1. 24/03/99Report to LHCC Referees Muon Group Status Report Outline: Muon Filter - New Geometry - Support System Optimisation Studies - Pad, Strip and Pad/Strip algorithms - Background Model Detector Technology and FE-Electronics Studies - MRPC R&D(CERN, UFRJ Rio) - RPC and TGC R&D (Rome I, Rome II) - CPC and WPC R&D(PNPI, CERN) - FE-Electronics(Cagliari, CERN, UFRJ Rio) Summary of Activities and Milestones for 1999

2. 24/03/99Report to LHCC Referees Motivation: Iron blocks from WANF will be used to build the muon filter Dimensions: Muon shield 1 has 30 cm thickness in TP Muon shields 2-5 have 70cm thickness in TP Iron from WANF has 40cm and 80 cm thickness Consequences: -› The proposed new configuration has the same number of nuclear interaction length: 23 -› The particle fluxes in M2 will be slightly higher -› There will be less multiple scattering between M1 and M2  better P T measurement (?) New Muon Filter Geometry

3. 24/03/99Report to LHCC Referees Muon System Support Structure Status: Preliminary studies have been done by S.Karpinnen in 1997/1998 (Technical Note EST/LEA/98-02) Constraints: Rails of DELPHI - endcap should be re-used if possible Clearance on cryogenics side is only 9.4m from BP at present, thus right part of muon stations cannot be moved out fully -›~12m clearance would simplify access to muon chambers significantly Consequences: -› Stations should be movable independent of absorber and of each other -› Chambers should be mounted on a frame hanging from the top -› Cables will be guided via the top Conceptual design for support structure under study in collaboration with infrastructure group

4. 24/03/99Report to LHCC Referees Electronics and Cables Locations for electronics: Boards with a kind of ASD chip on the chambers Majority-logic and synchronization unit on the sides of the stations Muon Trigger- and- DAQ-Electronics in the Control Room Engineer from Cagliari is working on overall design for Muon FE-electronics

5. 24/03/99Report to LHCC Referees Optimization Studies Goal: Significant reduction of electronics channels without deterioration of the physics performance Pad based algorithm : Optimization result ~15% less physical channels than TP ~25% less logical channels than TP physics performance: (cf. presentation of 22/10/98)

6. 24/03/99Report to LHCC Referees Optimization Studies Goal: Significant reduction of electronics channels without deterioration of the physics performance Pad based algorithm : Optimization result ~15% less physical channels than TP ~25% less logical channels than TP physics performance: (cf. presentation of 22/10/98)

7. 24/03/99Report to LHCC Referees Optimization Studies Rejection of Minimum-Bias-Events is achieved by: P T - cut between 1-2 GeV Choice of field of interest (FOI) -› implicit cut on muon momentum So far, only one x-FOI and one y-FOI per station has been used Improvement of performance possible with several FOI per station L0-Muon-Trigger:

8. 24/03/99Report to LHCC Referees Optimization Studies Field of Interest Optimisation: optimal FIOs per region change with required Minimum Bias retention improves physics performance Performance for optimal pad geometry (as presented before)

9. 24/03/99Report to LHCC Referees Optimization Studies Field of Interest Optimisation: optimal FIOs per region change with required Minimum Bias retention improves physics performance Performance for optimal pad geometry (as presented before)

10. 24/03/99Report to LHCC Referees Optimization Studies Strip based algorithm :  Improvement of physics performance due to finer granularity using strips  ~25% reduction of physical and ~50% reduction of logical channels possible  Simplification of chamber construction  Less robust against background Layout: one pad plane to resolve ambiguities

11. 24/03/99Report to LHCC Referees Optimization Studies Strip based algorithm :  strip layout is more sensitive to background than pads standard background background x2 background x3

12. 24/03/99Report to LHCC Referees Background Studies Background Model : Realistic description of the background is mandatory to - determine the performance of the L0-Muon-Trigger (including safety factor) - choose a technology for the muon chambers Current Model is - based on old detector and beampipe description and low statistics - providing only additional hits in stations 2-5, no particles Updated model will take into account - better description of beampipe and its shielding - muon system geometry, chamber description and digitization - new physics generators - neutron efficiencies for gas containing H 2 … Production based on updated model will start in May 1999

13. 24/03/99Report to LHCC Referees Optimization Studies Combined Pad / Strip layout : Pads in inner part of muon stations solve problem of high occupancy Strips in outer part allow significant reduction of physical / logical channels and provide better granularity -› improved physics performance Algorithm for combined Pad / Strip layout with FOI optimization ready

14. 24/03/99Report to LHCC Referees Optimization Studies Trigger implementation: Several geometries have been looked at from trigger implementation point of view, running the fast identification and the theoretical algorithm Combined pad/strip layout with strips in outer part of stations 2-5, pads in station 1and inner part of stations 2-5 - same granularity as TP - 33% reduction of logical channels Algorithm efficiency for B   X: Note sensitivity to background

