Search NASA⌕ Search

SEARCH · Search NASA

Results for “surface backgrounds”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Computational studies on scattering of radio frequency waves by density filaments in fusion plasmas

In modern magnetic fusion devices, such as tokamaks and stellarators, radio frequency (RF) waves are commonly used for plasma heating and current profile control, as well as for certain diagnostics. The frequencies of the RF waves range from ion cyclotron frequency to the electron cyclotron frequency. The RF waves are launched from structures, like waveguides and current straps, placed near the wall in a very low density, tenuous plasma region of a fusion device. The RF electromagnetic fields have to propagate through this scrape-off layer before coupling power to the core of the plasma. The scrape-off layer is characterized by turbulent plasmas fluctuations and by blobs and filaments. The variations in the edge density due to these fluctuations and filaments can affect the propagation characteristics of the RF waves—changes in density leading to regions with differing plasma permittivity. Analytical full-wave theories have shown that scattering by blobs and filaments can alter the RF power flow into the core of the plasma in a variety of ways, such as through reflection, refraction, diffraction, and shadowing [see, for example, Ram and Hizanidis, Phys. Plasmas 23, 022504 (2016), and references therein]. There are changes in the wave vectors and the distribution of power–scattering leading to coupling of the incident RF wave to other plasma waves, side-scattering, surface waves, and fragmentation of the Poynting flux in the direction towards the core. However, these theoretical models are somewhat idealized. In particular, it is assumed that there is step-function discontinuity in the density between the plasma inside the filament and the background plasma. In this paper, results from numerical simulations of RF scattering by filaments using a commercial full-wave code are described. The filaments are taken to be cylindrical with the axis of the cylinder aligned along the direction of the ambient magnetic field. The plasma inside and outside the filament is assumed to be cold. There are three primary objectives of these studies. The first objective is to validate the numerical simulations by comparing with the analytical results for the same plasma description—a step-function discontinuity in density. A detailed comparison of the Poynting flux shows that numerical simulations lead to the same results as those from the theoretical model. The second objective is to extend the simulations to take into account a smooth transition in density from the background plasma to the interior of the filament. The ensuing comparison shows that the deviations from the results of the theoretical model are quite small. The third objective is to consider the scattering process for situations well beyond a reasonable theoretical analysis. This includes scattering off multiple filaments with different densities and sizes. In conclusion, simulations for these complex arrangements of filaments show that, in spite of the obvious limitations, the essential physics of RF scattering is captured by the analytical theory for a single filament

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Building partnerships for development of sustainable energy systems with atmospheric measurements

Atmospheric dynamics often play a critical role in the sustainability and reliability of diverse forms of energy production. This is especially true for the growing number of renewable energy deployments that harness aspects of the environment for power production. While the University of Memphis has a strong research background in energy systems, we have little experience working with the Earth and Environmental Systems Science Division (EESSD) and their associated User Facilities. Of particular interest to us is the Atmospheric Science Research and the Atmospheric Radiation Measurement (ARM) user facility to address surface-boundary layer interactions and physical phenomena. One of the major challenges for understanding and developing energy systems and management platforms is accurate modeling/forecasting of atmospheric conditions across disparate spatial and temporal scales. These conditions are often required to understand the lowest levels of the atmospheric boundary layer, but are also important to understand higher atmospheric conditions where aerosols affect cloud development. The objective of this work was to develop partnerships with national laboratories for collaboration on environmental science and its intersection with sustainable energy systems, as well as to leverage the ARM user facility data repositories to enhance our research capabilities in energy systems and their inter-dependence on environmental systems for future engagement with EESSD. Specifically, we accomplished these objectives by (1) developing collaborations with Oakridge National Laboratory ARM Data Science and Integration Group which resulted in student internships, (2) employed ARM data to develope modeling of the atmospheric boundary layer optical turbulence, and (3) optimally-sized large-scale renewable energy systems and their associated energy storage systems with ARM repository data.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS1972

Ocean color determination through a scattering atmosphere

Measurements made of the surface level albedo for ocean water containing various concentrations of phytoplankton indicate a strong correlation between wavelength dependent albedo ratios and phytoplankton chlorophyll concentration. To sense surface level albedo ratios from space platforms it is necessary to correct for the scattering and absorption properties of the atmosphere for the wavelengths in question. Atmospheric scattering models were constructed to calculate corrections at two wavelengths, 0.46 and 0.54 millimicrons. Assuming a natural background uncertainty in the aerosol optical depth of 0.1, it is found that the chlorophyll concentration may be determined to within one standard deviation of from 0.5 to 2.5 milligrams per cubic meter. By remotely sensing the aerosol optical depth to a greater accuracy it appears feasible to detect chlorophyll concentrations to uncertainty approaching 0.1 milligram per cubic meter.

