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DOE OSTI2025

Mitigating field emission in SSR2 cryomodules for PIP-II

The SSR2 cavities for PIP-II have consistently been affected by field emission since the first cold tests with the unity coupler. A comprehensive root cause analysis was conducted to investigate the origin of this issue and to identify the fabrication, processing, and handling factors that have the greatest impact on field emission onset. New techniques were developed and effectively implemented to achieve field emission-free SSR2 cavities. In addition, effort was dedicated both to relating the radiation level measured at the test stand with the expected levels in the LINAC tunnel and to understand the evolution of field emission through the assembly steps. The challenge of overcoming field emission also led to a reassessment of design choices, enhancing our understanding of their effects on cavity performance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Consequences of minimal entanglement in bosonic field theories

In this paper, we study a recently discovered connection between scattering that minimally entangles and emergent symmetries. In a perturbative expansion, we have generalized the constraints of minimal entanglement scattering, beyond qubits, to general qudits of dimension d . Interestingly, projecting on any qubit subspaces, the constraints factorize, so that it is consistent to analyze minimal entanglement by looking at all such subspaces. We start by looking at toy models with two scalar fields, finding that minimal entanglement only allows quartic couplings which have instabilities at large field values and no symmetries. For the two Higgs doublet model, by considering H + H − → H + H − scattering, we show that minimal entanglement in this channel does not allow an interacting parameter point with enhanced symmetries. These results show that the connection between minimal entanglement and symmetries depends strongly on the scattering channels analyzed and we speculate on the potential resolutions. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1998

Soot and Sulfuric Acid from Aircraft: Is There Enough to Cause Detrimental Environmental E-kCTSs?

Aerosol from aircraft can affect the environment in three ways: First, soot aerosol has been implicated to cause Icing-tern ozone depletion at mid-latitudes in the lower stratosphere at a rate of approx. 5% per decade. This effect is in addition and unrelated to the polar ozone holes which are strongly influenced by heterogeneous chemistry on polar stratospheric clouds. Second, the most obvious effect of jet aircraft is the formation of visible contrails in the upper troposphere. The Salt Lake City region experienced an 8% increase in cirrus cloud cover over a 15-year period which covariates with an increase in regional commercial air traffic. If soot particles act as freezing nuclei to cause contrail formation heterogeneously, they would be linked to a secondary effect to cloud modification that very likely is climatologically important. Third, a buildup of soot aerosol could reduce the single scatter albedo of stratospheric aerosol from 0.993+0.004 to 0.98, a critical value that has been postulated to separate stratospheric cooling from warming. Thus arises an important question: Do aircraft emit sufficient amounts of soot to have detrimental effects and warrant emission controls? During the 1996 SUCCESS field campaign, we sampled aerosols in the exhaust wake of a Boeing 757 aircraft and determined emission indices for sulfuric acid (EI(sub H2SO4) = 9.0E-2 and 5.0E-1 g/kg (sub FUEL) for 75 and 675 ppm fuel-sulfur, respectively) and soot aerosol (2.2E-3 less than EI(sub SOOT) = l.lE-2 g/kg (sub FUEL)). The soot particle analysis accounted for their fractal nature, determined electron-microscopically, which enhanced the surface area by a factor of 26 and the volume 11-fold over equivalent-volume spheres. The corresponding fuel-sulfur to H2SO4 conversion efficiency was 10% (for 675 ppmm fuel-S) and 37% (for 75 ppmm fuel-S). Applying the H2SO4 emission index to the 1990 fuel use by the worlds commercial fleets of 1.3E11 kg, a conversion efficiency of 30% of 500 ppmm fuel-S would have led to an annual contribution to the atmospheric sulfur budget by aircraft of 2.E7 kg H2SO4. This is about one part in 1.E4 of anthropogenic sulfate from other sources. The soot emission index given above yielded a 1990 injection of soot aerosol by aircraft of 1.E6 kg. Thus, soot amounts to only five percent of the aerosol generated by aircraft. Its reactivity with ozone would have to be 20 times that of sulfuric acid particles to make it chemically significant. Nevertheless, the findings, of stratospheric soot loadings commensurate with aircraft fuel consumption, based on the emission index given above and the assumption of stratospheric residence times of the order of one year implicate aircraft as stratospheric polluters. A trend similar to soot of H2SO4 aerosol loading could not be deciphered, neither from in situ measurements nor SAGE II satellite extinction, against the "noise" due to volcanic eruptions. Observation of soot particles at 20 km altitude which, if emitted by aircraft were generated at 10-12 km altitude, suggests a displacement of those particles against gravity. Because eddy mixing is virtually absent in the lower stratosphere and isentropic mixing explains lofting to only about 15 km, radiometric forces acting on morphologically and chemically asymmetric soot particles must be considered a possibility. The consequence could be an extended residence time of soot against that of sulfuric acid aerosol that would lower the single scatter albedo with time.

