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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Protein–Protein Complex Stability Controls Substrate Scope in a β‐Ketoacyl‐ACP Reductase Specific for Medium Chains

Assembly-line enzymes carry out multistep synthesis of important metabolites by using acyl carrier proteins (ACPs) to shuttle intermediates along defined sequences of active sites. Despite longstanding interest in reprogramming these systems for metabolic engineering and biosynthetic chemistry, the mechanisms underlying their reaction order remain poorly understood and difficult to control. In this work, we describe a β-ketoacyl-ACP reductase from Pseudomonas putida (PpFabG4) with an unusual selectivity for medium chains and use it to explore the molecular basis of substrate specificity in enzymes that pull intermediates from fatty acid synthesis, a common route to specialized products. X-ray crystallography shows no obvious barriers to short-chain binding. Molecular simulations and supporting mutational analyses indicate that substrate preference arises instead from a weak enzyme–ACP interaction that is stabilized by medium acyl chains but not by short chains. Indeed, mutations that strengthen this interaction for PpFabG4 or weaken it for EcFabG, an Escherichia coli β-ketoacyl-ACP reductase with a broad substrate specificity, can enhance or reduce activity on short-chain substrates by over 100-fold. Our findings show how the stability of enzyme-ACP interactions can control substrate scope in promiscuous enzymes and guide the exchange of intermediates between (and within) assembly-line systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Correlating the Structural, Electronic, and Explosive Sensitivity Properties of CuII Tetrazine Complexes

The synthesis and characterization of explosive coordination complexes of Cu II with nitrogen-rich tetrazine ligands and nitrate counter-anions have been achieved. The complexes adopt a variety of coordination geometries including monomeric and dimeric architectures with five and six coordinate Cu II centers. The thermal stabilities of the complexes correlate to the strength of the Cu–nitrate interaction such that more strongly bound nitrates exhibit higher thermal stability. Exchanging amine groups on the coordinating ligands with 3,3'- dinitroazetidine groups led to changes in the solid-state structures and increases to the impact sensitivity of the resulting complexes relative to the corresponding amine derivatives.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Elucidating the impact of the ionomer equivalent weight on a platinum group metal-free PEMFC cathode via oxygen limiting current

Leveraging the interactions between ionomer and catalyst can increase the performance of proton exchange membrane fuel cells. The impacts of the equivalent weight (EW) of perfluorosulfonic acid–based ionomers on the platinum group metal-free electrode structure and fuel cell performance have not been fully explored. Four membrane electrode assemblies (MEAs) were prepared by using a commercial Fe–N–C catalyst, two perfluorosulfonic acid ionomers with different EWs, that is, Aquivion 720 (A720) and Nafion 1100 (N1100), and two ionomer-to-catalyst (I/C) ratios. The four MEAs were characterized to understand the impact of the ionomer EW and content on the capacitance, proton conductivity, and mass transport on the cathode. The mass transport resistance was measured for the first time using a new oxygen reduction reaction limiting current method enabling to couple the effects of oxygen diffusion with liquid water generation. Low EW ionomer combined with a moderate I/C results in improved performance due to its enhanced proton conductivity. However, when used at high I/C, it can cause severe water flooding at high current density due to the enhanced liquid water uptake, especially at high relative humidity, resulting in lower catalyst utilization and higher mass transport resistance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Understanding the Stabilization and Tunability of Divalent Europium 2.2.2B Cryptates

Lanthanides such as europium with more accessible divalent states are useful for studying redox stability afforded by macrocyclic organic ligands. Substituted cryptands, such as 2.2.2B cryptand, that increase the oxidative stability of divalent europium also provide coordination environments that support synthetic alterations of Eu(II) cryptate complexes. Two single crystal structures were obtained containing nine-coordinate Eu(II) 2.2.2B cryptate complexes that differ by a single coordination site, the occupation of which is dictated by changes in reaction conditions. A crystal structure containing a [Eu(2.2.2B)Cl] + complex is obtained from a methanol–THF solvent mixture, while a methanol–acetonitrile solvent mixture affords a [Eu(2.2.2B)(CH 3 OH)] 2+ complex. While both crystals exhibit the typical blue emission observed in most Eu(II) containing compounds as a result of 4f 6 5d 1 to 4f 7 transitions, computational results show that the substitution of a Cl– anion in the place of a methanol molecule causes mixing of the 5d excited states in the Eu(II) 2.2.2B cryptate complex. Additionally, magnetism studies reveal the identity of the capping ligand in the Eu(II) 2.2.2B cryptate complex may also lead to exchange between Eu(II) metal centers facilitated by π-stacking interactions within the structure, slightly altering the anticipated magnetic moment. Finally, the synthetic control present in these systems makes them interesting candidates for studying less stable divalent lanthanides and the effects of precise modifications of the electronic structures of low valent lanthanide elements.

