1. 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. Villa Olmo, Como 15-19 October 2001 1 A. Polini The ZEUS Micro-Vertex Detector Alessandro Polini DESY

2. Villa Olmo, Como 15-19 October 2001 A. Polini2 Outline n Physics Motivation n Detector Design n Standalone Test Measurements n Read-Out, DAQ and Control Infrastructure n First Experience after Installation in ZEUS n Summary and Outlook 0 20 40 60 80 100 120 140 160 180 200 020406080100 Voltage(V) Current(nA) 14C (bias 51V) 17C(bias 48V) 20C(bias51V) 23C(bias78V) 23C(bias65V) 30C(bias65V)

3. Villa Olmo, Como 15-19 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 = 1.5 7.5  10 31 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

4. Villa Olmo, Como 15-19 October 2001 A. Polini4 Detector Layout Forward Section 410 mm The forward section consists of 4 wheels with 28 wedged sensors/layer providing r-  information. Barrel Section 622 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±e± p

5. Villa Olmo, Como 15-19 October 2001 A. Polini5 The Upilex connection foils can be bent and glued to the ladder profile Two half modules are then glued together to form a full module Five full modules are disposed over a carbon fibre support 125 mm 64 mm Two single sensors are glued and electrically connected by gold plated Upilex foils Barrel MVD: Module and Ladder Structure

6. Villa Olmo, Como 15-19 October 2001 A. Polini6 Forward 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.

7. Villa Olmo, Como 15-19 October 2001 A. Polini7 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: C c >> C int > C b The charge sharing is a non linear function of the interstrip coordinate x 120  m Interstrip coordinate x CbCb CcCc C int p+ implantation of The readout strip p+ implantation of the intermediate strip particle 20  m Q LEFT Q RIGHT Silicon Microstrip Detectors

8. Villa Olmo, Como 15-19 October 2001 A. Polini8 Front-end and Read-out n Front-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. n Read-out –10 bit resolution ADC Modules with: n Common Mode, Pedestal and Noise Subtraction n Strip Clustering cluster data (for trigger purposes)  2 separate data buffers: cluster data (for trigger purposes) and raw/strip data for accepted events. n Global Tracking Trigger –Together with the Central Tracking Detector: new Global Tracking Trigger System. 1 full module raw data

9. Villa Olmo, Como 15-19 October 2001 A. Polini9 Hit Reconstruction: from previous Test Beam Results Based on charge sharing parameterization Fast algorithm with no assumption on charge sharing angle  (deg) Large impact angles require different reconstruction algorithms Intrinsic resolution of a half module

10. Villa Olmo, Como 15-19 October 2001 A. Polini10 The MVD System Test n 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: Cooling, Temperature, Humidity, LV, HV, Noise, Pedestals,Dark Current.

11. Villa Olmo, Como 15-19 October 2001 A. Polini11 MVD Cosmic System Test n Landau distributions from different ladders: è è The expected difference in the peak position is clearly seen! è è C0L1 (  0º) è è 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) n n Noise and Stability:

12. Villa Olmo, Como 15-19 October 2001 A. Polini12 MVD Cosmic System Test Results  ~80  m Without any alignment correction Geometrical efficiency Cyl. 0 Cyl. 1 Cyl. 2 Faulty Modules (4 of 206) First Track fit using all modules but one: resolution  ~80  m Dominated by systematics, confident to reach final resolution of  20  m

13. Villa Olmo, Como 15-19 October 2001 A. Polini13 Detector I/V Observed Properties During 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! Increasing temperature

14. Villa Olmo, Como 15-19 October 2001 A. Polini14 MVD Commissioning in ZEUS n ZEUS Requirements n DAQ System and Global Tracking Trigger n Radiation Monitor n First (Cosmic) ZEUS data

