C. Chilian

Measurement of k0 and Q0 values for iridium isotopes

There is an increasing demand for the chemical analysis of new materials containing iridium. The k0-method is an excellent method for the analysis of new materials but measured k0-values and Q0-values have been lacking for 191Ir(n,γ)192Ir, which offers greater sensitivity than 193Ir(n,γ)194Ir. In this work, the Q0-values were determined for the two reactions by the two-channel method, using five irradiation channels in two research reactors in Belgium and Canada. These measured Q0-values enabled the first determination of the resonance neutron Cd transmission factors for these two capture reactions, confirming suspicions that they are much less than unity. At the two laboratories, k0-values were measured for 192Ir and 194Ir and there was good agreement between the two laboratories. The k0-values for 192Ir are original measurements, while those for 194Ir are in good agreement with previously published values.

The NAA method at Polytechnique Montreal: an efficient alternative way to use the k 0 NAA models

At Ecole Polytechnique Montreal, the philosophy in performing neutron activation analysis (NAA) is long-term and application oriented. Thinking long-term implies a good understanding of the fundamentals of the method, of the samples, of the tools, reactor and detectors, and there must be constant innovation that is experimentally validated with extensive measurements. Application oriented means a NAA method developed to provide users with fast, sensitive, accurate and reliable analyses for various types of materials. This philosophy dictates the manner in which the developments in the areas of NAA software, peak-area calculation, dead-time correction, detection efficiency model, k0 and Q0 values, neutron moderation and neutron self-shielding are carried out. This paper presents a survey of the Laboratory’s methodology, reviewing a few of its unique features such as detector efficiency calibration and sample related perturbations of the neutron activation. These features are used as examples to provide the reader with an understanding of the philosophy and the evolution of the NAA method at Ecole Polytechnique.

Neutron self-shielding in irradiation channels of small reactors is isotropic

In order to predict the self-shielding effect in neutron activation of non-spherical samples in reactor neutron spectra, it is important to know whether the neutron field is sufficiently anisotropic to cause significant variations between horizontal and vertical sample orientation or with orientation relative to the direction towards the reactor core. Metal wires with significant neutron self-shielding were irradiated in several channels of the SLOWPOKE reactor at Ecole Polytechnique Montreal and the TRIGA reactor at the Jožef Stefan Institute. In all cases, the amount of thermal or epithermal self-shielding was found to be identical, within the experimental uncertainty, regardless of the orientation of the wire, indicating that the neutron field is essentially isotropic. Models used to predict neutron self-shielding need to be adjusted accordingly. In our Monte Carlo model, the tube-shaped neutron source was moved back into the moderator and reflecting materials near the sample location were included, which produced an isotropic neutron field at the sample location.

Comparison of gamma radiation effect on erbium doped fiber amplifiers

Optical amplifiers have many applications in space, such as transmitters, receivers, for satellite telecom, lidars and remote sensing.