Anions↗
DOE OSTI2021

A Ranked-Orbital Approach to Select Active Spaces for High-Throughput Multireference Computation

The past decade has seen a great increase in the application of high-throughput computation to a variety of important problems in chemistry. However, one area which has been resistant to the high-throughput approach is multireference wave function methods, in large part due to the technicalities of setting up these calculations and in particular the not always intuitive challenge of active space selection. As we look toward a future of applying high-throughput computation to all areas of chemistry, it is important to prepare these methods for large-scale automation. Here, we propose a ranked-orbital approach to select active spaces with the goal of standardizing multireference methods for high-throughput computation. This method allows for the meaningful comparison of different active space selection schemes and orbital localizations, and we demonstrate the utility of this approach across 1120 multireference calculations for the excitation energies of small molecules. Our results reveal that it is helpful to distinguish the method used to generate orbitals from the method of ranking orbitals in terms of importance for the active space. Additionally, we propose our own orbital ranking scheme that estimates the importance of an orbital for the active space through a pair-interaction framework from orbital energies and features of the Hartree–Fock exchange matrix. Here, we call this new scheme the “approximate pair coefficient” (APC) method and we show that it performs quite well for the test systems presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Atomic Orbital Implementation of Extended Symmetry-Adapted Perturbation Theory (XSAPT) and Benchmark Calculations for Large Supramolecular Complexes

We report an implementation of extended symmetry-adapted perturbation theory (XSAPT) in the atomic orbital basis, extending this method to systems where the monomers are large. In our “XSAPT(KS)” approach, monomers are described using range-separated Kohn–Sham (KS) density functional theory (DFT), with correct asymptotic behavior set by tuning the range-separation parameter ω in a monomer-specific way. This is accomplished either by conventional ionization potential (IP)-based tuning, in which ω is adjusted to satisfy the condition ε HOMO (ω) = -IP(ω), or else using a “global density-dependent” (GDD) condition, in which ω is fixed based on the size of the exchange hole. The latter procedure affords better results for both total interaction energies and energy components, when used in conjunction with our third-generation pairwise atom–atom dispersion potential (+aiD 3 ). Three-body (triatomic) dispersion terms are found to be important when the monomers are large, and we incorporate these by means of an Axilrod–Teller–Muto term, E disp,3B ATM , which reduces errors in supramolecular interaction energies by about a factor of 2. The XSAPT(KS) + aiD 3 + E disp,3B ATM (ωGDD) approach affords mean absolute errors as low as 1.2 and 4.2 kcal/mol, respectively, for the L7 and S12L benchmark test sets of large dimers. Such errors are comparable to those afforded by far more expensive methods, such as DFT-SAPT, and the closely related second-order perturbation theory with coupled dispersion (MP2C). We also survey the performance of various other quantum-chemical methods for these data sets and identify several semiempirical and DFT-based approaches whose accuracy approaches that of MP2C, at dramatically reduced cost.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Optical sensing of aqueous nitrate anion by a platinum( II ) triimine salt based solid state material

Selective and quantitative measurement of aqueous nitrate (NO 3 – ) anion is achieved using solid [Pt(Cl-4-tpy)Cl]ClO 4 salt (Cl-4-tpy = 4-chloro-2,2':6'2''-terpyridine), and as the salt supported on controlled porous glass. This detection method relies on the color change of the Pt(II) complex from yellow to red and intense luminescence response upon ClO 4 – exchange with NO 3 – due to concomitant enhancement of Pt∙∙∙Pt interactions. Finally, the spectroscopic response is highly selective for NO 3 – over a large range of halides and oxoanions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Two-dimensional ordering and collective magnetic excitations in the dilute ferromagnetic topological insulator ( Bi 0.95 Mn 0.05 ) 2 Te 3

