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At least 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

The Effect of Dose Rate on Composite Durability When Exposed to a Simulated Long-Term Lunar Radiation Environment

Human exploration of space beyond low Earth orbit (LEO) requires a safe living and working environment for crew. Composite materials are one type of material being investigated by NASA as a multi-functional structural approach to habitats for long-term use in space or on planetary surfaces with limited magnetic fields and atmosphere. These materials provide high strength with the potential for decreased weight and increased radiation protection of crew and electronics when compared with conventional aluminum structures. However, these materials have not been evaluated in a harsh radiation environment, as would be experienced outside of LEO or on a planetary surface. Thus, NASA has been investigating the durability of select composite materials in a long-term radiation environment. Previously, NASA exposed composite samples to a simulated, accelerated 30-year radiation treatment and tensile stresses similar to those of a habitat pressure vessel. The results showed evidence of potential surface oxidation and enhanced cross-linking of the matrix. As a follow-on study, we performed the same accelerated exposure alongside an exposure with a decreased dose rate. The slower dose ]rate is comparable to a realistic scenario, although still accelerated. Strain measurements were collected during exposure and showed that with a fastdose rate, the strain decreased with time, but with a slow ]dose rate, the strain increased with time. After the radiation exposures, samples were characterized via tensile tests, flexure tests, Fourier Transform Infrared Spectroscopy (FTIR), and Differential Scanning Calorimetry (DSC). The results of these tests will be discussed.

Rojdev, Kristina↗
NASA NTRS2004

Chemical Thinning Process for Fabricating UV-Imaging CCDs

The thinning stage of the postfabrication process reported in the immediately preceding article is notable in its own right. Although the thinning process was described in the preceding article as part of an overall process of fabrication of a supported charge-coupled device (CCD), it is more generally applicable to both free-standing and supported devices that have been fabricated in die and wafer formats. Like the thermocompression bonding process described in the preceding article, the thinning process is compatible with CCD-fabrication processes, as well as postfabrication processes that enhance the response of CCDs to ultraviolet (UV) light, including the delta-doping process. CCDs that are thinned by this process and then delta-doped exhibit high quantum efficiencies that are stable with time and with exposure to the environment.

Jones, TOdd↗
NASA NTRS2015

Determination of Roles of Microgravity and Ionizing Radiation on the Reactivation of Epstein-Barr Virus In Vitro

Astronauts experience symptomatic and asymptomatic herpes virus reactivation during spaceflight. We have shown increases in reactivation of Epstein-Barr virus (EBV), cytomegalovirus (CMV) and varicella zoster virus (VZV) and shedding in body fluids (saliva and urine) in astronauts during space travel. Alterations in immunity, increased stress hormone levels, microgravity, increased radiation, and other conditions unique to spaceflight may promote reactivation of latent herpes viruses. Unique mechanico-physico forces associated with spaceflight can have profound effects on cellular function, especially immune cells. In space flight analog studies such as Antarctica, bed rest studies, and NASA's undersea habitat (Aquarius), reactivation of these viruses occurred, but to a lesser extent than spaceflight. Spaceflight analogs model some spaceflight factors, but none of the analogs recreates all factors experienced in space. Most notably, microgravity and radiation are not included in many analogs. Stress, processed through the HPA axis and SAM systems, induces viral reactivation. However, the respective roles of microgravity and increased space radiation levels or if any synergy exists are not known. Therefore, we studied the effect of modeled space radiation and/or microgravity, independent of the immune system on the changes in cellular gene expression that results in viral (EBV) reactivation. The effects of modeled microgravity and low shear on EBV replication and cellular and EBV gene expression were studied in human B-lymphocyte cell cultures. Latently infected B-lymphocytes were propagated in the rotating wall bioreactor and irradiated with the various dosages of gamma irradiation. At specific time intervals following exposure to modeled microgravity, the cells and supernatant were harvested and reactivation of EBV were assessed by measuring EBV and gene expression, DNA methylation, and infectious virus production.

