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

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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Disentangling the Distant Stellar Halo Using K Giants in DESI Year 3 Data

We present a sample of 88,959 K giants from Dark Energy Spectroscopic Instrument Milky Way Survey Year 3 data, which we use to characterize the chemo-dynamical properties of the stellar halo at Galactocentric distances of 12 to ∼100 kpc. Using HDBSCAN, we identify five prominent stellar halo substructures: Aleph, the Sagittarius stream, Gaia-Sausage-Enceladus (GSE), Cetus-Palca, and the Orphan–Chenab stream. We present the properties of each of these structures as they appear in our catalog, and examine how uncertainties on distance affect the characterization of substructure with this approach. We also examine regions associated with previously reported overdensities (such as the Virgo Overdensities and the Sagittarius spur) that we do not recover with HDBSCAN. The size and distance range of our catalog allows us to explore in detail the residual stellar halo, comprising stars that we do not associate with any substructure. We find that samples of ∼2000 outer halo stars with both highly prograde and highly retrograde angular momenta have similar metallicity distribution functions (MDFs), which do not resemble the MDFs of either GSE or Sagittarius. Both the prograde and retrograde residual halo MDFs are bimodal, with a metal-poor peak at [Fe/H] ∼ −2 and a metal-rich peak at [Fe/H] ∼ −1.3 (prograde) or −1.5 (retrograde). The MDF for lower-angular-momentum residual halo K giants does not show clear evidence for a metal-poor peak, and broadly resembles the MDF of GSE, even at much lower binding energies than GSE itself. We discuss possible interpretations of these findings for GSE accretion scenarios.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

PROTOCALC, a W -band Polarized Calibrator for Cosmic Microwave Background Telescopes: Application to Simons Observatory and CLASS

Current- and next-generation cosmic microwave background (CMB) experiments will measure polarization anisotropies with unprecedented sensitivities. The need for high precision in these measurements underscores the importance of gaining a comprehensive understanding of instrument properties, with a particular emphasis on the study of the beam properties, and especially their polarization characteristics and the measurement of the polarization angle. In this context, a major challenge lies in the scarcity of millimeter polarized astrophysical sources with sufficient brightness and calibration knowledge to meet the stringent accuracy requirements of future CMB missions. This led to the development of a drone-borne calibration source designed for the frequency band centered on approximately 90 GHz, matching a commonly used channel in ground-based CMB measurements. The Prototype Calibrator for Cosmology, PROTOCALC, has undergone thorough in-lab testing, and its properties have been subsequently modeled through simulation software integrated into the standard Simons Observatory analysis pipeline. Moreover, the PROTOCALC system has been tested in the field, having been deployed twice on calibration campaigns with CMB telescopes in the Atacama Desert. The data collected constrain the roll angle of the source with a statistical accuracy of 0$^°_•$045.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

ELVES-Field: Isolated Dwarf Galaxy Quenched Fractions Rise below M ∗ ≈ 10 7 M ⊙

We use a new sample of low-mass (M * < 10 9 M ⊙ ) isolated galaxies from the Exploration of Local VolumE Survey-Field (ELVES-Field) to examine the star formation properties and sizes of field dwarf galaxies in the Local Volume (LV; D < 10 Mpc). This volume-limited sample was selected from nearly 3000 deg 2 of imaging, relying on surface brightness fluctuations to determine distances to the majority of the systems and is complete to M * ≈ 10 6 M ⊙ . Across the surveyed area, we catalog over 2300 candidate LV dwarfs, of which we confirm 95 as genuine LV members and reject over 1600 as background contaminants, with the remaining 600 candidates still requiring a distance measurement. Of the confirmed LV dwarfs, 46 are either new discoveries or confirmed via a distance measurement for the first time here. We explore different environmental criteria to select isolated dwarfs but primarily focus on dwarfs that are >2 × R vir in projection from any known group with M ⋆ > 10 9 M ⊙ . We find that, at higher dwarf masses (M ⋆ ≳ 10 7 M ⊙ ), essentially all field dwarfs are star forming as has been found before. In contrast, at M ⋆ ≲ 10 7 M ⊙ , ∼30% of field dwarfs appear to be quenched. Finally, we find that isolated dwarfs are noticeably smaller (∼20%) than satellite dwarfs of the same stellar mass, regardless of quenched status.