Employing elastic and inelastic neutron scattering (INS) techniques, we introduce the microscopic properties of the ferromagnetism in the dilute magnetic topological insulator ( Bi 0.95 Mn 0.05 ) 2 Te 3 . Neutron diffraction of polycrystalline samples shows the ferromagnetic (FM) ordering is long range within the basal plane, and mainly two dimensional (2D) in character with short-range correlations between layers below T C ≈ 13 K. Remarkably, we observe gapped and collective magnetic excitations in this dilute magnetic system. The excitations appear typical of quasi-2D FM systems despite the severe broadening of short-wavelength magnons which is expected from the random spatial distribution of Mn atoms in the Bi planes. A detailed investigation of the INS provides the average values for exchange couplings which are consistent with reports of carrier-mediated interactions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Kokes Awards for the 25th North American Catalysis Society Meeting

The biennial North American Catalysis Society (NACS) meeting is the premiere conferences in the area of catalysis, surface science, and reaction engineering. The 25th installment of this meeting will be held the week of June 4-9, 2017 in Denver, CO at the Hyatt Regency Hotel. Meeting objectives include bringing together leading researchers for intensive scientific exchange, providing students with an opportunity to present their work and interact with leaders in the field, and participate in service to scientific/technical community. Financial support to offset a portion of the associated costs – and specifically, registration fees, airline tickets, and hotel accommodations – encourages greater participation by graduate and undergraduate students, and often provides them the only opportunity to attend and meaningfully contribute to the conference. The funds sought in this proposal will be in support of the Richard J. Kokes Travel Award program. The eligibility criteria for undergraduates and graduate students applying for a merit-based Awards are that they must study at a university within the United States and present either a poster or presentation at the meeting. In the previous meeting in Pittsburgh, NACS received 200 applications and funded 110 students. Similarly, during the meeting in Louisville, NACS received 225 applications and funded nearly half of them. The NACS has an on-going tradition of encouraging graduate students (and more recently, undergraduates as well) to participate in and serve at the national meetings Providing financial support is one of the most effective means of accomplishing this goal. Their attendance significantly broadens their scientific training beyond what can be accomplished in the classroom, and offers them an opportunity to improve their communication and presentation skills. As an attendee to the 25th NAM, students will participate by listening to presentations from leading researchers from the U.S. and abroad, and they will be able to interact with them and receive invaluable advice regarding their research and future career. They will be able to meet with and debate with their peers from other universities, and learn about results from the latest technological innovations that could benefit their own research projects. Through their own service at the meeting – a requirement of the Kokes Travel Award – they will become active participating members of the catalysis community. The graduate and undergraduate students of today are the scientists and engineers of tomorrow. Proper training for them now leads to scientific breakthroughs and technological innovations in the future, and these in turn benefit the US economy. Catalysis permeates numerous aspects of our lives, and advances in the field result in more energy-efficient and environmentally-friendly chemical processes (e.g., catalytic convertors), improved fuel cell and battery performance and lifetimes, efficient alternative fuel and hydrogen production, enhanced utilization of biorenewable resources, and a cleaner environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Probabilistic Seismic Hazard Assessment for Georgia

