Villa Olmo, Como 15-19 October 2001 1 A. Polini ZEUS MVD Group: Bonn Univ., DESY- Hamburg, DESY-Zeuthen, Hamburg Univ., KEK-Japan, NIKHEF, Oxford Univ., Padova, Torino, Bologna and Firenze Univ. and INFN, UCL. The ZEUS The ZEUS Micro-Vertex Detector Micro-Vertex Detector Alessandro Polini DESY
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ZEUS MVD Group: Bonn Univ., DESY-Hamburg, DESY-Zeuthen, Hamburg Univ., KEK-Japan, NIKHEF, Oxford Univ., Padova, Torino, Bologna and Firenze Univ. and INFN,
Villa Olmo, Como October 2001 A. Polini3 A Microvertex for ZEUS at HERA ZEUS: upgrade of tracking system: MVD Straw Tube Tracker Global Tracking Trigger Tagging of long-lived particles (heavy flavour) Reconstruction of secondary vertices HERA: e ± p collider 2001 luminosity upgrade L = cm -2 s -1 higher sensitivity for very interesting, low cross sections major changes in interaction region last bending magnet inside experiment higher backgrounds, risks of radiation damage
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Villa Olmo, Como 15-19 October 2001 1 A. Polini
ZEUS MVD Group: Bonn Univ., DESY-Hamburg, DESY-Zeuthen, Hamburg Univ., KEK-Japan, NIKHEF, Oxford Univ., Padova, Torino, Bologna and Firenze Univ. and INFN, UCL.
The ZEUS The ZEUS Micro-Vertex DetectorMicro-Vertex Detector
Alessandro Polini DESY
Villa Olmo, Como 15-19 October 2001 A. Polini2
OutlineOutline
Physics Motivation Physics Motivation Detector DesignDetector Design Standalone Test Measurements Standalone Test Measurements Read-Out, DAQ and Control InfrastructureRead-Out, DAQ and Control Infrastructure First Experience after Installation in ZEUSFirst Experience after Installation in ZEUS Summary and OutlookSummary and Outlook
A Microvertex for ZEUS at HERAA Microvertex for ZEUS at HERA
ZEUS:upgrade of tracking system: • MVD• Straw Tube Tracker• Global Tracking Trigger
• Tagging of long-lived particles (heavy flavour)
• Reconstruction of secondary vertices
HERA:e± p collider 2001 luminosity upgrade
L= 1.5 7.51031cm-2s-1
•higher sensitivity for very interesting, low cross sections•major changes in interaction region•last bending magnet inside experiment•higher backgrounds, risks of radiation damage
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Detector LayoutDetector LayoutForward Section
410 mm
The forward section consists of 4 wheels with 28 wedged sensors/layer providing r- information.
Barrel Section622 mm
The Barrel section provides 3 layers of support frames (ladders) which hold 5 full modules, 600 square sensors in total, providing r- and r-z space points.
e± p
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The Upilexconnection foils canbe bent and gluedto the ladder profile
Two half modulesare then glued togetherto form a full module
Five full modules aredisposed over a carbon fibre support
125 mm64
mm
Two single sensorsare glued and electrically connected by gold plated Upilex foils
Barrel MVD: Module and Ladder StructureBarrel MVD: Module and Ladder Structure
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Forward MVD LayoutForward MVD Layout
Forward wheels:• 112 Si planes with wedge shape (480 readout strips);• r- measurement;• 1 wheel made of 14x2 detectors;• 4 wheels placed @ z = 311, 441, 571 and 721 mm from IP.
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• n-doped silicon wafers (300 m thickness) with p+ implantations (12 or 14 m wide), HAMAMATSU PH. K.K.
• 512 (480 for forward sensors) readout channels.
• Using the capacitive charge sharing, the analogue readout of one strip every 6 allows a good resolution (<20 m) despite the readout pitch of 120 m.
• Highest coupling to the front end electronics if:
Cc >> Cint > Cb
The charge sharing is a non linearfunction of the interstrip
Front-end and Read-outFront-end and Read-out Front-end Chip HELIX 3.0Front-end Chip HELIX 3.0
– 128 channel analog pipelined programmable readout system specifically developed for the HERA environment.
– ENC[e] 400 + 40*C[pF] (no radiation damage included).– Data read-out and multiplexed over the analog out.– Internal Test Pulse and Failsafe Token Ring (8 chips) capability.
Read-outRead-out– 10 bit resolution ADC Modules with:
Common Mode, Pedestal and Noise Subtraction Strip Clustering 2 separate data buffers: cluster data (for trigger purposes)cluster data (for trigger purposes) and raw/strip data
for accepted events. Global Tracking TriggerGlobal Tracking Trigger
– Together with the Central Tracking Detector: new Global Tracking Trigger System.
1 full module raw data
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Hit Reconstruction: from previous Test Beam Hit Reconstruction: from previous Test Beam ResultsResults
Based on charge sharing
parameterization
Fast algorithmwith no assumption on charge sharing
angle (deg)
Large impact anglesrequire different reconstruction
algorithms
Intrinsic resolution ofa half module
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The MVD System TestThe MVD System Test Following the assembly up to the final MVD, extensive tests and
monitoring of the detector have been performed. A Standalone Test Environment with a dedicated Cosmic Trigger has
been set up.
Large cosmic sample acquired: 2.5 Million triggered events.
Aim: Final checks of modules, cabling, cooling Laser alignment measurements Setup a complete read-out scheme Study detector response with real data Monitoring of various system components:
MVD Cosmic System TestMVD Cosmic System Test Landau distributions from different ladders:
The expected difference in the peak position is clearly seen!
C0L1 (0º) C1L1 (50º)
C0L1
C1L1
S/N 13
Pedestal stable at the level of 1-2 ADC-counts Entries above 20 ADC-counts in noise-distribution: 36 /25 (barrel/forward) Channels with unstable noise-performance: 119 (total for barrel and forward)
Noise and Stability:
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MVD Cosmic System Test Results MVD Cosmic System Test Results
~80 m
Withoutany alignmentcorrection
Geometricalefficiency
Cyl. 0 Cyl. 1 Cyl. 2FaultyModules (4 of 206)
First Track fit using all modules but one: resolution ~80 mDominated by systematics, confident to reach final resolution of 20 m
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Detector I/V Observed PropertiesDetector I/V Observed PropertiesDuring the system test increasing leakage currents have been observed in some modules. Further studies have shown that at decreasing temperature the relative humidity rises and the breakdown voltage decreases
21.8° 62%h.
22.5° 31%h.A careful checking and control of the humidity is required for the ZEUS MVD!
ZEUS Cosmic Data with CTD and MVDZEUS Cosmic Data with CTD and MVDBefore HERA commissioning started (July 2001), there was a short time window for a cosmic data run with the full ZEUS detector.
A Cosmic Event based on a CTD and Calorimeter Trigger.
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Summary and OutlookSummary and Outlook System Test System Test
– Complete MVD-system has been tested continuously for a longer period.– Stable operation of: Slow Control, Cooling, LV and HV Systems.– Dark currents are fairly stable in time at depl. voltage ( dry air flow is
important!)– Pedestal and noise performance is good. Faulty modules <2%.– Cosmic results show expected performance (Landau distributions, etc.).
Installation and Commissioning in ZEUSInstallation and Commissioning in ZEUS – MVD installation was successful (detector integration, cable routing).– Functioning of the DAQ System, the GTT environment as well as the
Control infrastructure established.– Radiation monitoring (active and passive system) available and working
during HERA startup.– Encouraging results looking at the next high luminosity period.