A measurement of the C-12(gamma,pi(+)n)B-11 reaction in quasifree pi-production kinematic regimes has been performed using tagged photons in conjunction with large solid angle pi and n detectors. The aim of the experiment was to investigate predicted modifications to the Delta excitation of nucleons and their subsequent propagation and decay, brought about by the nuclear medium. Differential cross sections an presented for photon energies spanning the Delta(1232) excitation region. The measurements are consistent with distorted wave impulse approximation calculations in which the amplitude for proton Delta excitation, followed by Delta propagation and decay to pi(+)+n, is reduced compared to that for a free p. However, because of uncertainties in the magnitudes of the final state interactions, it is concluded that improved calculations are required to obtain a quantitative estimate of Delta-medium effects.

The C-12(gamma,pn), C-12(gamma,pp), C-12(gamma,ppp), C-12(gamma,p pi+/-), C-12(gamma,p pi(+/-)) reactions have been studied using tagged photons of energy E-gamma=250-600 MeV. A model which includes all major absorption mechanisms and final state interactions gives results that agree well with the shapes of missing energy spectra, but for some channels the predicted cross sections are too large.

A ∼ 1 sr solid angle scintillation detector hodoscope for protons of up to ∼ 280 MeV and positive pions of up to ∼ 180 MeV energy has been developed for use in (γ,pN), (γ,pπ± and (γ,π+N) experiments with tagged photons. This paper reports the detailed design of the hodoscope and its performance for detecting protons and positive pions.

The 6Li(γ,np) and 6Li(γ,pp) reactions have been studied using tagged photons in the range 114 < Eγ < 600 MeV. Excitation functions and missing energy spectra are presented. The simple structure of 6Li and kinematical constraints are exploited to determine the relative importance of the various photoabsorption mechanisms. The genuine two-nucleon absorption can be identified up to photon energies of 500 MeV and is found to be most important at low missing energies. The 6Li(γ,np) data are well reproduced by predictions of a quasideuteron model.

Results are presented from a coincidence study of the C-12(gamma,pi(+)n)B-11 quasifree pion production reaction made in the Delta-resonance region using tagged photons. Cross sections for reactions originating on 1p-shell protons are found to be significantly larger than predicted by calculations based on quasifree pion production. It is suggested that more sophisticated calculations, perhaps including medium effects, may be required to reproduce the data.

The 12C(γ,p) differential cross-section in the Δ-resonance region has been measured using tagged photons. Data are presented for 20 MeV wide photon energy bins at 200, 300, 400 and 500 MeV and for proton angles from 52° to 128°. The present 12C(γ,p) measurements are compared with previous experiments carried out at Frascati, Tokyo and Bonn. Comparisons are also made with theoretical calculations developed at Gent and Valencia which provide an interpretation of the photon reaction mechanism in terms of the major contributing processes. Coincidence data with correlated neutrons, protons and pions are also presented.