Experiment Proposal - opera - Infn

9 p.e. and 6.9 p.e. at a distance from a photocathode of 2.5 m and 6.5 m, respectively. Attenuation
lengths of 14.3 m for 1.2 mm fibres with mirrors and 9.2 m without mirrors were measured.
The optimisation of the liquid scintillators is continuing. Due to the local scintillation light capture
and to the WLS conversion inside the fibre, a better performance of the liquid scintillator should be
achievable, as compared to those applications in which a long attenuation length is required.
A large system of six polycarbonate panels is under construction and will soon be tested. A possible
assembly scheme foresees bundles of guide fibres, connected with WLS fibres and coupled to the readout
devices at the corners of the planes. This allows full access to emulsion bricks with a possible reduction
of a distance between walls.
Figure 175: Layout of a possible liquid scintillator tracker (LST) detector to be used for OPERA.
9.2.2 Development of the Multi Track scanning approach
Groups of the OPERA Collaboration are following the approach of the so-called Multi-Tracking Systems
(MTS). Here we briefly describe the SySal system [97] originally developed by the Salerno group. Further
R&D programmes are underway in other European groups of OPERA and CHORUS, such as CERN,
Münster, Naples, NIKHEF and Rome.
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