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Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
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4

Technical Adequacy

CONDENSED MATTER PHYSICS: SOFT MATTER, BIOLOGY, AND BIOPHYSICS

The National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) instruments available for characterizing soft matter include structural measurements with Small-Angle Neutron Scattering (SANS) and reflectometry: Ultra Small Angle Neutron Scattering (uSANS); Very Small Angle Neutron Scattering (vSANS); two 30-meter SANS; Multi-Angle Grazing Incidence K-Vector (MAGIK) reflectometer; Polarized Beam Reflectometer (PBR); horizontal reflectometer (to be sunset); the new Chromatic Analysis Neutron Diffractometer or Reflectometer (CANDoR); and spectrometers to resolve short-time dynamics—Neutron Spin Echo Spectrometer (NSE) and High-Flux Backscattering Spectrometer (HFBS). This comprehensive suite of instruments enables soft matter researchers to address problems across multiple time and length scales, where the use of neutrons is necessary and critical. The portfolio of research, especially in complex and self-assembling systems, is impressive and competitive against other neutron scattering facilities across the world. The flexibility of vSANS, including large q-range and integration with a variety of sample environments, is a workhorse for high-impact science. Once fully outfitted with detectors, CANDoR will be a best-in-world reflectometer with unprecedented capabilities for a reactor neutron source and distinct advantages over spallation sources that will enable NCNR to carry out new and innovative science, especially in the time-resolved domain. Another significant improvement is the upgrade to NSE funded by a National Science Foundation (NSF)-Mid-Scale Research Infrastructure Program (MSRI) led by the Center for Neutron Science at the University of Delaware. The enhanced flux afforded by the liquid deuterium (LD2) moderator will be a further enhancement across this suite of spectrometers. The partnership with NSF to operate the Center for High Resolution Neutron Scattering (CHRNS), which supports the operation of vSANS, CANDoR, HFBS, and NSE spectrometers, continues to be a crucial component for continued access for users and leadership in soft matter research.

Accomplishments

NCNR continues to maintain a high-quality research portfolio in soft matter and is poised to continue its world-leading program in self-assembling systems. The scientific staff at NCNR responsible for the vSANS and CANDoR spectrometers are crucial for maintaining leadership and accessibility of neutrons for users. CANDoR was a risky endeavor originally but has been fully demonstrated. Its performance and low background will be a game changer in reactor-based reflectivity instruments once fully outfitted with detectors. The NCNR staff is commended for working through the challenges to realize this instrument. Completing this spectrometer should be a high priority.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
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NCNR continues to be a leader in the area of membrane biology and biophysics, including NSE measurements of membrane dynamics.1 The NSE spectrometer upgrade is a welcome and necessary improvement and will enable an improved program for U.S. researchers. However, NSE capabilities are surpassed by high-flux reactors available outside the United States, and so a continued focus on the scientific leadership in membrane dynamics will be key to making the most of the new instrument. The MAGIK reflectometer has a well-established and recognized program in measuring protein, small molecule, polymer interactions with supported membranes with a very high productivity/publication rate. The integration of steered molecular dynamics (MD) for analysis is important for extracting the greatest amount of information from data collected in this research area.2 Given that more than 60 percent of all FDA-approved small molecule drugs target membrane proteins, however, their structural characterization is particularly challenging with standard techniques. Further development of neutron reflectometry methods on supported membranes, along with the integration of MD simulations, is likely to aid in the development of small molecule drugs to inhibit this challenging class of drug targets. The nSoft industrial consortia with NCNR has demonstrated longevity and benefits not only to industry sponsors but also to the wider soft matter user community through developments in automated sample formulations and capillary-rheo SANS.

The quality of instruments and staff expertise is ushering in a new focus on time-resolved measurements. Absolute time stamp data acquisition is a significant advancement for reactor sources. Similar efforts directed toward analysis of neutron scattering data in the context of other complementary techniques, MD simulations to extract the most information possible on scientifically important topics, and use of artificial intelligence (AI), machine learning (ML), and automation will yield impactful results, and fast-tracking these efforts given the reactor shutdown was an efficient reallocation of staff time and effort. Likewise, NIST and NCNR are the appropriate place for implementing the Findability, Accessibility, Interoperability, and Reuse of Digital Assets (FAIR) data effort under CHRNS. These comprehensive efforts spanning data acquisition and analysis are going to have real impact on the soft matter and biological program. A lot of important soft matter dynamics occurs at the millisecond time scale and will be accessible by vSANS and CANDoR’s improved time resolution.3

The NCNR staff’s sustained efforts toward attracting new users for neutron scattering to address important questions not answerable from other techniques is applauded. The work in collaboration with J. Robertson4 investigating the role of lipid structure in membrane transporter dimerization is a great demonstration of how outreach by NCNR staff can grow the community. However, such activities are time consuming for staff in terms of developing the relationship, science question, and ultimately design of experiment and analysis. Ensuring sufficient staffing levels to support the user community and scientific enterprise is a critical need.

