A setup for fast cooling of liquids in sealed containers

We present a simple layout of a fast cooling system for liquids in sealed containers utilizing the large temperature gradients of cold nitrogen gas. Our system is optimized for about 20 cylindrical containers of 500 cm3, but the setup allows for simple up- and down-scaling as well as the use of arbitrary containers. We have characterized the cooling performance of our system experimentally for temperatures of the liquid in the range from room temperature down to the freezing point at ≈−2 ºC. With our system we achieve container cooling times as low as 3 min, a significant reduction if compared to cooling times with common methods in the range of 8 to 40 min. Modeling of the cooling process proves that convection within the liquid is crucial for quick heat transfer. For the cases studied here, the most important factor limiting the cooling rate is the thermal conductivity of the container material

Field induced phases in UPt2Si2

The tetragonal compound UPt2Si2 has been characterised as a moderately mass enhanced system with an antiferromagnetic ground state below T_N = 32 K. Here, we present an extensive study of the behavior in high magnetic fields. We have performed pulsed field magnetization and static field resistivity measurements on single crystalline samples UPt2Si2. Along the crystallographic a axis, at low temperatures, we find a metamagnetic-like transition in fields of the order 40 T, possibly indicating a first order transition. Along the crystallographic c axis, in magnetic fields of B>= ~24 T, we find distinct anomalies in both properties. From our analysis of the data we can distinguish new high field phases above the AFM ground state. We discuss the emergence of these new phases in the context of Fermi surface effects and the possible occurrence of a Lifshitz or electronic topological transition, this in contrast to previous modellings of UPt2Si2 based on crystal electric field effects.Comment: 10 pages, submitted to PR

Magnetic phase diagram and electronic structure of UPt2Si2 at high magnetic fields: a possible field-induced Lifshitz transition

Theoretical Physic

High field magnetization of UPt2Si2

International audienc

Magnetic phase diagram and electronic structure of UPt 2 Si 2 at high magnetic fields: A possible field-induced Lifshitz transition

International audienc