Bose-Einstein condensation in solid 4He.
We present neutron scattering measurements of the atomic momentum distribution n(k) in solid helium under a pressure p=41 bar (molar volume Vm=20.01+/-0.02 cm3/mol) and at temperatures between 80 and 500 mK. The aim is to determine whether there is Bose-Einstein condensation (BEC) below the critical temperature, Tc=200 mK, where a superfluid density has been observed. Assuming BEC appears as a macroscopic occupation of the k=0 state below Tc, we find a condensate fraction of n0=(-0.10+/-1.20)% at T=80 mK and n0=(0.08+/-0.78)% at T=120 mK, consistent with zero. The shape of n(k) also does not change on crossing Tc within measurement precision.
Diallo
S O
SO
Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2593, USA.
Pearce
J V
JV
Azuah
R T
RT
Kirichek
O
O
Taylor
J W
JW
Glyde
H R
HR