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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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DOE OSTI2013

Theoretical Particle Astrophysics

Abstract: Theoretical Particle Astrophysics. The research carried out under this grant encompassed work on the early Universe, dark matter, and dark energy. We developed CMB probes for primordial baryon inhomogeneities, primordial non-Gaussianity, cosmic birefringence, gravitational lensing by density perturbations and gravitational waves, and departures from statistical isotropy. We studied the detectability of wiggles in the inflation potential in string-inspired inflation models. We studied novel dark-matter candidates and their phenomenology. This work helped advance the DoE's Cosmic Frontier (and also Energy and Intensity Frontiers) by finding synergies between a variety of different experimental efforts, by developing new searches, science targets, and analyses for existing/forthcoming experiments, and by generating ideas for new next-generation experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Research in Neutrino Physics and Particle Astrophysics: Final Technical Report

The Boston University Neutrino Physics and Particle Astrophysics Group investigates the fundamental laws of particle physics using natural and man-made neutrinos and rare processes such as proton decay. The primary instrument for this research is the massive Super-Kamiokande (SK) water Cherenkov detector, operating since 1996 at the Kamioka Neutrino Observatory, one kilometer underground in a mine in Japan. We study atmospheric neutrinos from cosmic rays, which were first used to discover that neutrinos have mass, as recognized by the 2015 Nobel Prize in Physics. Our latest measurements with atmospheric neutrinos are giving valuable information, complementary to longbaseline experiments, on the ordering of massive neutrino states and as to whether neutrinos violate CP symmetry. We have studied a variety of proton decay modes, including the most frequently predicted modes such as p → e + π 0 and p → ν K + , as well as more exotic baryon number violating processes such as dinucleon decay and neutronantineutron oscillation. We search for neutrinos from dark matter annihilation or decay in the universe. Our group has made significant contributions to detector operation, particularly in the area of electronics. Most recently, we have contributed to planning for an upgrade to the SK detector by the addition of gadolinium to the water, which will enable efficient neutron capture detection.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Studies of High Energy Particle Astrophysics

This report covers the progress of the Michigan Technological University particle astrophysics group during the period April 15th, 2011 through April 30th, 2014. The principal investigator is Professor David Nitz. Professor Brian Fick is the Co-PI. The focus of the group is the study of the highest energy cosmic rays using the Pierre Auger Observatory. The major goals of the Pierre Auger Observatory are to discover and understand the source or sources of cosmic rays with energies exceeding 10**19 eV, to identify the particle type(s), and to investigate the interactions of those cosmic particles both in space and in the Earth's atmosphere. The Pierre Auger Observatory in Argentina was completed in June 2008 with 1660 surface detector stations and 24 fluorescence telescopes arranged in 4 stations. It has a collecting area of 3,000 square km, yielding an aperture of 7,000 km**2 sr.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Dark matter discovery potential of the Advanced Particle-Astrophysics Telescope

Gamma-ray observations of Milky Way dwarf galaxies have been used to place stringent constraints on the dark matter’s annihilation cross section. Here, in this paper, we evaluate the sensitivity of the proposed Advanced Particle-Astrophysics Telescope (APT) to dark matter in these systems, finding that such an instrument would be capable of constraining thermal relics with masses as large as m X ~ 600 GeV. Furthermore, in dark matter scenarios motivated by the observed Galactic Center gamma-ray excess, we predict that APT would detect several dwarf galaxies with high significance. Such observations could be used to test the predicted proportionality between the gamma-ray fluxes and J-factors of individual dwarf galaxies, providing us with an unambiguous test of the origin of the Galactic Center excess.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Astrophysical particle acceleration mechanisms in colliding magnetized laser-produced plasmas

Significant particle energization is observed to occur in numerous astrophysical environments, and in the standard models, this acceleration occurs alongside energy conversion processes including collisionless shocks or magnetic reconnection. Recent platforms for laboratory experiments using magnetized laser-produced plasmas have opened opportunities to study these particle acceleration processes in the laboratory. Through fully kinetic particle-in-cell simulations, we investigate acceleration mechanisms in experiments with colliding magnetized laser-produced plasmas, with geometry and parameters matched to recent high-Mach number reconnection experiments with externally controlled magnetic fields. 2-D simulations demonstrate significant particle acceleration with three phases of energization: first, a “direct” Fermi acceleration driven by approaching magnetized plumes; second, x-line acceleration during magnetic reconnection of anti-parallel fields; and finally, an additional Fermi energization of particles trapped in contracting and relaxing magnetic islands produced by reconnection. Furthermore, the relative effectiveness of these mechanisms depends on plasma and magnetic field parameters of the experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

Open problems in particle astrophysics

The search for an understanding of the nature of the Dark Matter is one of the fundamental problems in science. This contribution outlines the evidence for the existence of Dark Matter (DM), and discusses the possibility that it is formed by new type of Weakly Interacting Massive (m{approx} 100 GeV) elementary Particles (WIMPs). Possible methods to verify this hypothesis include the creation of these particles in high energy accelerators, the observation of the elastic scattering of ordinary nuclei with the DM particles that form the halo of the Milky Way, and the (indirect) observation of the products of the self annihilation of the DM particles in our Galaxy. Possible, controversial hints of the existence of WIMPs will be discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Exploring the Cosmic Frontier, Task A - Direct Detection of Dark Matter, Task B - Experimental Particle Astrophysics