Probabilistic Seismic Hazard Assessments (PSHA) form the basis for most contemporary seismic provisions in building codes around the world. The current building code of Georgia (2009) is not fully compatible with seismic hazard and design concepts of modern codes. The Ministry of Economy and Sustainable Development of Georgia is currently undertaking an update to the building code to align it with EuroCode. In conjunction with EuroCode, a National Annex specific to Georgia is needed, including seismic hazard values for the territory of Georgia. A comprehensive earthquake catalogue is fundamental to a robust PSHA in the region. The Caucasus has had an uneven seismic recording and reporting history both temporally and spatially. Therefore, there has been a strong regional effort to bring together data from all the countries in the Caucasus, to digitize and standardize paper-based data from the Soviet era, and to re-examine magnitude and location calculations. The earthquake catalogue resulting from this effort forms the basis for a reliable seismic hazard assessment. Recognizing these needs, the U.S. Department of Energy through Lawrence Livermore National Laboratory (LLNL) initiated a project in 2015 to engage and train local scientists in the Caucasus to install new equipment, to enhance the quality of seismic monitoring and reporting, and to improve and harmonize the regional earthquake catalogue. In 2016, the project scope was expanded to include the modernization of seismic hazard assessments. To this end, a series of workshops were held in Georgia, the first one of which presented an overview of PSHA and its components to various participants from the universities and other research organizations in the region. This kick-off workshop was followed by numerous hands-on training workshops in 2017 and 2018, covering all aspects of PSHA. In addition to their training goals, the workshops brought together existing and new information relevant to PSHA studies in the region, providing a platform for local scientists/engineers and experts from other parts of the world to interact, cooperate and discuss various pieces of the PSHA input. This report outlines the aspects of the earthquake catalogue development and PSHA project that were specifically undertaken to form the basis for the building code update in Georgia. Georgia straddles the Greater Caucasus and Lesser Caucasus Fold and Thrust belts, where the convergent tectonic setting generates significant earthquake activity. To the east of the country, evidence indicates the possibility of a remnant subducting slab that causes earthquakes deeper than 40km. This study systematically compiles and improves all available data on local seismicity, active faults, and ground motion attenuation characteristics of the region; and builds a framework to enable a contemporary PSHA to be carried out with the engagement of local scientists. To this end, six regional workshops were organized in total over a three-year period of time, with participation from the United States, Canada and Hungary as well as countries in the Caucasus: Georgia, Armenia, Azerbaijan and Turkey. The workshops served multiple purposes such as training, data collection, interactions between local earth scientists and engineers, and brainstorming and knowledge exchange among local and international experts.

Geosciences↗
DOE OSTI2022

Syntrophic Co-Cultures of Clostridium Organisms to Produce Higher Alcohols & Other C6-C8 Metabolites (Final Report)

The goal of this project was to advance the systems biology understanding and predictive modeling of synthetic & syntrophic Clostridium microbial consortia, focusing on elucidation of metabolic networks and environmental signals in the consortia. The project has direct applicability to lignocellulosic-biomass based production of higher alcohols as advanced biofuels and C6-C8 metabolites, that can be used as chemicals or serve as biofuel precursors. This project studied and optimized three synthetic syntrophic systems. It examined the population dynamics using flow-cytometry, time-lapse microscopy and PCR analysis. 13C-based tracer analyses was used to examine the metabolite exchange between the syntrophic cell populations and the impact of those interactions on the transcriptome of the individual populations. To enhance our analytical and predictive capabilities, genome-scale models (GSMs) for these syntrophies was developed. RNAseq data for these syntrophic coculture systems were acquired to enable a molecular level understanding of the syntrophies aiming to identify the genetic networks of each organism in the co-culture and compare those against the networks of pure cultures.

09 BIOMASS FUELS↗
DOE OSTI2024

Central Asia Seismic Hazard Assessment (CASHA): A Probabilistic Seismic Hazard Assessment for Kazakhstan, Kyrgyzstan and Tajikistan

