High-precision machining behavior of the single crystal scintillator, bismuth germanate (Bi4Ge5O12)

Abstract

This study focuses on understanding the machinability of a single-crystal scintillator, Bismuth Germanate (BGO), a material widely used in Time-of-Flight Positron Emission Tomography (ToF-PET). The micromachining process of such a hard, brittle material presents several challenges, particularly in maintaining surface integrity without inducing fractures or microcracks. In this work, we employed the Johnson-Holmquist 2 (JH-2) material model to simulate the micro-milling process of BGO. Experimental data from quasi-static uniaxial compression and split tests were used to estimate the key parameters for the JH-2 model. The simulation results closely aligned with experimental outcomes, confirming the reliability of the model in capturing the mechanical behavior of BGO under stress. Simulations were conducted with different machining parameters, successfully replicating the conditions observed in practical machining tests. Our findings demonstrate the impact of feed rate and depth of cut on the machinability of BGO, validating the use of the JH-2 model of this material. Looking ahead, this robust computational framework offers the potential to further optimize the machining process, ultimately enabling the production of high-performance heterostructures for scintillator applications in TOF-PET.