2-DIMENSIONAL LOCALIZATION OF NEUTRONS IN A LARGE-AREA LIQUID-SCINTILLATOR CELL

ORION is a sectorized 4 pi neutron detector: part of it being used as a time-of-flight spectrometer. In a sector, six phototubes collect the light created during the neutron slowing down. The amount of charge i ntegrated by each one strongly depends on the impact position of the n eutron. Several tests have been performed with cosmic rays to study in detail the relation between the collected charge distribution and the particle impact position. The results are presented and compared with a simulation based on simple assumptions of light propagation in this particular medium. The detailed analysis has revealed a rather good r esolution, better than 5 cm, and at the same time, regions of ambiguit y where the correct position could not always be extracted. A new dete ctor prototype, TOURNESOL, allowing one to overcome the present limita tions is under construction. (C) 1998 Elsevier Science B.V. All rights reserved.