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T: Fachverband Teilchenphysik

T 71: DAQ und Trigger 2

T 71.9: Vortrag

Donnerstag, 12. März 2009, 18:45–19:00, M110

The Implementation of an Inclusive φ Channel in the LHCb High Level Trigger using the Ring Imaging Cherenkov Detector Information — •Magnus Hov Lieng — TU Dortmund

The LHCb trigger system is designed to reduce the event rate from 40MHz to 2kHz. This system consists of two parts, the hardware based Level Zero (L0), and the software based High Level Trigger (HLT). Due to time constraints the HLT tracking efficiency is inferior to that of the offline reconstruction. This effect has a considerable impact on multiple track selections.

Several interesting channels contain a φ as the daughter of a B-decay. It can be envisaged that for these events one could trigger inclusively on φ→KK and thus only requiring two kaon tracks. However, in order to keep the background rate under control the separation between pion and kaon tracks is needed.

The LHCb Ring Imaging Cherenkov Detectors (RICH) have been designed with this task in mind. As the generation of the RICH data is computationally heavy this is normally not performed at the trigger level. However, faster, albeit less efficient algorithms have been implemented to remedy this.

This talk reviews the implementation of an inclusive φ trigger using data from the fast RICH algorithms, taking into consideration selection efficiency, background rate and computing time involved.