A Study of the Elastic Scattering of 2 to 3 MeV Neutrons by 40Ca and 32S Using an Associated Particle Time of Flight Spectrometer
An associated particle time of flight spectrometer based on the D(d,n)3He reaction has been developed using thin deuterated polythene targets. The competing D(d,p)3T was used to monitor the neutron output. The spectrometer has been used to study the elastic scattering of a 2 - 3 MeV neutrons in 40Ca and 32S; in each case the differential elastic scattering cross sections have been measured. In the angular range 20° - 100° in the laboratory frame of reference the results have been compared with an optical model analysis. Values of ¿2 per point of 3.46 and 2.84 for 40C and 32S respectively were obtained.
Multiple scattering effects in 7Li
Abstract The differential cross-sections for the production of 0.478 MeV γ-rays following the inelastic scattering of 14 MeV neutrons in large samples of LiF, which will be used in fusion reactor blankets, have been measured. The neutrons were produced using the 3H(d, n)4 α reaction, with the deuterons being accelerated by a 150 kV SAMES type accelerator. In order to reduce the background level the γ-ray signal was gated, osing a time of flight technique based on the α-particle associated with neutron production. Measurements of the γ-ray production differential cross-sections were made for various thicknesses of LiF. The results were compared to the predictions of the Monte Carlo Computer Code, MORSE, with an agreement of ±11% being achieved. In addition a phenomenological expression was found which is capable of predicting the variation in cross-sections with thickness due to multiple scattering effects to within ±12%.
An analytical approach to the design of electrodes in high-power, fast-transverse-flow CO2 lasers
Abstract Usually, the design of the electrodes of fast-transverse-flow CO 2 lasers relies more on experimental data than on theoretical analysis. Traditional systems sustain a stable, high-power discharge but the current distribution generates a peaked, non-uniform small-signal-gain pattern. We present a theoretical model suitable for the design of electrodes that achieves a quasi uniform gain distribution. The analysis, based on a two-temperature model and the gas-transport equations, computes the electron density that supports a flat gain pattern. Combining the desired electron density with the electron-balance equations, the model determines the required electric field. The results were used to design a new set of electrodes for a home-made fast transverse flow CO 2 laser. A stable, large volume discharge ( 4 × 8 × 90 cm 3 ) with very good uniformity was obtained. The resulting gain distribution was registered in a bi-dimensional map. The peak gain rose from 1.2 m - 1 , attained with the old electrode set, to 1.6 m - 1 with the new one and the gain showed a homogeneous profile.