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Angular distributions of the 3 H(d, n) 4 He neutron source reaction have been measured with a recoil proton detector for deuteron energies from 8 MeV to 16 MeV in 1 MeV steps. The relative distributions are related by means of an excitation function taken at zero degrees. The results are compared with recent data obtained with time-of-flight techniques. Calculations with phase shifts from the refined cluster model were performed, which included partial waves up to l = 3 and the two particle channels 3 H + d, n + 4 He and n + 4 He ∗ . They show remarkable agreement with the experimental angular distributions both in shape and in absolute magnitude.

The activation method was used to measure excitation functions for total or isomeric (n, 2n) cross sections in the energy region 12–18 MeV for 93 Nb, 96 Ru, 104 Ru, 103 Rh, 102 Pd, 110 Pd, 128 Te, 130 Te, 142 Nd, 192 Os, 191 Ir and 198 Pt. Isomeric (n, 2n) cross-section ratios were measured for 110 Pd, 128 Te, 130 Te and 198 Pt in the whole energy region stated and were further obtained for 93 Nb and 103 Rh for two energies by combining experimental isomeric cross sections with special (n, 2n) cross-section systematics. The measured total (n, 2n) cross sections are discussed with respect to the dependence of this quantity on the neutron excess of the target nucleus. Later the results are compared with predictions from the statistical theory and special consideration is given to the competition between γ and neutron emission. From the isomeric cross-section ratios spin cut-off parameters σ(& h ;) were deduced according to the method of Vandenbosch and Huizenga. The same analysis was also applied to all isomeric (n, 2n) crosssection ratios available from the literature. The resulting properties of σ(&ħ;) are compared with the theoretical predictions.

Special computer-programs are discussed which may be used in the analysis of measurements of fast neutron cross sections applying the activation method. For various shapes of the activated samples the average neutron energy and the average neutron flux density are calculated for the monoenergetic fast neutron sources usually used in experiments. Moreover, a method is described for deducing the absolute activities from the measured total decay curve which works sufficiently well also if several activities with different half-lives and intensities are present. All programs are written in ALGOL and are available on request.

The neutron therapy facility at the Radiotherapy Department of the University Hospital Hamburg-Eppendorf is described. This unit has been developed for clinical purposes according to the initiative and conception of the radiotherapist by AEG/Fed. Rep. of Germany and RDI/USA since 1969. The installation was completed at the beginning of 1974. Special treatment head and bed systems allow isocentric treatment and arc or multiple port therapy. For routine work operation conditions of 8 to 12 mA total beam current and 500 kV accelerating voltage are used. The neutron output at 12 mA is about 3.5 x 10(12) n/s giving a phantom dose rate of more than 20 rad/min for a field size of 17.8 x 17.8 cm2 at 80 cm source-skin distance. Technical installations for improvement of dose rate and half-life of the target are planned. Results of physical measurements about neutron energy distributions, contributions from neutrons and gamma-rays to the total absorbed dose, build-up effect, axial and lateral dose distributions as well as isodose profiles for different field sizes in a homogeneous phantom are presented. Bewteen February 1976 and November 1977 up to 180 patients have been treated.