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DOE OSTI2022

High Energy Physics Opportunities Using Reactor Antineutrinos

Nuclear reactors are uniquely powerful, abundant, and flavor-pure sources of antineutrinos that continue to play a vital role in the US neutrino physics program. The US reactor antineutrino physics community is a diverse interest group encompassing many detection technologies and many particle physics topics, including Standard Model and short-baseline oscillations, BSM physics searches, and reactor flux and spectrum modeling. The community's aims offer strong complimentary with numerous aspects of the wider US neutrino program and have direct relevance to most of the topical sub-groups composing the Snowmass 2021 Neutrino Frontier. Reactor neutrino experiments also have a direct societal impact and have become a strong workforce and technology development pipeline for DOE National Laboratories and universities. This white paper, prepared as a submission to the Snowmass 2021 community organizing exercise, will survey the state of the reactor antineutrino physics field and summarize the ways in which current and future reactor antineutrino experiments can play a critical role in advancing the field of particle physics in the next decade.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Overview and History of DOE's Hanford Site - 12502

Hanford's DOE offices are responsible for one of the largest nuclear cleanup efforts in the world, cleaning up the legacy of nearly five decades of nuclear weapons production. Nowhere in the DOE Complex is cleanup more challenging than at the Hanford Site in southeastern Washington. Hanford cleanup entails remediation of hundreds of large complex hazardous waste sites; disposition of nine production reactors and the preservation of one as a National Historic Landmark; demolition of hundreds of contaminated facilities including five enormous process canyons; remediation of billions of gallons of contaminated groundwater; disposition of millions of tons of low-level, mixed low-level, and transuranic waste; disposition of significant quantities of special nuclear material; storage and ultimate disposition of irradiated nuclear fuel; remediation of contamination deep in the soil that could impact groundwater; decontamination and decommissioning of hundreds of buildings and structures; and treatment of 56 million gallons of radioactive waste in 177 large underground tanks through the construction of a first-of-its-kind Waste Treatment Plant. Cleanup of the Hanford Site is a complex and challenging undertaking. The DOE Richland Operations Office has a vision and a strategy for completing Hanford's cleanup including the transition to post-cleanup activities. Information on the strategy is outlined in the Hanford Site Completion Framework. The framework describes three major components of cleanup - River Corridor, Central Plateau, and Tank Waste. It provides the context for individual cleanup actions by describing the key challenges and approaches for the decisions needed to complete cleanup. The U.S. Department of Energy (DOE), as regulated by the U.S. Environmental Protection Agency (EPA) and Washington State Department of Ecology (Ecology), is implementing a strategy to achieve final cleanup decisions for the River Corridor portion of the Hanford Site. The DOE Richland Operations Office (RL) and DOE Office of River Protection (ORP) have prepared this document to describe the strategy and to begin developing the approach for making cleanup decisions for the remainder of the Hanford Site. DOE's intent is that the Completion Framework document will facilitate dialogue among the Tri-Parties and with Hanford's diverse interest groups, including Tribal Nations, State of Oregon, Hanford Advisory Board, Natural Resource Trustees, and the public. Future cleanup decisions will be enhanced by an improved understanding of the challenges facing cleanup and a common understanding of the goals and approaches for cleanup completion. The overarching goals for cleanup are sevenfold. - Goal 1: Protect the Columbia River. - Goal 2: Restore groundwater to its beneficial use to protect human health, the environment, and the Columbia River. - Goal 3: Clean up River Corridor waste sites and facilities to: Protect groundwater and the Columbia River. Shrink the active cleanup footprint to the Central Plateau, and support anticipated future uses of the land. - Goal 4: Clean up Central Plateau waste sites, tank farms, and facilities to: Protect groundwater. Minimize the footprint of areas requiring long-term waste management activities. Support anticipated future uses of the land. - Goal 5: Safely manage and transfer legacy materials scheduled for off-site disposition including special nuclear material (including plutonium), spent nuclear fuel, transuranic waste, and immobilized high-level waste. - Goal 6: Consolidate waste treatment, storage, and disposal operations on the Central Plateau. - Goal 7: Develop and implement institutional controls and long-term stewardship activities that protect human health, the environment, and Hanford's unique cultural, historical and ecological resources after cleanup activities are completed. These goals embody more than 20 years of dialogue among the Tri-Party Agencies, Tribal Nations, State of Oregon, stakeholders, and the public. They carry forward key values captured in forums such as the Hanford Future Site Uses Working Group, Tank Waste Task Force, Hanford Summits, and Hanford Advisory Board Exposure Scenario Workshops, as well as more than 200 advice letters issued by the Hanford Advisory Board (http://www.hanford.gov/page.cfm/hab). These goals help guide all aspects of Hanford Site cleanup. Cleanup activities at various areas of the site support the achievement of one or more of these goals. These goals help set priorities to apply resources and sequence cleanup efforts for the greatest benefit. These goals reflect DOE's recognition that the Columbia River is a critical resource for the people and ecology of the Pacific Northwest. The 50-mile stretch of the river known as the Hanford Reach is home to the last free-flowing section of the river in the U.S. As one of the largest rivers in North America, its waters support a multitude of uses that are vital to the economic and environmental well being of the region and it is particularly important in sustaining the culture of Native Americans. Cleanup actions must protect this river. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Evolution of Stakeholder Relations at the Mound Laboratory-End of DoE's Mission to the Present - 19551