Improvements in SASSIE and SASView (names of software for analyzing data) are enabling users to better analyze their data in the long term but can be a drain on staff in the short term. The coordinated effort across facilities around the world is to be applauded, and NCNR leadership in SANS analysis and SASSIE was part of initiating these loose consortia. Integrating time-resolved studies and analysis will be another significant challenge and would benefit from broadening the collaborative team to include outside users and the soft matter community across both SANS and reflectivity. Reflectivity analysis in particular demands user-friendly software to enable nonexpert data analysis and interpretation.

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1 E. Kelley, NIST, 2021, “Measuring Lipid Membrane Dynamics on the Mesoscale with NSE,” presentation to the Panel on Assessment of the Center for Neutron Research, July 21.

2 F. Heinrich, NIST, 2021, “The Structure of Membrane-Associated Proteins,” presentation to the Panel on Assessment of the Center for Neutron Research, July 21.

3 A. Grutter, NIST, 2021, “CANDOR: A Polychromatic Next-Generation Reflectometer,” presentation to the Panel on Assessment of the Center for Neutron Research, July 21.

4 J. Robertson, Washington University, 2021, “Membrane Transporter Dimerization Driven by Differential Lipid Solvation Energetics,” presentation to the Panel on Assessment of the Center for Neutron Research, July 21.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
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Last, a number of the presentations demonstrated the importance of (1) NCNR’s talented postdoctorates contributing to and working with NCNR staff to push new research areas and advances; (2) the leveraging of tight collaborations with the University of Delaware and the Center for Neutron Science for sustained scientific productivity; and (3) the importance of the suite of instruments spanning SANS to NSE to tackle new research areas.

Challenges and Opportunities

As CANDoR becomes fully outfitted, it will surpass the capacity of MAGIK and PBR by a factor of about 5. Optimization of staff to fully support CANDoR and find additional partners for operating MAGIK and PBR may be possible with long-term or high-risk research programs. This is an opportunity and a challenge for NCNR to manage these instruments efficiently with limited resources.

NSE will be much improved. Operation of the spectrometer will be new, and obtaining knowledge transfer from Jülich will be important for rapidly integrating the new instrument into the user program. Broadening the user program across the soft matter domain is an opportunity to drive new and innovative science but requires significant staff effort and time.

Fully realized time-resolved studies will have an enormous impact on the science questions that NCNR can address. This opportunity will bring with it the challenge of developing the user program and software tools (including real-time visualization and post data analysis) to bring these techniques to the broadest possible user community in soft matter, biology, and biophysics. Many of the most pressing and impactful science questions to be addressed are by new users to neutron scattering. Reaching these potential users will require sustained outreach by NCNR staff and support to design and execute experiments and analyze the data.

HARD CONDENSED MATTER

Research conducted at or enabled by facilities at NCNR in the field of hard condensed matter are centered on fundamental and applied magnetism and the intertwined subjects of superconductivity and multiferroic materials. Understanding the physics of such materials is at the heart of solutions to sustainable energy, national security, advanced transportation and more. Leadership in the understanding and exploitation of advanced materials such as these has significant economic benefits through the nucleation of high-tech manufacturing and development of advanced devices. In particular, advanced magnetic materials are used extensively for data storage, in the area of health in a range of applications where they are attached to or implanted into the body, in home entertainment tech, and in advanced electricity generation and next-generation electric vehicles. Superconductors and magnets are both used in medical imaging devices. The promise of quantum computing is heavily dependent on understanding and developing quantum materials. Multiferroics are used as actuators in industrial and military applications with potential applications in next-generation information storage technologies. The structures of such systems are probed primarily by neutron diffraction on the powder diffractometer BT-1 and the triple-axis spectrometer BT-7, with larger-scale structures explored by SANS and reflectometry. Excitations may be explored through a suite of thermal and cold-neutron spectrometers, of which the Disc Chopper Spectrometer (DCS, NG-4) and, increasingly, the newer Multi-Axis Crystal Spectrometer (MACS, BT-9) strongly feature in the highest-profile publications, arguably because some of the most challenging current problems in magnetism involve quantum disorder, which is often characterized by continua of scattering over momentum space Q and energy that requires mapping over both parameters, a strength of MACS. The instrument suite is complemented by extensive sample environment equipment with expert technical support to enable systems to be studied over a wide range of temperature and magnetic field.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×

