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Muon spectrometer

Muon spectrometer. General introduction  E.V. Tracking system  Y. Le Bornec Trigger system  P. Dupieux Relevant news: detector construction started both for tracking and trigger detectors. Summary. Geometry monitoring system High level trigger Dipole Absorbers Integration

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Muon spectrometer

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  1. Muonspectrometer General introduction  E.V. Tracking system  Y. Le Bornec Trigger system  P. Dupieux Relevant news: detector construction started both for tracking and trigger detectors

  2. Summary • Geometry monitoring system • High level trigger • Dipole • Absorbers • Integration • Thermal studies L. Leistam

  3. Geometry Monitoring System PRR successfully passed (Lyon on March 11th 2003) • Alignment procedure for tracking chambers: • Initial positions of chambers mesured with straight muon tracks (B off) • Positions monitored during physics runs (B on)  GMS • GMS requirements: • Invariant Mass resolution 100 MeV in the  region • From front absorber + chambers  90 MeV(mult. scatt. + energy loss fluct.) • Constraints on alignment contribution: smaller than 45 MeV (i.e. sagitta resolution smaller than 70 mm) From initial alignment ssagitta  20 mm  From GMS : ssagitta  67 mm -

  4. The GMS setup • Longitudinal Monitoring System (LMS) • BCAM to link two adjacent stations • Proximity to link chambers of the same station • BCAM to link TPC and cavern walls • Transverse Monitoring System (TMS) • BCAM for in-plane monitoring Proximity and BCAM: derived from Rasnik system, already used/in use in other experiments

  5. GMS tools: Proximity CCD sensor Lens Coded Mask Diffusor IR LED ~15 cm D VME • Lens and CCD in the same enclosure • Distance CCD-Lens ~ 15 cm D ~ 30 cm • Precision for a single line: • along X and Y ~ 1 μm • along Z ~ 5.10-5 x D

  6. 4 m 8 m 12 m 16 m GMS tools: BCam CCD lasers lens D VME • Displacement determination: • along X and Y: shift of the image • along Z: distance between the spots Spots seen at different distances • Precision for a single line: • along X and Y ~ 5.10-6 x D • along Z ~ 4.10-4 x D

  7. Instruments: BCAM/PROX lasers CCD sensor socket lens • Mask:  PROX • L, d = 240, 30 mm, w = 200 g (40) mask  BCAM L, l, h = 91, 67, 30 mm, w = 280 g (96) • L, l, h = 30, 60, 55 mm, w = 100 g (160)

  8. Simulation of GMS performance Resolution on relative positions of two adjacent chambers (bending plane) • sagitta = 7 m • M = 2.7 MeV/c2 Including all possible effects: - chamber non-planarity (deformations) - optical element positioning accuracies - absolute position measurement - robustness vs. breakdown of elements Performance still within requirements Effect of intrinsic resolution: we are above the requirements by a factor of 4-5

  9. Items which deserves further studies… • Effects of thermal gradient: • Thermal specification for TCs in the dimuon spectrometer: • Max temperature Tmax= 40 °C, Max. thermal gradient:  Tmax= 20 °C • Test on bench in alice-like condition needed. Integration: tuning of passage of optical lines Calibration... Passage lignes vers TPC Passage dans plaque carré du front absorber souhaité Passage des lignes entre stations 3 et 4 Interaction Lignes Becam et supports bobine Perçages nécessaires dans supports

  10. Front end electronics 10 DDL data links ... e HLT L0 Local Trigger Circuits. pt Find clusters in tracking chambers. Online Tracker Improved Pt calculation HLT decision DimuonHLT overview • The goal is to improve the sharpness of the Pt cut, thereby removing more background particles. • Algorithm based on data from trigger stations and tracking stations 4 and 5 • Cluster finding • Partial track reconstruction • Improved Pt computation • Everything is done online and so it must be fast.

  11. Trigger DIU DDL like Interface with DAQ DDL Interface with HLT Cluster Finder Track Finder Decision DAQ 10 Tracking Chambers DIU Repeated for every DDL Publisher / Subscriber Framework Actual data communication Logical data communication Dimuon HLT implementation Data Flow Chain over Publisher Subscriber Framework (Heidelberg) Dimuon HLT activities: Cluster finder (FPGA)  Saha Institute, India Track finder and Pt calculation  Cape Town University

  12. Cluster finder and hit reconstruction - I Aim: to supply Recontructed Hits from Pad Hits for each cathode plane of St. 4 & 5 Constraints: Central Pb-Pb: ~140 particles  550 pads fired per detection plane Expected trigger rate - 1 kHz available time ~1 ms  FPGA (sitting on RORC card) • Basic Idea : • Each cluster is characterized by one Central Pad (i.e. Pad with max. charge). • To generate RecHits, it is not essential to make clusters (just identification of Central Pad) • Once the Central Pad is found, the hit position in y-direction ( bending plane) is obtained from the CG of the charge distribution between the Central Pad and its top and bottom neighbours.

  13. Cluster finder and hit reconstruction - II • Very preliminary results indicates that: •  Space resolutions ~ 100 mm are achievable • Processing time : extrapolation to FPGA performance of the time needed to process each Hijing event not far rom requirement (ms regime • Caveat • The data register needed for each cathode plane in the present scenario is too big (110 X 880) to fit in the RAM of FPGA (hardware constraint). • Immediate Plans: • Alternative data storage scheme • To test the whole chain with simulated rawdata which will have all features (header -> mapping) of real data. This data is expected to be available in the summer of 2004.

  14. System Benchmarks and prototyping (UCT CARMEN cluster) Server : dual PIII 1GHz (qgp3) Nodes : identical PIV 2.6 GHz hyperthreaded) Storage : Promise SCSI-IDE RAID array Network : Surecom 10/100 24 port switch , 2-port Gigabit backplane Network protocol : TCP/IP O/S : Server - RedHat 9, kernel 2.4.25 smp with updates. The Publisher-Subscriber software framework tested at UCT cluster: 1 publisher/1 subscriber data transmission (no algorithm calculation) Performance (message sending rate and network throughput) comparable to the Heidelberg cluster The dimuon HLT algorithm is currently being integrated into this framework.

  15. Simulation studies: space resolution vs. track reconstruction e HLT pt Skin width Cluster finder should aim at a coordinate resolution of 500 micros. Anything below this value effects the resolution negligibly and the resolution bottleneck is due to a poor choice of the Pt computation equation used. (see TDR)  to be improved

  16. plug Absorbers • FA and SA Absorber status: • ~ All components delivered • Assembly of components starting soon (tooling in construction) Upgrade ofthe platform supporting the plug (muon side) • better shielding against machine-induced background from LHC tunnel on trigger chambers

  17. Dipole Dipole pre-assembly in ALICE cavern: • Yoke completed • Coils soon

  18. Conclusions • All the muon spectrometer detectors entered the construction phase  see next talks • Several technical problems solved • Progress on: • Dimuon HLT : increasing activity, first results • GMS : PRR done, further test & fine tuning needed • Engineering/integration issues: • Absorbers and Dipole pre-assembly • Muon filter: tendering completed • …a lot of work carried out…..

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