Probabilistic seismic hazard assessments (PSHA) underpin the calculation of earthquake loads in most building codes around the world. In Central Asia, the building codes are slowly being updated to incorporate some of the contemporary concepts of seismic hazard representation. There is also a regional desire to coordinate hazard assessments and building code modernization. However, some challenges remain. Expertise in the region related to seismic hazard assessments is still largely compartmentalised, requiring a significant amount of training and capacity building in seismic hazard assessment related topics. In addition, there are vast amounts of seismic data (bulletin and waveforms), both from analogue and digital eras, that the region’s countries stored but until recently did not use or share among themselves or with the broader seismological community around the world. Finally, after the collapse of the Soviet Union in the 1990s, many of the countries’ seismic networks suffered a major setback with the lack of attention and budget to update existing equipment and installation of new instruments. In order to address these issues, the United States Department of Energy through Lawrence Livermore National Laboratory (LLNL) initiated a project in 2016 to engage and train local scientists in Central Asia to install new equipment, to enhance the quality of seismic monitoring and reporting, to improve and harmonise the regional earthquake catalogue, and to conduct national probabilistic seismic hazard assessments using the new and improved datasets. To achieve the seismic hazard assessment related goals, a series of workshops were held in Almaty, Kazakhstan; Bishkek, Kyrgyzstan; and Dushanbe, Tajikistan from 2016 until 2020. During the time that the COVID-19 pandemic restricted travel, workshops continued online (22 online workshops were hosted in two years). Finally, in May 2022, an in-person workshop in Istanbul, Turkey brought together all project participants along with civil engineers engaged with building code activities in their respective countries, providing a platform to discuss the implementation of the hazard models into updates of building codes in each country, as well as to discuss model parameters, sensitivity analyses and model results in terms of hazard maps, uniform hazard spectra and hazard deaggregations. The workshops were a combination of lectures and hands-on exercises, and included international participation as well as local scientists and engineers. The workshops served several purposes, including training, coordination of data collection, interactions between local earth scientists and engineers, and brainstorming and knowledge exchange among local and international experts. This report outlines the new earthquake catalogue compilation effort and the PSHA project undertaken in Kyrgyzstan, Tajikistan, and Kazakhstan as part of this initiative. The southern part of this region is tectonically active with moderate to high levels of both shallow crustal seismic activity and occurrence of deeper earthquakes under the Hindu Kush and Pamir mountain ranges. Deeper earthquakes also occur near southwestern Kazakhstan, under the eastern Greater Caucasus and Caspian Sea. Large portions of central and northern Kazakhstan, on the other hand, are in stable continental regions with low levels of seismic activity. This study systematically compiles and improves all available data on local seismicity, active faults, and ground motion attenuation characteristics of the region; and builds a framework to enable a contemporary PSHA to be carried out with the engagement of local scientists. While the project was regional, the seismic hazard assessments are primarily driven by the countries’ own national preferences and understanding of data collection, interpretation, and validation of results.

58 GEOSCIENCES↗
DOE OSTI2023

Characterization and Electrochemical Analysis of Acidic Condensate-Induced Corrosion on Aluminized Coating on Steel in Residential Heaters

Condensing furnace residential heaters are starting to replace outdated and less efficient non-condensing units in homes across the US. However, the burning of natural gas in these new units produces acidic gases, which can form acid droplets (H 2 SO 4 , HNO 3 , H 2 CO 3 , etc.) that are corrosive to low-grade heat exchanger metallic materials. Type-1 aluminized steel has been used in industrial applications, such as marine, heating, and automobile parts, due to its resistance to oxidation at elevated temperature. Many components of the condensing furnaces, including heat exchangers, are made from type-1 aluminized steel. We investigated the interaction of type-1 aluminized steel substrates with two acidic condensate liquids by 500 h corrosion exposures as well as short-term electrochemical impedance measurements. SEM plan and cross-sectional view images revealed damage to the Al-Si rich layer and exposure of the steel substrate. The non-uniform damage in the Al-Si rich layer was likely attributed to a pitting corrosion mechanism and induced by high acidity of the condensate liquid. Electrochemical impedance measurements in an acidic condensate revealed lower corrosion resistance of the aluminized steel surface with a weld line, identifying welded sections as preferential corrosion initiation sites.

36 MATERIALS SCIENCE↗
NASA NTRS1980

On nonlinear cascades of enstrophy over the tropics at 200 mb during two Northern Hemisphere summers

Diagnostic computations of nonlinear cascades of enstrophy have been performed in the wavenumber domain for two northern summers. Attention is focused on the interactions among the waves, the interaction between the zonal flow and a given wave and the exchanges due to the beta effect. It is found that two wave ranges (low and intermediate wavenumbers) cascade enstrophy to two ranges of wavenumbers. Calculations are also performed to evaluate the contribution from the standing (92-day mean) and transient modes to the nonlinear enstrophy cascade.