In November 1989, the same month the Berlin Wall fell, the US Environmental Protection Agency (EPA) placed the Mound Laboratory (Mound Plant or Mound site) in Ohio on the National Priorities List (NPL) due to volatile organic compound contamination in the groundwater. As a result of the Cold War ending, the United States sought to greatly reduce the nation's nuclear weapons arsenal, consolidate the US Department of Energy's (DOE) mission, and close many DOE facilities. In 1991, the City of Miamisburg learned that DOE was planning to close the Mound Laboratory. The city spent two years lobbying in Washington, DC, to keep the facility open; however, that effort was not successful. By 1993, DOE, EPA, and Ohio EPA had signed a Federal Facility Agreement that formalized EPA and Ohio EPA oversight of the DOE environmental cleanup of the Mound NPL site under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The decontamination and cleanup of the Mound site fell under two federal laws, CERCLA and the Resource Conservation and Recovery Act. DOE, EPA, Ohio EPA, the City of Miamisburg, and other local stakeholders all agreed that the Mound site should be cleaned up to an industrial/commercial land use standard. This would allow the site to transition into a privately owned business park. In 1994, the City of Miamisburg created the nonprofit Miamisburg Mound Community Improvement Corporation (MMCIC) that would own, market, and redevelop the site. The City also chartered the Mound Reuse Committee to act as an independent advisory organization, composed of representatives from the local community and business, government, education, and special interest groups. In 1994, DOE and the MMCIC entered into a lease agreement that facilitated immediate reuse of site buildings that were no longer required by DOE and did not require remediation. In 1995, DOE, EPA, and Ohio EPA developed the Mound 2000 Process to more effectively use CERCLA Removal Action authority to evaluate and remediate, as necessary, disparate areas of the Mound site. The Mound 2000 process divided the site into smaller, more manageable areas that accelerated cleanup and allowed areas to be reused more quickly. All areas of the Mound site were cleaned up to meet the EPA standard for industrial/commercial land use. The CERCLA process included opportunities for the public to review proposed cleanup strategies. Public input on cleanup and reuse included that from local citizens, businesses, Miamisburg City Council, local schools and financial institutions, Ohio EPA, Montgomery County, and the State of Ohio. In 1998, while site cleanup was still in process, DOE agreed to sell the entire Mound property to the MMCIC for $10.00. The site sales agreement accelerated reuse by allowing DOE to offer ownership of discrete land parcels to MMCIC as soon as EPA confirmed those areas met CERCLA standards for property transfer. This allowed the Mound site to become one of the first former DOE weapons sites to transition to reuse as a privately owned and operated community asset. Many other former DOE production facilities require continued federal ownership to protect the integrity of the environmental cleanup. In 2011, the MMCIC changed its name to the Mound Development Corporation (MDC) and continued to transition the site for reuse as part of the Mound Business Park. The MMCIC/MDC is a nonprofit economic development arm of the City of Miamisburg. DOE supported the economic development efforts with grants and matching funds. Individual land parcels were transferred from DOE to the MDC according to the DOE Mound Land Transfer Process. Ownership of parcels was transferred to the MDC via quitclaim deeds with no repair, replacements, or rebuild of areas. Each parcel's quitclaim deed contains the CERCLA institutional controls. To reduce the property tax burden, the Miamisburg City Council passed an ordinance that allowed the City to accept temporary ownership of specific parcels and hold ownership until the MDC could either lease or sell them. With the exception of one 23-acre parcel that includes the Operable Unit 1 area (site of former sanitary landfill), the entire site has been transferred to the MDC. Today, the former Mound Laboratory site is home to the vibrant Mound Business Park operated by the MDC. The site contains numerous buildings with active businesses and multiple areas suitable for new construction. Private companies continue cutting-edge work that carries forward the legacy of more than 50 years of DOE research, development, production, and inspiration from the former Mound Laboratory scientists, engineers, technicians, and support personnel. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Source term characterization for SNM pit storage facilities