Mehta, Satish K↗
NASA NTRS2016

Multidirectional Cosmic Ray Ion Detector for Deep Space CubeSats

Understanding the nature of anisotropy of solar energetic protons (SEPs) and galactic cosmic ray (GCR) fluxes in the interplanetary medium is crucial in characterizing time-dependent radiation exposure in interplanetary space for future exploration missions. NASA Glenn Research Center has proposed a CubeSat-based instrument to study solar and cosmic ray ions in lunar orbit or deep space. The objective of Solar Proton Anisotropy and Galactic cosmic ray High Energy Transport Instrument (SPAGHETI) is to provide multi-directional ion data to further understand anisotropies in SEP and GCR flux. The instrument is to be developed using large area detectors fabricated from high density, high purity silicon carbide (SiC) to measure linear energy transfer (LET) of ions. Stacks of these LET detectors are arranged in a CubeSat at orthogonal directions to provide multidirectional measurements. The low-noise, thermally-stable nature of silicon carbide and its radiation tolerance allows the multidirectional array of detector stacks to be packed in a 6U CubeSat without active cooling. A concept involving additional coincidence/anticoincidence detectors and a high energy Cherenkov detector is possible to further expand ion energy range and sensitivity.

Extraterrestrial Radiation↗
NASA NTRS2018

Simulated Space Radiation and Weightlessness: Vascular-Bone Coupling Mechanisms to Preserve Skeletal Health

We examined experimentally the effects of radiation and/or simulated weightlessness by hindlimb unloading on bone and blood vessel function either after a short period or at a later time after transient exposures in adult male, C57Bl6J mice. In sum, recent findings from our studies show that in the short term, ionizing radiation and simulate weightlessness cause greater deficits in blood vessels when combined compared to either challenge alone. In the long term, heavy ion radiation, but not unloading, can lead to persistent, adverse consequences for bone and vessel function, possibly due to oxidative stress-related pathways.

microgravity↗
NASA NTRS2017

Simulated Space Radiation and Weightlessness: Vascular-Bone Coupling Mechanisms to Preserve Skeletal Health

We examined experimentally the effects of radiation andor simulated weightlessness by hindlimb unloading on bone and blood vessel function either after a short period or at a later time after transient exposures in adult male, C57Bl6J mice. In sum, recent findings from our studies show that in the short term, ionizing radiation and simulate weightlessness cause greater deficits in blood vessels when combined compared to either challenge alone. In the long term, heavy ion radiation, but not unloading, can lead to persistent, adverse consequences for bone and vessel function, possibly due to oxidative stress-related pathways.

Microgravity↗
NASA NTRS2019

Are the Brighter Rocks on Bennu Products of Recent Mechanical Weathering, and Therefore Less Space-Weathered?

Our hypothesis is that the higher-albedo rocks on the surface of Bennu are products of thermal/mechanical weathering. If this suggestion is correct, then the higher albedo (~7–15%) of some rocks relative to the average background on Bennu (~4.5%) could be explained by their relatively fresh surfaces. Older rocks on Bennu would then be the darkest rocks— those that have experienced the most space weathering over time due to exposure to the space environment. Thermal/mechanical weathering (cracking of rocks) is a candidate mechanism for the particle ejection events observed to occur with regular frequency from the asteroid surface.

Keller, Lindsay P.↗
NASA NTRSDate not supplied

Hazards of Lunar Surface Exploration: Determining the Immunogenicity/Allergenicity of Lunar Dust

There are multiple Apollo program reports of lunar dust (LD) exposure leading to significant upper respiratory symptoms in select crewmembers. Possible mechanisms include particulate irritation, oxidization and release of noxious gas, or legitimate adaptive immune-mediated response. Although sterile non-protein matter would not be expected to be an allergen, one Apollo flight surgeon reported increasing symptoms upon repeated exposure, with associated eosinophilia indicative of allergy (*Acta Astronautica. 2008 63 (7–10): 980–987). Many ISS crews display a pattern of persistent immune system dysregulation and latent virus reactivation (NPJ Microgravity. 2015 Sep 3; 1:15013; NPJ Microgravity. 2017 Apr 12; 3:11). Some ISS crews manifest atypical respiratory and/or dermatitis symptoms which could have an allergic pathogenesis (J Allergy Clin. Immunol. Pract. 2016 Jul-Aug; 4(4):759-762.e8). It is logical to anticipate crew immune dysregulation would worsen during prolonged deep space missions. Planetary surface hazards will only complicate crew health risks. This study hypothesizes that LD exposure can alter susceptible individuals’ immune responses such that repeated exposure will elicit an IgE mediated allergic response either to the LD itself or concomitant antigen exposure during spaceflight. This will adversely increase clinical and operational impacts for long-duration lunar astronauts and affect countermeasure requirements for surface vehicles. Specific aims for this study are (1) Does in vitro LD exposure result in increased histamine from human peripheral blood basophils? (2) Can LD impact the capacity of CD4+ helper and/or CD19+ B-cell mediated IgE production? To address these questions, a set of in-vitro cell culture experiments will be employed (short and long term) using human peripheral blood mononuclear cells (PBMC) and basophils from both atopic and non-atopic individuals, as well as established human basophil and mast cell lines. Cells will be co-cultured with cellular mitogens, common recall antigens (tetanus, Der p1), nickel (as a possible allergenic component of LD), with or without graded amounts of LD, to study whether LD exposure for varying time intervals will alter the generation of selective immune responses associated with clinical allergic reactions. Measured outputs include supernatant-derived IgE, tryptase, histamine and selected cytokine levels. Cellular activation will be monitored by assessing activation markers via flow cytometry. EM/x-ray analysis will be used to determine cellular interactions with dust particles. The minimal amount of LD (Apollo 14 dust) and controls/simulants have been requested. This study, originally planned as an FY20/21 activity, was delayed due to the COVID pandemic. It is now scheduled to be performed during FY22.