Curran, R. J.↗
NASA NTRS1977

The Viking X ray fluorescence experiment - Analytical methods and early results

Ten samples of the Martian regolith have been analyzed by the Viking lander X ray fluorescence spectrometers. Because of high-stability electronics, inclusion of calibration targets, and special data encoding within the instruments the quality of the analyses performed on Mars is closely equivalent to that attainable with the same instruments operated in the laboratory. Determination of absolute elemental concentrations requires gain drift adjustments, subtraction of background components, and use of a mathematical response model with adjustable parameters set by prelaunch measurements on selected rock standards. Bulk fines at both Viking landing sites are quite similar in composition, implying that a chemically and mineralogically homogeneous regolith covers much of the surface of the planet. Important differences between samples include a higher sulfur content in what appear to be duricrust fragments than in fines and a lower iron content in fines taken from beneath large rocks than those taken from unprotected surface material. Further extensive reduction of these data will allow more precise and more accurate analytical numbers to be determined and thus a more comprehensive understanding of elemental trends between samples.

Clark, B. C., III↗
NASA NTRS1983

Radio science and the International Halley Watch

The radio observations planned for the perihelion passage of Halley's comet in 1986 within the framework of the International Halley Watch (IHW) are reviewed. The roles of radar astronomy, continuum radio astronomy, and spectral-line radio astronomy in investigating the size and surface characteristics of the cometary nucleus, the nature and kinematics of the parent molecules sublimating into the coma, the properties of the coma particulate matter, and the cometary plasma are examined. Problems related to the inaccuracy of comet position data and lacks of background-source information, simultaneous submillimeter observations, and Southern-Hemisphere radio observing time are discussed; and the observatories participating in the IHW network are listed in tables with their instrument parameters.

Irvine, W. M.↗
NASA NTRS1987

A 9 month long soft X-ray survey of the Large Magellanic Cloud. I - X-ray map at 1/4 keV

Data from the HEAO 1 low energy detector was used to map the diffuse 1/4 keV X-ray background around the LMC. Data was collected over 9 mos in 1977-1978 using detectors sensitive in the range 0.18-2.8 keV. Diffuse emission, rather than absorption, was observed from the LMC, as were two large emission (2 million K) regions with very low surface brightness. The regions coincided with the Shapley III supergiant shell of optical nebulosity and the LMC bar. Higher spatial resolution imagery is required if the emission features are to be confirmed as the same type of phenomena as the X-ray superbubble in Cygnus.

Singh, K. P.↗
NASA NTRS2006

Ice Mass Fluctuations and Earthquake Hazard

In south central Alaska, tectonic strain rates are high in a region that includes large glaciers undergoing ice wastage over the last 100-150 years [Sauber et al., 2000; Sauber and Molnia, 2004]. In this study we focus on the region referred to as the Yakataga segment of the Pacific-North American plate boundary zone in Alaska. In this region, the Bering and Malaspina glacier ablation zones have average ice elevation decreases from 1-3 meters/year (see summary and references in Molnia, 2005). The elastic response of the solid Earth to this ice mass decrease alone would cause several mm/yr of horizontal motion and uplift rates of up to 10-12 mm/yr. In this same region observed horizontal rates of tectonic deformation range from 10 to 40 mm/yr to the north-northwest and the predicted tectonic uplift rates range from -2 mm/year near the Gulf of Alaska coast to 12mm/year further inland [Savage and Lisowski, 1988; Ma et al, 1990; Sauber et al., 1997, 2000, 2004; Elliot et al., 2005]. The large ice mass changes associated with glacial wastage and surges perturb the tectonic rate of deformation at a variety of temporal and spatial scales. The associated incremental stress change may enhance or inhibit earthquake occurrence. We report recent (seasonal to decadal) ice elevation changes derived from data from NASA's ICESat satellite laser altimeter combined with earlier DEM's as a reference surface to illustrate the characteristics of short-term ice elevation changes [Sauber et al., 2005, Muskett et al., 2005]. Since we are interested in evaluating the effect of ice changes on faulting potential, we calculated the predicted surface displacement changes and incremental stresses over a specified time interval and calculated the change in the fault stability margin using the approach given by Wu and Hasegawa [1996]. Additionally, we explored the possibility that these ice mass fluctuations altered the seismic rate of background seismicity. Although we primarily focus on evaluating the influence of ice mass changes since the end of the little Ice Age, the study is partially motivated by paleoseismic evidence from Yakataga and Kodiak regions which suggests that earlier glacier retreat may be associated with large earthquakes [Sauber et al., 2000; Carver et al., 2003].

