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 V-m=20.01 +/- 0.02 cm(3)/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, T-c=200 mK, where a superfluid density has been observed. Assuming BEC appears as a macroscopic occupation of the k=0 state below T-c, we find a condensate fraction of n(0)=(-0.10 +/- 1.20)% at T=80 mK and n(0)=(0.08 +/- 0.78)% at T=120 mK, consistent with zero. The shape of n(k) also does not change on crossing T-c within measurement precision.