Accomplishments

The scientific impact of NCNR in hard condensed matter is world class, with a steady flow of very high impact publications. Several recent highlights involve topological spin excitations, such as work on excitations in the layered honeycomb ferromagnet CrI3 and on the kagome metal YMn6Sn6—the magnetic structure of the two systems was determined by diffraction measurements at BT-1 and BT-7, respectively. Neither of these instruments is technically world class, but they are nevertheless critical for establishing or confirming the magnetic structure of materials and the basis for exploring their excitations. NCNR does however enjoy technical poll-position in MACS, which is world leading in its class of instrument in terms of monochromatic cold-neutron flux. In recent years, MACS has been equipped with highly efficient wide-angle polarization analysis through a 3He cell, and most recently still, offers event-mode measurements that open up wholly new vistas for dynamic measurements, in terms of both time scale and synchronization with external probes or fields applied to the sample. For example, measurements on the highly frustrated spin-ice pyrochlore Ho2Ti2O7 in a pulsed magnetic field allowed stroboscopic neutron scattering studies of the magnetic fluctuations out to very long (> 0.1 ms) time scales that untangled contributions from dipolar and unique, low-temperature monopolar relaxation processes. A key feature of this work was close collaboration between in-house staff and a user group to develop and integrate the sample environment with the instrument to provide the pulsed field synchronized with data collection. A bespoke sample environment also allowed spectroscopy to be performed on MACS during microwave irradiation, which allowed excited states in a Cr8 single molecule magnet (SMM) to be selectively populated and studied, providing proof of principle for a much wider range of studies of SMMs.

The panel also notes continuing work to unravel the origins of unconventional superconductivity in the Ferromagnetic Spin-Triplet system UTe2, and in particular the interplay with magnetism, which has led to very high profile publications. While neutron scattering facilities at NIST have not yet been deployed in this work, NCNR scientists have played prominent roles, which is characteristic here. The strength of the condensed matter physics (CMP) program is as much owing to the strength of the in-house scientists and the collaborations they bring as to the instrumentation.

Last, the panel notes the impact of the ongoing drive to improve user services and in particular improvements to cryogenics to speed up cooling times and to reduce consumption of helium, an increasingly expensive and rare resource.

Challenges and Opportunities

MACS and the science it enables is stellar and is likely to deliver world-leading science for years to come, especially with the developments such as time stamping neutron arrival at the detectors and time-dependent fields (e.g., magnetic pulses) at the sample, and underpinned by excellent in-house science and technical support. This will be particularly important in exploiting the potential for time-dependent studies with unprecedented sensitivity (to low cross-section processes) or unrivalled dynamic range (time scales), where integration of external probes with the counting software will be essential.

Instruments BT-1 and BT-7 are no longer technically world class but nevertheless will continue to play a critical role in essential characterization of magnetic and superconducting systems—and indeed for a much wider range of scientific areas—that is also very hard to access elsewhere. It would have a huge negative impact on the CMP program if these were not at least maintained.

The importance of topological and other nano- to mesostructured materials is likely to continue to grow and will benefit from increased access to SANS instruments and other means of measuring and interpreting data from large-scale structures.

X-ray methods have been developing very quickly in the past decade and have made very significant inroads into areas that were traditionally the preserve of neutron scattering. This includes inelastic methods such as Resonant Inelastic X-Ray Scattering (RIXS), where excitations approaching 10 meV may be resolved, and samples may be much smaller—for example, atom-thick layers or films, of great

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×

interest in topological systems. However, it is likely to be some time before excitations close to and below 1 meV in energy may be resolved. Furthermore, the calculation or interpretation of scattering cross sections is far more straightforward for neutrons, and the control and precise and accurate measurement of the temperature of samples in the ultra-low regions is still crucial to understanding key phenomena in this field and is also far more satisfactory for neutrons compared to X rays.

