Performance analysis of a new positron camera geometry for high speed, fine particle tracking

Abstract

A new positron camera arrangement was assembled using 16 ECAT951 modular detector blocks. A closely packed, cross pattern arrangement was selected to produce a highly sensitive cylindrical region for tracking particles with low activities and high speeds. To determine the capabilities of this system a comprehensive analysis of the tracking performance was conducted to determine the 3D location error and location frequency as a function of tracer activity and speed. The 3D error was found to range from 0.54 mm for a stationary particle, consistent for all tracer activities, up to 4.33 mm for a tracer with an activity of 3 MBq and a speed of 4 m · s−1. For lower activity tracers (<10−2 MBq), the error was more sensitive to increases in speed, increasing to 28 mm (at 4 m · s−1), indicating that at these conditions a reliable trajectory is not possible. These results expanded on, but correlated well with, previous literature that only contained location errors for tracer speeds up to 1.5 m · s−1. The camera was also used to track directly activated mineral particles inside a two-inch hydrocyclone and a 142 mm diameter flotation cell. A detailed trajectory, inside the hydrocyclone, of a −212 + 106 µm (10−1 MBq) quartz particle displayed the expected spiralling motion towards the apex. This was the first time a mineral particle of this size had been successfully traced within a hydrocyclone, however more work is required to develop detailed velocity fields.