Sauber, J.↗
NASA NTRS2007

Reactive Nitrogen Distribution and Partitioning in the North American Troposphere and Lowermost Stratosphere

A comprehensive group of reactive nitrogen species (NO, NO2, HNO3, HO2NO2, PANs, alkyl nitrates, and aerosol-NO3) were measured in the troposphere and lowermost stratosphere over North America and the Atlantic during July/August 2004 (INTEX-A) from the NASA DC-8 platform (0.1-12 km). Less reactive nitrogen species (HCN and CH3CN), that are also unique tracers of biomass combustion, were also measured along with a host of other gaseous (CO, VOC, OVOC, halocarbon) and aerosol tracers. Clean background air as well as air with influences from biogenic emissions, anthropogenic pollution, biomass combustion, and stratosphere was sampled both over continental U. S., Atlantic and Pacific. The North American upper troposphere was found to be greatly influenced by both lightning NO(x) and surface pollution lofted via convection and contained elevated concentrations of PAN, ozone, hydrocarbons, and NO(x). Under polluted conditions PAN was a dominant carrier of reactive nitrogen in the upper troposphere while nitric acid dominated in the lower troposphere. Peroxynitric acid (HO2NO2) was present in sizable concentrations always peaking at around 8 km. Aerosol nitrate appeared to be mostly contained in large soil based particles in the lower troposphere. Plumes from Alaskan fires contained large amounts of PAN and very little enhancement in ozone. Observational data suggest that lightning was a far greater contributor to NO(x) in the upper troposphere than previously believed. NO(x) and NO(y) reservoir appeared to be in steady state only in the middle troposphere where NO(x)/NO(y) was independent of air mass age. A first comparison of observed data with simulations from four 3-D models shows significant differences between observations and models as well as among models. These uncertainties likely propagate themselves in satellites derived NOx data. Observed data are interpreted to suggest that soil sinks of HCN/CH3CN are at best very small. We investigate the partitioning and interplay of the reactive nitrogen species within characteristic air masses and further examine their role in ozone formation.

Singh, H. B.↗
NASA NTRS2023

Estimating the Subsolar Magnetopause Position from Soft X-Ray Images Using a Low-Pass Image Filter

The Lunar Environment heliospheric X-ray Imager (LEXI) and Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) missions will image the Earth’s dayside magnetopause and cusps in soft X-rays after their respective launches in the near future, to specify global magnetic reconnection modes for varying solar wind conditions. To support the success of these scientific missions, it is critical to develop techniques that extract the magnetopause locations from the observed soft X-ray images. In this research, we introduce a new geometric equation that calculates the subsolar magnetopause position ( R s ) from a satellite position, the look direction of the instrument, and the angle at which the X-ray emission is maximized. Two assumptions are used in this method: (1) The look direction where soft X-ray emissions are maximized lies tangent to the magnetopause, and (2) the magnetopause surface near the subsolar point is almost spherical and thus R s is nearly equal to the radius of the magnetopause curvature. We create synthetic soft X-ray images by using the Open Geospace General Circulation Model (OpenGGCM) global magnetohydrodynamic model, the galactic background, the instrument point spread function, and Poisson noise. We then apply the fast Fourier transform and Gaussian low-pass filters to the synthetic images to remove noise and obtain accurate look angles for the soft X-ray peaks. From the filtered images, we calculate R 2 and its accuracy for different LEXI locations, look directions, and solar wind densities by using the OpenGGCM subsolar magnetopause location as ground truth. Our method estimates R s with an accuracy of <0.3 R E when the solar wind density exceeds >10 cm -3 . The accuracy improves for greater solar wind densities and during southward interplanetary magnetic fields. The method captures the magnetopause motion during southward interplanetary magnetic field turnings. Consequently, the technique will enable quantitative analysis of the magnetopause motion and help reveal the dayside reconnection modes for dynamic solar wind conditions. This technique will support the LEXI and SMILE missions in achieving their scientific objectives.