In order to properly design a mobile system to validate and verify the presence of special nuclear materials for non-proliferation and safeguards applications, accurate modeling of source materials is imperative. In this work, models were developed for use in design assessments based on an AL-R8 SNM standardized container specification to determine the radioactive signatures for both highly enriched uranium (HEU) and weapons plutonium (WGPu) special nuclear materials (SNM) housed in the containers. Intrinsic gamma boundary leakage currents were evaluated for this system, performed using 3D fixed-source deterministic SN photon transport (PENTRAN) as well as with stochastic Monte Carlo methods (MCNP5). Group-dependent leakage radiation terms were calculated at two 'source box' interfaces within the models, one directly surrounding the SNM source, and one immediately surrounding the canister. Analysis showed good agreement between the two models for energy groups of interest, based on a 24 group gamma library established for HEU and WGPu gamma signatures of interest. Intrinsic and neutron induced gamma leakage was determined using Monte Carlo calculations, and the combined gamma signatures were then treated as a net gamma leakage to be used in subsequent photon transport calculations. Neutron leakage based on the BUGLE-96 47 group structure was determined using Monte Carlo calculations for the WGPu canisters. These results will be used to evaluate the source term from stored nuclear materials and augment our efforts to design a detection system to validate the presence of these materials for safeguards purposes. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Highly-efficient quantum Fourier transformations for certain non-Abelian groups

Quantum Fourier transformations are an essential component of many quantum algorithms, from prime factoring to quantum simulation. While the standard Abelian QFrT is well studied, important variants corresponding to non-Abelian groups of interest have seen less development. In particular, fast non-Abelian Fourier transformations are important components for both quantum simulations of field theories as well as approaches to the non-Abelian hidden subgroup problem. In this work, we present fast quantum Fourier transformations for a number of non-Abelian groups of interest for high energy physics, B T , B O , 6 Δ ( 27 ) , Δ ( 54 ) , and Σ ( 36 × 3 ) . For each group, we derive explicit quantum circuits and estimate resource scaling for fault-tolerant implementations. Our work shows that the development of a fast Fourier transformation can substantively reduce simulation costs by an up to three orders of magnitude for the finite groups that we have investigated.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Norms, Norm Sets, and Reference Groups: Implications for Household Interest in Energy Technologies

Household adoption of rooftop solar panels and battery storage can potentially reduce the negative environmental impacts of the electric grid. We argue that the number of socially close (friends and family) and geographically close (neighbors) others who have rooftop solar panels will affect norm expectations regarding how much others approve of solar panels and battery storage and expectations about how personally beneficial those technologies are likely to be. We test our hypotheses using survey data collected from California homeowners and find partial support. We find evidence for the significance of socially close others (rather than neighbors), highlighting the importance of identifying the appropriate reference groups when studying norms. Our results also provide insight into how one category of behavior (adoption of solar panels) can influence norm expectations about another less visible behavior (battery storage), suggesting a mechanism that may contribute to norms regulating private behaviors.

