The Micro Vertex Detector for the Compressed Baryonic Matter Experiment September, 7 – 9, 2011 St. Odile, France Joachim Stroth, Goethe-University Frankfurt / GSI for the CBM-MVD collaboration

The CBM-MVD collaboration Institut für Kernphysik, Goethe Universität Frankfurt am Main Samir Amar-Youcef, Norbert Bialas, Michael Deveaux, Dennis Doering, Melissa Domachowski, Christina Dritsa (now Univ. Giessen), Horst Düring, Ingo Fröhlich, Tetyana Galatyuk, Michal Koziel, Qiyan Li, Jan Michel, Boris Milanovic, Christian Müntz, Bertram Neumann, Paul Scharrer, Christoph Schrader, Selim Seddiki, Joachim Stroth, Tobias Tischler, Christian Trageser, Bernhard Wiedemann Institut Pluridisciplinaire Hubert Curien (IPHC), Strasbourg/France Jérôme Baudot, Grégory Bertolone, Nathalie Chon-Sen, Gilles Claus, Claude Colledani, Andrei Dorokhov, Wojchiech Dulinski, Marie Gelin-Galivel, Mathieu Goffe, Abdelkader Himmi, Christine Hu-Guo, Kimmo Jaaskelainen, Frédéric Morel, Fouad Rami, Mathieu Specht, Isabelle Valin, Marc Winter

Outline o RHIC physics at FAIR o The Compressed Baryonic Matter Experiment o Challenges for the Micro Vertex Detector o Design Principles o Mechanical Integration o Read-out o Sparsification and pre-processing

The FAIR accelerator Complex APPA CBM/HADES NuSTAR PANDA

Staged realization 2012: start of civil construction 2018: first beam o Modularized start version: – M0: SIS100 – M1: APPA – M1: CBM/HADES – M2: NuSTAR – M3: PANDA M0 M1 M2 M3

o Tunnel designed to contain both synchrotrons: SIS100+SIS300 o SIS100 fast ramping/cycling (11 AGeV Au) o SIS300 high energy and slow extraction (25A GeV Au ) Status of the SIS300

Compressed Baryonic Matter at FAIR o Dedicated high-rate fixed target experiment – Compact tracking (silicon) in a 1 TM dipole field – Flexible arrangement of PID detectors o HADES for day-one experiments at SIS100 o Two experiments at one single beam line

Dipol magnet Ring Imaging Cherenkov Detector Transition Radiation Detectors Resistive Plate Chambers (TOF) Electro- magnetic Calorimeter Silicon Tracking Stations Tracking Detector Muon detection System Projectile Spectator Detector (Calorimeter) Vertex Detector

First Level Event Selector V. Lindenstruth, J. de Cuveland et al. Frankfurt

Physics program of CBM Courtesy of T. Hatsuda Explore the nuclear phase diagram in the region of the first order phase transition

Rare and penetrating probes SPS Pb+Pb 30 A GeV Driving CBM experimental requirements in precision and rates

The CBM Physics Book The CBM Physics book is available now: Springer Series: Lecture Notes in Physics, Vol st Edition., 2011, 960 p., Hardcover ISBN:

Open Charm Measurements o Goal – comprehensive picture of charm production and propagation o Challenge – Rare probe – high precision displaced vertex reconstruction o Needs vertex detectors with – high resolution – minimal material budget – sufficient radiation tolerance o Calls for MAPS (MIMOSA-26 family) with high-resistivity epi and 180 nm technology. 300  m Silicon (equivalent) per layer!

Low-mass Di-electrons o Goal – Excitaion function of excess yield from 1 to 45 AGeV o Challenge – Background due to material budget of the STS – Sufficient  discrimination (missidentification <10 -4 ) o Reduction of background by reconstructing pairs from  -conversion and  -Dalitz decay Identified e + e - (central 25 AGeV Au+Au) After all cuts applied (central 25 AGeV Au+Au) Track Segment Identified e +/- Track Fragment Fake pair 3 per Au+Au event (central, 25 AGeV) 8 per Au+Au event

Experimental Challenges o General – High interactions rates (up to 100 kHz) with un- triggered (freely streaming) readout – Complex analysis on large data volume for First Level Event Selection (FLES) o MVD – Radiation tolerance (non-uniform irradiation): up to n eq (n.-ionizing) and 10 Mrad (ionizing) – Fast read-out (ultimately 10  s) – Operation in vacuum, material budget determined by power dissipation –  -electrons

Occupancies and fluency Mean number of hits per mm 2 and collision (station 1) Radiation tolerance: talk by Michael Deveaux

Intensity Fluctuations of Beam o Occupancy studies must take beam intensity fluctuation into account o Important also for on-chip buffer size o Peak to average values of extracted beam reach up to a factor 5 in 10  s intervals at SIS100

Design Concept o Planar stations assembled from identical modules (not VELO-like) o Minimal material budget in the active area – Lateral heat extraction – Read-out components mostly on the periphery o 2 stations at 5 and 10 cm (+ one at 15 cm?) downstream of the target o First stations integrates 2*5*4 = 40 sensors ~20 mm

Sensor Architecture o in-pixel pre-amp + CDS o column parallel read-out o binary charge encoding (?) o (switchable) zero-suppression o output buffers integrated at chip periphery o JTAG programmable o thinned to 50 μm

Heat evacuation (prototyping) Lateral heat evacuation feasible for 1W/cm 2 Alternative: CVD diamond for 1. station

Material Budget (prototyping) CVD ~150 µm: 0.11 % x/X o polyimide copper polyimide copper polyimide 10 mm < 8 mm active ~ 170 µm

Prototype o Build a quarter of MVD-station 1 with ~0.3% X0 o Use MIMOSA-26 sensors o Develop scalable readout system based on HADES TRB system Completion in 2012 Mechanical integration: talk by Tobias Tischler

DAQ concept ~ 2 Gbps LVDS, 8/10 bit encoded 2012 Passive, radiation tolerant FEE- board Mbps LVDS MIMOSA-26 (MIMOSIS-1) 2012 Combiner Board (LVDS to optical conversion, 8/10 bit encoding in Ver. 2012) Vacuum Window 340 Mbps optical CBM DAQ In Total: ~ 100 optical links: ~ 100 Gbps Mbps LVDS 2015 ~ 2 Gbps optical Concept of the readout system of the prototype (2012) and the final MVD (2015) Talks by Christoph Schrader and Jan Michel

Track Matching & Pattern recognition o Locally high occupancy due to – Event pile-up –  -electrons o MIMOSIS frame read-out (integration) time 30  s o STS time resolution 5 ns o Strategy: 4D track reconstruction in STS and extrapolation to MVD Time distribution of GEANT hits in detectors w.r.t. event t 0

Cluster topology Open charm case. Distortion of reconstructed track due to eventually unidentified track fragment. Di-electron case: Find conversion/Dalitz partner to avoid combinatorial background positron electron MVD1 MVD2 hadron  -electron MVD2 MVD1 Talk by Christina Dritsa

Project status & plan o Demonstrator completed in 2009 – Two M20 seonsors on RVC/TPG compound o Prototype in 2012 – One quarter of MVD, M26 – Scalable read-out – Basis for (pre)TDR o First beam SIS100 earliest in 2018 – Time for second prototype with final sensor