PPO, 0.4 g/L     bis-MSB, 3 mg/L
     WbLS-2        PC, 0.99%     PPO, 1.36 g/L   bis-MSB, 7.48 mg/L
       LS          LAB, 100%      PPO, 2 g/L      bis-MSB, 15 mg/L

\[tab:ScintComp\]

Optical Characterization Measurements
-------------------------------------

Ultraviolet-visible absorption spectroscopy of water, WbLS-1, and WbLS-2 were taken using a Shimandzu UV-1800 spectrophotometer. The optical attenuation spectrum of WbLS-2 is shown in figure \[fig:UVVIS\], along with that of a more recent WbLS formulation that also consists of 1% scintillator, the fluorescence emission spectrum, and the photomultiplier quantum efficiency spectrum for the PMTs used in this study. The optical attenuation of the more recent formulation of a LAB-based WbLS is markedly less than WbLS-2, after the purification of all starting materials and the addition of a surface-scattering reduction agent.

Fluorescence spectroscopy was carried out using a PTI fluoresence spectrometer. The excitation-emission spectrum of WbLS-2 is shown in figure \[fig:ExEmMap\], which exhibits an excitation wavelength dependence of the emission spectrum shape.

![Excitation-emission spectrum for WbLS-2.[]{data-label="fig:ExEmMap"}](WbLSExEmMapContour_v2.pdf){width="0.8\columnwidth"}

Proton Beam Measurements {#sec:BeamInfo}
------------------------

Two beamline instruments were developed for this study, Detectors A and B (figure \[fig:NSRLExpts\]).

![A schematic drawing of the instruments used in the proton beam measurements, Detector A and Detector B. See the text for details.[]{data-label="fig:NSRLExpts"}](13ASchematic_v4){width="0.8\columnwidth"}

![A schematic drawing of the 