Evaluation of the imaging performance of continuous detectors etched with laser induced optical barriers

Abstract

Several groups are actively investigating the performance of thick continuous crystals to determine the potential of this detector design. One method to alter the behavior of this detector is to etch laser induced optical barriers (LIOBs) into the crystal. This work explores the performance of thick continuous detectors etched partly into the crystal in a grid pattern. As a motivation for this study, system Monte Carlo simulations were used to investigate the added benefit in imaging performance of improved spatial resolution. Detector simulations were used to qualitatively study the potential of etching crystals in the entrance region in a grid pattern, by varying the opacity of the etchings. The behavior of the LIOBs in response to optical light was also investigated by etching several small cubes of LYSO with a single LIOB, varying the etching parameters among the cubes, and measuring the transmission of optical light through the cubes as a function of interaction position and incident angle. Last, thick crystals were etched in this pattern and the performance characterized. The results showed that the opacity of the etchings may be altered by varying the laser power and etching pattern, and that greater opacity results in more restricted light spread within crystals etched in a grid pattern. Thick crystals etched with LIOBs in this pattern showed slightly improved performance in the etched region of the crystals, and slightly degraded performance in the unetched region. This study illustrates, therefore, that etching crystals in a grid pattern is possible, and may result in improved overall spatial resolution, though the etching parameters must still be optimized.