Last, the critical dependence of the success of NCNR in this field on excellent staff requires a sustained, long-term campaign to attract or train the next generation, noting that there is greater competition than ever before for such people to go into other types of facilities (e.g., synchrotrons) or areas of science. The Ph.D. programs and postdoctoral research posts are essential for the long-term survival and effectiveness of this highly valuable national resource for this field.

Finding: The hard condensed matter program is producing world-class science. World-leading spectrometer MACS-II offers unique experimental capability (e.g., event mode measurements accessing unique time scales) that is already delivering stellar science with the promise of much more to come.

Finding: Instruments such as BT-1 and BT-7 are workhorses but are also essential to the delivery of very high quality science. There will be a negative impact if these capabilities are lost.

Finding: Excellent in-house staff attracts and enables effective partnerships with excellent external groups and is essential to world-class scientific output. It is critical to maintain a pipeline of such staff (e.g., through Ph.D. programs) and a broad portfolio of instrumentation capacity and capability.

CHEMICAL PHYSICS

Introduction

It is clear to the panel that the staff of NCNR is fully committed to supporting users. Positive comments on user experiences are plentiful and similar to these:

As a “major research facility service” to support independent researchers working at the cutting edge, NCNR is without equal in terms of customized support through integrated teamwork by beam scientists with associated support personnel focused on the needs of each individual user, whom they get to know.

The user office is outstanding and VERY helpful, we would have lost several beam days every cycle without their help and support.5

On the scientific side, the Chemical Physics team is highly productive. During 2019–2020, the team published several papers that are already highly cited (see Appendix D), in spite of their recent publication. The Chemical Physics team published a total of 79 papers during the 2019–2020 time frame, which have garnered a total of 1,362 citations, or approximately 17 citations per publication, an excellent record for very new papers. The whole of NCNR published a total of 530 papers; thus, Chemical Physics contributed approximately 15 percent of the productivity at NCNR.

Topics range from hydrogen storage and gas separation materials, metal-organic frameworks, hydrogen evolution materials, and alloy catalysts. Thus, the research is related to energy technologies, including new materials for electrodes or electrolyte in next-generation batteries, and photovoltaics, to optoelectronic technologies, and to separation science and catalytic systems, all of which are

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5 R. Dimeo, NIST, 2021, “Overview NCNR,” presentation to the Panel on Assessment of the Center for Neutron Research, July 20.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×

technologically/industrially relevant. Neutrons provide a particularly incisive probe in this field, where the structure and dynamics of hydrogen or hydrogen-rich molecules, as well as that of other light elements such as lithium, are critical to many of the key materials and processes. The NCNR suite of instruments is also well-adapted to this field, from powder diffraction measurements and SANS and reflectometry studies of nanomaterials and surfaces and interfaces, to inelastic and quasielastic studies of excitations and diffusion, many in combination with dedicated sample environment equipment—for example, to enable loading and manipulation of gases in situ.

Accomplishments

Many of the most highly cited recent publications from work at NCNR are in the field of energy technologies. Prominent examples include work to improve the performance of organic nanoparticles as photocatalysts for the conversion and storage of solar energy through hydrogen production.6 SANS studies of nanoparticles incorporating a semiconductor heterojunction revealed how control of their nanomorphology through the method of synthesis greatly increased their efficiency in generating hydrogen. Neutron depth profiling studies7 were used to explore the potential of solid electrolytes for lithium anodes for high-energy batteries, revealing the growth of lithium dendrites in situ and pointing to ways in which these materials might be used most effectively in future devices.

On the topic of metal-organic frameworks, a series of collaborative publications with research groups at University of Texas, San Antonio, Zhejiang University, and other groups in academia, novel porous materials including microporous organic frameworks (MOFs)8 and hydrogen-bonded organic frameworks (HOFs)9 were explored as ethane selective adsorbents for ethane/ethylene separations. Analysis of powder X-ray diffraction and single crystal diffraction was used to determine the structure of these materials. Adsorption in a flexible MOF was found to exhibit a rare increase of adsorption capacity with temperature attributed to sorbate sorbent interactions affecting the MOF structure, and an application in the separation of propylene from propane was demonstrated.10 Neutron powder diffraction measurements conducted at the BT-1 neutron powder diffractometer at NCNR provided evidence for weak binding of CO2 as the basis of C2H2/CO2 selectivity in an iron/nickel metal-organic framework with multiple binding sites.11 In the later study, diffraction data were collected in CO2- and C2D2-loaded MOF samples. The use of deuterated acetylene allowed to avoid the large incoherent neutron scattering background caused by the hydrogen in C2H2. These and other studies of selective gas adsorption in MOFs including the use of neutron diffraction of gas-loaded samples to obtain structural information12 constitute a success of NCNR.