15. 24/03/99Report to LHCC Referees MRPC R&D Participants: CERN, UFRJ Rio groups Status: First prototype (30cm  30cm) : - studied in testbeam in various configurations - ongoing tests with cosmic rays - timing properties are according to expectations (cf. presentation of 22/10/98) - rate capability of a few kHz/cm 2 has been achieved - problems with chamber noise at high rate not yet under control Second prototype (230cm  130cm) : - Construction techniques have been developed - Chamber soon ready for tests with cosmics (beam tests scheduled for May)

16. 24/03/99Report to LHCC Referees MRPC R&D Testbeam Results: time walk: ~ 1.5ns/kV time resol.: 1.5ns

17. 24/03/99Report to LHCC Referees MRPC R&D Status: FE-electronics board with better control of threshold has been designed - PCB is in preparation - continue tests with ASD8-B from UPenn Gas system with mass-flowmeters available for this years beam tests -›Improved control of gas mixture Plans for this year : Test small prototype with 4  0.7mm gas gap, plates of lower resistivity (a few 10 10  cm) and new FE-electronics board end of April at PS -›Allows to operate chamber at lower HV; expect improved performance Test large chamber end of May with SPS-beam Test small chamber in GIF end of June

18. 24/03/99Report to LHCC Referees RPC R&D Participants: Rome II RPC construction done in Italian industry (as for ATLAS and CMS) Status: Prototype of Single Gap RPC with - plates of low resistivity (8  10 9  cm) - 48cm  48cm active area - 16 strips with 3cm pitch along x - 16 strips with 3cm pitch along y - standard electronics with 10  30 amplification - gas mixture: C 2 H 2 F 4, iso-C 4 H 10, optional: SF 6 - studied in testbeam in November 1998

19. 24/03/99Report to LHCC Referees RPC R&D Testbeam Results: time resolution ~2 ns 1-2% SF 6 in gas mixture no SF 6 in gas mixture

20. 24/03/99Report to LHCC Referees RPC R&D Plans for this year : Two Double gap RPCs have been produced - using plates of low resistivity (a few 10 9  cm) - active area of 50cm  50cm and 25 strips of 2 cm pitch - tests scheduled for end of April (PS) and end of May (SPS) - tests in GIF end of June -›Expect improved performance w.r.t. rate capability and cross talk FE-Electronics: Tests with fast GaAs-Electronics (as for ATLAS RPC) foreseen in August

21. 24/03/99Report to LHCC Referees TGC R&D Participants: Rome I TGC construction done in collaboration with G.Mikenberg Status: Simple TGC prototype has been tested in November 1998 at the PS - 1.8mm wire spacing - gas mixture: CO 2 and n-C 5 H 12 TGC charge distributionTGC time distribution

22. 24/03/99Report to LHCC Referees TGC R&D Plans for this year : Two twin TGCs have been ordered - sensitive area: 25cm  80 cm - wire spacing 1.8mm, staggered - Resistance of graphite layer: ~200 k   - tests foreseen in July at the SPS

23. 24/03/99Report to LHCC Referees CPC R&D Participants: PNPI St.Petersburg Status: First prototype with pads of different size has been constructed at PNPI together with its FE-Electronics and tested in November 1998 at the PS - wire spacing: 2mm - preferred gas mixture: 30% CO 2, 60% Ar, 10% CF 4

24. 24/03/99Report to LHCC Referees CPC R&D Results : Time distributions Prototype performed very well Testbeam measurements are in good agreement with MC-simulations No deterioration up to very high rates cross-talk to neighbouring pads: ~5% charge distribution

25. 24/03/99Report to LHCC Referees CPC and WPC R&D Plans for this year : Continue studies with CPC prototype Work on backup-solution for outer region: WPC / WSC (Proportional chamber with simple construction) - sensitive area: 16cm  150 cm - 2 gaps of 5mm each, wires staggered, spacing 1.5mm - tests foreseen from May onwards at the PS and SPS

26. 24/03/99Report to LHCC Referees Activities and Milestones for 1999 Optimization Studies: propose optimal and realistic layoutMay study robustness against backgroundJune check feasibility of trigger implementation June -›Decide on muon system layoutJuly Detector Technology and FE-electronics Studies: first round of tests for various technologiesApril-July preliminary decision on technologiesAugust second round of tests for selected technologies Aug.-Nov. test of FE-chip candidates (Lab and testbeam)April-Nov. -›Choice of technologies December

27. 24/03/99Report to LHCC Referees Activities and Milestones for 1999 Optimization Studies: propose optimal and realistic layout study robustness against background check feasibility of trigger implementation -›Decide on muon system layout July Detector Technology Studies: first round of tests for various technologies preliminary decision on technologies second round of tests for selected technologies test of FE-chip candidates (Lab and testbeam) -›Choice of technologies Januar 2000