Hyangpyo Kim↗
DOE OSTI2017

Characterization of NORM in an Urban Environment using HPGe Measurements and MCNP6 Simulations

This work is part of a larger project aimed at producing an operationally relevant, validated simulation environment that can be used as a 'virtual testbed' for counterterrorism and counterproliferation efforts. Examples of such efforts include searches for illicit radiation sources before and during large special events, such as the presidential nominating conventions, inaugurations, and large sporting events. Once validated by laboratory and field measurements, this testbed can be used to test and validate algorithms and detector systems designed for various search missions in an urban environment. The detection of radioactive sources in a city is greatly complicated by natural background radiation, which emanates from various materials common to an urban environment, such as roadways, sidewalks, and building exteriors. The methods and results offered here represent the conclusion of an effort to characterize the concentration of naturally occurring radioactive material (NORM) in various elements in a controlled, but representative, urban environment. Some of the methods discussed in previous work will be briefly reiterated here, but more detail can be found in the preceding work. The location chosen for this effort was a Military Operations on Urban Terrain (MOUT) environment at the Fort Indiantown Gap (FTIG) National Guard training facility in Pennsylvania. This site was chosen because it replicates a small town where traffic and pedestrian access could be easily controlled, as to not interfere with the background measurements. This endeavor involved over 70 measurements using a high-purity germanium (HPGe) detector designed to ascertain the NORM concentrations in the soil, asphalt roads, gravel lots, concrete intersections, sidewalks, foundations, and walls found throughout the site. The NORM concentrations determined from this work will be incorporated into a large-scale simulation that can be used to investigate various search techniques and algorithms, detector types and setups, and to produce representative synthetic data for future work.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2016

Enhancing the accuracy of the Fowler method for monitoring non-constant work functions

The Fowler method is a prominent non-invasive technique to determine the absolute work function of a surface based on the photoelectric effect. The evaluation procedure relies on the correlation of the photocurrent with the incident photon energy hν which is mainly dependent on the surface work function χ. Applying Fowler’s theory of the photocurrent, the measurements can be fitted by the theoretical curve near the threshold hν⪆χ yielding the work function χ and a parameter A. The straightforward experimental implementation of the Fowler method is to use several particular photon energies, e.g. via interference filters. However, with a realization like that the restriction hν ≈ χ can easily be violated, especially when the work function of the material is decreasing during the measurements as, for instance, with coating or adsorption processes. This can lead to an overestimation of the evaluated work function value of typically some 0.1 eV, reaching up to more than 0.5 eV in an unfavorable case. A detailed analysis of the Fowler theory now reveals the background of that effect and shows that the fit-parameter A can be used to assess the accuracy of the determined value of χ conveniently during the measurements. Moreover, a scheme is introduced to quantify a potential overestimation and to perform a correction to χ to a certain extent. The issues are demonstrated exemplarily at the monitoring of the work function reduction of a stainless steel sample surface due to caesiation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Effect of biofilm coatings at metal-oxide/water interfaces II: Competitive sorption between Pb(II) and Zn(II) at Shewanella oneidensis /metal-oxide/water interfaces

