The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems, as established by test beam measurements and simulation studies, is described.

The spatial nonuniformities of the response and the absolute light yield in calorimeter modules with interleaved absorber and scintillator layers were investigated on high-energy muon and electron beams. A program for detailed simulation of light collection in scintillator tiles of the calorimeter using the Monte Carlo method was developed to describe the whole set of experimental results. The experimental data are in good agreement with the results of simulation.

The EXCHARM magnetic spectrometer is designed to study the characteristics of charmed-particle hadroproduction and search for exotic multiquark states. The spectrometer is located in the 5H neutron channel of the Serpukhov accelerator. The spectrometer is based on the C Pi-40A spectrometric magnet, 11 proportional chambers (a system of 25 signal planes), two multichannel threshold Cerenkov gas counters, and a system of scintillation counters. The electronics of the spectrometer is constructed mainly to the CAMAC standard, The average mass resolution for Lambda(0) reconstructed from the decay channel Lambda(0) ---> p pi(-) is 1.5 MeV/c(2), for K-S(0) (K-S(0) --> pi(+)pi(-)) is 3.8 MeV/c(2), and for <(Lambda)over bar>(0) (<(Lambda)over bar>(0) --> (p) over bar pi(+)) is 1.2 MeV/c(2). The geometric detection efficiency for products of Lambda(c)(+) charmed-baryon four-particle decays with Lambda(0) or a K-0 neutral strange particle is approximate to 0.45%.

A 32-channel threshold gaseous Cerenkov counter is described. The counter consists of a 420-cm-thick air radiator at atmospheric pressure. Spherical mirrors with a 214-cm radius of curvature along with FEU-125 and FEU-49B photomultipliers are used for collecting and detecting the Cerenkov radiation with the counter. Entrance windows of the photomultipliers are coated with films of spectrum-shifting materials. The charged-particle detection efficiency at the plateau of the threshold response (beta greater than or equal to 0.99984) is better than 97%. The counter is part of a charged-particle identifying system of the EXCHARM spectrometer.

The reaction ..pi../sup -/+d..-->..p+..pi../sup -/+..pi../sup -/+(p/sub s/) with emission of a proton forward and one of the ..pi../sup -/ mesons backward in the laboratory system has been studied at a ..pi../sup -/ momentum 3.65 GeV/c. Among the events of this reaction we have identified the production of ..delta../sup 0/ and N/sup asterisk0/ resonances into the forward hemisphere. The values and functional parameters of the isobar production cross sections dsigma/dU' = Aexp(-BU') in the range 0< or =U'< or =0.2 (GeV/c)/sup 2/ are ..delta..sigma = 6.3 +- 0.7 ..mu..b, B = 2.8 +- 2.0 (GeV/c)/sup -2/ for ..delta../sup 0/(1232) and ..delta..sigma = 43.0 +- 4.5 ..mu..b, B = 11.5 +- 2.8 (GeV/c)/sup -2/ for N/sup asterisk0/(1688). The production of the resonances occurs as the result of baryon exchange. Diffraction scattering of the incident pion by a virtual proton is observed. It is shown that with the descent of the nucleon from the mass shell the slope of the diffraction peak decreases.