A high-resolution tracking hodoscope based on capillary layers filled with liquid scintillator

Abstract Results are given on tests of a high-resolution tracking hodoscope based on layers of 26-μm-bore glass capillaries filled with organic liquid scintillator (1-methylnaphthalene doped with R39). The detector prototype consisted of three 2-mm-thick parallel layers, with surface areas of 2.1×21 cm 2 . The layers had a centre-to-centre spacing of 6 mm, and were read by an optoelectronic chain comprising two electrostatically focused image intensifiers and an Electron-Bombarded Charge-Coupled Device (EBCCD). Tracks of cosmic-ray particles were recorded and analysed. The observed hit density was 6.6 hits/mm for particles crossing the layers perpendicularly, at a distance of 1 cm from the capillaries’ readout end, and 4.2 hits/mm for particles at a distance of 20 cm. A track segment reconstructed in a single layer had an rms residual of ∼20 μm, and allowed determination of the track position in a neighbouring layer with a precision of ∼170 μm. This latter value corresponded to an rms angular resolution per layer of about 30 mrad. A comparison is made between capillary layers and silicon microstrip planes.