Feasibility of neutron diffraction on solid He-3

We have investigated the feasibility of neutron diffraction from solid He-3 . The experiment will be performed at the HMI, first aiming for the propert ies of the antiferromagnetic ordering in the BCC phase and the ferromagneti c order in the HCP phase. Signal and beam heating considerations are essent ial to account for the enormous neutron absorption cross section of 3He. Th e study shows that neutron diffraction and transmission experiments are pos sible, relying on the experience gained from the neutron diffraction experi ments on Cu and Ag at nanokelvin temperatures. A pressure cell has been dev eloped which complies with the conflicting demands arising from the neutron and ultralow temperature aspects of the experiment. This work is a first s tep in an extensive effort to characterize He-3 by neutron diffraction. (C) 2000 Elsevier Science B.V. All rights reserved.