project title: Experiments on supersolid 4He at the melting pressure
project leader: Sebastien Balibar
access given (in days): 14
access used (in days): 0
local host: Harry Alles
home institution: Department of Physics, ENS, Paris
country of institution: France
starting date (yyyy-mm-dd): 2006-03-26
This project is planned to investigate whether the phenomenon discovered in the torsional oscillator experiments by US scientists Eun-Seong Kim and Moses Chan in 2004, namely the observation of nonclassical rotational inertia with solid 4He below about 0.2 K, could be observed also on the melting curve of 4He. Kim and Chan have interpreted their results as the evidence of supersolid behavior and the possible supersolid transition should manifest an anomaly on the melting curve 4He. In our experiments the melting pressure of solid 4He will be measured from about 0.4 K down to the lowest temperatures of a few mK with an accurary of better than 1 microbar with a capacitive pressure gauge. During temperature sweeps we will also follow the crystal shape with our optical setup. Experiments are planned to be conducted first with 4He of natural purity (about 0.1 ppm of 3He impurities) and then with ultra pure 4He (0.3 ppb of 3He impurities).