Carlsten, Scott G. [Princeton Univ., NJ (United St↗
DOE OSTI2026

Legacy Analysis of Milky Way Dwarf Spheroidal Satellite Galaxies: An Update

Studies of Fermi Large Area Telescope (LAT) data coincident with dwarf spheroidal satellite galaxies (dSphs) of the Milky Way have put the most stringent constraints on models of annihilating dark matter (DM) with candidate masses in the GeV–TeV range. Recent results found the presence of small, local significance excesses from these targets, at the 2σ–3σ level. However, these excesses disagree on the predicted properties of the DM candidate, and their significance vanishes when considering correction factors for the number of trials. In this work, we apply key improvements to the analysis of dSphs. We use stricter cuts on the data, implement a method to adaptively model the background, and assume an updated framework for DM annihilation. We find that our improved background modeling leads to a better agreement between the model and the data. This produces an increase in the local and global significance of the dSph excess compared to previous studies. Finally, we find that the DM properties obtained in this work are less dependent on the sample of dSphs being considered compared to previous studies, while remaining in agreement with the predictions from the Galactic center excess observed by Fermi/LAT and the antiproton excess observed by the Alpha Magnetic Spectrometer (AMS-02). Considering our improvements, a future significant increase in the number of dwarfs may lead to a definitive confirmation or exclusion of the DM interpretation of the Galactic center excess.

cold dark matter↗
DOE OSTI2025

Ensuring continued operation of INSPIRE as a cornerstone of the HEP information infrastructure

The INSPIRE platform — the most widely-used discovery service specifically tailored to the needs of researchers in High Energy Physics (HEP) — has become a central component of the information infrastructure for the discipline. Despite this, INSPIRE's continued sustainability is frequently endangered by resource constraints, recently made more acute by the loss of support from historical funders changing their research priorities. If the European particle physics community wishes to ensure INSPIRE's long-term sustainability, the community should secure international support and ensure appropriate funding.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2016

Higgs Boson 2016

The Higgs boson burst into the public arena on July 4, 2012, when scientists working at the CERN laboratory announced the particle’s discovery. However the initial discovery was a bit tentative, with the need to verify that the discovered particle was, indeed, the Higgs boson. In this video, Fermilab’s Dr. Don Lincoln looks at the data from the perspective of 2016 and shows that more recent analyses further supports the idea that the Higgs boson is what was discovered.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Accelerator Science: Circular vs. Linear

Particle accelerator are scientific instruments that allow scientists to collide particles together at incredible energies to study the secrets of the universe. However, there are many manners in which particle accelerators can be constructed. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of circular and linear accelerators.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Fermions and Bosons

In particle physics, there are many different types of particles, mostly ending with the phrase “-on.” In this video, Fermilab’s Dr. Don Lincoln talks about fermions and bosons and what is the key difference between these two particles.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

When Computers Come First

Ruth Pordes was at Fermilab when computing equipment was first being moved into the laboratory offices. The elevated status of computers at the laboratory was made evident on move-in day.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Baby Bison at Fermilab

Fermilab’s first director, Robert Wilson, established the bison herd in 1969 as a symbol of the history of the Midwestern prairie and the laboratory’s pioneering research at the frontiers of particle physics. The herd remains a major attraction for families and wildlife enthusiasts. A herd of pure bison is a natural fit for a prairie ecosystem, like the kind that exists on the Fermilab site. Fermilab hosts 1,100 acres of reconstructed tall-grass prairie. A baby bison was born at Fermilab on April 20, 2017. Here is that story.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2017