Brian Crucian↗
NASA NTRSDate not supplied

Solar Absorptivity Degradation of Spacecraft Materials Due to UV and Charged Particles in the Gateway Environment

The Gateway Passive Thermal Control System (PTCS) Group has identified charged particle and UV degradation of Gateway materials as a knowledge gap for the Near Rectilinear Halo Orbit (NRHO) and transit environment. Candidate materials and coatings were subjected to expected mission UV and charged particle environments at NASA Goddard Space Flight Center (GSFC). In situ change in reflectivity was observed at specified intervals during testing such that change in solar absorptivity could be plotted as a function of time of solar exposure. Gateway will be an outpost in cislunar space designed to survive a 15-year mission to support human moon landings and future deep space exploration. The Gateway Passive Thermal Control System (PTCS) Group has identified charged particle and UV degradation of potential Gateway materials as a knowledge gap for the Near Rectilinear Halo Orbit (NRHO) and transit environment, especially the slow spiral transit planned for the first two modules. Solar absorptivity degradation is important to quantify because the end-of-life absorptivity impacts thermal performance of the system. To address this, ground testing is being completed at NASA Goddard Space Flight Center in which potential Gateway materials, including radiators, multi-layer insulation (MLI), and structural materials are subjected to the expected transit plus 15-year on-orbit charged particle fluence (9.86x1015 protons/cm2 at 2.5 keV and 3.1x1016 electrons/cm2 at 10 keV) and up to 5000 Equivalent Solar Hours (ESH). Reflectivity of a single sample of each material was measured in atmosphere and in vacuum inside the chamber after exposure to incremental levels of ESH and charged particle fluence. Increase in absorptivity of most samples were seen throughout the test including large differences in absorptivity of materials of the same category. Future testing will validate these results and include additional materials of interest.

materials in the space environment↗
NASA NTRSDate not supplied

Solar Absorptivity Degradation of Spacecraft Materials Due to UV and Charged Particles in the Gateway Environment

Traditionally, most of the data accumulated for material optical property degradation in space has been in the Low Earth Orbit (LEO) environment. However, Gateway is a new space station that will be assembled and flown in Near Rectilinear Halo Orbit (NRHO) for 15 years. Additionally, some Gateway modules will have a slow transit from Earth to NRHO that will take over a year to pass through the Van Allen Belts, which contain damaging charged particles. The environments Gateway modules will encounter are not well characterized. Environmental factors such as charged particles and ultraviolet (UV) radiation have been shown to significantly increase solar absorptivity (α) for some thermal control materials and coatings. Since α will impact thermal performance over the mission, the Gateway Passive Thermal Control System (PTCS) Group has identified charged particle and UV degradation of Gateway materials as a knowledge gap. Candidate materials and coatings were subjected to expected mission charged particle environments and over 5000 Equivalent Solar Hours (ESH) of UV at NASA Goddard Space Flight Center (GSFC). In situ change in reflectivity was observed at specified intervals during testing such that change in α could be plotted as a function of time of solar exposure.

