Spaghetti calorimeter. Research, development, application

摘要

The Spaghetti Calorimeter (SPACAL) is a detector intended primarily for the energy measurement of high-energy particles, but also provides spatial information and particle identification. It is a sampling calorimeter composed of plastic scintillating fibers, oriented in the direction of the particle, embedded in lead. The scintillation light is read out by photomultipliers, which are coupled to bunches of fibers through light guides, each forming a tower. It was developed as an electromagnetic (e.m.) and compensating hadronic calorimeter for use in future multi-TeV collider experiments. The largest prototype was installed for an alternative application as an hadronic calorimeter in the WA89 experiment, where it is used for the detection of neutrons resulting from (Sigma) decays. The basic concepts behind calorimetry are discussed in detail. Several prototypes were tested in beams of electrons and pions with energies up to 150 GeV. Resonable e.m. energy resolution, at (sigma)/E=12.9 % /(radical)E(GeV)+1.23%, was measured. Excellent hadronic energy resolution was found, at 30.6%/(radical)E(GeV)+1.0%, but the calorimeter was found to be slightly undercompensating with e /h=1.15. The position of the shower barycenter for both electrons and pions was easily found according to the relative energy deposits in the calorimeter towers. The calorimeter was also found to be able to provide effective discrimination between electrons and hadrons. The performance of SPACAL in the WA89 experiment at the Omega spectrometer at CERN was studied with the reconstruction of beam (Sigma)(sup -)particles via its decay (Sigma)(sup -)(yields)n(pi)(sup -). Details of the calibration of SPACAL with electrons and protons are presented. (orig.). (Atomindex citation 27:032174)