A novel detector design of overlapping plastic scintillator elements in cylindrical geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles: each particle traversing the detector from the axis outwards will produce light in several elements. The relative amounts of energy deposited in those elements allow one to interpolate on the particle trajectory beyond the resolution given by the granularity. The detector covers the angular range 10° ≤ Θlab ≤ 72° and 0° ≤ ϕ ≤ 360° with an inner layer of scintillator bars of triangular cross section and an outer layer of rings. The material is BC408. Tests with minimum ionizing electron beams show that spatial resolutions of ΔΘlab ≈ 1.5° and Δϕ12 ≈ 1.5° (FWHM) can be obtained for electrons or proton pairs with energies in the GeV range. In the EDDA experiment the ultimate spatial resolution is then determined by the size of the interaction area rather than by the intrinsic pulse height resolution of the detector.

A measurement of the total cross section for the reaction pd → pdπ° very close to threshold has been carried out at the IUCF Cooler. The deuteron with its known "nuclear structure" is the simplest system where pion production on nuclei can be investigated and mechanisms other than the quasi-free production may become important. In this contribution the experimental setup and the data analysis are described. Total cross sections for pd → pdπ° in the range 0.1 < η < 1.0 are reported.

Energy spectra and multiplicities of neutrons from the reaction system 838 MeV32S projectiles on197Au have been measured in coincidence with binary fragmentations. Neutron detection was performed simultaneously in a 4π scintillator sphere and by time-of-flight. The linear momentum transfer (LMT) and the excitation energyE CN * are deduced with the folding angle technique. Neutron multiplicities are compared for consistency and discussed as a measure of LMT andE CN * . The saturation ofM 4π (E CN * ) beyondE CN * ≈400 MeV seen for several systems of high fissility (x≧0.8) is attributed to the spreading of the folding angle distribution and the increasing competition of charged particle evaporation.