Optical Property↗
NASA NTRSDate not supplied

Hazards of Lunar Surface Exploration: Determining the Immunogenicity/Allergenicity of Lunar Dust

Although infrequent, there have been Apollo program reports of lunar dust (LD) exposure leading to notable upper respiratory symptoms in select crewmembers. Possible mechanisms include particulate irritation, oxidization and release of noxious gas, or legitimate adaptive immune-mediated response. Although sterile non-protein matter would not be expected to be an allergen, one Apollo flight surgeon reported increasing symptoms upon repeated exposure with associated eosinophilia, indicative of allergy (*Acta Astronautica. 2008 63 (7–10): 980–987). Many ISS crews display a pattern of persistent immune system dysregulation and latent virus reactivation (NPJ Microgravity. 2015 Sep 3; 1:15013; NPJ Microgravity. 2017 Apr 12; 3:11). Some ISS crews manifest atypical respiratory and/or dermatitis symptoms which could have an allergic pathogenesis (J Allergy Clin. Immunol. Pract. 2016 Jul-Aug; 4(4):759-762.e8). It is logical to anticipate crew immune dysregulation would worsen during prolonged deep space missions. Planetary surface hazards will only complicate crew health risks. This study with investigate if LD exposure will elicit an IgE mediated allergic response either to the LD itself or concomitant antigen exposure during spaceflight. Allergic reactivity could adversely increase clinical and operational impacts for long-duration lunar astronauts and affect countermeasure requirements for surface vehicles. Specific aims for this study are to answer two questions: (1) Does in vitro LD exposure result in increased histamine from human peripheral blood basophils? (2) Can LD impact the capacity of CD4+ T helper and/or CD19+ B-cell mediated IgE production? To address these questions, after the proposal and selection by NASA, our laboratory has separately requested and been approved for receipt of actual LD samples from the Apollo 16 mission. These samples will be used during the study to complete the proposed set of in vitro cell culture experiments (short and long term), using human peripheral blood mononuclear cells (PBMC) and basophils from both atopic and non-atopic individuals. Cells will be co-cultured with cellular mitogens, common recall antigens (Der p1), fine ground silica quartz (as a possible allergenic component of LD), or LD, to study whether LD exposure for varying time intervals will alter the generation of selective immune responses associated with clinical allergic reactions. Measured outputs include supernatant-derived IgE, tryptase, histamine, and selected cytokine levels. Cellular activation will be monitored by assessing activation markers via flow cytometry. EM/x-ray analysis will be used to determine cellular interactions with dust particles. A series of validation experiments was initiated in FY22 once the delivery of LD was received. Based on initial experimental findings, we are optimizing the culture conditions, LD concentrations, and refining our other protocol stimuli.

Audrie A. Colorado↗
NASA NTRSDate not supplied

Hazards of Lunar Surface Exploration: Determining the Immunogenicity/Allergenicity of Lunar Dust

Although infrequent, there have been Apollo program reports of lunar dust (LD) exposure leading to notable upper respiratory symptoms in select crewmembers. Possible mechanisms include particulate irritation, oxidization and release of noxious gas, or legitimate adaptive immune-mediated response. Although sterile non-protein matter would not be expected to be an allergen, one Apollo flight surgeon reported increasing symptoms upon repeated exposure with associated eosinophilia, indicative of allergy (*Acta Astronautica. 2008 63 (7–10): 980–987). Many ISS crews display a pattern of persistent immune system dysregulation and latent virus reactivation (NPJ Microgravity. 2015 Sep 3; 1:15013; NPJ Microgravity. 2017 Apr 12; 3:11). Some ISS crews manifest atypical respiratory and/or dermatitis symptoms which could have an allergic pathogenesis (J Allergy Clin. Immunol. Pract. 2016 Jul-Aug; 4(4):759-762.e8). It is logical to anticipate crew immune dysregulation would worsen during prolonged deep space missions. Planetary surface hazards will only complicate crew health risks. This study with investigate if LD exposure will elicit an IgE mediated allergic response either to the LD itself or concomitant antigen exposure during spaceflight. Allergic reactivity could adversely increase clinical and operational impacts for long-duration lunar astronauts and affect countermeasure requirements for surface vehicles. Specific aims for this study are to answer two questions: (1) Does in vitro LD exposure result in increased histamine from human peripheral blood basophils? (2) Can LD impact the capacity of CD4+ T helper and/or CD19+ B-cell mediated IgE production? To address these questions, after the proposal and selection by NASA, our laboratory has separately requested and been approved for receipt of actual LD samples from the Apollo 16 mission. These samples will be used during the study to complete the proposed set of in vitro cell culture experiments (short and long term), using human peripheral blood mononuclear cells (PBMC) and basophils from both atopic and non-atopic individuals. Cells will be co-cultured with cellular mitogens, common recall antigens (Der p1), fine ground silica quartz (as a possible allergenic component of LD), or LD, to study whether LD exposure for varying time intervals will alter the generation of selective immune responses associated with clinical allergic reactions. Measured outputs include supernatant-derived IgE, tryptase, histamine, and selected cytokine levels. Cellular activation will be monitored by assessing activation markers via flow cytometry. EM/x-ray analysis will be used to determine cellular interactions with dust particles. A series of validation experiments was initiated in FY22 once the delivery of LD was received. Based on initial experimental findings, we are optimizing the culture conditions, LD concentrations, and refining our other protocol stimuli.

