The Micro Vertex Detector for the

Compressed Baryonic Matter Experiment

September, 7 – 9, 2011 St. Odile, France

Joachim Stroth, Goethe-University Frankfurt / GSIfor 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/FranceJérôme 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

Outlineo RHIC physics at FAIRo The Compressed Baryonic Matter Experimento Challenges for the Micro Vertex Detectoro Design Principleso Mechanical Integrationo Read-out o Sparsification and pre-processing

The FAIR accelerator Complex

APPA

CBM/HADES

NuSTAR

PANDA

Staged realization

2012: start of civil construction2018: first beam

o Modularized start version:– M0: SIS100– M1: APPA– M1: CBM/HADES– M2: NuSTAR– M3: PANDA

M0

M1

M2M3

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 FAIRo 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 experimentsat one single beam line

Dipolmagnet

Ring ImagingCherenkovDetector

Transition Radiation Detectors

ResistivePlate Chambers(TOF)

Electro-magneticCalorimeter

SiliconTrackingStations

Tracking Detector

Muondetection System

Projectile SpectatorDetector(Calorimeter)

VertexDetector

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 CBMexperimental requirements in precisionand rates

The CBM Physics Book

The CBM Physics book is available now: Springer Series: Lecture Notes in Physics, Vol. 814 1st Edition., 2011, 960 p., Hardcover ISBN: 978-3-642-13292-6

Open Charm Measurementso 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 epiand 180 nm technology.

300mm Silicon (equivalent)per layer!

Low-mass Di-electronso Goal

– Excitaion function of excess yield from 1 to 45 AGeVo Challenge

– Background due to material budget of the STS– Sufficient p discrimination (missidentification <10-4)

o Reduction of background by reconstructing pairs from g-conversion and p-Dalitz decay

Identified e+e-

(central 25 AGeV Au+Au)After all cuts applied(central 25 AGeV Au+Au)

eegp 0

Track Segment

Identified e+/-

eemediumg

Track Fragment

Fakepair

3 per Au+Au event(central, 25 AGeV)

8 per Au+Au event

Experimental Challengeso 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 1014 neq (n.-ionizing) and 10 Mrad (ionizing)– Fast read-out (ultimately 10 ms)– Operation in vacuum, material budget determined by

power dissipation– d-electrons

Occupancies and fluency

Case p-A

Limitation Rad. tolerance

Max. coll. rate ~ 107 coll./sPeak occupancy ~ 0.5 %

Ionizing rad. dose < 5 MRad

Non Io. rad. dose 1014 neq/cm²

Case Au-Au

Limitation Occupancy

Max. coll. rate ~ 6 x 104 coll./sPeak occupancy ~ 5 %

Ionizing rad. dose < 10 MRad

Non Io. rad. dose ~1013 neq/cm²

Mean number of hits per mm2 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 sizeo Peak to average values of extracted beam reach up to a factor

5 in 10 ms 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 peripheryo 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 Architectureo in-pixel pre-amp + CDS o column parallel read-out o binary charge encoding (?) o (switchable) zero-suppressiono output buffers integrated at chip periphery o JTAG programmable o thinned to 50 μm

Heat evacuation (prototyping)

Lateral heat evacuation feasible for 1W/cm2

Alternative: CVD diamond for 1. station

Material Budget (prototyping)

CVD ~150 µm:0.11 % x/Xo

polyimidecopper

polyimide polyimide

polyimidecopper

polyimidepolyimide

10 mm < 8 mm

active

~ 17

0 µm

Prototypeo 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

2015

340 Mbps LVDS

MIM

OSA

-26

(MIM

OSI

S-1)

2012

Combiner Board(LVDS to optical conversion, 8/10 bit encoding in Ver. 2012)

Vacu

um W

indo

w

340 Mbps optical

CBM DAQ

2015 - In Total:~ 100 optical links: ~ 100 Gbps

2012

340 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 recognitiono Locally high occupancy due to

– Event pile-up– d-electrons

o MIMOSIS frame read-out (integration) time 30mso STS time resolution 5 nso Strategy: 4D track reconstruction in STS and extrapolation

to MVD

Time distribution of GEANT hits in detectors w.r.t. event t0

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

d-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