Peter Remeijer

Observation of3He crystallization down to 1 mK using a cooled CCD camera

We describe a new setup for optical observations (particularly of helium crystals) at ultralow temperatures. It is conceptually different from the usual optical setups, which require the use of optical windows in the cryostat. Our optical system, including the light source and camera, is placed inside the vacuum can of a dilution refrigerator cryostat. We have succeeded in filming the growth of3He crystals in contact with the superfluid B phase, down to 1 mK. The optical system can easily be combined with a nuclear demagnetization stage, and a simple extension of the image transport system will allow us to study3He crystals in high magnetic fields. The entire setup is described, and some typical images are shown.

Field Dependence of the Superfluid 3He A1 and A2 Transitions

AbstractWe present new results on the magnetic field dependence of the superfluid transition temperatures of the A1and A2phases of3He. The

The properties of vacancies in solid 4He as studied by pressure measurements

T_c^{A_1 }

Thermometry in 15 tesla

transition temperature has been measured up to 15 T, the

The polarization dependence of the viscosity of saturated3 He−4 He mixtures

T_c^{A_2 }

Optical observations of3He crystals down to 1 mK

up to 12 T, at the melting pressure. The temperature was measured by an in situ field independent glass thermometer. The results are in agreement with extrapolations from earlier experiments, and with calculations of the splitting