We describe the construction and performance of a scintillating fiber detec
tor used in the near detector for the K2K (KEK to Kamioka, KEK E362) long b
aseline neutrino oscillation experiment. The detector uses 3.7 m long and 0
.692 mm diameter scintillating fiber coupled to image-intensifier tubes (II
T), and a CCD camera readout system. Fiber sheet production and detector co
nstruction beg-an in 1997, and the detector was commissioned in March 1999.
Results from the first K2K runs confirm good initial performance: position
resolution is estimated to be about 0.8 mm, and track finding efficiency i
s 98 +/- 2% for long tracks (i.e., those which intersect more than 5 fiber
planes). The hit efficiency was estimated to be 92 +/- 2% using cosmic-ray
muons, after noise reduction at the offline stage. The possibility of using
the detector for particle identification is also discussed. (C) 2000 Publi
shed by Elsevier Science B.V. All rights reserved.