Horne, Christine↗
DOE OSTI2012

IRREGULAR SLOSHING COLD FRONTS IN THE NEARBY MERGING GROUPS NGC 7618 AND UGC 12491: EVIDENCE FOR KELVIN-HELMHOLTZ INSTABILITIES

We present results from two {approx}30 ks Chandra observations of the hot atmospheres of the merging galaxy groups centered around NGC 7618 and UGC 12491. Our images show the presence of arc-like sloshing cold fronts (CFs) wrapped around each group center and {approx}100 kpc long spiral tails in both groups. Most interestingly, the CFs are highly distorted in both groups, exhibiting 'wings' along the fronts. These features resemble the structures predicted from non-viscous hydrodynamic simulations of gas sloshing, where Kelvin-Helmholtz instabilities (KHIs) distort the CFs. This is in contrast to the structure seen in many other sloshing and merger CFs, which are smooth and featureless at the current observational resolution. Both magnetic fields and viscosity have been invoked to explain the absence of KHIs in these smooth CFs, but the NGC 7618/UGC 12491 pair are two in a growing number of both sloshing and merger CFs that appear distorted. Magnetic fields and/or viscosity may be able to suppress the growth of KHIs at the CFs in some clusters and groups, but clearly not in all. We propose that the presence or absence of KHI distortions in CFs can be used as a measure of the effective viscosity and/or magnetic field strengths in the intracluster medium.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Moonshine, superconformal symmetry, and quantum error correction

Special conformal field theories can have symmetry groups which are interesting sporadic finite simple groups. Famous examples include the Monster symmetry group of a c = 24 twodimensional conformal field theory (CFT) constructed by Frenkel, Lepowsky and Meurman, and the Conway symmetry group of a c = 12 CFT explored in detail by Duncan and Mack-Crane. The Mathieu moonshine connection between the K3 elliptic genus and the Mathieu group M24 has led to the study of K3 sigma models with large symmetry groups. A particular K3 CFT with a maximal symmetry group preserving (4, 4) superconformal symmetry was studied in beautiful work by Gaberdiel, Taormina, Volpato, and Wendland [41]. The present paper shows that in both the GTVW and c = 12 theories the construction of superconformal generators can be understood via the theory of quantum error correcting codes. The automorphism groups of these codes lift to symmetry groups in the CFT preserving the superconformal generators. In the case of the N = 1 supercurrent of the GTVW model our result, combined with a result of T. Johnson-Freyd implies the symmetry group is the maximal subgroup of M24 known as the sextet group. (The sextet group is also known as the holomorph of the hexacode.) Building on [41] the Ramond-Ramond sector of the GTVW model is related to the Miracle Octad Generator which in turn leads to a role for the Golay code as a group of symmetries of RR states. Moreover, (4, 1) superconformal symmetry suffices to define and decompose the elliptic genus of a K3 sigma model into characters of the N = 4 superconformal algebra. The symmetry group preserving (4, 1) is larger than that preserving (4, 4).

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Local time stepping for the shallow water equations in MPAS

In this work we assess the performance of a set of local time-stepping (LTS) schemes for the shallow water equations implemented in the Model for Prediction Across Scales (MPAS). The goal of LTS is to speed up the simulation by allowing different time-steps on different regions of the computational grid. The LTS schemes considered here were originally introduced by Hoang et al. (2019) [26], who laid out the mathematical foundation of the methods. Here, the authors take on the task of presenting a fast, efficient and scalable parallel implementation of these LTS methods on high performance computing machines, with the aim to provide a recipe for other climate modeling groups that may be interested in employing LTS algorithms in their codes. As a matter of fact, even if MPAS is our framework of choice, our approach is general enough and could be of interest to other groups beyond the MPAS community. Due to their nature, LTS methods possess an inherent load imbalance that needs to be carefully addressed in order to obtain efficient scalability. Even more important is the far from trivial task of computing the right-hand side terms only on specific LTS regions during the time-stepping procedure. An inefficient handling of this task causes a drastic decay of the CPU time performance, making the LTS algorithms practically of no use. The emphasis of the present work is therefore on the computational and parallel aspects of the LTS methods, whose proper treatment is crucial to make the methods run faster against existing strategies, such as for instance high-order explicit global time-stepping schemes. This is in fact the ultimate goal of using an LTS procedure and it is the one to which we direct all our optimization efforts.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Exploring pluralism – Different stakeholder views of the expected and realised value of strategic environmental assessment (SEA)