Challenges and Opportunities

In the area of Chemical Physics, there is excellent in-house expertise in both science and techniques, including in situ capabilities to develop much more, thus the opportunity to continue supporting and growing this area is well justified. As with other areas within NCNR, the challenge of replacing older equipment is certainly there and requires careful prioritizing to maintain a technological advantage.

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6 See J. Kosco, et al., in Appendix D.

7 See F. Han, et al., in Appendix D.

8 See J. Pei, et al., in Appendix D.

9 See X. Zhang, et al., in Appendix D.

10 See M.-H. Yu, et al., in Appendix D.

11 See J. Gao, et al., in Appendix D.

12 See R.-B. Lin, et al., in Appendix D.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×

ENGINEERING PHYSICS

Introduction

NCNR’s current effort in engineering physics is focused on (1) stress analysis of industrial-scale parts (e.g., automotive, made by additive manufacturing) using residual stress diffractometer; (2) imaging of complex engineering devices evolution during operation, including materials aspects of novel battery technologies; and (3) analysis of microcrack formation in concrete, as it affects seismic resilience of existing structures critical for the U.S infrastructure. These efforts are consistent with the aspects of the NCNR mission supporting NIST in serving U.S. industries and manufacturing. These activities are of great societal impact because, based on neutrons unique capabilities to probe nondestructively the interior of structures and components, they provide information regarding the aging of infrastructure (e.g., concrete used in construction of buildings), and of parts and devices that are used in everyday life (e.g., batteries and automotive parts) which allow scientists and engineers to improve safety and reliability. The impact of these activities to the United States can be significant as, for example, the cost to owners to repair concrete in the United States is estimated to be $20 billion per year.13 Evidently, they also contribute to the timely development of new products based on novel technologies.

Accomplishments

Accomplishments in engineering physics include unique studies of engineering devices and serving U.S. industry and manufacturing. Impressive capabilities to analyze real-world samples and phenomena affecting structural properties during operation are available and they are combined with data analytics and multilevel resolution capabilities. Although publications in engineering journals may not be as highly cited as more science-focused publications, the work produced is of high value to the engineering research community and the U.S. industry and public. For example, neutron diffraction (BT-8 Residual Stress Diffractometer optimized for depth profiling of residual stresses in large components)14 combined with synchrotron X-ray diffraction (XRD) provided understanding of residual stress and strain caused by rapid melting and fast cooling encountered in additive manufacturing.

Challenges and Opportunities

There are opportunities to expand the range of industrially relevant problems addressed, especially with respect to the number of complex samples that can be analyzed and the range length and time scales that can be probed by combination of existing instruments and the development of new ones. An example is the ongoing development of a novel neutron imaging far field interferometer. The combination of interferometry, imaging, and small-angle scattering, which are all signature techniques of NCNR, to achieve structural characterization in heterogeneous materials (porous materials, concrete, gels) over extended length scales can have a transformative impact on hierarchical and architected materials for their emerging and established uses. Applications range from reliability of structural components in residential buildings, transportation, defense, and energy production, to packaging of food and medicine to ensure safety and efficacy. In addition to industry already involved in such activities at NCNR, this effort should

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13 American Society of Civil Engineers, “Investment Gap 2020–2029,” ASCE’s 2021 Infrastructure Report Card, https://infrastructurereportcard.org/resources/investment-gap-2020-2029/, accessed January 20, 2022.

