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DOE OSTI2020

Initial Exploration of the Use of Mixed Precision in Iterative Solvers (B639388 Subcontract Quarter I Report)

The first quarter of the project was primarily spent identifying potential projects at the intersection of finite precision analysis, mixed precision computation, and Krylov subspace methods. We summarize our findings in the remainder of the document. Other activities include attending biweekly xSDK meetings as well as contributing material to the technical report and journal versions of the multiprecision landscape paper. The subsequent quarter will be spent selecting a subset of the described projects to focus on, performing initial numerical experiments to evaluate the potential for the use of mixed precision, and developing initial theoretical analysis.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2020

Towards Use of Mixed Precision in ECP Math Libraries [Exascale Computing Project]

The use of multiple types of precision in mathematical software has the potential to increase its performance on new heterogeneous architectures. The xSDK project focuses both on the investigation and development of multiprecision algorithms as well as their inclusion into xSDK member libraries. This report summarizes current efforts on including and/or using mixed precision capabilities in the math libraries Ginkgo, heFFTe, hypre, MAGMA, PETSc/TAO, SLATE, SuperLU, and Trilinos, including KokkosKernels. It contains both numerical results from libraries that already provide mixed precision capabilities, as well as descriptions of the strategies to incorporate multiprecision into established libraries.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2021

Towards Use of Mixed Precision in ECP Math Libraries

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2020

Replicated Computational Results (RCR) Report for "Adaptive Precision Block-Jacobi for High Performance Preconditioning in the Ginkgo Linear Algebra Software''

In, a practical implementation of a novel adaptive precision block-Jacobi preconditioner is introduced. In particular, the authors present a heavily-tuned GPU implementation of the adaptive precision block-Jacobi preconditioner within the Ginkgo numerical linear algebra library. The performance of the methodology and implementation is demonstrated using the proposed preconditioning scheme within Ginkgo’s high-performance Conjugate Gradient (CG) implementation on an NVIDIA Volta GPU. In this report, we replicate a subset of the computational results presented in. The focus is generating results from Fig. 9 to evaluate the performance of using Ginkgo’s CG solver integrated with either the full or the adaptive precision block-Jacobi preconditioner applied to a variety of test cases

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2026

MAMBA: A Prototype Modern Modular Bubble Chamber for Precision Measurement of Neutrino Nucleus Cross Sections

High precision measurements of neutrino interactions are essential for the success of future neutrino oscillation experiments. Understanding the interaction rate and precise energy spectrum requires understanding of neutrino interactions and nuclear effects. Measuring interactions in a light nuclear target , such as Hydrogen or deuterium, would provide highly valuable input to reduce reduce the uncertainties associated with neutrino-nucleus cross sections, relevant for upcoming experiments like the Deep Underground Neutrino Experiment (DUNE) and Hyper-Kamiokande (Hyper-K). A bubble chamber presents an opportunity to study a light nuclear target using hydrogen in the liquid phase as a working fluid. However historical hydrogen bubble chamber designs if placed in modern neutrino beams would miss a significant fraction of the total number of available interactions. We present a bubble chamber prototype, MAMBA, which will be used to investigate strategies for inexpensively enabling continuous cycling through improved cooling at scale and expanding the active time of historic bubble chambers. MAMBA aims to demonstrate the feasibility of precision neutrino–nucleon measurements at conditions comparable to modern beams.

Martínez Casales, María [Fermilab] (ORCID:00000003↗

DOE OSTI2020

Cloud Atlas: High-precision HST/WFC3/IR Time-resolved Observations of Directly Imaged Exoplanet HD 106906b