Pueschel, R. F.↗

NASA NTRS2010

The Fourier-Kelvin Stellar Interferometer (FKSI): Infrared Detection and Characterization of Exozodiacal Dust to Super-Earths, A Progress Report

The Fourier-Kelvin Stellar Interferometer (FKSI) is a structurally connected infrared space interferometer with 0.5 m diameter telescopes on a 12.5 m baseline, and is passively cooled to approx.60K. The FKSI operates in the thermal infrared from 3-8 microns in a nulling (or starlight suppressing) mode for the detection and characterization of exoplanets, debris disks, extrasolar zodiacal dust levels. The FKSI will have the highest angular resolution of any infrared space instrument ever made with its nominal resolution of 40 mas at a 5 micron center wavelength. This resolution exceeds that of Spitzer by a factor of 38 and JWST by a factor of 5. The FKSI mission is conceived as a "probe class" or "mid-sized" strategic mission that utilizes technology advances from flagship projects like JWST, SIM, Spitzer, and the technology programs of TPF-I/Darwin. During the past year we began investigating an enhanced version of FKSI with 1-2 m diameter telescopes, passively cooled to 40K, on a 20-m baseline, with a sunshade giving a +/- 45 degree Field-of-Regard. This enhanced design is capable of detecting and characterizing the atmospheres of many 2 Earth-radius super-Earths and a few Earth-twins. We will report progress on the design of the enhanced mission concept and current status of the technologies needed for this mission.

Danchi, W.↗

DOE OSTI2023

One and Two-Body Current Contributions to Lepton-Nucleus Scattering

Modeling lepton-nucleus scattering with the accuracy required to extract neutrino-oscillation parameters from long- and short-baseline experiments necessitates retaining most quantum-mechanical effects. One such effect is the interference between one- and two-body current operators in the transition currents, which has been known to enhance the cross-sections, especially in transverse kinematics. In this work, we incorporate such interference in the spectral function formalism, which combines relativistic currents and kinematics with an accurate description of the initial target state. Our analysis of lepton-scattering off $^{12}$C demonstrates that interference effects appreciably enhance the transverse electromagnetic response functions and the flux-folded neutrino-nucleus cross section, in both cases, improving the agreement with experimental data. We discuss the impact on the neutrino-oscillation program and the determination of nucleon axial form factors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Influence of Nb alloying on Nb recrystallization and the upper critical field of Nb 3 ⁢Sn

