Hodoscope

Behind the honeycomb drift chamber, a hodoscope is placed for timing measurement. Figure 36 shows a schematic view of the hodoscope. There are two identical sets of hodoscopes, EHOD1 and EHOD2, half staggered to each other. Estimated electron rate is 10 MHz at most. To keep singles rate of each slat well below 1 MHz, the hodoscope is segmented into 25 scintillator slats, each of which is 10 mm thick, 40 mm wide, and 120 mm long. Each of them is equipped with acrylic light guides and Hamamatsu H6612 3/4" phototubes on both ends. Expected time resolution of the hodoscope is 50 ps (rms).