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NCNR in Relation to Neutron Facilities Nationally and Internationally

A number of metrics are commonly used to provide some measure of performance of a user facility such as NCNR. Among them are the degree of user demand—or oversubscription—as well as the quantity and quality of published output. Other measures of performance include the number of students trained, beam-days sold to industry, and case studies that illustrate the impact on society at large of the research carried out.

The level of user demand is not in itself a measure of performance, but rather an indicator of the size and strength of the community that chooses to use a particular institute where there is a choice. Levels of demand tend to self-regulate when they start to rise significantly, with users becoming discouraged if success rates drop too low. The over-subscription level at NCNR of approximately 2.1 indicates that it is in good health.

Performance indicators based on published output are difficult to establish and interpret. Gathering reliable data is a challenge. The institute itself can use a combination of searches in electronic databases and information received from users and instrument scientists as they share news about their recent publications. Such measures of quality will vary between various scientific domains; for example, impact factors of journals in the life sciences are significantly higher than in fundamental physics.

Probably the most widely used measure of quality by neutron scattering centers is the Vettier index, established by a former Institut Laue Langevin (ILL) science director, Christian Vettier.1 For the purposes of this report, a pragmatic approach has been adopted; the Vettier approach is used as one indicator of quality and is provided alongside the total number of publications in Table 3.1 for all user facilities in the United States, together with some of the other leading centers worldwide.

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1 This was based on a “shopping basket” list containing a number of relatively high-impact journals in which science performed at neutron scattering centers is commonly published. (The list was revised in 2008 and comprises the following journals: Nature, Nature: Physics, Nature: Materials, Science, PhysicalReview Letters, Physical Review B,C,E, JACS, Macromolecules, Langmuir, Journal of Molecular Biology,European Physics Journal: E, European Physics Letters, and Chemistry of Materials . The appearance of few European publications is due to political pressure to support such journals by members of the ILL scientific council but does not have a significant impact on the final values.) ILL takes charge of this process, first gathering papers through an electronic search (Thomson Web of Science) for the occurrence of the word “neutron” in papers from the shopping basket that bears the name of each institute. Each paper found in this way is checked manually to ensure that it is appropriate. The fact that at present only one institute gathers the data and checks each paper manually means for practical reasons that the number of journals considered is relatively small and does not evolve quickly with time, so it may not reflect changes in the journals in which scientists chose to publish. So, for example, not all of the strongest work in soft condensed matter and chemistry—areas of particular strength at NCNR—is captured by this approach. A better approach would be for each neutron scattering center to contribute a complete list of its publications every year to a common database, ensuring that the impact of every publication may be taken into consideration—an initiative to do this was launched at the last International Conference on Neutron Scattering meeting.



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3 NCNR in Relation to Neutron Facilities Nationally and Internationally A number of metrics are commonly used to provide some measure of performance of a user facility such as NCNR. Among them are the degree of user demand—or oversubscription—as well as the quantity and quality of published output. Other measures of performance include the number of students trained, beam-days sold to industry, and case studies that illustrate the impact on society at large of the research carried out. The level of user demand is not in itself a measure of performance, but rather an indicator of the size and strength of the community that chooses to use a particular institute where there is a choice. Levels of demand tend to self-regulate when they start to rise significantly, with users becoming discouraged if success rates drop too low. The over-subscription level at NCNR of approximately 2.1 indicates that it is in good health. Performance indicators based on published output are difficult to establish and interpret. Gathering reliable data is a challenge. The institute itself can use a combination of searches in electronic databases and information received from users and instrument scientists as they share news about their recent publications. Such measures of quality will vary between various scientific domains; for example, impact factors of journals in the life sciences are significantly higher than in fundamental physics. Probably the most widely used measure of quality by neutron scattering centers is the Vettier index, established by a former Institut Laue Langevin (ILL) science director, Christian Vettier.1 For the purposes of this report, a pragmatic approach has been adopted; the Vettier approach is used as one indicator of quality and is provided alongside the total number of publications in Table 3.1 for all user facilities in the United States, together with some of the other leading centers worldwide. 1 This was based on a “shopping basket” list containing a number of relatively high-impact journals in which science performed at neutron scattering centers is commonly published. (The list was revised in 2008 and comprises the following journals: Nature, Nature:Physics, Nature:Materials, Science, Physical Review Letters, Physical Review B,C,E, JACS, Macromolecules, Langmuir, Journal of Molecular Biology, European Physics Journal:E, European Physics Letters, and Chemistry of Materials. The appearance of few European publications is due to political pressure to support such journals by members of the ILL scientific council but does not have a significant impact on the final values.) ILL takes charge of this process, first gathering papers through an electronic search (Thomson Web of Science) for the occurrence of the word “neutron” in papers from the shopping basket that bears the name of each institute. Each paper found in this way is checked manually to ensure that it is appropriate. The fact that at present only one institute gathers the data and checks each paper manually means for practical reasons that the number of journals considered is relatively small and does not evolve quickly with time, so it may not reflect changes in the journals in which scientists chose to publish. So, for example, not all of the strongest work in soft condensed matter and chemistry—areas of particular strength at NCNR—is captured by this approach. A better approach would be for each neutron scattering center to contribute a complete list of its publications every year to a common database, ensuring that the impact of every publication may be taken into consideration—an initiative to do this was launched at the last International Conference on Neutron Scattering meeting. 7