Chen, T.-C.↗
NASA NTRS2018

Information Quality Cluster and Usability

The Information Quality Cluster (IQC) of the Federation of Earth Science Information Partners (ESIP) has been active since 2014 with membership from multiple organizations including NASA and NOAA. The purpose of this presentation is to foster collaboration between the IQC and the ESIP Usability Cluster. The IQC's activities are motivated partly by the guidelines on information quality from several federal agencies. The agencies developed the guidelines complying with a request in 2002 from the Office of Management and Budget (OMB). The OMB request resulted from a congressional mandate, namely, Section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Public Law 106-554; H.R. 5658). NASA's guidelines, for example, emphasize the need for high information quality indicating the various types of public users of information from NASA's missions and programs. The IQC's vision is to become an authoritative and responsive resource of information and guidance to data providers on how best to implement data quality standards and best practices, so that the implementations comply with the various agencies' guidelines, as well as provide users with the best quality of information possible. The IQC interacts with various national and international organizations and encourages collaboration for exchange of information. The IQC considers four aspects of information quality: Scientific Quality, Product Quality, Stewardship Quality and Service Quality. The IQC has considered several use cases to identify issues in capturing, describing, providing access to, and enabling use of information on quality. Several of these use cases point to issues about the usability of information. Collaboration between the IQC and Usability Cluster will be beneficial for arriving at solutions to such issues.

Remote Sensing; Data Systems; Information Quality;↗
NASA NTRS2017

Airspace Technology Demonstration II (ATD-2): American Airlines CLT Ramp Training RTC/RMTC: Baseline Integrated Arrival/ Departure/Surface (IADS) - ATD-2 Tech Transfer 1 - Phase 1

This training material was created to train CLT (Charlotte Douglas International Airport) ramp controllers on the ATD-2 (Airspace Technology Demonstration-2) system. It includes an overview of ATD-2 and the RTC/RMTC (Ramp Traffic Console/Ramp Manager Traffic Console). It discusses many interface details, data exchange and integration, metering modes, and scheduler advisories. It concludes with interactive exercises on all topics of the training course.

RTC/RMTC↗
NASA NTRSDate not supplied

Mitigating Microbial Contamination Risks in CO 2 Removal Systems for Long-Duration Space Missions

Crewed missions to Mars and beyond pose new challenges for the crew and the technological solutions they depend upon. Crucial considerations in designing the next generation of Environmental Control and Life Support Systems (ECLSS) include enhanced reliability and autonomy, given the challenges of resupply and resource recovery in remote missions. One significant challenge faced in various sectors of the International Space Station and ECLSS is the phenomena of microbial growth, particularly biofilm formation. As such, microbial growth is a critical consideration in the design phase of new ECLSS systems. Two novel CO2 removal systems—Liquid-Amines CO2 Removal (LACR) and Cold-Surface CO2 Deposition (CDep)—are currently under development at the NASA Ames Research Center to meet the needs of extended space travel. In this presentation, the authors aim to make a risk assessment of microbial growth in LACR and CDep through: 1) a comprehensive literature review to identify LACR and CDep components most vulnerable to microbial contamination and 2) wet lab testing commencing with a subscale test of the most susceptible component of CDep. The literature review revealed that the hollow-fiber Liqui-Cel membrane employed in CDep exhibits the highest susceptibility to microbial growth. Our wet lab tests corroborated these findings, as airborne microbes introduced into the membrane led to considerable biomass accumulation. These results indicate a significant risk of microbial invasion into the membranes. To prevent microbial growth in CDep or other CO2 removal systems, proper ECLSS arrangement is essential—a CO2 removal system should remain behind the charcoal-HEPA filters, condensing heat exchanger, and Trace Contaminant Control System. In summary, anticipating potential microbial interactions within ECLSS for remote crewed missions is vital to mission success. It should, therefore, be included as one of the many factors when designing future ECLSS systems to perform reliably and consistently to support astronaut life.

A. Nicolas Whitlock↗
DOE OSTI2024

Search for 2p2h Interactions in the NOνA Near Detector

The physics of 2p2h interactions and their contribution to the NO$\nu$A near detector data are not fully understood. This study attempts to shed some light on these interactions and the accuracy of the models used to simulate them through a search for a specific 2p2h interaction in the NO$\nu$A near detector. By performing an event selection algorithm based on particle identifier algorithms run over reconstructed data, a signal region is created to minimize the background while maximizing the number of 2p2h events where a muon neutrino interacts with a neutron and a proton coupled by a meson exchange current and produces two protons and one muon. In the signal region, separation is found between the signal events and the background in plots of the angles between the protons and the muon. Although a full statistical analysis is not completed in this study, comparing the angle plots for simulation and data shows that the model used to simulate the events reasonably approximates reality and that the near detector data likely includes signal events. Signal events are also identified in event displays, further indicating that there is some contribution of the signal to the overall NO$\nu$A near detector data.

Gable, Kyle↗