Observation of a new excitation in bcc solid 4He by inelastic neutron scattering

We report neutron scattering measurements of the phonons in bcc solid 4He. In general, only 3 accoustic phonon branches should exist in a monoatomic cubic crystal. In addition to these phonon branches, we found a new ''optic-like'' mode along the [110] direction. One possible interpretation of this new mode is in terms of localized excitations unique to a quantum solid.Comment: Text and 4 figures, to appear in Phys. Rev. Let

COMMENTS ON THE PAPER, ''EVIDENCE FOR A NEW PHASE OF SOLID sup3sup 3He''.

This report addresses the the comments on the paper "Evidence For a New Phase of Solid He$sup 3$"

Liquid and crystalline neutron matter

From sixth Texas symposium on relativistic astrophysics; New York, New York, USA (18 Dec 1972). Results of calculations of the ground-state energies of liquid and crystalline neutron matter are presented. It is found that neutron matter will crystallize at a density near normal nuclear density. This results indicates that a large fraction of the interior of a neutron star consists of crystalline neutron matter. An intuitive physical discussion is given to illuminate this result. Furthermore, it is suggested that, contrary to the usual point of view, low-density matter should be regarded as a quantum liquid'' which is almost'' a quantum crystal''. (2 figures, 1 table) (auth