Nb 3 Sn conductors are important candidates for high-field magnets for particle accelerators, and they continue to be widely used for many laboratory and NMR magnets. However, the critical current density, J c , of present Nb 3 Sn conductors declines swiftly above 12-15 T. State-of-the-art Ta- and Ti-doped strands exhibit upper critical field, H c2 , values of ~ 24-26.5 T (4.2 K) and do not reach the FCC target J c , which serves as the present stretch target for Nb 3 Sn development. As recently demonstrated, to meet this goal requires enhanced vortex pinning but an independent and supplementary approach is to significantly enhance H c2 . In this study, we have arc-melted multiple Nb alloys with added Hf, Zr, Ta and Ti and drawn them successfully into monofilament wires to investigate the possibilities of H c2 enhancement through alloying. H c2 (T) was measured for all samples in fields up to 16 T and some up to 31 T. We have found that all alloys show good agreement with the standard Werthamer, Helfand, and Hohenberg (WHH) fitting procedure without the need to adjust the paramagnetic limitation parameter (α) and spin-orbit scattering parameter (λ so ). The evaluation of dH c2 /dT near T c , which is proportional to the electronic specific heat coefficient γ and the normal state resistivity ρn, allows a better understanding of the induced disorder introduced by alloying in the A15 phase. So far, we have observed that Hf alloying of pure Nb can enhance H c2 (0) by 3-4 T to ~28 T, while adding just 1 at. %Hf or Zr into a Nb4Ta base alloy can raise H c2 (0) to ~31 T. Very importantly we find that Hf and Zr raise the alloy recrystallization temperature above the usual A15 reaction temperature range of 650°C – 750°C, thus ensuring denser A15 phase nucleation in the Nb alloy grain boundaries, possibly leading to a more homogeneous A15 phase Sn content and refined A15 grain size. Furthermore, the potential for further advancements in Nb 3 Sn properties is explored in relation to the recrystallization of the Nb alloy and the factors controlling the upper critical field.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2023

Voltage scanning and technical upgrades at the Collinear Resonance Ionization Spectroscopy experiment

To optimize the performance of the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at CERN-ISOLDE, technical upgrades are continuously introduced, aiming to enhance its sensitivity, precision, stability, and efficiency. Recently, a voltage-scanning setup was developed and commissioned at CRIS, which improved the scanning speed by a factor of three as compared to the current laser-frequency scanning approach. This leads to faster measurements of the hyperfine structure for systems with high yields (more than a few thousand ions per second). Additionally, several beamline sections have been redesigned and manufactured, including a new field-ionization unit, an electrostatic bend with a larger deflection angle, and improved ion optics. The beamline upgrades are expected to yield an improvement of at least a factor of 5 in the signal-to-noise ratio by avoiding the use of high-power lasers (which yield non-resonantly produced ions) and providing time-of-flight separation between the resonant ions and the collisional background.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

NASA NTRS1998

Effect of halogenation on the nonlinear optical properties of porthyrin and substituted porphyrins

The effect that fluorine and chlorine substitution has on the nonlinear optical properties of porphyrin, tetramethylporphyrin and tetraphenylporphyrin has been theoretically studied. The calculations of nonlinear optical properties have been obtained by performing finite-field calculations on structures determined by semiempirical methods. In addition, tetra(p-chlorophenyl)porphyrin and tetra(p-bromophenyl)porphyrin were synthesized by the condensation of pyrrol and the appropriate aldehyde. Thin films of polymethylmethacrylate were obtained containing these materials, by spin coating onto glass substrates. The films were characterized by third-harmonic generation. It was determined that the experimental conditions enhance the third-order polarizability of the tetraphenylporphyrins by a factor of about 1.6.

Cardelino, Beatriz H.↗

NASA NTRS2004

Comparison of Local Scale Measured and Modeled Brightness Temperatures and Snow Parameters from the CLPX 2003 by Means of a Dense Medium Radiative Transfer Theory Model