This paper explores the concept of pluralism by evaluating different stakeholder views on the expected and realised value of strategic environmental assessment (SEA). The research followed a single embedded case study approach (of a national-level SEA for renewable energy planning in South Africa) and engaged with four different stakeholder groups, namely government, industry, conservation groups, and interested and affected parties (IAPs). A total of 21 different value expectations (VEs) across all four stakeholder groups were identified. However, stakeholder groups contrast significantly in terms of VEs, with government concerned more with process and mandate; industry with cost, efficiency and certainty; conservation groups with data and technical aspects; and the IAPs with local scale issues. In terms of realisation of VEs the results suggest that SEA does provide opportunities for learning; focussing project level EIA and providing spatial guidance on the location of projects. However, SEA was less successful in realising integration of decision making and alignment of policy within government. Recognition and better understanding of the pluralistic nature of expected and realised VEs could potentially improve the legitimacy of SEA processes and methodologies if they are designed and implemented to accommodate pluralism.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2013

Building Stakeholder Trust: Defensible Government Decisions - 13110

Administrative decisions must be grounded in reasonable expectations, founded on sound principles, and bounded by societal norms. Without these first principles, attaining and retaining public trust is a Herculean task. Decisions made by governmental administrators must be both transparent and defensible: without the former the agency will lose the public's trust and support (possibly prompting a legal challenge to the decision) and without the latter the decision may fail to withstand judicial scrutiny. This presentation and accompanying paper delves into the process by which governmental decisions can achieve both defensibility and openness through building stakeholder trust with transparency. Achieving and maintaining stakeholder trust is crucial, especially in the environs of nuclear waste management. Proving confidence, stability, and security to the surrounding citizenry as well as those throughout the country is the goal of governmental nuclear waste remediation. Guiding administrative decision-making processes and maintaining a broad bandwidth of communication are of incalculable importance to all those charged with serving the public, but are especially essential to those whose decisional impacts will be felt for millennia. A strong, clear, and concise administrative record documenting discrete decisions and overarching policy choices is the strongest defense to a decisional challenge. However, this can be accomplished using transparency as the fundamental building block. This documentation allows the decision-makers to demonstrate the synthesis of legal and technical challenges and fortifies the ground from which challenges will be defended when necessary. Further, administrative actions which capture the public's interest and captivate that interest throughout the process will result in a better-informed, more deeply-involved, and more heavily-invested group of interested parties. Management of information, involvement, and investment on the front-end of the process reaps rewards far more efficiently than attempts to assuage and mitigate the concerns of those parties after the fact and there are a number of tools Savannah River Remediation (SRR) has deployed that render transparency an ally in this context. The makers, applicators, and beneficiaries of policies and decisions will all benefit from strong administrative records which document decisional choices in an open and transparent manner and from timely, up-front management of concerns of interested parties. The strongest defense to decisional challenges is an ability to demonstrate the basis of the decision and the reason(s) that the decision was chosen over other alternatives. Providing a sound basis for defending challenges rather than avoiding or fighting over them allows the deciding entity the greatest opportunity to produce value for its customer. Often, a transparent process that invites public participation and is open for public review and comment will thwart challenge genesis. An entity that has to devote resources to defending its choices obviously cannot utilize those resources to further its mission. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Learning non-Higgsable gauge groups in 4D F-theory

