Contamination Studies of LaCl$_3$:Ce Scintillators

Original lanthanum halide scintillators suffered significantly from internal alpha contamination due to
²²⁷
Ac. As the effect of this contamination has been substantially reduced, and the crystal sizes have grown towards volumes that are useful for many applications, the effect of the gamma-, beta-, and x-ray-contamination due to
¹³⁸
La in these materials has risen to the foreground. This paper discusses and quantifies the current status of lanthanum halide contamination. Included are comparisons with other internally-contaminated, commercially-available scintillators and computer simulation results to breakdown contamination versus background contributions. Although the high resolution of the lanthanum halides holds great promise, the internal activity clearly places limits on their superiority