Speaker
Dr
Michele Quinto
(INFN, Sezione di Bari)
Description
The TOTEM (TOTal cross section, Elastic scattering and diffraction
dissociation Measurement at the LHC) experiment at LHC, has been
designed to measure the total proton-proton cross-section with a
luminosity independent method, based on the optical theorem, and study
the elastic and diffractive scattering at the LHC energy.
To cope with the increased intensity of the LHC run 2 phase, and the
increase on statistics required by the extension of the TOTEM physics
program, approved for the 2016 run campaign, the previous VME based
DAQ has been substituted by a new one based on the Scalable Readout
System (SRS).
The system is composed of 16 SRS-FECs, and one SRS-SRU; it features a
throughput of ~120MB/s, saturating the SRS-FEC 1Gb/s link, for an
overall 2GB/s data transfer rate into the online PC farm. This
guarantee a baseline maximum trigger rate of ~24kHz, to be compared
with the 1KHz of the previous VME based system. This trigger rate will
be further improved,up to 100kHz trigger rate, implementing second
level trigger algorithm in the SRS-SRU.
The new system design fulfills the requirements for an increased
efficiency, providing higher bandwidth, and increasing the purity of
the data recorded supporting both a zero suppression algorithm and a
second-level trigger based on pattern recognition algorithms
implemented in hardware. Moreover a full compatibility with the legacy
front-end hardware has been guaranteed, as well as the interface with
the CMS experiment DAQ and the LHC Timing Trigger and Control (TTC)
system.
A complete re-design of the firmware, leveraging the usage of
industrial strength firmware technologies, has been undertook to
provide a set of common interfaces and services between the standard
system modules to the specific one of the user's application. This to
allow an efficient development and easier insertion of different zero
suppression and second-level trigger algorithms and a share of
firmware blocks between different SRS components. Furthermore, to
avoid packed losses and improve reliability of the UDP data
transmission, a solution has been adopted that uses the Ethernet Flow
control and New API (NAPI) mode driver, featuring a ticketing
algorithms at the application layer.
In this contribution we will describe in details the full system and
performances during the commissioning phase at the LHC Interaction
Point 5 (IP5).
Primary author
Dr
Michele Quinto
(INFN, Sezione di Bari)