14 T.Q. Phan, M. Strantza, M.R. Hill, T.H. Gnaupel-Herold, J. Heigel, C.R. D’Elia, A.T. DeWald, et al., 2019, Elastic residual strain and stress measurements and corresponding part deflections of 3D additive manufacturing builds of IN625 AM-bench artifacts using neutron diffraction, synchrotron X-ray diffraction, and contour method, Integrating Materials and Manufacturing Innovation, 8:318–334, https://doi.org/10.1007/s40192-019-00149-0.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×

engage the broader academic research community to determine challenges and design instruments for emerging research problems with high technological and societal impact. This engagement will eventually lead to the desirable outcome of recruitment of new industry participants. Challenges in both hardware (e.g., the fabrication of resolution-preserving dynamic transmission micro-grating) and software (AI to extract microstructural information) as well as the selection of high-impact problems to be addressed are an opportunity to engage the broader engineering community from academia and industry to participate in these forward-looking developments. NCNR’s achievements in engineering physics could be further highlighted beyond journal publications in media accessible to the public to disseminate the importance of neutron research and instrumentation development to change and improve everyday life. Some of these are highlighted on the NIST website.15

NEUTRON SCIENCE

The Neutron Physics Group (NPG), which is part of the Physical Measurement Laboratory (PML), operates eight beams at NCNR and focuses on three main areas: calibration and metrology, fundamental science, and applied physics research. It also has partnerships with the University of Maryland, the University of Waterloo, and the Department of Energy (DOE) Nuclear Physics (NP) and Energy Efficiency and Renewable Energy (EERE) programs. It operates through proposals and collaborations with universities and industry.

Accomplishments

The fundamental science experiments aim to test the standard model and go beyond the standard model to search for new physics—for example, search for a fifth force. These are very long term experiments (several years), focused on increasing precision through systematic tests, and cross-checks between different types of measurements. The electron-antineutrino correlation (aCORN) experiment has been running since 2017 and has already produced two publications. The neutron lifetime experiment was in progress on BL-2 until the unplanned shutdown and was planned to run through 2022, when the planned shutdown (for cold source upgrade) will occur. The Precision Neutron Metrology project at NCNR is developing Photon Assisted Neutron Detector (PhAND) thermal detectors and uses a unique NIST PML capability by measuring the absolute activity of an alpha source to ultimately determine neutron fluence with world-best precision. The neutrino physics project Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) determines the number of neutrinos that should be seen as a function of energy. This allows the group to resolve discrepancies between measured and calculated numbers of neutrinos.

As discussed in Chapter 2, the Interferometry facility is one of four in the world and one of the best two.16,17 A notable accomplishment was the introduction of the orbital angular momentum to create neutrino spin-orbit lattices in analogy to optical lattices produced by circularly polarized light.18 The group has also developed a novel measurement of the neutron charge radius, by using Pendellösung interference (interference inside a Bragg diffracting crystal). The Far Field Interferometry project aims at

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15 NIST, https://www.nist.gov/industry-impacts, accessed January 21, 2022.

16 K. Weigandt, et al., NIST, 2021, “Neutron Interferometric Microscopy Small Forces and Hierarchical Structures,” presentation to the Panel on Assessment of the Center for Neutron Research, July 21.

17 J. Nico, NIST, 2021, “Recent Neutron Physics Group Activities at the NCNR,” presentation to the Panel on Assessment of the Center for Neutron Research by S. Dewey and D. Hussey, July 21.

18 D. Sarenac, et al., “Generation and Detection of Spin-Orbit Coupled Neutron Beams,” Proceedings of the National Academy of Sciences, October 8, 2019, https://www.pnas.org/content/116/41/20328, accessed January 21, 2022.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×

developing a 10-meter-long path interferometer to explore weak interactions and increase sensitivity for measuring the gravitational constant (G).

The imaging group is developing a first-in-the-world tomography system that uses simultaneously neutron and X-ray beams, critical for testing infrastructure quality (fractures, pores, etc.).

Challenges and Opportunities

The NG-C fundamental physics beamline currently has the highest cold flux in the United States, but this is anticipated to be doubled with the liquid deuterium cold source, and furthermore with very low fast neutron and gamma backgrounds. The upgrades will allow a change in experiment post-outage, with a neutron spin rotation experiment planned.

Developments in thermal neutron detectors for use in demanding environments such as space, allowing for exciting applications such as Detecting Object’s Water with Spatial Epithermal-Neutron Resolution (DOWSER) for deployment on a planetary rover.19

The alpha-gamma neutron metrology activity is a unique NIST capability that can measure the absolute activity of an alpha source and determines neutron fluence with a world-best precision of 0.06 percent. This will become a user facility in the future, with potential applications in research and in industry.

