The sense of the DANSE Organizational Meeting at Caltech on March 13, 2003 was that the DANSE software architecture offers a new approach to satisfy the data analysis needs of the SNS, and to satisfy the future needs of all North American neutron facilities. Important technical decisions need to be made on formats for data streams and support for component templates. These issues are solvable. Working (although primitive) prototypes of them were already demonstrated. The steps needed for DANSE to move forward as a project were discussed towards the end of the Organizational Meeting. It is hoped that this summary of the discussion will promote the broader dialog that is needed now.
There is an obvious constraint on the path forward for DANSE. No one individual has the scientific breadth to direct the software development in all fields of neutron scattering science. The software needs of different communities need to be determined by the communities themselves. Prioritization of tasks and directions within these subfields of neutron scattering needs to be done with care. Software that is overly specialized will not have a long-term impact. Nevertheless, DANSE offers the opportunity to elevate the scientific level of experimental work, and connect to modern theory. The importance of new or more sophisticated methods of data analysis, modeling, and theory, need to be assessed by the scientific sub-communities to optimize the scientific impact of the DANSE software development.
A simple structure for organizing the software subprojects is along the lines of traditional neutron meetings and review committees. These are listed below, together with opportunities for new developments in these fields. In parentheses are suggestions by some attendees of possible institutional interest:
Diffraction and crystal structure (NCNR, Lujan, IPNS)
Refinement methods, pair distribution function methods, connection to ab-initio structure calculations.
Engineering Diffraction (Lujan, SNS, NCNR)
beamline optimization for measurements, connection to solid mechanics analyses
Large structures (SANS and reflectometry) (NCNR)
Analysis of off-specular scattering, inelastic scattering, Fourier inversion methods
Inelastic Scattering (Caltech, NCNR)
Single crystal analysis with TOF instruments, fitting parametric dynamics models to data, ab-initio simulation of experimental data
Neutronics and nuclear physics (SNS)
Resolution calculations, performance optimization of instruments with experimental input, [Subsequent conversation with Geoff Greene suggested that the role in DANSE for nuclear physics is probably small]
Theory (IPNS)
Ab-initio calculations of structure for support of diffraction measurements
molecular and solid-state dynamics for inelastic scattering
Another way to organize the subprojects is along the lines of the scientific opportunities that cross several classes of instruments or measurements. This organization could follow scientific fields rather than instruments and techniques. If not an actual paradigm for project organization, some of these scientific topics below could provide infrastructural support for the projects listed above. Some suggestions presented at the meeting were:
Magnetism and its study by elastic and inelastic scattering inelastic
Theory of materials structure and dynamics by ab-initio methods
Crystal symmetry and how it affects scattering.
Biology, specifically protein crystallography (contact W. Minor at U. Va)
Simultaneous analysis of x-ray and neutron scattering data, exploiting differences in x-ray form factors.
Monte-Carlo inversion methods involving a large range of Q and E for both diffraction measurements of structure and inelastic scattering measurements of dynamics.
More futuristic opportunities were also suggested. It is possible that others should be added to the list which includes:
Imaging methods utilizing phase contrast
Real-time measurements
Coherence and cohesion of the DANSE project requires interactions between the personnel. To some extent this will be the formation of a virtual facility with principal investigators plus scientific staff. Suggested parts of this infrastructure include:
Education of the technical persons in the software architecture and some education in computer science. The education function of DANSE needs to be formalized so that it can span the range of needs from new users to sophisticated professionals already in the field.
A collaboratory system for remote interactions is needed, and well-suited for a software project. Remote conferencing exists today with some limitations, but perhaps the greater challenge is developing a project communications plan that works smoothly across several different institutions.
The needs of the broad field of neutron scattering science can be covered with an instruments-based approach, a scientific subfield approach, or some combination of them. The path forward depends on a number of factors such as sources of funding, and interest at neutron facilities, universities, and other activities at national laboratories. These will be discussed at greater length after the DANSE project is proposed to the Experimental Facilities Advisory Committee of the SNS on March 27, 2003. Nevertheless, now is the right time for members of the neutron scattering community to think about what scientific software subprojects are important, and how they could be organized to provide the largest scientific impact.