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The essential features, constructional details and performance of a 480-channel detector of lead glass total absorption Cherenkov counters are described. Results are presented on the linearity, energy and spatial resolution for electrons and photons in the energy range up to 4.8 GeV. The behaviour of charged hadrons in the detector is also described.

A photon tagging system which measures the energy of photons in a bremsstrahlung spectrum is described. The apparatus covers a photon energy range of 2 GeV starting 160 MeV below the energy of the incident electron beam. 192 counters provide a nominal resolution between 6 MeV for a photon energy 160 MeV below the incident electron energy and 11 MeV for a photon energy 2160 MeV below the incident electron energy.

A large aperture magnet spectrometer (LAMP 2) is described which was used in a tagged photon beam to collect 1.5 x 10 7 triggers from photoproduction processes in hydrogen. The techniques employed for the data acquisition and subsequent event reconstruction and kinematic identification are described and evaluated.

A method is described for using magnetic measurements taken at regularly spaced positions, of the main field component only, to parametrise a magnetic field region. The novel feature of the method is the way in which the parameters of the least squares fit can be found without the inversion of large matrices. Data are presented from a real application of the method.

A photon tagging array which measures the energy of photons in a bremsstrahlung spectrum is described. The apparatus covers an energy range of 1600 MeV starting 250 MeV below the energy of the incident electron beam. Sixty-four tagged channels provide a theoretical resolution of ±12.5MeV and measurements indicate the overall resolution, using a 1 100 radiation length radiator, to be better than ±17.5MeV. Design and constructional features are incorporated which permit considerable reductions in the installation, survey and monitoring requirements.