A 5-Axis Calibration Stage for Depth-of-Interaction-Correcting Scintillation Crystals

New laser-induced optical-barrier technology designed to reduce depth-of-interaction blurring requires a new calibration approach. Calibration by using a collimated beam of gamma rays to acquire a mean detector response function is important for maximum-likelihood estimation of interaction location. We have designed and built a 5-axis calibration stage to meet this need. The calibration system is able to move independently in 3 linear and 2 rotational dimensions to allow for complete control of collimated beam position and direction. This allows us to simulate gamma rays coming through a pinhole from any angle in the field of view. The need for precision in the movements between positions of the system motivated the use of a probe to map out the detector. Collision detection and automation in the software simplifies and speeds up the calibration process.