MAGNETIC NEUTRON SCATTERING FROM K2NiF4

La diffusion magnétique des neutrons a été étudiée au-dessus et au-dessous de la température de transition dans l'antiferromagnétique à deux dimensions K2NiF4. L'étude inélastique sur un spectromètre à trois axes a indiqué que près de TN la forme de S||(O, E) et S⊥(O, E) est très différente de celle obtenue pour les systèmes à trois dimensions avec l'échange de Heisenberg. On a trouvé que S||(O, E) a une largeur extrêmement étroite comparée à S||(O, E) dans le voisinage de TN. S⊥(O, E) montre un petit changement avec la température lorsque T est augmenté au-dessus de TN.The magnetic scattering of neutrons has been investigated both above and below the transition temperature in the two-dimensional antiferromagnet K2NiF4. Inelastic studies on a triple-axis spectrometer have indicated that near TN the behavior of S||(O, E) and S⊥(O, E) differ considerably from results obtained for three-dimensional systems with Heisenberg exchange. S||(O, E) was found to have an extremely narrow line width compared to S⊥(O, E), in the vicinity of TN. S⊥(O, E) also showed little change with temperature as T was increased from TN

Thermochromatographic investigations of fission product transport and chemistry. [HTGR]

A thermochromatographic technique has been developed to investigate the chemical states of fission products from irradiated fuel as well as in fission product simulation studies. Some recent work on iodine transport and on release of fission products from irradiated fuel kernels will be discussed