Microwave remote sensing offers distinct advantages for observing the cryosphere. Solar illumination is not required, and spatial and temporal coverage are excellent from polar-orbiting satellites. Passive microwave measurements are sensitive to the two most useful physical quantities for many hydrological applications: physical temperature and water content/state. Sensitivity to the latter is a direct result of the microwave sensitivity to the dielectric properties of natural media, including snow, ice, soil (frozen or thawed), and vegetation. These considerations are factors motivating the development of future cryospheric satellite remote sensing missions, continuing and improving on a 26-year microwave measurement legacy. Perhaps the biggest issues regarding the use of such satellite measurements involve how to relate parameter values at spatial scales as small as a hectare to observations with sensor footprints that may be up to 25 x 25 km. The NASA Cold-land Processes Field Experiment (CLPX) generated a dataset designed to enhance understanding of such scaling issues. CLPX observations were made in February (dry snow) and March (wet snow), 2003 in Colorado, USA, at scales ranging from plot scale to 25 x 25 km satellite footprints. Of interest here are passive microwave observations from ground-based, airborne, and satellite sensors, as well as meteorological and snowpack measurements that will enable studies of the effects of spatial heterogeneity of surface conditions on the observations. Prior to performing such scaling studies, an evaluation of snowpack forward modelling at the plot scale (least heterogeneous scale) is in order. This is the focus of this paper. Many forward models of snow signatures (brightness temperatures) have been developed over the years. It is now recognized that a dense medium radiative transfer (DMRT) treatment represents a high degree of physical fidelity for snow modeling, yet dense medium models are particularly sensitive to snowpack structural parameters such as grain size, density, and depth---parameters that may vary substantially within a snowpack. Microwave radiometric data and snow pit measurements collected at the Local-Scale Observation Site (LSOS) during the third Intensive Observation Period (IOP3) of the CLPX have been used to test the capabilities of a DMRT model using the Quasi Crystalline Approximation with Coherent Potential (QCA-CP). The radiometric measurements were made by the University of Tokyo s Ground Based Microwave Radiometer-7 (GBMR-7) system. We evaluate the degree to which a DMRT-based model can accurately reproduce the GBMR-7 brightness temperatures at different frequencies and incidence angles.

Tedescol, Marco↗

NASA NTRSDate not supplied

TPSAS-NF1676L-32020-DND

The Earth Polychromatic Imaging Camera (EPIC) instrument aboard the Deep Space Climate Observatory (DSCOVR) satellite has a constant unique view of the sunlit disk of the Earth from the Lagrange-1 (L1) point nearly a million miles away from the Earth. The DSCOVR EPIC team released the version 2 dataset last year which included many enhancements, such as improved navigation, stray-light correction, and flat-fielding. Since there is no on-board calibration for EPIC, its 10 spectral channels must be calibrated using other methods, such as inter-calibrating with sensors with on-board calibration hardware. VIIRS is a well-calibrated instrument with similar spectral channels as EPIC. Spectral band induced radiance differences between VIIRS and EPIC are mitigated using Spectral Band Adjustment Factor (SBAF). We will extend the previous calibrations from prior studies to include more recent data by ray-matching EPIC with VIIRS over all-sky tropical ocean (ATO) and deep convective cloud (DCC) conditions. In addition to ATO and DCC ray-matching, we will validate these results by utilizing DCC as invariant targets to monitor sensor degradation. DCC behave as solar diffusers in the tropics and when collectively analyzed can be used to monitor the degradation of the EPIC sensor. Improvement to our dynamic navigation adjustment algorithm, as well as exploring the view angle response of the EPIC CCD array, will be examined for their effectiveness and presented at the conference.

C O Haney↗

DOE OSTI2020

Collinear drop

We introduce collinear drop jet substructure observables, which are unaffected by contributions from collinear radiation, and systematically probe soft radiation within jets. These observables can be designed to be either sensitive or insensitive to process-dependent soft radiation originating from outside the jet. Such collinear drop observables can be exploited as variables to distinguish quark, gluon, and color neutral initiated jets, for testing predictions for perturbative soft radiation in Monte Carlo simulations, for assessing models and universality for hadronization corrections, for examining the efficiency of pileup subtraction methods, and for any other application that leaves an imprint on soft radiation. We discuss examples of collinear drop observables that are based both on clustering and on jet shapes. Using the soft-collinear effective theory we derive factorization expressions for collinear drop observables from QCD jets, and carry out a resummation of logarithmically enhanced contributions at next-to-leading-logarithmic order. We also identify an infinite class of collinear drop observables for which the leading double logarithms are absent.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1977

Energization pf polar-cusp electrons at the noon meridian

Observations gained with an electrostatic analyzer on board the low altitude, polar orbiting Aeriel 4 satellite demonstrate that the directional, differential spectra of polar-cusp electron intensities are regulated by the sign of the interplanetary magnetic field (IMF) elevation angle. In the energy range 200 is approximately less than E is approximately less than 700 eV, spectra of polar cusp electron intensities were not observed to respond to changes in the sign of the IMF elevation angle. At greater densities, spectra were found to be significantly harder when the IMF angle of elevation was greater than 0 deg, with a factor of approximately 10 typical for 2-keV electron intensities. These enhanced intensities appear to be localized within approximately a one hour sector of magnetic local time centered on the noon meridian.

