Probing the Upper Limit of Nonclassical Rotational Inertia in Solid Helium 4

Observation of Non-classical Rotational Inertia in Solid Helium - an Indication of Superflow in Solids?

The phenomenon of Non-Classical Rotational Inertia, in which a body does not rotate with its rotating container, has been recently observed in solid Helium-4. This property is shared by superfluid liquid helium. The recent findings might be evidence of superflow in solids. Superfluidity or flow sans dissipation is commonly associated with liquids. Counter-intuitive as it may seem, quantum mecha...

Classical rotational inertia of solid 4He.

The observation of reduced rotational inertia in a cell containing solid 4He has been interpreted as evidence for superfluidity of the solid. We propose an alternative explanation: slippage of the solid, due to grain boundary premelting between the solid and dense adsorbed layers at the container wall. We calculate the range of film thickness, and determine the viscosity that will account for t...

Superfluidity in Solid Helium-4

HELIUM , SOLID 1 Helium , Solid

Helium was first solidified at the famous Kamerlingh Onnes low-temperature physics laboratories in Leiden by W. H. Keesom [1] on June 25, 1926. The initial experiments by Sir Francis Simon at Oxford University and by Keesom and their collaborators focused on the melting curve, the specific heat, and the thermal conductivity of solid helium as a test of our early understanding of solids. These m...

the effect of task cognitive complexity and time limit on the performance of the learners with different proficiency levels in second language writing skill

this study investigated the effects of manipulating the cognitive complexity of tasks along +/- few elements and the time limits on l2 learners writing performance. to conduct the study, 60 iranian efl learners with two levels of proficiency, low and high intermediate, were selected and assigned to three groups based on the time devoted to task completion. the participants performed both a simp...