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Comparisons of neutron scattering centers should also take into account the relative size of operations, such as the number of instrument days, the number of staff associated scientifically or technically with each instrument, and the budget, noting that there is generally a delay of a year or two between performing an experiment and publishing the results. For example, noting the relative scale of the operations (in terms of instrument days, budget—that for the ILL is at least twice as large as that for the NCNR—and staffing levels per instrument, with 4.5 and 7.0 full-time equivalent staff [FTEs] for NCNR and ILL respectively), the NCNR scores very highly for the quantity and quality of its output and, together with ISIS (the pulsed neutron and muon source at the Rutherford Appleton Laboratory in Oxfordshire, U.K.), is comfortably among the top three centers in the world in terms of the number of high-impact publications. It will take a few more years before SNS (Spallation Neutron Source at the Oak Ridge National Laboratory), HFIR (High Flux Isotope Reactor at the Oak Ridge National Laboratory), MLZ (Meier-Leibnitz Zentrum, based at the FRM-II reactor in Germany), and ANSTO (Australian Nuclear Science and Technology Organisation) reach a steady state in terms of the number of instrument days, after which a more meaningful comparison can be made between different institutes. The success of the NCNR over the years is largely attributable to their strategy of building on areas of strength, matching instruments with support facilities, fostering in- house scientific and technical expertise, and attracting a strong user community to bring their science there as well. The instrumentation is particularly strong for the study of large-scale structures (SANS [small angle neutron scattering], incorporating USANS [ultra-small angle neutron scattering], and reflectometry), with complementary sample- environment equipment such as rheometers. Spectroscopy has also benefitted from strong instrumentation, with MACS-II (Multi Axis Crystal Spectrometer) a world-leading addition to the stable, and is matched by very strong user groups and in-house scientists in this field. This combination of strong users and in-house scientists has also ensured excellent output in diffraction, despite instrumentation that is not world-leading; even stronger science could emerge with a modest investment in an upgrade here. The NCNR’s instrumentation and neutron technology are among the best in the world. It is world-leading in the SEOP (spin-exchange optical pumping) technology for 3 He polarisation optics, and it has a small but high-quality activity in neutron optics and detector developments. The multiplexed reflectometer, CANDOR (chromatic analysis neutron diffractometer or reflectometer), promises a step-change in capability in its field and is likely to be of great interest to those at other steady-state sources; NCNR staff described exciting prospects in very-high-resolution imaging using a novel neutron microscope that borrows from concepts developed for the Chandra X-ray Observatory; a collaboration has been established between NIST, the Massachusetts Institute of Technology, and NASA with the aim of reaching 1 µm spatial resolution. All of this is indicative of an NCNR culture in which creative thinking is encouraged and thrives. 8

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TABLE 3.1 Comparison of NCNR with Other Neutron Facilities NCNRa HFIRb SNSb LANSCEc ILLd ISISe MLZf ANSTOg Number of 23 12 15 8 40 28 26 5-7 instruments Days of operation 267 150 200 125 200 120 240 285 per year Number of 323 307 231 131 552 436 172 92 publications in 2010 Number (and 62 (19) 49 (16) 36 (16) 28 133 (16) 70 (16) 42 (24) 32 (17) percentage) of high-impact publications (using the Vettier index) Measure of 19.0 5.8 13.0 7.6 14.5 7.7 36.3 9.8 facility output = (number of instruments x number of days) ÷ number of papers Type of neutron Reactor Reactor Spallation Spallation Reactor Spallation Reactor Reactor source Megawatts 20 85 1.0 0.1 58 0.25 20 20 NOTE: Figures represent data for 2012. a NIST Center for Neutron Research, available at http://www.ncnr.nist.gov/AnnualReport/FY2012/AR_2012_large.pdf. Data reported here are for mid-2011 to mid-2012. b High Flux Isotope Reactor at the Oak Ridge National Laboratory; Spallation Neutron Source at the Oak Ridge National Laboratory, available at http://neutrons.ornl.gov/media/pubs/2012-published.shtml. c Lujan Neutron Scattering Center at the Los Alamos Neutron Science Center Spallation Neutron Source at the Oak Ridge National Laboratory. Data supplied by Lujan. d Institut Laue-Langevin, available at http://www.ill.eu/fileadmin/users_files/Annual_Report/AR- 12/page/publications.htm. e Spallation Neutron Source in the United Kingdom, available at http://www.isis.stfc.ac.uk/about- isis/annual-review/2012/isis-annual-review-2012-pdf13438.pdf. f Meier-Leibnitz Zentrum based at the FRM-II reactor, Germany, available at http://www.mlz- garching.de/annual-reports. g Australian Nuclear Science and Technology Organisation, available at http://neutron.ansto.gov.au/Bragg/proposal/PublicationList.jsp?year=2012&type=1. 9