CBM@FAIR – Self-Triggered Front-CBM@FAIR – Self-Triggered Front-End Electronics and Challenges End Electronics and Challenges for Data Acquisition and Event for Data Acquisition and Event

SelectionSelection

CBM CBM Study of Super-Dense Baryonic Matter with Heavy-Ion Collisions at FAIR-SIS- Study of Super-Dense Baryonic Matter with Heavy-Ion Collisions at FAIR-SIS-300300

Open Charm Event Open Charm Event Selection –Selection –

Driving Force for FEE and Driving Force for FEE and DAQDAQ

Walter F.J. Müller, GSI Darmstadtfor the CBM Collaboration

http://www-cbm.gsi.de

Exploration of the QCD phase diagram in regions of high baryon densities and moderate temperatures.

From n-XYTER to CBM-XYTER –From n-XYTER to CBM-XYTER –ASICs for Silicon Strip and Gas Detector ReadoutASICs for Silicon Strip and Gas Detector Readout

Physics Topics Observables

In-medium modifications of hadrons

Strangeness in matter

Indications of deconfinement

Critical point

D0, D±

J/Ψ,Ψ' e+e- (μ+ μ-)

K, , , ,

π, K

, , e+e- (μ+μ-)

D0, D±, D±s, c

Micro-Vertex Detector (MVD)

Silicon Tracking System (STS) in dipole magnet

Ring Imaging Cherenkov (RICH) or

Muon identification system (MUCH)

Transition Radiation Detectors (TRDs)

Time-of-flight (TOF) system

Electromagnetic Calorimeter (ECAL)

Projectile Spectator Detector (PSD)

Rare Probes

•High luminosity 107 int/sec (Au+Au)

•High count rates typ. 100 kHz/channel

Selective Triggers

•J/Ψ, Ψ'

•open charm (D,Λc)

Open charm:

D (c = 312 m): D+ K-++ (9.5%)

D0 (c = 123 m): D0 K-+ (3.8%) D0 K- + + -

(7.5%)

Ds (c = 150 m):

D+s K+ K- +

(5.3%)

+c (c = 60 m):

+c pK-+ (5.0%)

No simple, single track level trigger primitive, like high pt, available to tag events of interest.

The only selective signature is the detection of the decay vertex.

Track reconstruction in STS/MVD anddisplaced vertex search required in thefirst trigger level.

Such a complex trigger is not feasiblewithin the latency limits of

conventionalFront-End Electronics, typically 4 μsecat LHC.

Work without L1 trigger

Use Self-triggered Front-End Electronics

Self-Triggered Front-EndsSelf-Triggered Front-Ends No Trigger, front-end has to detect all valid hits autonomously

CBM is a fixed-target experiment, thus no bunch crossing clock,

interactions occur at random times

Use timestamps to organize and correlate data

Ship all hits, tagged with a timestamp, to subsequent databuffer and processing stages.

Typical parameters (for 107 int/sec and 1% occupancy):100 kHz channel hit rate600 kbyte/sec per channel data flow100 Mbyte/sec data flow for a 128 channel ASIC

High-Speed DAQ and Event BuildingHigh-Speed DAQ and Event Building No Trigger, all data readout of FEE ASICs

Expected data flow in CBM: ~ 1 TByte/sec

High-throughput DAQ and event building

In other fields working with self-triggered Front-end is natural, because a trigger is not possible or not needed, e.g.

- Neutron scattering- Positron emission tomography

The neutron scattering community developed in the context of the EU project DETNI an ASIC designed for the readout of Silicon strip and fast gas detectors.

Manufacturing and characterization of the chip is done in a GSI-DETNI cooperation.

Key parameters of the n-XYTER chip:

128 channels32 MHz readout rate1 ns time stamp binning140/20 ns peaking time233 e + 13 e/pf ENC (amplitude)200 e + 27e/pF ENC (threshold)Technology: 0.35 μm AMS

Used in CBM for detector R&D ofSilicon Strip and Pad (STS/MUCH)GEM chambers (MUCH)MAPMT (RICH)

Architecture of a single n-XYTER channel Concept of Token Ring Readout

See: A.S.Brogna et al, NIM A568(2006)301

The CBM-XYTER, a 2nd generation ASIC is currently being developed for CBM.Main improvements:

- min. 2 Mrad TID radiation tolerance

- reduced power consumption- on-chip conversion of pulse height- serial interface- Technology: 0.18 μm UMC

The CBM-XYTER will be used for Silicon and GEM sub-systems in CBM and PANDA and potentially other FAIR experiments.

High-Speed TrackingHigh-Speed Tracking

See: J.Adamczewski et al, CHEP-07 Proceedings

See: I.Kisel et al, NIM A566(2006)85; CPC(2008) in press

First tests of Event Building on clusters with alow overhead high throughput InfiniBand Switch

Throughput > 500 MByte/sec/node Scales well to 110 nodes (Uni Mainz Cluster)

Very efficient tracking algorithms are essential for the feasibility of the open charm event selection

Co-develop Silicon tracker layout and trackingalgorithm for best overall performance

CPU time for track reconstruction and fit

Best results were obtained with aCellular Automaton based track finderwith integrated Kalman filter track fit

allows usage of double-side strip detectors even at high track densities

highly optimized code- field approximated by polynomials- compact, cache-efficient data- most calculations SIMDized- fast on standard PC's- well adapted to next generation

many-core and wide-SIMD processors

- already ported to IBM cell processor

very fast when only hard quasi-primary

tracks are reconstructed, as needed in the online first level event

selection of open charm candidates

supports reconstruction of soft tracksdown to 100 MeV/c, as needed in theoffline analysis

MVD +STS

RICH or MUCH

TRDs ECALTOF

PSD