Speaker
Dr
Vasily Shebalin
(University of Hawaii at Manoa)
Description
Data taking with the Belle II detector at the SuperKEKB electron-positron collider in Japan started in April 2018 with low luminosity. During the second stage of data-taking, which started in March 2019, SuperKEKB has reached the luminosity of 1.05\times10^{34}cm^{-2}s^{-1} and Belle II collected about 10~fb^{-1} of integrated luminosity, moving towards the design luminosity of 5\times10^{35} cm^{-2}s^{-1}. Particle identification in the barrel region is provided by the Time-Of-Propagation(TOP) detector. The device consists of 16 bars of fused silica which serve as a source of Cherenkov photons and as a light guide at the same time. A unique feature of the detector is that particle identification is based on the combined measurement of the time-of-flight and Cherenkov angle using the precise arrival times of detected photons and their spatial distribution. To achieve good pion-kaon separation the photon arrival times must be measured with a resolution of approximately 100 ps or better. Microchannel plate photomultipliers together with dedicated high-speed electronics for 2.7 GSa/s waveform sampling are used to achieve this timing resolution in a total of 8192 channels. In this report we give an overview of the TOP detector system, present the current status of its operation and plans toward the high occupancy conditions expected at the design luminosity of the SuperKEKB collider.
Primary author
Dr
Vasily Shebalin
(University of Hawaii at Manoa)
