Finding: For five decades, the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) has played a vital role in National Bureau of Standards (NBS) and then NIST internal research, calibration and metrology, and standards development as well as providing an outsized role in advancing neutron scattering in the United States as a user facility for the external scientific academic, national laboratories, and industrial communities.

Finding: Until 2021, NCNR has had an excellent safety and reliability record, and from 2016 to 2019 has delivered an average of 220 days of operation per year.

Finding: Owing to the onset of the global COVID-19 pandemic, NCNR suspended operations of the reactor from March 17, 2020, and restarted it on July 15, 2020, with reduced staffing, internal use only of the instruments, and some support for mail-in external user operations. The reactor and beamline instruments ran in this way for three run cycles, with an intention to begin another cycle in February 2021. On February 3, 2021, the reactor experienced an automatic unplanned shutdown owing to fission products detected in the confinement building upon normal startup. There were no health or safety impacts on personnel, the public, or the environment; however, the reactor remains shut down while NCNR determines the root cause of the incident, implements corrective and preventative actions, and requests a restart from the Nuclear Regulatory Commission (NRC). This comes 2 years before the planned 11-month reactor shutdown set to begin in calendar year 2023 to upgrade the cold neutron source from hydrogen to deuterium before switching from high enriched uranium (HEU) to low enriched uranium (LEU) fuel.

Conclusion: The unplanned shutdown has greatly affected the U.S. neutron scattering community. The need for relicensing of the reactor in 2029 and current plan for HEU to LEU conversion in the same year will challenge NCNR (extensive work required for relicensing, increased but unknown cost of yet to be developed fuel) and increase the downtime for the U.S. scientific user community.

RECOMMENDATION: To minimize impact to the user community, the National Institute for Standards and Technology (NIST) Center for Neutron Research (NCNR) leadership should make sure that the scheduled downtime for the NCNR cold source upgrade does not coincide with the planned shutdown of the High-Flux Isotope Reactor at Oak Ridge National Laboratory for its high enriched uranium to low enriched uranium conversion and reactor vessel upgrade. NCNR staff should develop a formal plan for user access during the 2023 shutdown as well as a formal plan for user access with the other U.S. neutron facilities.

Finding: Massive amounts of data and metadata are being generated from new and upgraded instruments and from the combination of simultaneous characterization techniques on the same

sample, overwhelming current data management systems. There is increasing demand for timestamped data, metadata, and data storage utilizing the principles of Findability, Accessibility, Interoperability, and Reuse of Digital Assets (FAIR).

Conclusion: As a standards agency, there is an opportunity for NIST and NCNR to be leaders in community efforts to establish standards in data markup and data management utilizing FAIR principles at large data rates.

RECOMMENDATION: The National Institute for Standards and Technology (NIST) Center for Neutron Research (NCNR) instrument staff should collaborate with and learn from NIST staff outside NCNR who are working on data standards. They should resist the urge to develop their own software tools from scratch and ensure that they make use of community efforts in image reconstruction and analysis and maintain their good connection to the neutron and X-ray imaging community.

Key Finding: The NCNR reactor (known as the National Bureau of Standards Reactor, or NSBR) is among the oldest operating large research reactors in the world, at more than 50 years of age. The current U.S. Nuclear Regulatory Commission (NRC) license will expire in 2029, and a new operating license application will be required. There are plans to change the nuclear fuel from high enriched uranium (HEU) to low enriched uranium (LEU). When operating an aging nuclear reactor, there are known issues that need to be addressed. Unfortunately, there are also unknown aging issues that can arise and can be very difficult to address. The design, construction, and licensing of a new research reactor will be lengthy and costly, on the order of 10 years and a billion dollars.

Key Finding: The National Bureau of Standards Test Reactor (NBSR) staff has given some consideration to a new reactor concept and a study has been commissioned on the economic impacts of reactor-based neutron scattering. The planning process for a new reactor has begun but is moving slowly without new funding for a science case and for design of a new reactor tailored for cold neutron instruments and using LEU fuel. A long shutdown of NCNR would have a major impact on both the U.S. fundamental research effort as well as U.S. industrial competitiveness.

