Performance Estimations for readout board of CDC in Belle II

Sumitted to PubDB: 2026-05-15

Category: Master Thesis

Tags: CDC

Principal Authors Masayoshi Oki
Date 2025-02-20
Belle II Number BELLE2-MTHESIS-2026-044
Abstract In this study, we evaluated the performance of a readout board developed for the upgrade of the Belle II experiment at High Energy Accelerator Research Organization (KEK). The Belle II experiment aims to search for new physics by colliding electron and positron beams and precisely measuring the resulting decay processes. To increase the number of data samples, the experiment is currently undergoing upgrades toward higher luminosity, where luminosity is defined as the interaction rate per unit cross section. The detector studied in this work is the Central Drift Chamber (CDC), which measures the momentum and energy loss of charged particles using their tracking information. The upgrade for high-luminosity operation focuses on the following four improvements: 1. Reduction of crosstalk, in which a signal in one channel induces false signals in neighboring channels 2. Replacement of the current readout-board chip with a new ASIC offering improved radiation tolerance, since the existing system is approaching the end of its operational lifetime under radiation exposure 3. Reduction of ASIC power consumption to prevent malfunctions caused by voltage drops along the power cables 4. Increase of the ADC sampling frequency to obtain more precise waveform information Prototype boards were developed in several stages, followed by operation tests and performance evaluations. In particular, from November 6 to 12, 2024, a beam test was conducted at the ITDC detector development facility at KEK to evaluate the detector-readout connection and measure the position resolution. This paper describes the details of these performance evaluations. In addition, during the evaluation studies, we obtained a new insight into the origin of crosstalk, which can generate fake hits in the detector, and this finding will also be discussed.
Institute Osaka-Metropolitan

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