Performance of the Belle II imaging Time-Of-Propagation (iTOP) detector in first collisions

Sumitted to PubDB: 2019-09-26

Category: Talk, Visibility: Public

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Authors	Martin Bessner
Date	Feb. 22, 2019
Belle II Number	BELLE2-TALK-CONF-2019-130
Abstract	The iTOP detector is a novel Cherenkov detector developed for particle identification at Belle II, an upgrade of the previous Belle experiment at KEK. The SuperKEKB accelerator, an upgrade of KEKB, collides electrons and positrons with a design luminosity of 8*10^(35)/(cm^2 s). In order to exploit the high collision rate Belle II has a trigger rate of up to 30 kHz. The iTOP detector uses quartz bars as source of Cherenkov photons. The photons are reflected inside the bars until they hit photomultipliers at one end. The spatial distribution and precise arrival times of the detected photons are used to reconstruct the Cherenkov angle. To achieve a good pion-kaon separation the photon arrival times have to be measured with a resolution better than 100 ps. Microchannel plate photomultipliers together with dedicated high-speed electronics for 2.7 GSa/s waveform sampling are used to achieve this timing resolution. The iTOP detector consists of 16 modules with 512 channels each, in total the detector has 8192 channels. First collisions were recorded in Spring 2018. A phase of physics operation with a ramp up to full luminosity starts March 2019. In this talk the design of the iTOP detector will be shown and experience and results from initial operation will be discussed together with an outlook on future running conditions.
Conference	VCI2019