Competitive sorption of Pb(II) and Zn(II) on Shewanella oneidensis MR-1 biofilm-coated single-crystal α-Al 2 O 3 (1 –1 0 2) and α-Fe 2 O 3 (0 0 0 1) surfaces was investigated using long-period X-ray standing wave-florescence yield (LP-XSW-FY) spectroscopy. In situ partitioning of aqueous Pb(II) and Zn(II) between the biofilms and underlying metal-oxide substrates was probed following exposure of these complex interfaces to equi-molar Pb and Zn solutions (0.01 M NaNO 3 as background electrolyte, pH = 6.0, and 3-h equilibration time). At higher Pb and Zn concentrations (≥10 –5 M), more than 99% of these ions partitioned into the biofilms at S. oneidensis /α-Al 2 O 3 (1 –1 0 2)/water interfaces, which is consistent with the partitioning behavior of both Pb(II) or Zn(II) in single-metal-ion experiments. Furthermore, no apparent competitive effects were found in this system at these relatively high metal-ion concentrations. However, at lower equi-molar concentrations (≤10 –6 M), Pb(II) and Zn(II) partitioning in the same system changed significantly compared to the single-metal-ion systems. The presence of Zn(II) decreased Pb(II) partitioning onto α-Al 2 O 3 (1 –1 0 2) substantially (~52% to ~13% at 10 –7 M, and ~23% to ~5% at 10–6 M), whereas the presence of Pb(II) caused more Zn(II) to partition onto α-Al 2 O 3 (1 –1 0 2) surfaces (~15% to ~28% at 10 –7 M, and ~1% to ~7% at 10 –6 M) .The higher observed partitioning of Zn(II) (~28%) at the α-Al 2 O 3 (1 –1 0 2) surfaces compared to Pb(II) (~13%) in the mixed-metal-ion systems at the lowest concentration (10 –7 M) suggests that Zn(II) is slightly favored over Pb(II) for sorption sites on α-Al 2 O 3 (1 –1 0 2) surfaces under our experimental conditions.

58 GEOSCIENCES↗
NASA NTRS2014

Investigating the Sensitivity of Surface-Level Nitrate Seasonality in Antarctica to Primary Sources Using a Global Model

Determining the sources of total nitrate (TNIT NO-3 + HNO3) reaching Antarctica is a long-standing challenge. Here we analyze the monthly sensitivity of surface-level TNIT in Antarctica to primary sources using a global 3-D chemical transport model, GEOS-Chem, and its adjoint. Modeled seasonal variation of TNIT concentrations shows good agreement with several measurement studies, given that the lack of post-depositional processing in the model leads to an expected underestimate of maximum values in November through January. Remote NOx sources have the greatest impact May-July, during when the model background concentrations are sensitive to NOx emissions from fossil fuel combustion, soil, and lightning originating from 25S to 65S. In this season, NOx is transported to Antarctica as TNIT, which is formed above continental source regions at an altitude of 5-11 km. In other seasons, more NOx is transported as a reservoir species (e.g., peroxyacetyl nitrate, PAN) through the free troposphere, transforming into TNIT within a cone of influence that extends to 35S and above 4 km altitude. Photolysis of PAN over Antarctica is the main driver of modeled NOx seasonality. Stratospheric production and loss of tracers are relatively unimportant in monthly sensitivities in GEOS-Chem, driving only a few percent of surface level variability of TNIT. A small peak concentration in August is captured by the model, although some measured values in August fall outside the range of simulated concentrations. Modifications to the model to represent sedimentation of polar stratospheric clouds (PSCs) lead to increased surface level August TNIT concentrations. However, this simple representation does not explicitly account for PSC particle deposition or disappearance of the tropopause in the middle of winter, and thus the influence of stratospheric nitrate sources estimated in this study is likely a lower bound.

stratosphere↗
DOE OSTI2021

Definition of a new (Doniach-Sunjic-Shirley) peak shape for fitting asymmetric signals applied to reduced graphene oxide/graphene oxide XPS spectra

The existence of asymmetry in X-ray photoelectron spectroscopy (XPS) photoemission lines is widely accepted, but line shapes designed to accommodate asymmetry are generally lacking in theoretical justification. Here in this work, we present a new line shape for describing asymmetry in XPS signals that is based on two facts. First, the most widely known line shape for fitting asymmetric XPS signals that has a theoretical basis, referred to as the Doniach-Sunjic (DS) line shape, suffers from a mathematical inconvenience, which is that for asymmetric shapes the area beneath the curve (above the x-axis) is infinite. Second, it is common practice in XPS to remove the inelastically scattered background response of a peak in question with the Shirley algorithm. The new line shape described herein attempts to retain the theoretical virtues of the DS line shape, while allowing the use of a Shirley background, with the consequence that the resulting line shape has a finite area. To illustrate the use of this Doniach-Sunjic-Shirley (DSS) line shape, a set of spectra obtained from varying amounts of graphene oxide (GO) and reduced GO on a patterned, heterogeneous surface are fit and discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Stationary Bragg reflection of laser light in inhomogeneous absorbing plasmas inside inertial confinement fusion Hohlraums