HD 106906b is an ∼11M{sub Jup}, ∼15 Myr old directly imaged exoplanet orbiting at an extremely large distance from its host star. The wide separation (7.″11) between HD 106906b and its host star greatly reduces the difficulty in direct-imaging observations, making it one of the most favorable directly imaged exoplanets for detailed characterization. In this paper, we present HST/WFC3/IR time-resolved observations of HD 106906b in the F127M, F139M, and F153M bands. We have achieved ∼1% precision in the lightcurves in all three bands. The F127M lightcurve demonstrates marginally detectable (2.7σ significance) variability with a best-fitting period of 4 hr, while the lightcurves in the other two bands are consistent with flat lines. We construct primary-subtracted deep images and use these images to exclude additional companions to HD 106906 that are more massive than 4 M{sub Jup} and locate at projected distances of more than ∼500 au. We measure the astrometry of HD 106906b in two HST/WFC3 epochs and achieve precisions better than 2.5 mas. The position angle and separation measurements do not deviate from those in the 2004 HST/ACS/HRC images for more than 1σ uncertainty. We provide the HST/WFC3 astrometric results for 25 background stars that can be used as reference sources in future precision astrometry studies. Our observations also provide the first 1.4 μm water band photometric measurement for HD 106906b. HD 106906b’s spectral energy distribution and the best-fitting BT-Settl model have an inconsistency in the 1.4 μm water absorption band, which highlights the challenges in modeling atmospheres of young planetary-mass objects.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2020

Into the UV: A Precise Transmission Spectrum of HAT-P-41b Using Hubble’s WFC3/UVIS G280 Grism

The ultraviolet–visible wavelength range holds critical spectral diagnostics for the chemistry and physics at work in planetary atmospheres. To date, time-series studies of exoplanets to characterize their atmospheres have relied on several combinations of modes on the Hubble Space Telescope’s STIS/COS instruments to access this wavelength regime. Here for the first time, we apply the Hubble WFC3/UVIS G280 grism mode to obtain exoplanet spectroscopy from 200 to 800 nm in a single observation. We test the G280 grism mode on the hot Jupiter HAT-P-41b over two consecutive transits to determine its viability for the characterization of exoplanet atmospheres. We obtain a broadband transit depth precision of 29–33 ppm and a precision of on average 200 ppm in 10 nm spectroscopic bins. Spectral information from the G280 grism can be extracted from both the positive and negative first-order spectra, resulting in a 60% increase in the measurable flux. Additionally, the first Hubble Space Telescope orbit can be fully utilized in the time-series analysis. We present detailed extraction and reduction methods for use by future investigations with this mode, testing multiple techniques. We find the results to be fully consistent with STIS measurements of HAT-P-41b from 310 to 800 nm, with the G280 results representing a more observationally efficient and precise spectrum. HAT-P-41b’s transmission spectrum is best fit with a model with T {sub eq} = 2091 K, high metallicity, and significant scattering and cloud opacity. With these first-of-their-kind observations, we demonstrate that WFC3/UVIS G280 is a powerful new tool to obtain UV–optical spectra of exoplanet atmospheres, adding to the UV legacy of Hubble and complementing future observations with the James Webb Space Telescope.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2021

Excalibur: A Nonparametric, Hierarchical Wavelength Calibration Method for a Precision Spectrograph

Excalibur is a nonparametric, hierarchical framework for precision wavelength calibration of spectrographs. It is designed with the needs of extreme-precision radial-velocity (EPRV) instruments in mind, which require calibration or stabilization to better than 10{sup −4} pixels. Instruments vary along only a few dominant degrees of freedom, especially EPRV instruments that feature highly stabilized optical systems and detectors. Excalibur takes advantage of this property by using all calibration data to construct a low-dimensional representation of all accessible calibration states for an instrument. Excalibur also takes advantage of laser-frequency combs or etalons, which generate a dense set of stable calibration points. This density permits the use of a nonparametric wavelength solution that can adapt to any instrument or detector oddities better than parametric models, such as a polynomial. We demonstrate the success of this method with data from the Extreme Precision Spectrograph (EXPRES), which uses a laser-frequency comb. When wavelengths are assigned to laser comb lines using excalibur, the rms of the residuals is about one-fifth that of wavelengths assigned using polynomial fits to individual exposures. Radial-velocity measurements of HD 34411 show a reduction in rms scatter over a 10 month time baseline from 1.17 to 1.05 m s{sup −1}.

