Science and Technology at the NCNR

NCNR admirably balances attention to development, construction, and maintenance with support of a broad range of scientific and technical investigations. Much of the successful balance is due to carefully constructed cooperation with the many beam users who bring samples for short visits. From this visiting population and its own research staff, the NCNR management chooses the best kinds of target stations to serve scientific needs. Particularly because the SNS will be filling many needs, the NCNR has thoughtfully chosen to build detectors and to develop facilities specifically for the many investigations that will not be optimally served by the SNS. In so doing, the facility has earned high priority for support within NIST.

Because of the very broad range of topics being addressed at NCNR and its members’ wish for substance in presentation, the panel heard descriptions of only about half of the research activities conducted at the NCNR. The facility is providing excellent data, for example, on the states of water at low temperature and in the vicinity of macromolecules. It is bringing a better view of proteins in solutions, particularly as distinct from crystal structures, and is revealing new levels of polymer organization that correlate with the toughness of materials. The renowned work on multiferroics, materials that show ferromagnetic and ferroelectric properties, is progressing rapidly.

The NCNR hosts fundamental physics studies of the properties of the neutron, as well as a number of more applied physics measurements, on a total of seven ports. The cold beam lines (NG-6 and -7) are a world-class site for basic physics with the neutron, competitive with the Institut Laue-Langevin (ILL) in Grenoble, France.

The neutron lifetime and a set of parameters describing correlations between the neutron spin and the kinematic parameters of the decay electron, proton, and antineutrino provide the most model-independent source of information on the unitarity of the Cabibbo-Kobayashi-Maskawa matrix, which in turn is an avenue to extensions of the standard model. The Standard Model is now known to be broken with the discovery of neutrino mass and oscillations, and it is important to find other deviations in order to advance to a new, correct, and predictive model. The neutron lifetime has long been a topic of study at NIST, although the most precise measurements (which do not mutually agree) were made at ILL. To resolve this situation, NIST and a group of universities are developing a new measurement based on magnetically trapped ultracold neutrons.

Perhaps the most important neutron physical parameter for the new physics is a possible electric dipole moment (EDM), which would be zero if nature respected the symmetry CP (charge conjugation and parity reversal). This bears directly on the question of why the universe contains matter but essentially no antimatter, because it would reveal a source of CP violation larger than the (inadequate) amount contained within the Standard Model. A large U.S. neutron EDM project is planned for the SNS, but NIST scientists in collaboration with other universities and Argonne National Laboratory are investigating a completely different approach that might be as sensitive and that would have different systematics. A proof-of-principle test is a measurement of the magnetic dipole moment. This creative approach and plan hold promise. This experiment has been approved and is under development at the NCNR.



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An Assessment of the National Institute of Standards and Technology Center for Neutron Research: Fiscal Year 2007 Science and Technology at the NCNR NCNR admirably balances attention to development, construction, and maintenance with support of a broad range of scientific and technical investigations. Much of the successful balance is due to carefully constructed cooperation with the many beam users who bring samples for short visits. From this visiting population and its own research staff, the NCNR management chooses the best kinds of target stations to serve scientific needs. Particularly because the SNS will be filling many needs, the NCNR has thoughtfully chosen to build detectors and to develop facilities specifically for the many investigations that will not be optimally served by the SNS. In so doing, the facility has earned high priority for support within NIST. Because of the very broad range of topics being addressed at NCNR and its members’ wish for substance in presentation, the panel heard descriptions of only about half of the research activities conducted at the NCNR. The facility is providing excellent data, for example, on the states of water at low temperature and in the vicinity of macromolecules. It is bringing a better view of proteins in solutions, particularly as distinct from crystal structures, and is revealing new levels of polymer organization that correlate with the toughness of materials. The renowned work on multiferroics, materials that show ferromagnetic and ferroelectric properties, is progressing rapidly. The NCNR hosts fundamental physics studies of the properties of the neutron, as well as a number of more applied physics measurements, on a total of seven ports. The cold beam lines (NG-6 and -7) are a world-class site for basic physics with the neutron, competitive with the Institut Laue-Langevin (ILL) in Grenoble, France. The neutron lifetime and a set of parameters describing correlations between the neutron spin and the kinematic parameters of the decay electron, proton, and antineutrino provide the most model-independent source of information on the unitarity of the Cabibbo-Kobayashi-Maskawa matrix, which in turn is an avenue to extensions of the standard model. The Standard Model is now known to be broken with the discovery of neutrino mass and oscillations, and it is important to find other deviations in order to advance to a new, correct, and predictive model. The neutron lifetime has long been a topic of study at NIST, although the most precise measurements (which do not mutually agree) were made at ILL. To resolve this situation, NIST and a group of universities are developing a new measurement based on magnetically trapped ultracold neutrons. Perhaps the most important neutron physical parameter for the new physics is a possible electric dipole moment (EDM), which would be zero if nature respected the symmetry CP (charge conjugation and parity reversal). This bears directly on the question of why the universe contains matter but essentially no antimatter, because it would reveal a source of CP violation larger than the (inadequate) amount contained within the Standard Model. A large U.S. neutron EDM project is planned for the SNS, but NIST scientists in collaboration with other universities and Argonne National Laboratory are investigating a completely different approach that might be as sensitive and that would have different systematics. A proof-of-principle test is a measurement of the magnetic dipole moment. This creative approach and plan hold promise. This experiment has been approved and is under development at the NCNR.

OCR for page 9
An Assessment of the National Institute of Standards and Technology Center for Neutron Research: Fiscal Year 2007 There is an initiative to develop high-capacity hydrogen storage for fuel cells, small relative to the amount of work being done by industry but critical for the systematic investigation that is possible at the NCNR. Of concern to the panel and to the staff at NIST was the loss of an NIH/NCRR grant for the study of biological materials. The formal consortium operating the AND/R instrument has ended, and NIST is concerned about losing momentum in this research area. Appropriately, NCNR wants to continue its biological work and is trying to forge new associations. An important opportunity will be lost if the NIH grant cannot be replaced. The ongoing collaboration between NCNR and both the Child Health and Human Development Institute and the Cancer Institute at the NIH is a positive sign for the restoration of funding. Within the larger purview of soft materials, NCNR should develop more relationships with leaders in the field to enhance and drive science. What is needed is a strong biology and soft matter center to complement the capabilities at NCNR. There are already productive interactions with the Biochemical Science Division at the NIST Chemical Science and Technology Laboratory. With characteristic foresight, NCNR is now interviewing candidates for a scientist who will take a permanent staff position and who will lead the soft matter research. Other mechanisms such as visiting scholars and systematic visits with nearby institutions such as the NIH can be created to allow NCNR to build a center of excellence. The science and technology to which the panel was exposed are strong. In 2006 there were 35 papers in high-impact journals (Nature, Physical Review Letters, Science, Proceedings of the National Academy of Sciences, and the Journal of the American Chemical Society). Taking into account the aforementioned soft matter and biological sciences, it can be judged that science is healthy at NCNR.