\subsection{30mm Measurements}
\label{sec:30mm}
\subsubsection{CTR Results}
Two identical polished Proteus LYSO:Ce $2\times2\times30$ mm$^3$ scintillator crystals, which we will refer to as 30A and 30B, are measured at DOI values between 0 and 30 mm in 2.5 mm increments alternating between the two scintillator crystals. This is to determine the contribution, if any, of systematic errors introduced by differences in coupling, alignment and surface finish. Each measurement is repeated with and without PTFE tape. The PTFE tape covers all faces except that in contact with the photodetector. Several tightly-bound layers of PTFE are used to increase adhesion with the scintillator crystal. Measurements with complete wrapping will referred to as the wrapped configuration. Likewise no wrapping is referred to as the unwrapped configuration. Each measurement was taken for 54 minutes each. As in the standard coincidence measurements, the first 5 minutes prior to data collection are ignored to ensure temperature stability within the sealed apparatus box.