Key Conclusion: Additional input is warranted from the research community to understand its needs, more detailed design concepts, and a more robust cost estimate for the new reactor. It is important to have a design that is optimized for LEU fuel and that allows for future modifications because the new reactor should operate for 50 years. The opportunity here is to rethink the needs for science with neutrons 50 years out for both industry and the U.S. scientific community and to provide that case to Congress in order to obtain the funding for a new reactor able to meet those needs.

KEY RECOMMENDATION: The Director of the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) should take a leadership role and own this mission with full support of NIST. The Director of NCNR should commission a study to define what the research community needs for the next 50 years in addition to the economic study already commissioned. In parallel and starting as soon as possible, the Director of NIST and the Director of NCNR should be proactive with the Visiting Committee on Advanced Technology, the User Group Executive Committee, the local community, the U.S. Nuclear Regulatory Commission (NRC), and the appropriate congressional committees to ensure support and to build the case for constructing a new research reactor.

Finding: There is a critical need for the United States to develop a compelling future vision for powerful neutron facilities, including reactors to maintain competitiveness with Europe and Asia with better resourced and staffed facilities.

Conclusion: The prolonged shutdown of the NCNR reactor, newer facilities, and better staffing abroad may cause leading-edge scientists, both instrument scientists and users, to move to work and do their research at the best facilities, not in the United States.

Finding: Remote use of the instruments by outside users is hampered by NIST firewalls. After the restart of operations during COVID-19, only on-site staff and users could perform experiments, with samples sent to NCNR. This requires more staff to perform the “remote” experiments. Automation of sample environments and experiments are beginning to be realized.

Conclusion: The future staffing needs and systems that allow automation for instruments will increase owing to the likely increase in users wanting to conduct remote experiments. This is especially the case for serving the needs of industry, which is important for enabling NIST’s mission.

RECOMMENDATION: The National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) leadership and staff should continue to work on enhancements to systems and/or staffing to serve remote users and to increase automation to better serve the user community into the future. The team should consider developing and strengthening its connections to university-based engineering research groups with links to industry as a mechanism for increased usage of the engineering diffractometer, and potentially as a mechanism for support for additional staffing.

Finding: NCNR has been successful at recruiting and retaining high-quality staff, and this is one of the key factors in the good productivity and outsized scientific impact. There is a very successful postdoctoral program that is quite diverse and results in a relatively high number of placements into academic positions at the end of the postdoctorate.

Key Finding: The long-term impact of 7 years of flat budgets has caused a reduction of NCNR instrument staff by 20 percent, to a level significantly below international standards.

Key Conclusion: 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 continue to maintain a pipeline of such staff (e.g., through Ph.D. and postdoctoral programs) with a broad portfolio of instrumentation capacity and capability.

Key Conclusion: The reduction of instrument staff, already low by international standards, is reducing capabilities essential for a world-class user facility and reducing NCNR’s ability to develop and continuously upgrade cutting-edge instruments, necessary for a very old reactor to increase scientific productivity. Improvements in efficiency and technology developments have reached their limits of maximizing the efforts of the current staff over the past 7 years of flat budgets. If this continues, it is likely to even more greatly impact staff morale and the scientific productivity of the facility. More staff is needed in hardware and especially software to realize the potential of time-resolved studies.

KEY RECOMMENDATION: The National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) leadership should work with NIST leadership to ensure the support of NCNR at the level of staffing it needs to continue to develop upgrades and enhancements to instruments to ensure a world-class user facility.

Finding: NCNR hosts a suite of 30 neutron beam instruments, of which 17 are neutron scattering instruments operated by NCNR and 13 are imaging, analytical chemistry, and neutron physics instruments operated by the NIST Physical Measurement and Materials Measurement Laboratories.

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: The staff and users at NCNR have continued to upgrade and enhance the instrument suite in a rolling program, building on their strengths and ensuring that they remain on, or close to, the cutting edge of neutron scattering instrumentation. The work is leveraged with additional funding from NSF and NIST programs, and NCNR has been successful in being responsive to such opportunities.

