R. Brugnera

The ZEUS barrel and rear muon detector

Abstract Design, construction and performance characteristics of the ZEUS barrel and rear muon detector are presented.

Tests of OPERA RPC detectors

OPERA is part of the CNGS project and it is an experiment dedicated to the observation of long-baseline numu into nutau oscillations through tau appearance. Resistive Plate Chambers (RPCs) with bakelite electrodes are used to instrument the 2 cm gaps between the magnetized iron slabs of the two spectrometers. The RPC installation ended in may 2004 on the first spectrometer and in march 2005 on the second one. Before the installation, every RPC is subjected to a complete test chain in order to reject the poorer quality detectors. The tests are performed in dedicated facilities to ensure the proper RPC gluing, to measure its electrical properties and to verify the response to cosmic rays and the intrinsic noise levels. We have also tested the long term stability of real size OPERA RPC prototypes operated at cosmic ray fluxes for more than one year. On small size prototypes we are performing studies on the gas mixtures in order to reduce the total charge released in the gas for each detector count. The validation of the installed RPCs has been performed with pure nitrogen. A small part of them has been also tested with the gas mixture Ar/C2H2F4/i-C4H10 /SF6=75.4/20/4/0.6

The OPERA magnetic spectrometer

The OPERA neutrino oscillation experiment foresees the construction of two magnetized iron spectrometers located after the instrumented lead-nuclear emulsion targets. The spectrometer consists of a dipolar magnet without air gaps. The driving coils are located in the return yokes which are connected by two columns of iron slabs interleaved with Resistive Plate Chambers. The particle trajectories are measured by layers of vertical drift tube planes located before and after the magnet. In this paper we review the construction of the spectrometers. In particular, we describe the results obtained front the magnet and RPC prototypes and the installation of the final apparatus at Gran Sasso. We present the ballistic techniques employed to calibrate the field in the bulk of the magnet and the results in term of field uniformity and magnetic properties of the iron. Moreover, we demonstrate that a field calibration at the level of 3% can be reached and we discuss the limiting systematics. The mass production of RPC started in Jan 2003. Results of the tests and issues concerning the mass production are reported. Finally, the expected physics performance of the detector is described; estimates rely on numerical simulations and the outcome of the tests described above.

The LST analog read-out system of the ZEUS muon detector

Abstract A muon position detector based on limited streamer tubes has been built for the ZEUS experiment at the HERA e-p collider at Desy. The tubes are arranged in chambers equipped with electronics circuitry providing an analog read-out of induced signals on strips set orthogonal to the tube wires. The electronic module for charge amplification and conversion will be described including some results obtained from the complete system.