This report summarizes the work of Task A and B for the period 2013-2016. For Task A the work is for direct detection of dark matter with the single-phase liquid argon experiment Mini-CLEAN. For Task B the work is for the search for new physics in the analysis of fluorescence events with the Auger experiment and for the search for the indirect detection of dark matter with the HAWC experiment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Final Report for DoE Grant DE-SC-0011689 - Studies of Particle Astrophysics at the Cosmic Frontier

Our research focuses on the “Cosmic Frontier”, one of the three principle thrusts of the DoE Office of Science High Energy Physics research program. The 2013 community summer study “Snowmass on the Mississippi” catalyzed joint work to describe the status and future prospects of this research thrust. Over its history, the field of cosmic ray studies has provided many discoveries of central importance to the the progress of high energy physics, including the identification of new elementary particles, measurements of particle interactions far above accelerator energies, and the confirmation of neutrino oscillations. In our research we continued this tradition, employing 2 instruments (the Auger Observatory and the HAWC Observatory) to study high energy physics questions using cosmic rays. One approach to addressing particle physics questions at the cosmic frontier is to study the very highest energy cosmic rays. This has been the major thrust of our research effort. The two largest currently operating ultra-high energy cosmic ray (UHECR) observatories are the Pierre Auger Observatory in the Southern hemisphere, covering an area of 3000 km 2 and the Telescope Array (TA) in the Northern hemisphere, covering about 700 km 2 . The observatories sample the cosmic ray air showers at ground level (with 1660 water Cerenkov stations in the Auger surface detector), and also measure the longitudinal development of air showers on clear moonless nights (approx. 10% of the events) using atmospheric fluorescence detectors. The observatories have recently installed low energy extensions, which provide an overlap with the LHC energy regime. The Auger and TA teams have established joint working groups to discuss experimental methods, compare data analyses and modeling, and perform cross calibrations. Another approach is to study high energy gamma rays. The High Altitude Water Cerenkov (HAWC) gamma-ray observatory is located at 4100 m above sea level near Pico de Orizaba in central Mexico. HAWC is the most sensitive, wide field of view, TeV gamma-ray observatory in operation. After 4 years of construction, operation of the full detector began in March 2015. The HAWC detector contains 300 tanks each 7.3 m in diameter and 4.5 m deep containing pure water. Each water tank is instrumented with 4 upward-viewing photomultiplier tubes mounted at their bottom. The water tanks record the energy deposited by and arrival times of the constituent components of impinging extensive air showers (EAS). The tanks are close-packed to optimize the spatial sampling of the shower front. The distribution of deposited energy across the shower is used for gamma-hadron rejection. Showers with large energy deposit away from the core are rejected as being hadron-initiated. The detector operates at full efficiency above 3 TeV. The angular resolution above that energy approaches 0.1 degree. As the detector operates both day and night, the wide field of view of ~2 sr, allows ~2/3 of the sky to be observed each day.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Heavy Particle Collision Data for Fusion and Astrophysics

A wide range of applications, for example, diagnostics and modeling of fusion plasmas, interpretation of astronomical observations and modeling of astrophysical environments, and simulation of material processing plasmas, require large, accurate, and complete collections of data for electron, photon, heavy particle, and surface interactions. Consequently, over several decades, experimental and theoretical efforts have been developed in order to measure or to calculate such data, and to synergistically explore the fundamental physical mechanisms that underlie interactions at the atomic scale. The present report illustrates some of the recent progress in development of techniques and their use in describing heavy particle collisions, in particular, those involving ions interacting with atoms and simple molecules, with specific applications of the resulting data in fusion energy research and astrophysics.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Cosmology intertwined: A review of the particle physics, astrophysics, and cosmology associated with the cosmological tensions and anomalies

The standard Λ Cold Dark Matter (ΛCDM) cosmological model provides a good description of a wide range of astrophysical and cosmological data. However, there are a few big open questions that make the standard model look like an approximation to a more realistic scenario yet to be found. In this paper, we list a few important goals that need to be addressed in the next decade, taking into account the current discordances between the different cosmological probes, such as the disagreement in the value of the Hubble constant H 0 , the σ 8 – S 8 tension, and other less statistically significant anomalies. While these discordances can still be in part the result of systematic errors, their persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the necessity for new physics or generalisations beyond the standard model. In this paper, we focus on the 5.0 σ tension between the Planck CMB estimate of the Hubble constant H 0 and the SH0ES collaboration measurements. After showing the H 0 evaluations made from different teams using different methods and geometric calibrations, we list a few interesting new physics models that could alleviate this tension and discuss how the next decade's experiments will be crucial. Moreover, we focus on the tension of the Planck CMB data with weak lensing measurements and redshift surveys, about the value of the matter energy density Ω m , and the amplitude or rate of the growth of structure ( σ 8 , f σ 8 ). We list a few interesting models proposed for alleviating this tension, and we discuss the importance of trying to fit a full array of data with a single model and not just one parameter at a time. Additionally, we present a wide range of other less discussed anomalies at a statistical significance level lower than the H 0 – S 8 tensions which may also constitute hints towards new physics, and we discuss possible generic theoretical approaches that can collectively explain the non-standard nature of these signals. Finally, we give an overview of upgraded experiments and next-generation space missions and facilities on Earth that will be of crucial importance to address all these open questions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Rapid Acceleration of Outcomes in Physics: Final Report for the Nuclear Physics, Particle Physics, Astrophysics, and Cosmology (NPAC) Umbrella Project