15. Villa Olmo, Como 15-19 October 2001 A. Polini15 The ZEUS Detector bunch crossing time: 96 ns ZEUS: 3-Level Trigger System (Rate  500Hz  40  5 Hz) e±e± 27.5 GeV p 920 GeV Event Builder Third Level Trigger cpucpucpucpucpucpu CALCTD Offline Tape Global Second Level Trigger GSLT Accept/Reject Global First Level Trigger GFLT Accept/Reject CTD Front End CAL OtherComponents OtherComponents CTDSLTCALSLT CALFLTCTDFLT ~10 ms 5Hz 40Hz 500Hz 10 7 Hz Event Buffers 5  s pipeline ~0.7  s

16. Villa Olmo, Como 15-19 October 2001 A. Polini16 Network Connection to the ZEUS Event Builder (~100 Hz) The MVD Data Acquisition System and GTT ADCM modules Lynx OS CPU AnalogLinks NIM + Latency Clock + Control ADCM modules Lynx OS CPU AnalogLinks NIM + Latency Run Control and Online Monitoring Environment Main MVDDAQ server, Local Control, Event-Builder Interface Global Tracking Trigger Processors (GFLT rate 800 Hz) ADCM modules Lynx OS CPU AnalogLinks NIM + Latency Clock+ Control VME (C+C Slave) Crate 1 (MVD bottom) Analog Data MVD HELIX Front-End & Patch-Boxes Central Tracking Detector Read-out CTD 2TP modules Lynx OS CPU NIM + Latency HELIX Driver Front-end Lynx OS CPU GSLT 2TP modules Lynx OS CPU Lynx OS CPU VME (C+C Slave) Crate 2 (MVD forward) VME (C+C Master) Crate 0 (MVD top) VME TP connection Data from CTD NIM + Latency TP connection to Global Second Level Trigger Global Second Level Trigger Decision VME HELIX Driver Crate Global First Level Trigger,Busy, Error NIM + Latency Slow control + Latency Clock modules Fast Ethernet/ Gigabit Network VME CPU Boot Server and Control Clock+ Control MVD VME Readout

17. Villa Olmo, Como 15-19 October 2001 A. Polini17 The Global Tracking Trigger Read-out LatencyAfter GTT processingMVD-GTT Trigger Latency ms Concept: n Combined second level trigger using information from CTD, MVD (and the new Forward Tracker) n Higher quality event reconstruction and rate reduction n Z vertex resolution 9 cm (CTD only)  400  m (MVD+CTD+GTT) n Decision required within existing SLT (<15 ms) Full online latency measurements and data file playback capability. First average latencies obtained using MonteCarlo events through complete DAQ system and trigger algorithm are encouraging. Input rate 400Hz Dijet sample

18. Villa Olmo, Como 15-19 October 2001 A. Polini18 16 PIN diodes in 8 modules ( 1cm 2, z fwd =110, z rear =-100 cm) continuous radiation measurement, beam dump 8 RADFET (z fwd =200, z rear =-160 cm) real-time integrating dosimeter: wide dynamic range 1 mGy to 3kGy Thermo-luminescence dosimeters (TLD): two types (neutron, photon sensitive) measure precisely integrated dose (monthly exchanged) The ZEUS Radiation Monitor System

19. Villa Olmo, Como 15-19 October 2001 A. Polini19 Radiation Monitoring Proton beam current In HERA Increase of plateau current PIN diode current ~50 Gy absorbed so far (diode measurements, confirmed by Radfets & TLDs) Final diode readout with beam dump capability being finalized (automatic beam dump at integrated dose of 10..50 mGy per accident). Expected background irradiation in 5 years of operation (experiment lifetime): 50 Gy/year = 5 µGy/s MVD and readout electronics tested up to 3 kGy, operation still possible, but reduction of S/N Max. tolerable dose: 100-300 Gy/year = 10-30 µGy/s MVD Leakage Current increased ~1  A During machine setup

20. Villa Olmo, Como 15-19 October 2001 A. Polini20 ZEUS Cosmic Data with CTD and MVD Before 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.

21. Villa Olmo, Como 15-19 October 2001 A. Polini21 Summary and Outlook 4 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.). 4 Installation 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.