Investigation of Improvement of Pellet Tracking System

Abstract: A pellet target is an internal target system for accelerator experiments in nuclear and particle physics. The target consist of small spheres of frozen hydrogen, called pellets. The pellets interact with high energy accelerator-beam particles in a particle accelerator. The challenge is to track these pellets for good accuracy of interaction position in both time and space. The pellets are tracked with lasers and cameras. The main goal of this project was to develop a method to find the best time resolution and to optimize the efficiency of the pellet tracking system. This project addresses challenges with making trustworthy measurements were stability in the setup, difficulties with alignment and optimizing of exposure cycles. Because of stability issues, a more stable and robust module that also will ease adjustment of alignment is under construction. A well-aligned setup can be confirmed in two ways. Firstly by confirming that the cameras detect pellet signals for a about 300 micron-height change of the laseror the camera and secondly that a focus interval is within 100 micron. A mathematical model that calculates class-distributions for varying exposure cycles and shifts can be used to predict the results from a measurement with pellets. The model can be used for testing an appropriate exposure cycle before running it with pellets. In addition, an appropriate laser power should be chosen since the effects of both too low or too high power gives misleading results. This project has contributed to progress in the field of pellet tracking.