The Nuclear Physics, Particle Physics, Astrophysics, and Cosmology (NPAC) Initiative addresses the first question by supporting experiments that would directly detect dark matter when it interacts with very sensitive detectors. There are two leading candidates for dark matter that are plausibly detectable in terrestrial searches: axions and weakly-interacting massive particles, or WIMPs. Early NPAC investments supported PNNL involvement in the Axion Dark Matter eXperiment (ADMX), which has produced the world’s most sensitive axion search to date. Work associated with the current generation of the experiment is funded by the DOE Office of High Energy Physics (HEP), while R&D toward future searches for higher mass axions proceeds under NPAC. Likewise, early NPAC support for WIMP searches has graduated to the HEP-supported Super Cold Dark Matter Search (SuperCDMS) experiment. SuperCDMS has produced world-leading limits on potential WIMP candidates as well as a number of other exotic candidates and processes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Particle Theory & Cosmology

1. Executive Summary (April 1, 2012 - March 31, 2015) Title: Particle Theory, Particle Astrophysics and Cosmology Qaisar Shafi University of Delaware (Principal Investigator) Stephen M. Barr, University of Delaware (Co-Principal Investigator) Thomas K. Gaisser, University of Delaware (Co-Principal Investigator) Todor Stanev, University of Delaware (Co-Principal Investigator) The proposed research was carried out at the Bartol Research included Professors Qaisar Shafi Stephen Barr, Thomas K. Gaisser, and Todor Stanev, two postdoctoral fellows (Ilia Gogoladze and Liucheng Wang), and several graduate students. Five students of Qaisar Shafi completed their PhD during the period August 2011 - August 2014. Measures of the group’s high caliber performance during the 2012-2015 funding cycle included pub- lications in excellent refereed journals, contributions to working groups as well as white papers, and conference activities, which together provide an exceptional record of both individual performance as well as overall strength. Another important indicator of success is the outstanding quality of the past and current cohort of graduate students. The PhD students under our supervision regularly win the top departmental and university awards, and their publications records show excellence both in terms of quality and quantity. The topics covered under this grant cover the frontline research areas in today’s High Energy Theory & Phenomenology. For Professors Shafi and Barr they include LHC related topics including supersymmetry, collider physics, fl vor physics, dark matter physics, Higgs boson and seesaw physics, grand unifi and neutrino physics. The LHC two years ago discovered the Standard Model Higgs boson, thereby at least partially unlocking the secrets behind electroweak symmetry breaking. We remain optimistic that new and exciting physics will be found at LHC 14, which explain our focus on physics beyond the Standard Model. Professors Shafi continued his investigations in cosmology, specifically on supergravity and GUT infl models, primordial gravity waves, dark matter models. The origin of baryon and dark matter in the universe has been explored by Professors Barr and Shafi The research program of Professors Gaisser and Stanev address current research topics in Particle Astrophysics, in particular atmospheric and cosmogenic neutrinos and ultra-high energy cosmic rays. Work also included use of LHC data to improve tools for interpreting cascades generated in the atmosphere by high-energy particles from the cosmos. Cosmogenic neutrinos produced by interactions of ultra-high energy cosmic rays as they propagate through the cosmic microwave background radiation provides insight into the origin of the highest energy particles in nature. Overall, the research covered topics in the energy, cosmic and intensity frontiers.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Improved receiver noise calibration for ADMX axion search: 4.54 to 5.41 μeV

Axions are a well-motivated candidate for dark matter. The preeminent method to search for axion dark matter is known as the axion haloscope, which makes use of the conversion of axions to photons in a large magnetic field. Because of the weak coupling of axions to photons, however, the expected signal strength is exceptionally small. To increase signal strength, many haloscopes make use of resonant enhancement and high gain amplifiers, while also taking measures to keep receiver noise as low as possible such as the use of dilution refrigerators and ultra-low-noise electronics. In this paper, we derive the theoretical noise model based on the sources of noise found within a typical axion haloscope receiver chain, using the Axion Dark Matter eXperiment (ADMX) as a case study. We present examples of different noise calibration measurements at 1280 MHz taken during ADMX’s most recent data-taking run. These new results shed light on a previously unidentified interaction between the cavity and Josephson Parametric Amplifier as well as provide a better understanding of the systematic uncertainty on the system noise temperature used in the axion search analysis for this data-taking run. Finally, the consistency between the measurements and the detailed model provide suggestions for future improvements within ADMX and other axion haloscopes to reach a lower noise temperature.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