Victor Andrei
(Kirchhoff-Institut fuer Physik/ Universitaet Heidelberg")
The level-1 calorimeter trigger is a hardware-based system with the goal of identifying
high-pt objects within an overall latency of 2.5us. It is composed of a preprocessor
system which digitises 7200 analogue input channels, determines the bunch-crossing of
the interaction and provides a fine timing and energy calibration; and two subsequent
digital
processors.
The Preprocessor plays a central role during integration of the system as it provides
digitisation and readout of calorimeter signals and serves as a digital signal source
for the
subsequent processors.
Results of data taken with cosmic muons are shown, and the experience
gathered during the system integration is described.
Summary
The high luminosity and bunch-crossing rate of the LHC pose a particular
challenge to the trigger.
The ATLAS level-1 calorimeter trigger has to process 7200 trigger towers within an
overall latency of 2.5us. reducing the event rate from 40 MHz to below 100 kHz. It is
realised completely in hardware, including ASICs and FPGAs, in a VME-based system.
The Preprocesor of the ATLAS Level-1 calorimeter trigger is a compact system which
digitises the detector signals, determines the bunch-crossing number of the
interaction and provides a fine timing and energy calibration. The result is sent to
two digital
processors, the Cluster Processor and the Jet-Energy Processor. The Cluster Processor
identifies electrons/photons and taus. The Jet-Energy Processor identifies jets and
computes missing and total transverse energy. Both digital processors provide their
information
to the Central Trigger Processor which generates the level-1 decision.
The Preprocessor is a highly modular system consisting of eight crates hosting a
total of 124
Preprocessor modules. Each of these modules processes 64 channels in
parallel, with the main signal processing performed in the custom-built
Preprocessor ASICs located in 16 four-channel Multichip Modules.
The location of the Preprocessor within the trigger system, combined with the fact
that it
provides its own DAQ readout path leads it to play a central role when it
comes to integrating the trigger with the detectors. It is the only place where
digital readout of all trigger towers in parallel is possible. Tasks that are
addressed include channel-mapping connectivity tests, timing measurements and
signal quality tests.
This talk gives an introduction to the tasks of the level-1 calorimeter trigger with
focus on the Preprocessor system. Data taken with cosmic muons are shown in addition
to results from the system integration.
Rainer Stamen
(Kirchhof-Institut fur Physik / Universitaet Heidelberg)
A HIDVEGI
(Fysikum, Stockholm University)
A.O. DAVIS
(STFC Rutherford Appleton Laboratory)
A.R. GILLMAN
(STFC Rutherford Appleton Laboratory)
A.T. WATSON
(School of Physics and Astronomy, University of Birmingham)
B BAUSS
(Institut fuer Physik, University of Mainz)
B.M. BARNETT
(STFC Rutherford Appleton Laboratory)
C BOHM
(Fysikum, Stockholm University)
C GEWENIGER
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
C.J. CURTIS
(School of Physics and Astronomy, University of Birmingham)
C.N.P. GEE
(STFC Rutherford Appleton Laboratory)
D.P.C. SANKEY
(STFC Rutherford Appleton Laboratory)
D.P.F. PRIEUR
(STFC Rutherford Appleton Laboratory)
E EISENHANDLER
(Physics Department, Queen Mary, University of London)
E.-E WOEHRLING
(School of Physics and Astronomy, University of Birmingham)
E.-E. KLUGE
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
F FOEHLISCH
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
F RUEHR
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
G MAHOUT
(School of Physics and Astronomy, University of Birmingham)
H.-C. SCHULTZ-COULON
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
I.P. BRAWN
(STFC Rutherford Appleton Laboratory)
J.P. THOMAS
(School of Physics and Astronomy, University of Birmingham)
J.R.A. BOOTH
((School of Physics and Astronomy, University of Birmingham))
K MAHBOUBI
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
K MEIER
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
K SCHMITT
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
M BENDEL
(Institut fuer Physik, University of Mainz)
M JOHANSEN
(Fysikum, Stockholm University)
M.P.J. LANDON
(Physics Department, Queen Mary, University of London)
P ADRAGNA
(Physics Department, Queen Mary, University of London)
P HANKE
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
P WEBER
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
P.J.W. FAULKNER
(School of Physics and Astronomy, University of Birmingham)
P.M. WATKINS
(School of Physics and Astronomy, University of Birmingham)
R ACHENBACH
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
R STAMEN
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
R.J. STALEY
(School of Physics and Astronomy, University of Birmingham)
S HELLMAN
(Fysikum, Stockholm University)
S RIEKE
(Institut fuer Physik, University of Mainz)
S SILVERSTEIN
(Fysikum, Stockholm University)
S TAPPROGGE
(Institut fuer Physik, University of Mainz)
S.J. HILLIER
(School of Physics and Astronomy, University of Birmingham)
T TREFZGER
(Institut fuer Physik, University of Mainz)
U SCHAEFER
(Institut fuer Physik, University of Mainz)
V LENDERMANN
(Kirchhoff-Institut fuer Physik, University of Heidelberg)
V.J.O. PERERA
(STFC Rutherford Appleton Laboratory)
Victor Andrei
(Kirchhoff-Institut fuer Physik/ Universitaet Heidelberg")
W QIAN
(STFC Rutherford Appleton Laboratory)
