Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “COSMIC RADIATION”

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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Solar Flare Activity from 2006 to 2016 according to Data from the PAMELA and ARINA Spectrometers

In the period from 2006 to 2016, experiments based on the use of the PAMELA and ARINA spectrometers and aimed at detecting cosmic rays were performed on board the RESURS-DK1 satellite. Although the main goal of these experiments was to study the galactic component of cosmic rays, the instruments in question also detected, over a broad energy range, solar particles accelerated in powerful explosive processes on the Sun (solar flares). A list of solar events in which the PAMELA and ARINA spectrometers detected, in various years of their operation, an increase in the intensities of fluxes of solar protons whose energies were above 45 MeV is presented among other things.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Ten years of CR physics with PAMELA

The satellite borne Pamela instrument is dedicated to the precise and high statistics study of CR fluxes on a four decades energy range. Pamela experiment is the last step of the “Russian-Italian Mission” (RIM) program established in 1992 between several Italian and Russian institutes and with the participation of Sweden and Germany. Designed as a cosmic ray observatory at 1 AU, it extensive program is made possible thanks to the outstanding performance of the instrument, the low energy threshold, the quasi-polar orbit and the 10 years duration of the observation. The physics program pays particular attention to the study of particles and antiparticles fluxes and includes search for dark matter, primordial antimatter, new matter in the Universe, study of cosmic-ray propagation, solar physics and solar modulation, and terrestrial magnetosphere. Very important is the discovery of the anomalous increase of the positron flux at energies higher that 50 GeV (the so called “Pamela anomaly”), and the abrupt spectral hardening of H and He, challenging the current paradigm of cosmic-ray acceleration and propagation in the Galaxy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

On propagators of nonlocal relativistic diffusion of galactic cosmic rays

This report discusses a new model of cosmic ray propagation in the Galaxy. In contrast to the known models based on the principles of Brownian motion, the proposed model agrees with the relativistic principle of speed limitation and takes into account the large-scale turbulence of the interstellar medium, justifying introduction of fractional differential operators.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Production, characterization and operation of $^{76}$Ge enriched BEGe detectors in GERDA

The GERmanium Detector Array (Gerda) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay (0νββ) of 76 Ge. Germanium detectors made of material with an enriched 76 Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of theexperiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new 76 Ge enriched detectors of broad energy germanium (BEGe)-type were produced. A subgroup of these detectors has already been deployed in Gerda during Phase I. The present article reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the 76 Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. Lastly, the detector performance fulfills the requirements needed for the physics goals of Gerda Phase II.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Notes on the Lumped Backward Master Equation for the Neutron Extinction/Survival Probability

The expected or mean neutron number (or density) provides an adequate characterization of the neutron population and its dynamical excursions in most neutronic applications, in particular power reactors. Fluctuations in the neutron number, originating from the inherent randomness of neutron interactions and fission neutron multiplicities, are relatively small and ignorable for operational purposes, although measurements of the variance and time correlations provide valuable diagnostic information on fundamental reactor physics parameters. However, it is well known that there exist situations of great interest and importance in which a strictly deterministic description, or even one supplemented with a knowledge of low order statistical averages (variance, correlation), provides an incomplete and very unsatisfactory description of the state of the neutron population. These situations are marked by persistent large fluctuations in the neutron number where the emergence of a deterministic phase is suppressed. Such situations are strongly stochastic and therefore unpredictable (i.e., the mean is not representative of the actual population), and can arise either by design or by accident. Examples where the stochastic behavior of neutron populations must be taken into account include: nuclear weapon single-point safety assessment; criticality excursions in spent fuel storage and in the handling of fissile solutions in fuel fabrication and reprocessing; approach to critical under suboptimal reactor start-up conditions; preinitiation in fast burst research reactors; and weak nuclear signatures in the passive detection of nuclear materials. What distinguishes strongly stochastic neutronic systems from strongly deterministic systems is that, in the former, neutron multiplication occurs in the presence of weak neutron sources, such as spontaneous fission and background (cosmic) radiation. Weak sources (in a sense that can be made quite precise) lead to well separated fission chains (a fission chain is defined as the initial source neutron and all its subsequent progeny) in which some chains are short lived while others propagate for unusually long times. Under these conditions, fission chains do not overlap strongly and this precludes the cancellation of neutron number fluctuations necessary for the mean to become established as the dominant measure of the neutron population. The fate of individual chains then plays a defining role in the evolution of the neutron population in strongly stochastic systems, and of particular interest and importance in supercritical systems is the extinction probability, defined as the probability that the neutron chain (initiating neutron and its progeny) will be extinguished at a particular time, or its complement, the time-dependent survival probability. The time-asymptotic limit of the latter, the probability of divergence, gives the probability that the neutron population will grow without bound, and is more commonly known as the probability of initiation or just POI. The ability to numerically compute these probabilities, with high accuracy and without overly restricting the underlying physics (e.g., fission neutron multiplicity, reactivity variation) is clearly essential in developing an understanding of the behavior of strongly stochastic systems.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2012

