STOPGAP—A time-of-flight extension for the Belle II TOP barrel PID system

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 1058; p. 168752
• Main Authors: Hartbrich, Oskar, Tamponi, Umberto, Varner, Gary S.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: United States Elsevier B.V 01.01.2024
• Subjects: Belle II; Particle identification; PID; Belle II; PID; Particle identification
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2023.168752

The BelleII barrel region is instrumented with the Time of Propagation (TOP) particle identification system. Due to its mechanical design, the individual TOP modules do not overlap, leaving a gap of around 2 cm between them in the azimuthal direction. This leads to a 6%–9% drop in acceptance, depending on the track’s momentum. We propose a solution to remedy these gaps by instrumenting them with fast silicon detectors to directly measure the time-of-flight of traversing particles. We present here a simulation study discussing the performance requirements and the possible sensor technologies, and we demonstrate that such a project could be realised with novel, fast monolithic CMOS sensors, or alternatively AC-LGAD sensors, both of which are expected to reach MIP timing resolutions of down to 50 ps or better.