The neutron interferometry group is able to perform high-precision measurements thanks to the very long, best in the world, stability of their instruments. This allows experiments such as entangling the neutron spin and angular momentum to create lattices of spin-orbit coupled states. A far field interferometry proof of concept has also been demonstrated (the INFER/IMS project), with a potential 10-meter-long path, which would be suitable for studying the weak interaction, for example.

The neutron imaging group of the NIST Physical Measurements Laboratory operating on BT-2 and NG-6 is very strong and highly impactful. It also operates a user program, allocating 25 percent of beamtime on the BT-2 instrument through a refereed proposal system, with additional access available through a collaborative access mechanism. Significant impacts have been demonstrated in fuel-cell technology with partnerships with General Motors and EERE at DOE. The group leverages the results with innovative software developments for processing the multitudes of data—for example, automated image segmentation tools. The recently installed (August 15, 2021) Cold Neutron Imaging Instrument (CNII) is commissioned and working well. There is a well-defined plan for developing this instrument. The upgrades are being coordinated with the guide renewals that are planned (NG-6 in this case) to optimize both. With the planned cold-source upgrade, the new curved supermirror, and a new innovative neutron imaging lens, imaging with time and spatial resolutions close to synchrotron-like performance will be possible for neutron imaging.

As well as the opportunities, significant challenges are experienced as a result of the outages, and this will significantly impact the entire NPG program. The NG-6 guide will start to be dismantled in October 2022 and will not be fully reinstalled and commissioned until 2026, 2 years after the completion of the cold source. Some instrument upgrades will be undertaken during the dark period. Of course, the result will be significantly improved performance across the entire suite of instruments.

Finding: NCNR has a vibrant research program that generates about 350 peer-reviewed papers per year, with above-average impact in terms of very highly cited papers. In a 2018 citation study by the Canadian group Science-Metrix, NCNR appears as the leading neutron facility in terms of average relative citations. In this metric, the world average number of citations is 1.0, and 1.2 would be 20 percent more citations than the average. NCNR scores nearly 2 (1.95) on this scale, with other world neutron facilities in the range 1.03 to 1.57 (for the period 2000–2017). The report also points out that

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19 J. Nico, NIST, 2021, “Recent Neutron Physics Group Activities at the NCNR,” presentation to the Panel on Assessment of the Center for Neutron Research, July 22.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×

“The NCNR is … the only institution examined to have displayed consistently high performances across most indicators.”

Finding: NCNR has world-class scientific standing in soft and hard condensed matter and biology, including self-assembling systems and membrane dynamics, topological insulators, and exotic superconductivity-magnetic interactions. The neutron science facilities are unique in the brightness of the cold flux, the stability of the flux, and the measurement precision, enabling many fundamental science measurements beyond the standard model. Industrially relevant measurements and characterization in chemical physics and engineering physics include dynamics of polymers, gels, and complex fluids, minerals and rocks, materials for energy technologies such as metal organic frameworks, catalysts and in situ measurements, and residual stress in industrial materials. The development of an instrument is in progress that will simultaneously combine X-ray and neutron tomography and will enable nondestructive testing of infrastructure such as concrete.

Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
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Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
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Page 27
Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×
Page 28
Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×
Page 29
Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×
Page 30
Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×
Page 31
Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×
Page 32
Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×
Page 33
Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×
Page 34
Suggested Citation:"4 Technical Adequacy." National Academies of Sciences, Engineering, and Medicine. 2022. An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021. Washington, DC: The National Academies Press. doi: 10.17226/26418.
×
Page 35
Next: 5 Portfolio of Scientific Expertise »
An Assessment of the Center for Neutron Research at the National Institute of Standards and Technology: Fiscal Year 2021 Get This Book
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At the request of the National Institute of Standards and Technology (NIST), the National Academies of Sciences, Engineering, and Medicine has, since 1959, annually assembled panels of experts from academia, industry, medicine, and other scientific and engineering communities to assess the quality and effectiveness of the NIST measurements and standards laboratories. The NIST Center for Neutron Research (NCNR) is one of six major research organizational units consisting of five laboratories and one user facility at NIST. It is one of only three neutron scattering user facilities in the United States, with 30 instruments, supporting roughly one-third of the U.S. neutron scattering instruments and users. This report assesses the scientific and technical work performed by the NCNR, as well as the portfolio of scientific expertise within the organization and dissemination of program outputs.

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