Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 18: Instrumentation and Applications II

HK 18.5: Talk

Tuesday, March 9, 2004, 16:30–16:45, C

High Level Trigger Identification of High Energy Jets in ALICE — •Constantin Loizides — August-Euler-Str. 6, 60487 Frankfurt

One interesting observable at ALICE will be the measurement of the inclusive jet cross section at 100 to 200 GeV transversal jet energy and its fragmentation function; both to be compared to pp. The window of about 100 to 200 GeV transversal jet energy is compatible with the expected p_t resolution of the inner tracking complex (ITS+TPC+TRD) and the energy of the leading parton, but requires an HLT online processing of TPC data at a rate of 200 Hz central PbPb in order to collect sufficient statistics. The online trigger algorithm running on the HLT system is based on charged tracking and jet recognition using a cone jet finder algorithm,which might be improved by the additional online evaluation of the EM calorimeter towers. The dependence of the efficiency versus the selectivity of the trigger has been studied by simulations of pp and PbPb interactions using PYTHIA and HIJING events. For a chosen parameter set of the trigger algorithm the triggered events are the relevant sample of events to be further analyzed by offline. Their resulting jet E_t distribution and the corresponding fragmentation functions might be sensitive to different jet attenuation scenarios.