R&D of KLM Upgrade for Direct Measurement of Neutral Hadron Momentum via Time-of-Flight in Belle II

Xiyang Wang; Hongyu Zhang; Shiming Zou; Zibing Bai; Deqing Fang; Kairui Huang; Ziyu Liu; Yugang Ma; Weiqi Meng; Ting Wang; Xiaolong Wang; Shiqing Xie; Mingjie Yang; Junhao Yin; Mingkuan Yuan; Wanyi Zhuang

arXiv · 2503.06128

R&D of KLM Upgrade for Direct Measurement of Neutral Hadron Momentum via Time-of-Flight in Belle II

Xiyang Wang·Hongyu Zhang·Shiming Zou·Zibing Bai·Deqing Fang·Kairui Huang·Ziyu Liu·Yugang Ma·Weiqi Meng·Ting Wang·Xiaolong Wang·Shiqing Xie·Mingjie Yang·Junhao Yin·Mingkuan Yuan·Wanyi Zhuang

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Abstract

Accurate momentum determination of a neutral hadron, such as a KL meson or a neutron, remains a significant challenge in particle physics and nuclear physics experiments. The Belle II experiment presents an opportunity to address this challenge through an upgrade incorporating Time-of-Flight (TOF) capability for its large KL and Muon Detector (KLM). We investigate the feasibility of momentum determination via TOF measurement. To achieve high time resolution for the KLM upgrade, we conduct research and development of cost-effective plastic scintillators in collaboration with GaoNengKeDi Company, and technology utilizing silicon photomultipliers(SiPMs) arrays. A bulk attenuation length of 120 \pm 7 cm has been achieved with a 135 cm-long sample, along with a time resolution of 70 \pm 7 ps at its midpoint. A 50 cm-long scintillator demonstrates an exceptional time resolution of 47 \pm 2 ps. These results highlight the potential of the proposed technology for improving neutral hadron momentum measurements in an upgraded Belle II KLM detector.

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Xiyang Wang, Hongyu Zhang, Shiming Zou, Zibing Bai, Deqing Fang, Kairui Huang, Ziyu Liu, Yugang Ma, Weiqi Meng, Ting Wang, Xiaolong Wang, Shiqing Xie, Mingjie Yang, Junhao Yin, Mingkuan Yuan, Wanyi Zhuang. 2025-03-08. R&D of KLM Upgrade for Direct Measurement of Neutral Hadron Momentum via Time-of-Flight in Belle II. https://arxiv.org/abs/2503.06128

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