Estimation of Cosmic Induced Contamination in Ultra-low Background Detector Materials

This document presents the result of investigating a way to reliably determine cosmic induced backgrounds for ultra-low background materials. In particular, it focuses on those radioisotopes produced by the interactions with cosmic ray particles in the detector materials that act as a background for experiments looking for neutrinoless double beta decay. This investigation is motivated by the desire to determine background contributions from cosmic ray activation of the electroformed copper that is being used in the construction of the MAJORANA DEMONSTRATOR. The most important radioisotope produced in copper that contributes to the background budget is 60 Co, which has the potential to deposit energy in the region of interest of this experiment. Cobalt-60 is produced via cosmic ray neutron collisions in the copper. This investigation aims to provide a method for determining whether or not the copper has been exposed to cosmic radiation beyond the threshold which the Majorana Project has established as the maximum exposure. This threshold is set by the Project as the expected contribution of this source of background to the overall background budget.

Navarrete, Estanislao Aguayo↗
DOE OSTI2013

Muon Radiography for Non-Destructive, Non-Invasive Assay and Long-Term Monitoring of Nuclear Fuel Debris and Fuel Assemblies.

We propose developing a muon cosmic ray radiography system dedicated to the task of assay and long-term safeguard monitoring of Fukushima fuel debris or fuel assemblies. The system would be non-destructive and non-invasive, using naturally occurring cosmic radiation to assay the entire volume of the fuel debris container. The technique distinguishes between materials and is especially sensitive to measuring the location and amount of heavy elements such as uranium and plutonium. Scope of the feasibility study would encompass a) demonstrating material assay (location and amount) of a regular-shaped depleted uranium object sealed in a debris container, and b) repeating the material assay of debris-proxy materials of irregular shape (corium), sealed in a debris container. Muon radiography of each container would result in a unique “fingerprint” of the contents, useful for long-term safeguards monitoring.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Collaborative Research: A Model of Partially Ionized Plasma Flows with Kinetic Treatment of Neutral Atoms and Nonthermal Ions

