Fig. 1. Schematic overview of the SciFi tracking detector.

Fig. 2. IIT-CCD chain.

Fig. 3. Fiber lifetime as a function of temperature. The measured fiber was Kuraray SCSF-78M version 1.1 (anti-O₂ type).

Fig. 4. Schematic view of a SciFi sheet. The upper figure shows a top view and the lower figure shows a cross-sectional view.

Fig. 5. Schematic view of the fiber sheet production system.

Fig. 6. Fiber bundle assembly. Five fiber sheets are gathered into each bundle.

Fig. 7. Method for illuminating fiducial fibers with electroluminescent (EL) plates. Black paint coating the fiber sheet is scraped off selected fiducial fibers. Light from the EL plate enters only these fibers (solid arrows), while the others remain shielded (dashed arrow).

Fig. 8. (Top): Typical IIT image taken by CCD. The units on the axes are CCD pixel number. The background of small circles denotes the parameterized fiber positions determined from EL calibration. An enlarged view of a hit is shown at bottom. The hit is defined as a cluster of fibers which overlap the pixel clusters.

Fig. 9. The mean values of N_pixel as a function of hit position. The data (open circles) are the measured values for cosmic-ray muons. They agree well with the prediction from Eq. (2) (solid line). After the attenuation correction, the position dependence is negligible (solid circles).

Fig. 10. Typical distribution for the number of pixels (N_pixel) for cosmic-ray muons. Dots with error bars represent data and the histogram shows pixel simulation results. We required N_pixel≥2.

Fig. 11. (a) Hit efficiency and (b) noise rate for various cut values on N_pixel, estimated with cosmic-ray data. The arrows show the chosen analysis cut.

Fig. 12. Hit efficiency for each layer estimated with cosmic-ray muons (solid circles for data and histogram for Monte Carlo simulation).

Fig. 13. Track finding efficiency as a function of track length, expressed in terms of the number of SciFi layers traversed, for cosmic-ray muons (solid circles) and for muon tracks from ν_μ charged-current interactions generated by the Monte Carlo simulation (histogram).

Fig. 14. Typical residual distribution for cosmic-ray muon track fits for a representative layer (layer 9). To obtain this figure, we excluded the measured point in layer 9, and tested it against the fit results.

Fig. 15. Typical ν_μ event candidate in the Fine-Grain detector including SciFi detector.

Fig. 16. Number of tracks found in ν_μ event candidates. The total number of events in a Monte Carlo prediction is normalized to that in the data. The errors shown are statistical only. The systematic error at each data point is about 5%.

Fig. 17. Linearity of IIT: (a) The mean value of N_pixel as a function of N_p.e. (the number of photoelectrons) from the LED test. (b) The mean value of N_pixel as a function of p/M from the beam test with a proto-type detector using the proton and pion beams. The simplified Bethe–Bloch formula (solid curve) reproduces the data points well.

Fig. 18. The N_pixel distribution for (a) μ candidates and (b) proton candidates from ν_μ events containing two tracks. The data (solid circles) agree with the Monte Carlo prediction (histogram). The hatched histogram shows the proton contribution.

Table 1. Measured light yield Y₀ and attenuation length λ. The detection efficiency after 4 m light propagation for a double-layered fiber sheet was calculated using Y₀ and λ