Radiochemical Research with the Linear Electron Accelerator MEA

Abstract

The Medium-energy Electron Accelerator (MEA) of the National Institute for Nuclear Physics and High-Energy Physics at Amsterdam is since a number of years in operation for carrying out a fullscale program on nuclear physics and radiochemistry. The maximum energy attainable is about 500 MeV and will be raised to about 600 MeV in the foreseeable future. Such energies in combination with beam intensities up to ΙΟΟμΑ render the facility an interesting tool for the production of a broad spectrum of radionuclides. To this end the energy of the electrons is first -in part -converted to a strongly forwardpeaked Bremsstrahlung photon beam, by passage through a sheet of a suitable high-Z element such as Ta or W.At present a beam line for electronenergies <140 MeV is equipped with relatively thin convertors (< 0.5 mm W = 0.14 radiation length) and a sweep magnet to provide a 'clean' photon beam -with a continuous spectrumfree of residual electrons [1], Samples to be irradiated are placed in the open air on the axis of the photon beam at about 60 cm downstream from the convertor. External targets are very helpful for controlling irradiation conditions. For instance, for gasphase irradiations targets can be readily irradiated at elevated temperatures in case of materials with high boiling points.