instruments used in the proton beam measurements, Detector A and Detector B. See the text for details.[]{data-label="fig:NSRLExpts"}](12CSchematic_v3){width="0.8\columnwidth"}

Detector A was fabricated using black ABS polymer to supress light reflections from the walls. The 130 mm x 115 mm x 63.5 mm detector volume was filled with water during initial irradiations, then WbLS-2. Two PMTs (Hamamatsu R7723, 51 mm diameter) observed the liquid volume; one placed downstream from the beam so as to allow detection of Cherenkov light, and one placed upstream from the beam so as to suppress detection of Cherenkov light. To allow for any variability in the photomultiplier response, all measurements were repeated with the PMT locations relative to the beam direction swapped. The PMT response was found to be similar for each tube (figure \[fig:PMTresponse\]). We report the averaged values of the PMT response hereafter. Two 2x2x0.5 cm plastic scintillator hodoscopes (H1 and H2) were used for triggering and to define the beam location.

Detector B consists of two right cylindrical 150 mm x 150 mm tubs. Tub 1 was fabricated using 6.35 mm thick white teflon and Tub 2 was fabricated using 6.35 mm thick aluminium coated with black perfluoroalkoxy alkane paint on its inner surface. 