AN EXTENDED EXPERIMENTAL NEUTRON-DIFFRACTION STUDY ON GASEOUS AND LIQUID KR

With the improvements introduced in the last decade in the data analys is and in the construction of neutron diffractometers with related det ection systems, the static structure factor S(kappa) of a Simple one-c omponent fluid can be presently determined with an accuracy of a few p arts per thousand. This improvement in the performance of the experime ntal techniques makes the neutron S(kappa) measurements a powerful too l in the analysis of microscopic properties like the interparticle int eraction law and in the test of new refined theoretical approaches to the description of the phase transitions. We review here the results o f an extended set of diffraction measurements on fluid Kr in the liqui d phase along three different isotherms and in the gas phase in proxim ity of the liquid-gas transition. The structure factors and the corres ponding density derivatives are discussed and compared to theoretical results. From the data in the critical region an estimate of the corre lation length and its critical behaviour has been derived, even though a more reliable determination of these quantities requires a closer a pproach to the critical conditions.