Semiautomatic dimensional screening of plastic scintillator cubes using image analysis and robotics

Abstract

Large-scale particle physics detectors often contain millions of repeated components, making precise and efficient quality control essential. We have developed a semiautomatic system for dimensional screening of 1 cm$^3$ plastic scintillator cubes for their potential use in future neutrino detectors. The system employs a motorized rotating stage, six high-resolution cameras, and image analysis software to measure cube size, surface protrusions, and the positions of holes for wavelength-shifting fibers used in optical readout. Based on these measurements, each cube is automatically classified as either acceptable or defective. We constructed and validated a prototype system, achieving a measurement precision of 10 $μ$m and over 80% consistency with manual screening. To enable classification of cubes into 48 groups based on hole positions while preserving their orientation, we introduced a 6-axis robotic arm. The completed system achieved a rejection rate of 3.1%. Our approach contributes to scalable, precise, and efficient quality control for future large-scale particle physics detectors.

Figures (14)

• Figure 1: 2$\times$2$\times$2 scintillator cubes and WLS fibers used for SuperFGD.
• Figure 2: Overview of the prototype scintillator inspection and screening system.
• Figure 3: Image acquisition unit of the inspection system.
• Figure 4: Design of the cube platform with a cube in Imaging Point 1 (left) and Imaging Point 2 (right). Labels of opposing faces of the cube are paired as (1,6), (2,5), and (3,4) like a standard die.
• Figure 5: Schematic diagram of the control system.