A HighEfficiency and High Resolution Straw Tube Tracker
A High-Efficiency and High. Resolution Straw Tube Tracker for the LHCb Experiment Niels Tuning NIKHEF Amsterdam, The Netherlands On behalf of the LHCb Outer Tracker Collaboration 1) Detector Construction 2) Beam Test Results 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning
LHCb in a nutshell Both b’s are produced forward: • • pp with s =14 Te. V L = 2. 1032 cm-2 s-1 • 1012 b-hadrons per year Aim: measure CP violation and rare decays • Bs mixing • CKM angle γ • Small branching fractions • … 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning All affected by new particles inside loops! 2
The LHCb experiment Status down in the pit: LHCb is real ! Dipole magnet 27 Octobre 2005 Calorimeter IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 3
LHCb experiment: The Outer Tracker ¼ station prototype: Outer Tracker 6 m 5 m 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 4
The Outer Tracker • • Cracow: all straw-support panels Warsaw: 124 short modules (6 types) Heidelberg: 62 long modules NIKHEF: 130 long modules Two Halves: Module Type F S 2 S 3 One large module: § 34 x 490 cm 2 § 4 x 64 = 256 channels S 1 340 mm 2400 mm Total nr of channels: 3070 mm 27 Octobre 2005 2900 mm § 53. 760 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 5
Outer Tracker: Detector and Electronics • Straw: § Radius: 2. 5 mm § Length: 2. 5 m • Gas: § Ar/CO 2 70/30, flush at 1 volume/2 hr § Drift time: ~45 ns for 2. 5 mm • Electronics: § ASDBLR chip: • Amplifies, shapes and discriminates • Profit from ATLAS TRT ASDBLR § OTIS chip: OTIS • Measure time with accuracy < 1 ns § Gigabit Optical Link (GOL) • Serializes and ships data at 1 MHz 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning GOL 6
OT Module Production 1) Cutting Straws 2) Straws aligned on template 3) Glue on panel 27 Octobre 2005 4) Panel on straws IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 7
OT Module Production: wiring • Wire quality was problem § Wire: W/Au § Curliness: difficult for the wiring § Gold layer: high currents § Rejection caused tight delivery schedule, but good wire quality eventually for all modules Bad Good 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 8
Outer Tracker: Module production Ready • We will produce last module next Monday ! • Ship to CERN in January 2006 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 9
OT - Quality Assurance Per Wire: • Wire Tension: • Dark Current 70 g <2 n. A Per Module: • Gas Tightness: <10 -4 l/s • Response to source: ± 10 % Findings: • • • Spotted timely Bad wire quality Leaky gluing procedure Bad gas flow in outer straws Bad soldering of connectors Missing wire locators … 27 Octobre 2005 Adapted Procedure All solved! Total number of bad channels: • • Dead, tripping or noisy <1‰ IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 10
Final module check: radio-active sources Check detector response: • • Current from 90 Sr β-source Pulse height from monochromatic 55 Fe γ-source • Full scan of the entire module Good Example: Bad Example: # Wire Current (n. A) § Every cm 2 of the OT is checked Example of uniform response 5 meter Example of non-uniform response Wire locators 27 Octobre 2005 Position +20% IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 11
Beam Test First, get the cables sorted… Project leader Chief electronics 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 12
Beam Test • Final detector modules • Final prototype electronics • 6 Ge. V electrons at DESY • • Efficiency Resolution Noise Cross talk vs • HV • Amplifier threshold • Position along straw beam See: LHCb-2005 -076 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 13
Beam Test efficiency profile: Efficiency, ε Drift time (ns) rt-relation: r (mm) 2. 45 mm Resolution and efficiency for different HV and amplifier threshold 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 14
• Good efficiency and resolution for HV > 1520 V § ε 98% § σ 200 µm • Corresponds to Gain>50, 000 Resolution (mm) Beam test: detector performance 0. 6 0. 2 0 1400 Efficiency, ε 100 0 1200 27 Octobre 2005 1400 1550 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning HV(V) 15
§ ε 98% § σ 200 µm • Corresponds to 3 – 5. 5 f. C • Electronic noise at 750 m. V (= 3. 5 f. C): § 5 k. Hz / straw § 0. 03% occupancy § Acceptable Efficiency, ε • Good efficiency and resolution for 700< thr < 900 m. V Resolution (µm) Beam test: detector performance Amplifier Threshold (m. V) 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 16
Hits Not everything is perfect… • Cross talk: 1700 V, 800 m. V § Probability that neighbours fire § 5%: acceptable • Reflections: Channel § Straw not terminated § New version of ASDBLR faster shaping § 20% have additional after-pulse § Effect much reduced depending on readout mode 27 Octobre 2005 100 cm, 1600 V, 760 m. V In middle IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning HV(V) 225 cm, 1600 V, 760 m. V Close to end 17
Summary • Module production finished this week! • Beam Test: detector characteristics determined: § § Good efficiency (>98%) Good resolution (<200 µm) Noise level acceptable (~5 k. Hz) With some flexibility • 1520 – 1600 V • 3 -5 f. C threshold To do: • Mechanical support • Services § HV, LV § Gas § Cooling Install and commision in 2006 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 18
Backup: ageing studies • No news since report last year in the IEEE 2004 NSS-MIC conference (Oct 2004, Rome) by Sebastian Bachmann § Session N 39: Radiation Damage Effects II - Aging of Gaseous Detectors § Title: Ageing Studies for the Straw Tube Detectors for the LHCb Outer Tracking System No ageing observed Studies continue 27 Octobre 2005 IEEE 2005 Nuclear Science Symposium, Puerto Rico, Niels Tuning 19
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