Laser-produced plasma in inertial confinement fusion (ICF) Hohlraums are marked with density non-uniformity whose length scale can go down to micrometers. This scale is of the order of the laser wavelength. The WKB approximation, which is classically used in radiation-hydrodynamic codes to compute the laser trajectory, cannot correctly take into account such small-scale inhomogeneity of the plasma. Going beyond this approximation, we predict a novel mechanism for the laser reflection. Here we show that an electromagnetic plane wave with wave number k resonates with the k B =2 k Fourier component of a multimode perturbation of the background density and generates a reflected wave. It is the first time that this reflection is considered for stationary inhomogeneous ICF plasmas, and the energy absorption is taken into account. This mechanism, which is a form of Bragg reflection, can occur away from the critical surface and generate a drift of the location of the laser absorption. Furthermore, this absorption will be periodically modulated with a k B wave number. The stationary Bragg reflection can explain ongoing discrepancies between experimental and numerical data about laser trajectory and absorption in ICF Hohlraums.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Development of a tagged source of Pb-206 nuclei

There is a particular class of unavoidable backgrounds that plague low-background experiments and rare event searches, particularly those searching for nuclear recoil event signatures: decaying daughters of the 238 U nuclear decay chain, which result from radon plate-out on detector materials. One such daughter isotope, 210 Po, undergoes α-decay and produces a recoiling 103 keV 206 Pb nucleus. In this study, to characterize this important background in the context of noble element detectors, we have implemented a triggered source for these 206 Pb recoils in a dual-phase xenon time projection chamber (Xe TPC) within the Davis Xenon R&D testbed system (DAX). By adhering 210 Po to the surface of a PIN diode and electrically floating the diode on the cathode of the TPC, we tag the α signals produced in the PIN diode and trigger on the correlated nuclear recoils in the liquid xenon (LXe). Lastly, we discuss our methods for 210 Po deposition, electronic readout of the PIN diode signals at high voltage, and analysis methods for event selection.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Sequential Electrochemical Flow Cell for Complex Multicomponent Electrocatalysis

A highly efficient flow cell for sequential electrolysis containing two complete electrochemical cells, capable of generating reactive species at the upstream working electrode and transporting them to the downstream working electrode, is demonstrated. Deconvolution of the intermixed electrode circuits is accomplished through analysis of the inherent resistance of the electrolyte, which allows for precise and independent control of the electrochemical potential at each electrode without altering concentrations of supporting or background electrolyte species. Sequential electrolysis involving oxidation of hydrogen and reduction of the generated protons downstream is demonstrated at nearly 100% efficiency on Pt-decorated dealloyed porous Nb catalysts. The conversion efficiency of the catalysts is discussed in terms of their geometries and active surface composition, elucidating strategies for use of sequential electrolysis cells for fundamental and applied studies.

25 ENERGY STORAGE↗
DOE OSTI2018

A Letter of Intent for MATHUSLA: a dedicated displaced vertex detector above ATLAS or CMS.

In this Letter of Intent we propose the construction of MATHUSLA (MAssive Timing Hodoscope for Ultra-Stable neutraL pArticles), a dedicated large-volume displaced vertex detector (DV) for the HL-LHC on the surface above ATLAS or CMS. Such a detector, which can be built using existing technologies with a reasonable budget in time for the HL-LHC upgrade, could search for neutral long-lived particles (LLPs) without trigger limitations and with very low or zero backgrounds, allowing it to probe LLP cross sections and lifetimes up to several orders of magnitude beyond the reach of ATLAS or CMS. MATHUSLA would also act as a cutting-edge cosmic ray telescope at CERN, exploring many open questions in cosmic ray and astro-particle physics.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