Interactions of flows of partially ionized, magnetized plasma are frequently accompanied by the presence of both thermal and non-thermal (pickup) ion components. Such interactions cannot be modeled using traditional MHD equations and require more advanced approaches to treat them. If a nonthermal component of ions is formed due to charge exchange and collisions between the thermal (core) ions and neutrals, it experiences the action of magnetic field, its distribution function is isotropized, and it soon acquires the velocity of the ambient plasma without being thermodynamically equilibrated. This situation, e. g., takes place in the outer heliosphere –- the part of interstellar space beyond the solar system whose properties are determined by the solar wind interaction with the local interstellar medium. This is also possible in laboratory, at million degrees and above, when plasma is conducting electricity far too well, which makes Ohmic heating ineffective. To attain the target temperatures one needs additional heating eventually playing a dominant role. Among such sources is a so-called neutral particle beam heating. This is a wide-spread technique (Joint European Torus and International Thermonuclear Experimental Reactor experiments) based on the injection of powerful beams of neutral atoms into ohmically preheated plasma. In this project we have investigated the energy and density separation between the thermal and nonthermal components in the solar wind and interstellar plasmas. A new model has been developed in which we solve the ideal MHD equations for mixture of all ions and the kinetic Boltzmann equation to describe the transport of neutral atoms. As a separate capability, we can treat the flow of neutral atoms in a multi-component fashion, where neutral atoms born in each thermodynamically distinct region are governed by the Euler gas dynamic equations. We also describe the behavior of pickup ions either kinetically, using the Fokker--Planck equation, or as a separate fluid. Our numerical simulations have demonstrated that pickup ions play a major role in the interaction of the solar wind and (partially ionized) interstellar medium plasmas. Our teams have investigated the stability of the surface (the heliopause) that separates the solar wind from the local interstellar medium, the transport of galactic cosmic rays, the properties of the heliotail flow, and modifications to the bow wave in front of the heliopause due to charge exchange between the neutral H atoms born in the solar wind and interstellar ions. Modeling results have been validated against observational data, such as obtained by the Interstellar Boundary Explorer (IBEX), and made it possible to shed light on the structure of energetic neutral atom maps created by this spacecraft.. We have also demonstrated that charge-exchange modulated heliosphere is a source of anisotropy of the multi-TeV cosmic ray flux observed in a number of Earth-bound air shower experiments. Newly developed codes are implemented within a Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS), a publicly available code being developed by our team for over 12 years. MS-FLUKSS scales well up to 160,000 computing cores and has been ported on major supercomputers in the country. Efficient parallelization and data choreography in the continuum simulation modules are provided by Chombo, an adaptive mesh refinement framework managed by Phillip Colella's team at LBNL. We have implemented in-house, hybrid (MPI+OpenMP) parallelization of the kinetic modules that solve the Boltzmann equation with a Monte Carlo method. Currently, the kinetic modules are being rewritten to take advantage of the modern CPU-GPU supercomputer architecture. The scope of the project allowed us to enhance plasma research and education in such broad, multidisciplinary field as physics of partially ionized plasma and its application to space physics and fusion science. Besides the impact on the modeling of complex physical systems, our approach to computational resource management for complex codes utilizing multiple algorithm technologies appears to be a major advance on current approaches. The development of sophisticated resource management will be essential for all future modeling efforts that incorporate a diversity of scales and physical processes. Our effort provided leadership in promoting computational science and plasma physics within the UAH and FIT campuses and, through the training of a broad spectrum of scientists and engineers, fostering new technologies across the country.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

SuperCDMS Underground Detector Fabrication Facility

The SuperCDMS SNOLAB dark matter experiment processes Ge and Si crystals into fully tested phonon and ionization detectors at surface fabrication and test facilities. If not mitigated, it is anticipated that trace-level production of radioisotopes in the crystals due to exposure to cosmic rays at (or above) sea level will result in the dominant source of background events in future dark matter searches using the current SuperCDMS detector technology. Fabrication and testing of detectors in underground facilities shielded from cosmic radiation is one way to directly reduce production of trace levels of radioisotopes, thereby improving experimental sensitivity for the discovery of dark matter beyond the level of the current experiment. In this report, we investigate the cost and feasibility to establish a complete detector fabrication processing chain in an underground location to mitigate cosmogenic activation of the Ge and Si detector substrates. For a specific and concrete evaluation, we explore options for such a facility located at SNOLAB, an underground laboratory in Sudbury, Canada hosting the current and future experimental phases of SuperCDMS.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

A Vertical Deburring Algorithm for Muon Tomography

Los Alamos researchers have developed a technology that improves the quality of images generated by muon tomography techniques,where naturally existing cosmic radiation is used as an energy source for identifying very dense materials. When using muon tomography,blurring can occur on the vertical aspect of images, making it more difficult to interpret data. This vertical de-blurring technology will correct these abnormalities and improve image quality for better evaluation of containers that may have dense matter such as special nuclear materials. This technology has been demonstrated in the laboratory and was evaluated in the field for efficacy.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Skipper-CCD Quantum Efficiency Analysis

Scientific skipper-CCDs with single-electron resolution present dozens of possibilities for detecting dark matter candidates. Fermilab's Cosmic Physics Center contributes to the DarkNESS mission, which aims to place a skipper multi-chip module in a 6U CubeSat designed for low earth orbit. The DarkNESS nanosat will have the capability to search for 1-10keV band X-rays that may originate from DM decays. One of the challenges of detection in space is the large amount of cosmic radiation contributing to sensor noise. To mitigate this, an aluminum shield is proposed to be placed on the sensor. This project aims to test and characterize the energy resolution with a shield of various thicknesses (0-100nm) using a single CCD and an iron-55 x-ray source. ROOT analysis was used to parse data from several runs into sections based on shield thickness, create strategic data cuts, and characterize Fano plus signal shot noise in the sensor.

