THE EUROPEAN HYBRID SPECTROMETER

The final version of the European hybrid spectrometer (EHS) is described. EHS was used in the NA27 experiment to study charm particles produced in View the MathML source interactions. A rapid cycling, high resolution bubble chamber (LEBC) produced bubbles of 17 \u3bcm diameter which were measured with a precision of 2.5 \u3bcm. Short-lived charm particles are observed with an efficiency up to 90% (D\ub1). The spectrometer accepts 70% of all particles produced, including approximately 100% of those in the forward hemisphere and the momenta of charged particles are measured to better than 1% over the whole momentum range. The charged particle identification detectors give information on 84% of the spectrometer tracks, half of which obtain unique identification. Two lead glass detectors measure the energy of electromagnetic showers such that the \u3c00 mass distribution has a fwhm of View the MathML source. Hadronic showers are measured with two iron/scintillator calorimeters. The mass resolutions are 3.0, 0.9 and 11 View the MathML source for K0, \u39b0 and D 12 charged particles respectively. The D0 mass is measured to be (1865.1 \ub1 1.8 \ub1 0.8