI - ηMDT - A cut at Δη<0.04 selects almost all reconstructed muons with pT>20 GeV - Removes random segments and low-pT and non-pointing muons 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration Effect of Δη cut Rate fraction Acceptance(staco) RPC Δη<0.2 11.2% 88.8% RPC Δη<0.04 8.1% 88.1% Working point chosen in this study: we expect to improve by better definition of Δη Most fakes are removed just by asking any coincidence further reduction (>30%) comes from the better momentum cutting on Δη A spatial resolution better than ~4 cm is required for a cut resolution Δη~0.005 FURTHER IMPROVEMENTS [under study]. : by tuning the cut for each chamber (roads) By using the η of the BW strip instead the η of the ROI much better resolution cutting on Δφ 09/05/2014 G. Aielli for the RPC collaboration

TILE stand alone vs. complete system 1.05<|η|<1.24 BIS678 +EIL +EIL+Tile TILE stand alone Bkg. Rate increase Efficiency 80±1% (83.1%) acceptance 98.6±0.4% 99.1±0.3% Total Rate Fraction μ=7 6.8±0.1% 9.1±0.1% 11.1±0.1% Background 5.5% 7.6% 9.7% +27% Fraction extrap. to μ=140 ~7% ~10% ~16.5% ~5.5% ~8.5% ~15% +76% In the high pileup situation TILE stand alone rejection worsen with μ. The enhancement of the BIS+EIL4 is on 83% of the acceptance Further improvement in possible by refining the Dh cut fir the BW strip or tube 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration sMDT layout 16 BIS 7+8 sMDT chambers, 15 mm tube diameter BIS 7 part: 2 multilayers of 4 tube layers, spacer height unchanged 2 x 4 x 60 = 480 tubes/ chamber, 1.66 m long BIS 8 part (extension of bottom multilayer of BIS 7): 4 x 30 = 120 tubes/ chamber, 0.83 m long Same front-end electronics board design as for BMG chambers (sectors 12 & 14). Collaboration with IHEP Protvino on drift tube assembly and test. 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration BIS7/8 sMDT alignment Present weakness of the alignment in BIS7 and BIS8: BIS7 is connected optically to the barrel BIS8 is not connected optically at all Acceptance of BIS7 and BIS8 is in the end-cap: they should be aligned to end-cap chambers 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 BOS BMS BIS CSS EMS EOS BEE 1 2 3 4 5 6 7 8 2 1 1 2 EES EIS Advantages of the proposal (to be studied carefully) BIS7 and BIS8 will be merged: a single object is much easier to align than two Preserve Existing optical links to the barrel opportunity to links to the end-cap optical system Extend BEE-EIS optical link to BIS7/8 Complemented with other optical links to EIS All EIS optical links are in fact links to the NSW  ease the layout of the new optical lines BIS8 EIS2 BIS7 EIS2 09/05/2014 G. Aielli for the RPC collaboration

G. Aielli for the RPC collaboration sMDT core estimate CORE cost BIS-7&8 sMDTs #Units Cost/unit (CHF) Total cost (kCHF) Al tubes 9600 3,6 34,6 Wire 14,6 km 1000/km 14,6 Endplugs 19200 7,2 138,2 Gas connectors 1,8 Supports/ chamber 16 1000 16,0 Faraday cages/ chamber 500 8,0 Gas distribution/ chamber 400 6,4 HV&RO distribution boards 800 100 80,0 Mezzanine cards w. HPTDCs 350 140,0 Assembly jigging 1 10 10,0 Transport tools Total chamber material 490,4 Part of the former system can be recycled, in particular cabling and services The old mezzanines can be recuperated to the MDT spares Cost estimated on a small system production (BMG) Cost covered by MPI 09/05/2014 G. Aielli for the RPC collaboration