Large liquid-scintillator trackers for neutrino experiments

(eng) Results are given on tests of large particle trackers for the detection of neutrino interactions in long-baseline experiments. Module prototypes have been assembled using TiO2-doped polycarbonate panels. These were subdivided into cells of cross-section and length, filled with liquid scintillator. A wavelength-shifting fibre inserted into each cell captured a part of the scintillation light emitted when a cell was traversed by an ionizing particle. Two different fibre-readout systems have been tested: an optoelectronic chain comprising an image intensifier and an electron-bombarded CCD (EBCCD); and a hybrid photodiode (HPD). New, low-cost liquid scintillators have been investigated for applications in large underground detectors. Testbeam studies have been performed using a commercially available liquid scintillator. The number of detected photoelectrons for minimum-ionizing particles crossing a module at different distances from the fibre readout end was 6–12 with the EBCCD chain and a mirror at the non-readout end; 4–10 with the HPD and no mirror. The light-attenuation lengths in the fibres were with the EBCCD and with the HPD. The detector response to electron showers has also been measured. After ten radiation lengths of lead, the transverse position of the incoming electron was determined with a precision of a few millimetres for electrons of , and with a precision of 1.5– for electrons of .