Key Conclusion: The upgrades and continual enhancements to instruments are owing to the outstanding quality of NCNR staff, with time to perform its own research and to collaborate on science with external users. It is essential for continued success at NCNR that the instrument staff can continue to perform its own research, thus attracting and retaining the best staff and users, and that this program of upgrades and enhancements is supported as a core part of facility operations to meet its mission to the user community.

Finding: The D2 cold source project is currently on track and well managed.

Conclusion: The opportunity to have enhanced long-wavelength flux for the cold neutron instruments is notable, and with the conversion to LEU now scheduled to occur in 2029 at the earliest, there will be a significant period of operations where the user community will benefit from this flux enhancement.

Finding: Several instruments at NCNR are unique in the world or will be world class with continuing development, allowing research that can be done nowhere else. These are (1) the Chromatic Analysis Neutron Diffractometer or Reflector (CANDoR) instrument, a multiplexed, “white-beam” neutron reflectometer that makes use of banks of graphite monochromators, closely coupled with detectors, to measure reflectivity curves at multiple wavelengths simultaneously; (2) the Very Small Angle Neutron Scattering (vSANS) instrument; (3) the Neutron Interferometric Microscopy-Far Field Imaging system conceptual design; and (4) the new capability of time-resolved data acquisition at the Multi-Axis Crystal Spectrometer (MACS) enabled by sophisticated complex sample environments.

Key Finding: Upgrades or planned upgrades to several instruments will bring them to par or nearly to par with global counterparts. These are the Neutron Spin Echo Spectrometer (NSE) upgrade and the Polarized Large Angle Resolution Spectrometer (PoLAR) secondary continuous-angle multiple energy analysis spectrometer for the Spin Polarized Inelastic Neutron Spectrometer (SPINS) replacement.

Finding: Planned upgrades to the BT-8 engineering diffractometer and planned replacement of the NG-5, NG-6, and NG-7 beam guides using supermirror optics will represent significant advances.

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 “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.

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: The NCNR user program continues to enjoy enormous success in terms of productivity, scientific impact, and user satisfaction. Publication rates and impacts are high compared to international user facilities. The Center for High Resolution Neutron Scattering (CHRNS) is a longstanding impactful NIST-NSF partnership that provides user support, education, and outreach to the academic scientific community, and has been renewed for another 5 years. The number of proposals to use beamtime were oversubscribed by roughly a factor of 2, and supported users continued to rise to roughly 3,000 per year in 2020.

Finding: NCNR sponsors highly effective partnerships, cooperative agreements, and consortia for academia and industry as well as intra- and interagency collaborations.

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.

Conclusion: It would be beneficial for NCNR to consider increasing the number of partnership agreements, as long as they are meaningful, to further diversify the academic engagement and scientific impact of the center.

RECOMMENDATION: The National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) should consider developing and strengthening its connections to university-based engineering research groups with links to industry as a mechanism for increased usage of the engineering diffractometer and other industry-relevant instruments, and potentially as a mechanism for support for additional staffing.

Finding: NCNR has been very active in outreach activities. The flagship outreach program is the long-running Center for High Resolution Neutron Scattering (CHRNS)-sponsored summer school for graduate students and young scientists, which pivoted successfully to fully online in 2020. More than 30 percent of the attendees are from underrepresented groups, and more than three-quarters of the attendees return as users. CHRNS pursues many avenues for engaging researchers from institutions that serve diverse groups, including travel support for an additional graduate student as part of the beamtime allocated to awarded proposals, outreach, and tours during the year from middle school up to high school and summer programs for teachers, high school students, and undergraduates. CHRNS will use the opportunity provided by the current increased telework environment to develop a new virtual or hybrid activity that will incorporate some of the most successful aspects of the virtual summer school. This program, which will have a specific focus on enhancing the diversity of CHRNS users, will be started soon.

Conclusion: NCNR pursues most of the myriad outreach activities through CHRNS, in order to recruit underrepresented groups into science, technology, engineering, and mathematics (STEM) fields and new neutron scattering users and to assist local schools and communities.

RECOMMENDATION: Information on the size, underrepresented population served, and outcomes of the many training, partnership, and outreach activities per year should be provided in the future in order to better assess their impact.