47 OTHER INSTRUMENTATION↗

DOE OSTI2023

Snowmass 2021 Whitepaper: Proton Structure at the Precision Frontier

An overwhelming number of theoretical predictions for hadron colliders require parton distribution functions (PDFs), which are an important ingredient of theory infrastructure for the next generation of high-energy experiments. This whitepaper summarizes the status and future prospects for determination of high-precision PDFs applicable in a wide range of energies and experiments, in particular in precision tests of the Standard Model and in new physics searches at the high-luminosity Large Hadron Collider and Electron–Ion Collider. We discuss the envisioned advancements in experimental measurements, QCD theory, global analysis methodology, and computing that are necessary to bring unpolarized PDFs in the nucleon to the N2LO and N3LO accuracy in the QCD coupling strength. Special attention is given to the new tasks that emerge in the era of the precision PDF analysis, such as those focusing on the robust control of systematic factors both in experimental measurements and theoretical computations. Various synergies between experimental and theoretical studies of the hadron structure are explored, including opportunities for studying PDFs for nuclear and meson targets, PDFs with electroweak contributions or dependence on the transverse momentum, for incisive comparisons between phenomenological models for the PDFs and computations on discrete lattice, and for cross-fertilization with machine learning/AI approaches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1970

Navigation for space shuttle approach and landing using an inertial navigation system augmented by data from a precision ranging system or a microwave scan beam landing guidance system

A preliminary study has been made of the navigation performance which might be achieved for the high cross-range space shuttle orbiter during final approach and landing by using an optimally augmented inertial navigation system. Computed navigation accuracies are presented for an on-board inertial navigation system augmented (by means of an optimal filter algorithm) with data from two different ground navigation aids; a precision ranging system and a microwave scanning beam landing guidance system. These results show that augmentation with either type of ground navigation aid is capable of providing a navigation performance at touchdown which should be adequate for the space shuttle. In addition, adequate navigation performance for space shuttle landing is obtainable from the precision ranging system even with a complete dropout of precision range measurements as much as 100 seconds before touchdown.

Mcgee, L. A.↗

NASA NTRS1971

Study of precise positioning at L-band using communications satellites

The L-band positioning experiment is reported which encompassed experiment design, experimentation, and data reduction and analysis. In the experiment the ATS-5 synchronous satellite L-band transponder was used in conjunction with the modified ALPHA 2 navigation receivers to demonstrate the technical capability of precision position fixing for oceanographic purposes. The feasibility of using relative ranging techniques implemented by two identical receiving systems, properly calibrated, to determine a line of position accurately on the surface of the earth was shown. The program demonstrated the level of resolution, repeatibility, precision, and accuracy of existing modest-cost effective navigation equipment. The experiment configuration and data reduction techniques were developed in parallel with the hardware modification tasks. Test results verify the ability of a satellite-based system to satisfy the requirements of precision position fixing.

Source record↗

NASA NTRS1974

Feedback precision and postfeedback interval duration

Precision of feedback gain was manipulated in a simple positioning task. An optimum was found; an increase in precision past that optimum produced deleterious effects upon rate of acquisition. In a second study, increasing postfeedback interval removed that optimum. The feedback precision effects were then replicated in a timing task. The combined results of the 3 studies were interpreted as supportive of an information-processing approach to the study of postfeedback interval events for simple motor skills. The findings additionally supported specific predictions by Bilodeau and deductions from Adams' 1971 theory of motor learning.