Wells, Megan E. [U. Illinois, Chicago]↗
DOE OSTI2016

PLASMA EFFECTS ON EXTRAGALACTIC ULTRAHIGH-ENERGY COSMIC-RAY HADRON BEAMS IN COSMIC VOIDS. II. KINETIC INSTABILITY OF PARALLEL ELECTROSTATIC WAVES

The linear instability of an ultrarelativistic hadron beam in the unmagnetized intergalactic medium (IGM) is investigated with respect to the excitation of parallel electrostatic and electromagnetic fluctuations. This analysis is important for the propagation of extragalactic ultrarelativistic cosmic rays from their distant sources to Earth. As opposed to the previous paper, we calculate the minimum instability growth time for Lorentz-distributed cosmic rays which traverse the hot IGM. The growth times are orders of magnitude higher than the cosmic-ray propagation time in the IGM. Since the backreaction of the generated plasma fluctuations (plateauing) lasts longer than the propagation time, the cosmic-ray hadron beam can propagate to the Earth without losing a significant amount of energy to electrostatic turbulence.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Explaining TeV cosmic-ray anisotropies with non-diffusive cosmic-ray propagation

Constraining the behavior of cosmic ray data observed at Earth requires a precise understanding of how the cosmic rays propagate in the interstellar medium. The interstellar medium is not homogeneous; although turbulent magnetic fields dominate over large scales, small coherent regions of magnetic field exist on scales relevant to particle propagation in the nearby Galaxy. Guided propagation through a coherent field is significantly different from random particle diffusion and could be the explanation of spatial anisotropies in the observed cosmic rays. We present a Monte Carlo code to propagate cosmic particle through realistic magnetic field structures. We discuss the details of the model as well as some preliminary studies which indicate that coherent magnetic structures are important effects in local cosmic-ray propagation, increasing the flux of cosmic rays by over two orders of magnitude at anisotropic locations on the sky. Furthermore, the features induced by coherent magnetic structure could be the cause of the observed TeV cosmic-ray anisotropy.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Bayesian analysis of cosmic ray propagation: evidence against homogeneous diffusion

We present the results of the most complete scan of the parameter space for cosmic ray (CR) injection and propagation. We perform a Bayesian search of the main GALPROP parameters, using the MultiNest nested sampling algorithm, augmented by the BAMBI neural network machine-learning package. This is the first study to separate out low-mass isotopes (p, p-bar , and He) from the usual light elements (Be, B, C, N, and O). We find that the propagation parameters that best-fit p, p-bar , and He data are significantly different from those that fit light elements, including the B/C and {sup 10}Be/{sup 9}Be secondary-to-primary ratios normally used to calibrate propagation parameters. This suggests that each set of species is probing a very different interstellar medium, and that the standard approach of calibrating propagation parameters using B/C can lead to incorrect results. We present posterior distributions and best-fit parameters for propagation of both sets of nuclei, as well as for the injection abundances of elements from H to Si. The input GALDEF files with these new parameters will be included in an upcoming public GALPROP update.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

DAMPING OF MAGNETOHYDRODYNAMIC TURBULENCE IN PARTIALLY IONIZED PLASMA: IMPLICATIONS FOR COSMIC RAY PROPAGATION

We study the damping processes of both incompressible and compressible magnetohydrodynamic (MHD) turbulence in a partially ionized medium. We start from the linear analysis of MHD waves, applying both single-fluid and two-fluid treatments. The damping rates derived from the linear analysis are then used in determining the damping scales of MHD turbulence. The physical connection between the damping scale of MHD turbulence and the cutoff boundary of linear MHD waves is investigated. We find two branches of slow modes propagating in ions and neutrals, respectively, below the damping scale of slow MHD turbulence, and offer a thorough discussion of their propagation and dissipation behavior. Our analytical results are shown to be applicable in a variety of partially ionized interstellar medium (ISM) phases and the solar chromosphere. The importance of neutral viscosity in damping the Alfvenic turbulence in the interstellar warm neutral medium and the solar chromosphere is demonstrated. As a significant astrophysical utility, we introduce damping effects to the propagation of cosmic rays in partially ionized ISM. The important role of turbulence damping in both transit-time damping and gyroresonance is identified.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