Craven, J. D.↗

NASA NTRS1981

Photochemical processes induced by a major warming of the upper atmosphere - Variations in mesospheric trace constituents

The temperature rise and enhanced winds during an upper atmospheric warming cause substantial changes in the high level ozone profile of the sunlit winter hemisphere. Calculations based on a photochemical model, using temperatures measured at Fort Churchill during a major warming, predict a factor of 2 variation in the ozone number density near 60 km over a time period of approximately 3 weeks. This temporal variability at a fixed location results from the planetary wave structure of the temperature field and reflects a similar longitudinal behavior at a given time. The ozone number density at fixed altitude is a maximum when the temperature is greatest at and below this level. This is due primarily to thermal expansion of the atmosphere which results in a large increase in pressure at constant altitude. However, chemical activity during a warming decreases the mesospheric ozone mixing ratio at fixed pressure. The ozone mixing ratio at constant pressure during the peak of the event studied is near 75% of its unperturbed value. The predicted variability of ozone in longitude and time demonstrates the need for hemispheric scale information on trace gas abundances, temperature, and winds in order to delineate adequately the response of upper atmospheric composition to a major perturbation.

Frederick, J. E.↗

NASA NTRS2004

Flight Simulator Evaluation of Display Media Devices for Synthetic Vision Concepts

The Synthetic Vision Systems (SVS) Project of the National Aeronautics and Space Administration's (NASA) Aviation Safety Program (AvSP) is striving to eliminate poor visibility as a causal factor in aircraft accidents as well as enhance operational capabilities of all aircraft. To accomplish these safety and capacity improvements, the SVS concept is designed to provide a clear view of the world around the aircraft through the display of computer-generated imagery derived from an onboard database of terrain, obstacle, and airport information. Display media devices with which to implement SVS technology that have been evaluated so far within the Project include fixed field of view head up displays and head down Primary Flight Displays with pilot-selectable field of view. A simulation experiment was conducted comparing these display devices to a fixed field of view, unlimited field of regard, full color Helmet-Mounted Display system. Subject pilots flew a visual circling maneuver in IMC at a terrain-challenged airport. The data collected for this experiment is compared to past SVS research studies.

Arthur, J. J., III↗

DOE OSTI2021

Variational Self-Consistent Theory for Beam-Loaded Cavities

A new variational theory is presented for beam loading in microwave cavities. The beam{field interaction is formulated as a dynamical interaction whose stationarity according to Hamilton’s principle will naturally lead to steady-state solutions that indicate how a cavity’s resonant frequency, Q and optimal coupling coefficient will detune as a result of the beam loading. A driven cavity Lagrangian is derived from first principles, including the effects of cavity wall losses, input power and beam interaction. The general formulation is applied to a typical klystron input cavity to predict the appropriate detuning parameters required to maximize the gain (or modulation depth) in the average Lorentz factor boost, (Δ γ). Numerical examples are presented, showing agreement with the general detuning trends previously observed in the literature. The developed formulation carries several advantages for beam-loaded cavity structures. It provides a self-consistent model for the dynamical (nonlinear) beam{field interaction, a procedure for maximizing gain under beam-loading conditions, and a useful set of parameters to guide cavity-shape optimization during the design of beam-loaded systems. Enhanced clarity of the physical picture underlying the problem seems to be gained using this approach, allowing straightforward inclusion or exclusion of different field configurations in the calculation and expressing the final results in terms of measurable quantities. Two field configurations are discussed for the klystron input cavity, using finite magnetic confinement or no confinement at all. Formulating the problem in a language that is directly accessible to the powerful techniques found in Hamiltonian dynamics and canonical transformations may potentially carry an additional advantage in terms of analytical computational gains, under suitable conditions

