Sep 25 – 29, 2006
Valencia, Spain
Europe/Zurich timezone

The readout system for the LHCb Outer Tracker

Sep 26, 2006, 11:45 AM
25m
Valencia, Spain

Valencia, Spain

IFIC – Instituto de Fisica Corpuscular Edificio Institutos de Investgación Apartado de Correos 22085 E-46071 València SPAIN

Speaker

Dirk Wiedner (Physikalisches Institut Uni Heidelberg)

Description

The LHCb Outer Tracker is composed of 55000 straw drift tubes. The requirements for the OT electronics is the precise (1ns) drift time measurement at 6% occupancy and 1MHz readout. Charge signals form the straw detector are amplified, shaped and discriminated by ATLAS ASDBLR chips. Drift-times are determined and stored in the OTIS TDC and output to a GOL serializer at L0 accept. Optical fibers carry the data 120m to the TELL1 acquisition board. The full readout chain performed well in an e- test beam.

Summary

The Outer Tracker of the LHCb detector is composed of 55000 straw
drift tubes of 5mm diameter.
The requirements for the OT electronics is the precise (1ns) drift
time measurement, permitting a track resolution of 200 um in
the bending plane, at 6% occupancy and 1MHz readout.
The readout electronics is based on three ASIC chips, the ASDBLR
amplifier from ATLAS, the OTIS TDC developed at the ASIC lab in
Heidelberg and the GOL (gigabit optical link) serializer from CERN EP.
All on-detector electronics for one module end is housed in a shielded
metal box.

The charge signal from the straw anode wires is amplified, shaped and
discriminated by an 8 channel ASDBLR chip with 12ns shaping time.
Four ASDBLRs on 2 PCBs are connected to one OTIS TDC.
The relative time between the discriminated hit signal and the bunch
clock is determined by the OTIS TDC with the help of a delay locked
loop. The 64 inverters in the DLL lead to a time resolution of
25ns/64 = 390ps. Drift times are 6-bit encoded and written to a
240 bit wide L0-buffer. At L0-accept hits within a 75ns window are
readout and a header containing OTIS location, L0-id, Bunch-Id plus
status is prepended.

L0 accepted data from 4 TDCs runs to the GOL chip.
The GOL serializes 32
input bits to a 1.6 Gbit/s output, driving a VCSEL diode. Optical
fibers carry the data 120m to the TELL1 acquisition board.
On the TELL1 daughter boards with 12 inputs each convert the optical
serial data back to paralell electrical data. FPGAs on the TELL1 are
programmed to synchronize, zero suppress and reformat the data.
At 1MHz events are transmitted through multiple Gigabit ports to a more than 1000
node computing farm.

The newly developed outer tracker electronics was used for data
taking in an e- test beam. Reading out 512 channels the full chain
proved excellent performance.

Primary author

Dirk Wiedner (Physikalisches Institut Uni Heidelberg)

Co-authors

Mr Adrianus Berkien (NIKHEF) Mr Albert Rausch (Physikalisches Institut Uni Heidelberg) Dr Antonio Pellegrino (NIKHEF) Mr Bart Hommels (NIKHEF) Prof. Bernhardt Spaan (University of Dortmund) Mr Eduard Simioni (NIKHEF) Mr Edwin Bos (NIKHEF) Prof. Franz Eisele (Physikalisches Institut Uni Heidelberg) Dr Gerhardus Apeldoorn (NIKHEF) Dr Iuri Bagaturia (Physikalisches Institut Uni Heidelberg) Mr Jacopo Nardulli (NIKHEF) Mr Jan Knopf (Physikalisches Institut Uni Heidelberg) Dr Jan Spelt (NIKHEF) Dr Jeroen van Tilburg (NIKHEF) Dr Johan Blouw (Physikalisches Institut Uni Heidelberg) Mr Johannes Albrecht (Physikalisches Institut Uni Heidelberg) Mr Kai Warda (Physikalisches Institut Uni Heidelberg) Mr Marc Deissenroth (Physikalisches Institut Uni Heidelberg) Dr Marcel Merk (NIKHEF) Mr Mirco Nedos (University of Dortmund) Dr Niels Tuning (NIKHEF) Mr Peter Vankov (NIKHEF) Mr Rainer Schwemmer (Physikalisches Institut Uni Heidelberg) Dr Rolf Dubitzky (Physikalisches Institut Uni Heidelberg) Mr Rudolf Rusnyak (Physikalisches Institut Uni Heidelberg) Dr Sebastian Bachmann (Physikalisches Institut Uni Heidelberg) Mrs Tanja Haas (Physikalisches Institut Uni Heidelberg) Dr Thomas Bauer (NIKHEF) Mr Tjeerd Ketel (NIKHEF) Mr Tom Sluijk (NIKHEF) Dr Ulrich Trunk (Physikalisches Institut Uni Heidelberg) Prof. Ulrich Uwer (Physikalisches Institut Uni Heidelberg) Dr Uwe Stange (Physikalisches Institut Uni Heidelberg) Dr Yuri Guz (HEP Institute Protvino)

Presentation materials