We apply machine learning techniques to solve a specific classification problem in 4D F-theory. For a divisor D on a given complex threefold base, we want to read out the non-Higgsable gauge group on it using local geometric information near D. The input features are the triple intersection numbers among divisors near D and the output label is the non-Higgsable gauge group. We use decision tree to solve this problem and achieved 85%-98% out-of-sample accuracies for different classes of divisors, where the data sets are generated from toric threefold bases without (4,6) curves. We have explicitly generated a large number of analytic rules directly from the decision tree and proved a small number of them. As a crosscheck, we applied these decision trees on bases with (4,6) curves as well and achieved high accuracies. Additionally, we have trained a decision tree to distinguish toric (4,6) curves as well. Finally, we present an application of these analytic rules to construct local base configurations with interesting gauge groups such as SU(3).

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Streamlining or sidestepping? Political pressure to revise environmental licensing and EIA in Brazil

In the Anthropocene, governments are increasingly being forced to take action to minimize or reverse human impacts on the environment. One of the most widespread legal instruments to prevent negative impacts on the environment is Environmental Impact Assessment (EIA). Almost all countries have an EIA system in place aimed at mitigating the diverse impacts causing by development projects. A common drawback of such systems is that they are often ineffective and time-consuming, and are therefore frequently viewed by politicians as “in the way” of development. This is the case in Brazil, where EIA has had a very limited influence on decision-making and where environment reforms (e.g. the new Forest Code) have often been strongly influenced by powerful lobbies (e.g. agribusiness groups, industry actors, etc.) and conservative legislators. Continuing this trend, the most recent political developments have seen the proposal of a series of amendments aimed at “streamlining” the Brazilian EIA system. In this viewpoint, we provide an in depth analysis of the proposed changes, highlighting the serious consequences that would accompany the weakening of environmental licensing and EIA legislation in Brazil.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2012

Purposes, paradigms and pressure groups: Accountability and sustainability in EU environmental assessment, 1985-2010

Twenty five years since the introduction of the European Union (EU) environmental impact assessment (EIA) Directive in 1985 this paper reflects on the extent to which environmental assessment (EA) processes, over the course of their evolution over the last 25 years in the EU, have provided a platform for enhancing accountability and sustainability. Surprisingly-in the context of legal mandates for EA-there is little reference in the EA literature explicitly to the literature on accountability and the role EA may play in this increasingly important aspect of governance. The paper explores EA implementation principally from an environmentalist perspective and particularly the way in which NGOs and other advocates for the environment in the UK and EU have used the EA legislation as a lever for increasing democratic, corporate and professional accountability of proponents and decision-makers alike. From an a historical analysis, including two historical EIA case studies and two contemporary SEA case studies, it becomes clear that EA has had an important role to play-at the legislative level in providing the requirements for accountability, and at the implementation level as the lever that can be used to hold individuals, organisations and authorities to account for their actions. The relationship with the shift to sustainability is a close one, since sustainable development demands greater public involvement in decision-making and greater accountability of executive decisions to the public. The lessons from this analysis allow the development of a nascent policy-oriented theory regarding EA's role in accountability, which provides a framework for a distinctive new area of EA research and policy analysis. Moreover, an accountability perspective on EA could help re-frame EA for policy makers from being purely an informational and procedural instrument to one which promotes better accountability and sustainability simultaneously. - Highlights: Black-Right-Pointing-Pointer Little attention in the literature to environmental assessment (EA) and accountability. Black-Right-Pointing-Pointer Evolution of EA in the EU influenced by shifting policy paradigms and demands for accountability. Black-Right-Pointing-Pointer EIA and SEA, as formal procedures, can provide platforms for accountability. Black-Right-Pointing-Pointer Four case studies illustrate how NGOs and others have used EA to further accountability. Black-Right-Pointing-Pointer A policy-oriented theory provides a basis for considering future evolution of EA in the EU.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Profiling overstory survival trends following varying thinning and burning disturbance regimes in a mixed pine-hardwood forest in the US South