43 PARTICLE ACCELERATORS↗

DOE OSTI2022

MAGNETIC FIELD MAPPING OF 1.3 GHz SUPERCONDUCTING RADIO FREQUENCY NIOBIUM CAVITIES

Niobium is the material of choice to build superconducting radio frequency (SRF) cavities, which are fundamental building blocks of modern particle accelerators. These cavities require a cryogenic cool-down to ~2 - 4 K for optimum performance minimizing RF losses on the inner cavity surface. However, temperature-independent residual losses in SRF cavities cannot be prevented entirely. One of the significant contributor to residual losses is trapped magnetic flux. The flux trapping mechanism depends on different factors, such as surface preparations and cool-down conditions. We have developed a diagnostic magnetic field scanning system (MFSS) using Hall probes and anisotropic magneto-resistance sensors to study the spatial distribution of trapped flux in 1.3 GHz single-cell cavities. The first result from this newly commissioned system revealed that the trapped flux on the cavity surface might redistribute with increasing RF power. The MFSS was also able to capture significant magnetic field enhancement at specific cavity locations after a quench.

Parajuli, I. P.↗

DOE OSTI2023

MoS 2 Nanoplatelets on Hybrid Core-Shell (HyCoS) AuPd NPs for Hybrid SERS Platform for Detection of R6G

In this work, a novel hybrid SERS platform incorporating hybrid core-shell (HyCoS) AuPd nanoparticles (NPs) and MoS 2 nanoplatelets has been successfully demonstrated for strong surface-enhanced Raman spectroscopy (SERS) enhancement of Rhodamine 6G (R6G). A significantly improved SERS signal of R6G is observed on the hybrid SERS platform by adapting both electromagnetic mechanism (EM) and chemical mechanism (CM) in a single platform. The EM enhancement originates from the unique plasmonic HyCoS AuPd NP template fabricated by the modified droplet epitaxy, which exhibits strong plasmon excitation of hotspots at the nanogaps of metallic NPs and abundant generation of electric fields by localized surface plasmon resonance (LSPR). Superior LSPR results from the coupling of distinctive AuPd core-shell NP and high-density background Au NPs. The CM enhancement is associated with the charge transfer from the MoS 2 nanoplatelets to the R6G. The direct contact via mixing approach with optimal mixing ratio can effectively facilitate the charges transfer to the HOMO and LUMO of R6G, leading to the orders of Raman signal amplification. The enhancement factor (EF) for the proposed hybrid platform reaches ~10 10 for R6G on the hybrid SERS platform.

36 MATERIALS SCIENCE↗

NASA NTRS1992

Testing a Mars science outpost in the Antarctic dry valleys

Field research conducted in the Antarctic has been providing insights about the nature of Mars in the science disciplines of exobiology and geology. Located in the McMurdo Dry Valleys of southern Victoria Land (160 deg and 164 deg E longitude and 76 deg 30 min and 78 deg 30 min S latitude), research outposts are inhabited by teams of 4-6 scientists. It is proposed that the design of these outposts be expanded to enable meaningful tests of many of the systems that will be needed for the successful conduct of exploration activities on Mars. Although there are some important differences between the environment in the Antarctic dry valleys and on Mars, the many similarities and particularly the field science activities, make the dry valleys a useful terrestrial analog to conditions on Mars. Three areas have been identified for testing at a small science outpost in the dry valleys: (1) studying human factors and physiology in an isolated environment; (2) testing emerging technologies (e.g. innovative power management systems, advanced life support facilities including partial bioregenerative life support systems for water recycling and food growth, telerobotics, etc.); and (3) conducting basic scientific research that will enhance understanding of Mars while contributing to the planning for human exploration. It is suggested that an important early result of a Mars habitat program will be the experience gained by interfacing humans and their supporting technology in a remote and stressful environment.

Andersen, D. T.↗