Darmstadt 2016 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 54: Instrumentation XV

HK 54.2: Talk

Thursday, March 17, 2016, 14:15–14:30, S1/01 A2

Improvements of the ALICE High Level Trigger for LHC Run 2 to facilitate online reconstruction, QA, and calibration — •David Rohr for the ALICE collaboration — Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt

ALICE is one of the four major experiments at the Large Hadron Collider (LHC) at CERN. Its main goal is the study of matter under extreme pressure and temperature as produced in heavy ion collisions at LHC. The ALICE High Level Trigger (HLT) is an online compute farm of around 200 nodes that performs a real time event reconstruction of the data delivered by the ALICE detectors. The HLT employs a fast FPGA based cluster finder algorithm as well as a GPU based track reconstruction algorithm and it is designed to process the maximum data rate expected from the ALICE detectors in real time. We present new features of the HLT for LHC Run 2 that started in 2015. A new fast standalone track reconstruction algorithm for the Inner Tracking System (ITS) enables the HLT to compute and report to LHC the luminous region of the interactions in real time. We employ a new dynamically reconfigurable histogram component that allows the visualization of characteristics of the online reconstruction using the full set of events measured by the detectors. This improves our monitoring and QA capabilities. During Run 2, we plan to deploy online calibration, starting with the calibration of the TPC (Time Projection Chamber) detector's drift time. First proof of concept tests were successfully performed using data-replay on our development cluster and during the heavy ion period at the end of 2015.