Directionality for wearable, closely packed radiation detector arrays

This work defines directionality as the act of estimating a radiation source's angular coordinate on the horizontal plane within a single measurement, usually up to a few seconds. This work develops a directionality algorithm for general use in wearable, closely packed detector arrays. The algorithm was demonstrated on three $2^{″}\times 2^{″}\times 4^{″}$ NaI(Tl) detectors. Directionality performance was quantitatively assessed by observing misclassification rates within the confusion matrices. These misclassification behaviors were condensed into a single number, the Mean Absolute Error (MAE), and a trend between directionality performance and uncollided gamma fluence is reported. The MAE was measured to be 8.2$°$ using a 113.4 $\mu$Ci Cs-137 source and 17.8$°$ using a 34.6 $\mu$Ci Co-60 source, where both sources were placed 172.4 cm away. Finally, this directionality algorithm was demonstrated in the case of static detector array with a moving source where an MAE of 12.7$°$ was observed for a 113 $\mu$Ci Cs-137 source at an average distance of 350.0 cm away.