The Birth of the Cosmic Frontier

Scientists Rocky Kolb and Mike Turner recount the time they first proposed that Fermilab – dedicated to the study of the universe's smallest constituents — expand its program to include the stars, galaxies and the cosmos.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

The Birth of the Web at Fermilab

Fermilab's website was born in June 1992, thanks in part to Tim Berners-Lee, who invented the World Wide Web in 1989. Fermilab's Ruth Pordes tells the origin story.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

The Science of the Deep Underground Neutrino Experiment (DUNE)

This 4-minute animation shows how the international Deep Underground Neutrino Experiment will help scientists understand how the universe works. DUNE will use a huge particle detector a mile underground to embark on a mission with three major science goals: 1.) Study an intense, 1,300-kilometer-long neutrino beam to discover what happened after the big bang: Are neutrinos the reason the universe is made of matter? 2.) Use 70,000 tons of liquid argon to look for proton decay and move closer to realizing Einstein’s dream of a unified theory of matter and energy. 3.) Catch neutrinos from a supernova to watch the formation of neutron stars and black holes in real time. About 1,000 scientists from 160 institutions in 30 countries are working on the Deep Underground Neutrino Experiment, hosted at the Department of Energy’s Fermi National Accelerator Laboratory and South Dakota’s Sanford Underground Research Facility. DUNE collaborators come from institutions in Armenia, Brazil, Bulgaria, Canada, Chile, China, Colombia, Czech Republic, Finland, France, Greece, India, Iran, Italy, Japan, Madagascar, Mexico, Netherlands, Peru, Poland, Romania, Russia, South Korea, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom, and the United States of America.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

50 Years of Fermilab

America’s leading particle physics laboratory is turning 50 years old this year. Fermilab’s Dr. Don Lincoln remembers the laboratory’s first half century and looks forward to the fascinating research topics that Fermilab’s scientific staff are looking at as they leap forward into the future.

50TH ANNIVERSARY↗
DOE OSTI2017

The Mandela Effect

The Mandela effect is an idea that people move between parallel universes. Its name arises because some people have firm memories of Nelson Mandela dying in prison, when in fact he was released and went on to be President of South Africa. In this video, Fermilab’s Dr. Don Lincoln explains to his pet Albert why this is such a silly idea.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2017

Virtual Walk: The Construction of the Long Baseline Neutrino Facility

This 2-minute animation shows a virtual walk through the large caverns of the Long-Baseline Neutrino Facility, which will house the Deep Underground Neutrino Experiment. To create the caverns for the huge DUNE particle detectors, construction crews will excavate more than 800,000 tons of rock a mile underground at the Sanford Underground Research Facility in South Dakota. Scientists and dignitaries broke ground for this project on July 21, 2017. When construction is complete, DUNE scientists will send an intense neutrino beam through 1,300 kilometers of rock from the Department of Energy’s Fermilab to the DUNE particle detectors to understand the role that neutrinos – the most abundant matter particles in the universe – play in our cosmos. About 1,000 scientists from more than 160 institutions in 30 countries work on the Deep Underground Neutrino Experiment.

42 ENGINEERING↗
DOE OSTI2017

Fermilab Heroes of the LHC: Joel Butler

Particle physics research is both international and collaborative, with large national laboratories working together to most efficiently advance science. Joel Butler, Distinguished Scientist at Fermi National Accelerator Laboratory is the leader of the Compact Muon Solenoid experiment at the CERN laboratory in Europe. In this video, Joel tells us a bit about what it’s like.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Chasing Down Gravitational Wave Sources with the Dark Energy Camera

On August 17, 2017, scientists using the Dark Energy Camera tracked down the first visible counterpart to a gravitational wave signal ever spotted by astronomers. Using data provided by the LIGO and Virgo collaborations, scientists embarked on a quest for the unknown, and discovered a new wonder of the universe. Includes interviews with Fermilab’s Jim Annis and Brandeis University’s Marcelle Soares-Santos.

79 ASTRONOMY AND ASTROPHYSICS↗