Rogers, C. A., Jr.↗

NASA NTRS1973

Low cost automated precise time measurement system

The Aerospace Guidance and Metrology Center (AGMC) has the responsibility for the dissemination of Precise Time and Time Interval (PTTI) to Air Force timing systems requiring microsecond time. In order to maintain traceability to the USNO Master Clock in Washington D.C., and accomplish efficient logging of time and frequency data on individual precision clocks, a simple automatic means of acquiring precise time has been devised. The Automatic Time Interval Measurement System (ATIMS) consists of a minicomputer (8K Memory), teletype terminal, electronic counter, Loran C receiver, time base generator and locally-manufactured relay matrix panel. During the measurement process, the computer controls the relay matrix which selects for comparison 13 atomic clocks against a reference clock and the reference versus Loran C. Through use of the system teletype, the operator is able to set the system clock (hours, minutes and seconds), examine and/or modify all clock data and constants, and set measurement intervals. This is done in a conversational manner. A logic flow diagram, system schematic, source listing and software components are included in the presentation.

Alpert, A.↗

NASA NTRS1974

Precise time and time interval (PTTI), an overview

Present applications of precise time and frequency (T/F) technology can be grouped as follows: (1) Communications systems which require T/F for time division multiplexing and for using spread spectrum techniques. (2) Navigation systems which need T/F for position fixing using a timed signal. (3) Scientific-Metrological applications which use T/F as the most precisely reproducible standard of measurement. (4) Astronomical-Space applications which cover a variety of the most demanding applications such as pulsar research, Very Long Baseline Interferometry (VLBI) and laser/radar ranging. In particular, pulsar time-of-arrival measurements require submicrosecond precision over a period of one-half year referred to an extraterrestrial inertial system, and constitute the most stringent requirements for uniform timekeeping to date.

Winkler, G. M. R.↗

NASA NTRS1976

Absolute calibration of the RADSCAT scatterometer using precision spheres

Tests using precision sphere targets suspended from balloons were conducted to calibrate the received-power/transmitted-power tatio of the RADSCAT scatterometer. Comparisons were made of these measured results with theoretical return from spheres. The RADSCAT scatterometer measurements at 13.9 GHz should be corrected by -2.4 dB, and those at 9.3 GHz, by -4.3 dB. The techniques described should be generally applicable to calibration of scatterometers where measurement precision is of prime importance. Inferred from the magnitude of these RADSCAT corrections was the present state of technology in building precision scatterometers.

Grantham, W. L.↗

NASA NTRS1975

Proceedings of the 7th Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting

The Proceedings contain the papers presented at the Seventh Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting and the edited record of the discussion period following each paper. This meeting provided a forum to promote more effective, efficient, economical and skillful applications of PTTI technology to the many problem areas to which PTTI offers solutions. Specifically the purpose of the meeting is to: disseminate, coordinate, and exchange practical information associated with precise time and frequency; acquaint systems engineers, technicians and managers with precise time and frequency technology and its applications; and review present and future requirements for PTTI.

Source record↗

NASA NTRS1980

The Seasat Precision Orbit Determination Experiment

The objectives and conclusions reached during the Seasat Precision Orbit Determination Experiment are discussed. It is noted that the activities of the experiment team included extensive software calibration and validation and an intense effort to validate and improve the dynamic models which describe the satellite's motion. Significant improvement in the gravitational model was obtained during the experiment, and it is pointed out that the current accuracy of the Seasat altitude ephemeris is 1.5 m rms. An altitude ephemeris for the Seasat spacecraft with an accuracy of 0.5 m rms is seen as possible with further improvements in the geopotential, atmospheric drag, and solar radiation pressure models. It is concluded that since altimetry missions with a 2-cm precision altimeter are contemplated, the precision orbit determination effort initiated under the Seasat Project must be continued and expanded.

Tapley, B. D.↗

NASA NTRS1982

Kinematic precision of gear trains

Kinematic precision is affected by errors which are the result of either intentional adjustments or accidental defects in manufacturing and assembly of gear trains. A method for the determination of kinematic precision of gear trains is described. The method is based on the exact kinematic relations for the contact point motions of the gear tooth surfaces under the influence of errors. An approximate method is also explained. Example applications of the general approximate methods are demonstrated for gear trains consisting of involute (spur and helical) gears, circular arc (Wildhaber-Novikov) gears, and spiral bevel gears. Gear noise measurements from a helicopter transmission are presented and discussed with relation to the kinematic precision theory.

Litvin, F. L.↗