Development and Testing of a Modular Large-Area Cosmic Ray Telescope Using Scintillator-Fiber Hybrid Design for Millimeter-Level Muon Tracking

TL;DR

The paper addresses the need for millimeter-level muon tracking to calibrate space-based calorimeters like HERD CALO. It presents a modular, large-area telescope that combines scintillating bars with a two-layer fiber mat in orthogonal detector planes, using an encoding-based readout to dramatically reduce channels while preserving precision. Key results show a hit-position resolution of about $1.89\,\mathrm{mm}$ and per-layer efficiency above $96\%$, with the full system achieving roughly $85\%$ efficiency, validating the cost-effective design for ground calibration and potential adaptation to other experiments. The approach offers a scalable, low-cost path to high-resolution muon tracking and imaging in challenging environments.

Abstract

Cosmic-ray muons, owing to their high penetration power and abundance, have been widely employed as a natural probe in experimental particle physics. We developed a meter-scale cosmic-ray muon telescope, consisting of two parallel super-layers (1 m $\times$ 1 m) separated vertically by one meter. A super-layer is composed of two orthogonal detection layers, of which each consists of eighteen modules arranged in parallel and packed closely together. A module consists of a plastic scintillating bar precisely aligned and stacked on top of an underlying scintillating fiber mat. The telescope employs a detection scheme combining scintillating bars and fibers to meet the requirement of spatial resolution and to reduce the number of readout electronic channels. This article presents the comprehensive development of the telescope, encompassing its geometric design, data acquisition system, and performance evaluation. Experimental results show that the telescope achieves a position resolution better than 2 mm and an overall detection efficiency of $\sim$85%. The innovative design keeps the manufacturing cost low while maintaining high spatial resolution and detection efficiency.

Figures (19)

• Figure 1: The telescope test setup.(Left) The simplified diagram of particle tracking detectors.(Right)
• Figure 2: Cross-sectional structure of a module.
• Figure 3: Detection efficiency distribution for particles passing through an N-layer fiber mat obtained from Geant4 simulation. The X-axis represents the number of fiber layers in the mat ($N_{\rm Fibers}$), while the Y-axis denotes detection efficiency.
• Figure 4: Assembly of the PMT base for the telescope.
• Figure 5: The assembled module (left) and polished end-face of a scintillating fiber bundle (right).