immunology↗
DOE OSTI2022

Recent results from NOvA

We present the most recent 3-flavor neutrino oscillation results from the NOvA long-baseline experiment, using a joint fit of $\nu_\mu \to \nu_\mu$, $\bar{\nu}_{\mu} \to \bar{\nu}_{\mu}$, $\nu_\mu \to \nu_{e}$, and $\bar{\nu}_{\mu}\to \bar{\nu}_{e}$ channels, and an accumulated exposure of $13.6 \times 10^{20}$ protons-on-target of neutrino beam and $12.5 \times 10^{20}$ protons-on-target of antineutrino beam. The best-fit values for the atmospheric parameters are $\Delta m^2_{32} = (2.41\pm0.07)\times 10^{-3}$ eV$^2$, $\sin^2\theta_{23} = 0.57^{+0.03}_{-0.04}$ and $\delta_{CP} = (0.82^{+0.27}_{-0.87}) \pi$. The data disfavor combinations of oscillation parameters that lead to large asymmetries between the rates of $\nu_{e}$ vs $\bar{\nu}_{e}$ appearance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Searching for Neutrino Tridents in the NOvA Near Detector

This dissertation presents a search for neutrino trident production in the NOvA near detector through the coherent ``dimuon" channel: $\nu_\mu +\hspace{1pt}\text{X} \rightarrow \nu_\mu + \mu^- + \mu^+ +\hspace{1pt}\text{X}$. Trident production is a rare, purely electroweak process with sensitivity to physics beyond the Standard Model. The theoretical background, motivation for studying the process, and previous experimental measurements are reviewed. The analysis uses data collected by the NOvA near detector (ND) from Fermilab's Neutrinos at the Main Injector (NuMI) beam between November 2014 and February 2024, corresponding to an exposure of $25.5\times 10^{20}$ protons on target. The ND is a segmented tracking calorimeter located 800~m from the beam target, receiving neutrinos with a mean energy of 2~GeV. A multi-pass background reduction strategy is implemented, including the development of a novel dimuon-specific tracking technique. Trident candidates are identified using a boost ed decision tree classifier trained on simulated signal and background events. Limited background Monte Carlo statistics necessitate the use of functional fits to sideband data, which are extrapolated to estimate backgrounds in the signal region. The unblinded data contain 9 trident-like events, with an estimated background of 5.66 $\pm$ 5.15 events. This yields a best fit estimate of 3.34 tridents compared to the Standard Model prediction of 4.66. A profiled Feldman-Cousins method is used to determine a 90\% confidence interval of [0,9.1] on the number of signal events, corresponding to an upper limit of 1.95$\times$ the Standard Model prediction. This result represents the lowest energy search for trident events to date, and the first experimental contribution to the process in 27 years.

Bowles, Reed Scott [Indiana U.]↗
DOE OSTI2025

Measurements of differential charged-current cross sections on argon for electron neutrinos with final-state protons in MicroBooNE

This work presents single-differential electron-neutrino charged-current cross sections on argon measured using the MicroBooNE detector at the Fermi National Accelerator Laboratory. The analysis uses data recorded when the Neutrinos at the Main Injector beam was operating in both neutrino and antineutrino modes, with exposures of $2 \times 10^{20}$ and $5 \times 10^{20}$ protons on target, respectively. A selection algorithm targeting electron-neutrino charged-current interactions with at least one proton, one electron, and no pions in the final topology is used to measure differential cross sections as a function of outgoing electron energy, total visible energy, and opening angle between the electron and the most energetic proton. The interaction rate as a function of proton multiplicity is also reported. The total cross section is measured as [4.1 $\pm$ 0.4 (stat.) $\pm$ 1.2 (syst.)]$ $$\times 10^{-39} \mathrm{cm}^{2}/ \mathrm{nucleon}$. The unfolded cross-section measurements are compared to predictions from neutrino event generators commonly employed in the field. Good agreement is seen across all variables within uncertainties.

