Meeting report

Neutron powder diffraction

A Workshop on Advanced Neutron Powder Diffraction Instrumentation and Data Analysis Techniques was held Aug. 22, 1997 in Toronto, Ontario, Canada. The workshop was organized by J. Jorgensen (USA) and had two components:

The morning sessions concerned instrumentation, and focused on resolution, large multidetectors and design of new focusing monochromators. It was shown that, while powder diffractometers are getting more expensive, they are capable of impressive improvements in resolution and intensity that will allow applications of neutron powder diffraction to new areas of science and technology. Topics covered included: an overview of the D2B multi-Soller powder diffractometer at the ILL (P. Radaelli); differing approaches to focusing monochromator design (T. Vogt and M. Popovici); the use of focusing monochromators to push the limits of sample size (I. Goncharenko), developments at the new Swiss national source (L. Keller); overview of the C2 DUALSPEC diffractometer and program at Chalk River, Canada (I. Swainson); and time-of-flight instrumentation (T. Kamiyama and R. Ibberson).

Data refinement and handling formed the second component of the workshop. Topics included: development of RIETAN-96T (F. Izumi); the merits of maximum entropy methods (S. Kumazawa); analysis of time-of-flight data using the Cambridge Crystallographic Subroutine Library (W. David); recent additions to the powder analysis components of GSAS, and the virtual reality modelling output now available from the PC version (R. Von Dreele).

At the end of the day, the floor was opened to discussion on future directions. The liveliest discussions concerned the smallest samples that people had successfully used and the features available in various refinement packages. The workshop proved to be a highly successful forum for the exchange of ideas and discussion of the latest developments.

Ian Swainson
CPD Newsletter No. 19, 1997