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

The Hardware of the ATLAS Pixel Detector Control System

Sep 28, 2006, 11:20 AM
Valencia, Spain

Valencia, Spain

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


Tobias Henss (Univerity of Wuppertal)


The innermost part of the ATLAS experiment will be a pixel detector, built around 1750 individual detector modules. To operate the modules, readout electronics and other detector components, a complex power supply and control system is necessary. The unique power, grounding and control requirements are described, along with the custom made components of our power and control systems. These include remotely programmable regulator stations, the power supply system for the optical transceivers, several monitoring units and the interlock system.


The requirements of the pixel detector have made specific
developments necessary for
the hardware components of the detector control system.
An efficient operation
requires a preferably individual adjustment of the different
control parameters.
Further design constraints are the high power density in the
detector volume, the
floating grounding scheme of the ATLAS detector and the
sensitivity of the read out
chips developed in deep sub micron technology. Especially
the power supply system,
consisting of nearly 5000 individually controllable supply
lines, requires solutions
which are adapted to the detector needs and which in
parallel are economically priced.
The remotely programmable regulator stations, which are
installed as close as
possible to the detector modules, provide individual floating
power outputs with low
ripple to the front end electronics. At the same time they
protect the sensitive
chips against transients. The internal control of the regulator
station is handled by
a FPGA from Actel, while the link into the control system is
handled by the ELMB, the
ATLAS wide used front end IO unit.
The design of the supply system for the opto transceiver
boards is based on
components, which can directly be controlled by the ELMB. In
this way a reasonable
priced solution has been found which allows individual
setting and adjustment for
each of the more than thousand channels.
In the positions where common power supplies are used to
provide voltages to several
loads additional monitoring units are integrated which allow
to investigate the
behaviour of individual modules. The design constraints,
precision and compatibility
to the ATLAS grounding scheme, are fulfilled by the
presented LV and HV monitoring
systems. In this way more than 8000 monitoring channels
complete the low and high
voltage system.
As specially irradiated detector modules can be destroyed by
heat ups, a thermal
interlock system is developed which acts directly on the
related power supplies. In
addition other equipment can suffer from extreme heat and
human being must be
protected against risks due to lasers. Therefore these
devices are connected to the
interlock system as well. The presented interlock matrix,
whose design is based on
the use of a FPGA, allows a dedicated control of small
equipment groups and helps in
this way to keep the number of channels out of service as
low as possible.
All presented hardware components passed intensive
electrical studies and
investigation in our system tests and are currently under
production. To simplify the
production and to have an easy maintenance the systems
are built in a modular way,
combining different building blocks. As everywhere the
ELMBs are used for
communication, the integration into the ATLAS wide control
system can easily be

Primary author

Tobias Henss (Univerity of Wuppertal)


A. Andreani (INFN Milano) A. Andreazza (INFN Milano) C. Meroni (INFN Milano) F. Sabatini (INFN Milano) G. Boyd (University of Oklahoma) J. Boek (Univerity of Wuppertal) J. Schultes (Univerity of Wuppertal) K. Einsweiler (LBNL Berkeley) K. Lantzsch (Univerity of Wuppertal) M. Citterio (INFN Milano) P. Kind (Univerity of Wuppertal) P. Maettig (Univerity of Wuppertal) S. Kersten (Univerity of Wuppertal) S. Latorre (INFN Milano)

Presentation materials