Abratenko, P. [Tufts U. (main)]↗
NASA NTRS1985

Use of aluminum as an oxidation barrier for titanium

A study is conducted of the use of aluminum coatings as oxidation retardants for Ti alloys, using room temperature normal emittance and spectral emittance as bases for the characterization of oxidation properties with and without the coatings. Thermal exposures were conducted in a thermogravimetric analysis apparatus in which specimen weight was continuously monitored. The results obtained indicate that the weight gains are proportional to the square root of the time for uncoated alloys and for 649 C-exposed aluminum-coated alloys. For the 704 C-exposed aluminum-coated alloys, weight gain exhibits a low rate for short and a high rate for long exposure times, implying that the 0.5-micron coating's protection decreases for long exposures at this temperature.

Unnam, J.↗
NASA NTRS1990

Investigation of the reaction kinetics between SiC fibers and selectively alloyed titanium matrix composites and determination of their mechanical properties

During high temperature exposure, an interfacial reaction occurs between SiC fiber reinforcement and titanium matrices which can be detrimental to the mechanical properties of the composite. The reaction kinetics between SCS-6 fibers and Ti-1100 were determined at 800 to 1000 C and found to be slower than those of other currently used titanium alloys (Ti-15-3, Ti-6-4). The experimentally determined reaction kinetics for Ti-1100 were extrapolated to 700 C and found to accurately predict reaction zone size after 1000 hours of exposure. Predictions of the time to consume the surface layer on the SCS-6 and SCS-9 fibers were made in an effort to estimate the time that the fiber will retain its strength in Ti-1100 during isothermal exposure at high temperatures. Using this approach, the strength of an SCS-6 fiber in Ti-1100 should be retained for over 20,000 hours at isothermal exposures less than 800 C. Strength predictions using the rule of mixtures for a unidirectional Ti-1100/SCS-6 composite are presented for short term exposures up to 700 C. Room temperature tests of an as-fabricated 20 volume percent fiber/Ti-1100 composite yielded a UTS of 226 ksi (1490 MPa) which is close to that predicted by the ROM.

Gundel, Douglas B.↗
DOE OSTI2022

Search for Higgs Portal Scalars and Heavy Neutral Leptons Decaying in the MicroBooNE Detector

This thesis presents a search for Higgs Portal Scalars (HPS) and Heavy Neutral Leptons (HNL) decaying in the MicroBooNE liquid argon time projection chamber (LArTPC). The measurement was performed using data collected in-time with the Neutrino at the Main Injector (NuMI) beam with a total exposure corresponding to $7.01 \times 10^{20}$ protons on target. Mono-energetic HPS and HNL would be produced from kaons decaying at rest in the NuMI hadron absorber, before travelling ${\sim}100$~m to the MicroBooNE detector where they decay. A single selection and search strategy is used to target decays of HPS to $\mu\mu$ pairs and HNL to $\mu\pi$ pairs. The results are expressed as limits, at the $90\%$ confidence level, on the mixing angles that control the rates of production and decay for each new particle. For the HNL model, upper limits are set on the mixing parameter $\mumix$ in the range [$12.9 \times 10^{-8}$, $0.54 \times 10^{-8}$] for HNL with masses in the region $246$--$385$~MeV. % This represents an order of magnitude increase in sensitivity to the previous MicroBooNE HNL result. For the HPS model, limits on the scalar-Higgs mixing angle $\theta^2$ are set, excluding a region with a lower boundary between [$31.3 \times10^{-9}$, $1.09 \times 10^{-9}$] and an upper boundary between [$2.50 \times 10^{-5}$, $5.05 \times 10^{-9}$] for scalars with a mass of $212$--$275$ MeV. These results set the first constraints in this region of parameter space from a dedicated experimental search for HPS.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