ON THE CHEMISTRY OF HYDRIDES OF N ATOMS AND O{sup +} IONS

Previous work by various authors has suggested that the detection by Herschel /HIFI of nitrogen hydrides along the low-density lines of sight toward G10.6-0.4 (W31C) cannot be accounted for by gas-phase chemical models. In this paper we investigate the role of surface reactions on dust grains in diffuse regions, and we find that formation of the hydrides by surface reactions on dust grains with efficiency comparable to that for H{sub 2} formation reconciles models with observations of nitrogen hydrides. However, similar surface reactions do not contribute significantly to the hydrides of O{sup +} ions detected by Herschel /HIFI that are present along many sight lines in the Galaxy. The O{sup +} hydrides can be accounted for by conventional gas-phase chemistry either in diffuse clouds of very low density with normal cosmic-ray fluxes or in somewhat denser diffuse clouds with high cosmic-ray fluxes. Hydride chemistry in dense dark clouds appears to be dominated by gas-phase ion–molecule reactions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

MODELING THE SUN’S SMALL-SCALE GLOBAL PHOTOSPHERIC MAGNETIC FIELD

We present a new model for the Sun’s global photospheric magnetic field during a deep minimum of activity, in which no active regions emerge. The emergence and subsequent evolution of small-scale magnetic features across the full solar surface is simulated, subject to the influence of a global supergranular flow pattern. Visually, the resulting simulated magnetograms reproduce the typical structure and scale observed in quiet Sun magnetograms. Quantitatively, the simulation quickly reaches a steady state, resulting in a mean field and flux distribution that are in good agreement with those determined from observations. A potential coronal magnetic field is extrapolated from the simulated full Sun magnetograms to consider the implications of such a quiet photospheric magnetic field on the corona and inner heliosphere. The bulk of the coronal magnetic field closes very low down, in short connections between small-scale features in the simulated magnetic network. Just 0.1% of the photospheric magnetic flux is found to be open at 2.5 R {sub ⊙}, around 10–100 times less than that determined for typical Helioseismic and Magnetic Imager synoptic map observations. If such conditions were to exist on the Sun, this would lead to a significantly weaker interplanetary magnetic field than is currently observed, and hence a much higher cosmic ray flux at Earth.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Stability of Sulphur Dimers (S{sub 2}) in Cometary Ices

S{sub 2} has been observed for decades in comets, including comet 67P/Churyumov–Gerasimenko. Despite the fact that this molecule appears ubiquitous in these bodies, the nature of its source remains unknown. In this study, we assume that S{sub 2} is formed by irradiation (photolysis and/or radiolysis) of S-bearing molecules embedded in the icy grain precursors of comets and that the cosmic ray flux simultaneously creates voids in ices within which the produced molecules can accumulate. We investigate the stability of S{sub 2} molecules in such cavities, assuming that the surrounding ice is made of H{sub 2}S or H{sub 2}O. We show that the stabilization energy of S{sub 2} molecules in such voids is close to that of the H{sub 2}O ice binding energy, implying that they can only leave the icy matrix when this latter sublimates. Because S{sub 2} has a short lifetime in the vapor phase, we derive that its formation in grains via irradiation must occur only in low-density environments such as the ISM or the upper layers of the protosolar nebula, where the local temperature is extremely low. In the first case, comets would have agglomerated from icy grains that remained pristine when entering the nebula. In the second case, comets would have agglomerated from icy grains condensed in the protosolar nebula and that would have been efficiently irradiated during their turbulent transport toward the upper layers of the disk. Both scenarios are found consistent with the presence of molecular oxygen in comets.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