Belle II iTOP Optics: Design, Construction and Performance

TL;DR

The paper details the design, construction, and initial performance testing of the iTOP Cherenkov counter for particle identification in the Belle II experiment, highlighting successful assembly and preliminary results.

Contribution

It introduces the design and assembly process of the novel iTOP detector modules and reports initial performance test results at Belle II.

Findings

All modules successfully assembled and installed.

Initial laser and cosmic ray tests demonstrate functional performance.

First performance data indicate promising particle identification capabilities.

Abstract

The imaging-Time-of-Propogation (iTOP) counter is a new type of ring-imaging Cherenkov counter developed for particle identification at the Belle II experiment. It consists of 16 modules arranged azimuthally around the beam line. Each module consists of one mirror, one prism and two quartz bar radiators. Here we describe the design, acceptance test, alignment, gluing and assembly of the optical components. All iTOP modules have been successfully assembled and installed in the Belle II detector by the middle of 2016. After installation, laser and cosmic ray data have been taken to test the performance of the modules. First results from these tests are presented.