Prescribed burning as a silvicultural tool may be effective for achieving various management objectives, yet some practitioners have concerns about inadvertently increasing overstory tree mortality. Using extensive data from a long-term, ongoing study in northcentral Alabama, USA, that systematically applies a variety of thinning and prescribed burning disturbances on mixed pine-hardwood stands, we assess survival trends for different groups of trees. The primary research question is whether more frequent prescribed burns adversely affects overstory survival versus infrequent or no burns; secondary questions explore whether overstory survival trends differ based on thinning level, species group, or size class. Interest is in broad groups of trees, not individual tree survival or mortality; consequently, survival analysis methods are used, including nonparametric Kaplan-Meier (KM) techniques for examining single grouping factors, and parametric accelerated failure time models for analyzing simultaneous effects of multiple covariates. Leveraging relatively recent methodological advances, the statistical techniques are adjusted for interval censored data. KM survival curves showed that more frequent prescribed fires did not result in differing survival trends. Also, trees in unthinned stands had the lowest 14-year survival compared to thinned stands, oaks had the highest survival compared to pines and the others species group, and the smallest size class of overstory trees had the lowest survival. In conclusion, these results support managing transitional mixed pine-hardwoods using thinning and multiple prescribed fires to restore specific species composition and structure.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Optimization of ray-tracing simulations to confirm performance of the GP-SANS instrument at the High-Flux Isotope Reactor

The CG-2 beamline at the High Flux Isotope Reactor (HFIR) exhibits a notable discrepancy between observed count rates and the count rates we would expect based on a Monte-Carlo neutron ray-trace simulation. These simulations consistently predict count rates approximately five times greater than those observed in four separate experimental runs involving different instrument configurations. This discrepancy suggests that certain factors are causing losses in measurements that are not adequately accounted for in the simulation, in particular guide reflectivity or misalignment. To investigate these discrepancies, a high-dimensional simulation parameter approach is applied in order to understand the losses. Region of Interest (ROI) groups along the instrument are assigned to different surfaces of the guide components within the simulation. This allows the parameters of those guide components to be varied as a group to minimize the complexity of the search space. The result is an optimization of simulation parameters using an iterative scheme that aims to minimize the difference between experimentally measured count rates and simulated count rates across all tested collimator combinations. This proposed methodology holds the potential to reveal previously unrecognized sources of intensity loss in the CG-2 beamline at HFIR and improve the accuracy of simulations, leading to enhanced understanding and performance of the beamline for various scientific applications.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2013

Cation-Cation Interactions in [(UO2)2(OH)n](4-n) Complexes

The structures and bonding of gas-phase [(UO2)2(OH)n]4-n (n=2-6) complexes have been studied using density functional theory (DFT), MP2 and CCSD(T) methods with particular emphasis on ground state structures featuring cation-cation interactions (CCIs) between the uranyl groups. An interesting trend is observed in the stabilities of members of this series of complexes. The structures of [(UO2)2(OH)2]2+, [(UO2)2(OH)4] and [(UO2)2(OH)6]2- featuring CCIs are found at higher energies (by 3-20 kcal/mol) in comparison to their conventional μ2-dihydroxo structures. In contrast, the CCI structures of [(UO2)2(OH)3]+ and [(UO2)2(OH)5]- are respectively almost degenerate with and lower in energy than the structures with the μ2-dihydroxo format. The origin of this trend lies in the ‘symmetry’-based need to balance the coordination numbers and effective atomic charges of each uranium center. The calculated IR vibrational frequencies provide signature probes that can be used in differentiating the lowenergy structures and in experimentally confirming the existence of the structures featuring CCIs. Analysis of the bonding in the structures of [(UO2)2(OH)3]+ and [(UO2)2(OH)5]- shows that the CCIs and bridging hydroxo between the dioxo-uranium units are mainly electrostatic in nature.

Complexes↗
DOE OSTI2014

Quantum money with classical verification

We propose and construct a quantum money scheme that allows verification through classical communication with a bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification. Our scheme is secure against adaptive adversaries - this property is not directly related to the possibility of classical verification, nevertheless none of the earlier quantum money constructions is known to possess it.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