The TOTEM DAQ based on the Scalable Readout System (SRS)

Michele Quinto,Adrian Fiergolski,Emilio Radicioni,Francesco S Cafagna,S Dalla Torre,F Tessarotto,B Gobbo,S Levorato,L Ropelewski

doi:10.1051/epjconf/201817407003

Abstract

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 and study the elastic and diffractive scattering at the LHC energies. In order to cope with the increased machine luminosity and the higher statistic required by the extension of the TOTEM physics program, approved for the LHC’s Run Two phase, the previous VME based data acquisition system has been replaced with a new one based on the Scalable Readout System. The system features an aggregated data throughput of 2GB / s towards the online storage system. This makes it possible to sustain a maximum trigger rate of ∼ 24kHz, to be compared with the 1KHz rate of the previous system. The trigger rate is further improved by implementing zero-suppression and second-level hardware algorithms in the Scalable Readout System. The new system fulfils the requirements for an increased efficiency, providing higher bandwidth, and increasing the purity of the data recorded. Moreover full compatibility has been guaranteed with the legacy front-end hardware, as well as with the DAQ interface of the CMS experiment and with the LHC’s Timing, Trigger and Control distribution system. In this contribution we describe in detail the architecture of full system and its performance measured during the commissioning phase at the LHC Interaction Point.

Highlights

IntroductionThe TOTEM (TOTal cross section, Elastic scattering and diffraction dissociation Measurement at the LHC) [1] 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 to study the elastic and diffractive scattering at the LHC energies
The TOTEM (TOTal cross section, Elastic scattering and diffraction dissociation Measurement at the LHC) [1] 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 to study the elastic and diffractive scattering at the LHC energies.To perform these measurements, TOTEM requires a good acceptance for particles produced at very small angles with respect to the beam
TOTEM’s coverage in pseudo-rapidity spans the ranges 3.1 ≤ |η| ≤ 4.7 and 5.3 ≤ |η| ≤ 6.5 on both sides of the Interaction Point (IP); this is accomplished by two gas detector telescopes, named T1 and T2

Summary

Introduction

The TOTEM (TOTal cross section, Elastic scattering and diffraction dissociation Measurement at the LHC) [1] 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 to study the elastic and diffractive scattering at the LHC energies To perform these measurements, TOTEM requires a good acceptance for particles produced at very small angles with respect to the beam. The future physics programme of TOTEM requires an increase of statistics by a factor 10 to 100 This goal has to be reached by minimizing the data taking time; for TOTEM, this means to take the maximum advantage, in terms of statistics, from the few special runs in which a machine optics configuration, reserved for TOTEM, is provided. The program includes the data acquisition system upgrade whose main requirement is to increase by more than one order of magnitude the experiment trigger rates

Data acquisition system upgrade

System design and verification

Hardware data processing

System commissioning and operation