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At least 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Developing inductively driven diagnostic X-ray sources to enable transformative radiography and diffraction capabilities on Z

Penetrating X-rays are one of the most effective tools for diagnosing high energy density experiments, whether through radiographic imaging or X-ray diffraction. To expand the X-ray diagnostic capabilities at the 26-MA Z Pulsed Power Facility, we have developed a new diagnostic X-ray source called the inductively driven X-pinch (IDXP). This X-ray source is powered by a miniature transmission line that is inductively coupled to fringe magnetic fields in the final power feed. The transmission line redirects a small amount of Zs magnetic energy into a secondary cavity where 150+ kA of current is delivered to a hybrid X-pinch. In this report, we describe the multi-stage development of the IDXP concept through experiments both on Z and in a surrogate setup on the 1 MA Mykonos facility. Initial short-circuit experiments to verify power ow on Z are followed by short-circuit and X-ray source development experiments on Mykonos. The creation of a radiography-quality X-pinch hot spot is verified through a combination of X-ray diode traces, laser shadowgraphy, and source radiography. The success of the IDXP experiments on Mykonos has resulted in the design and fabrication of an IDXP for an upcoming Z experiment that will be the first-ever X-pinch fielded on Z. We have also pursued the development of two additional technologies. First, the extended convolute post (XCP) has been developed as an alternate method for powering diagnostic X-pinches on Z. This concept, which directly couples the current owing in one of the twelve Z convolute posts to an X-pinch, greatly increases the amount of available current relative to an IDXP (900 kA versus 150 kA). Initial short-circuit XCP experiments have demonstrated the efficacy of power ow in this geometry. The second technology pursued here is the inductively driven transmission line (IDTL) current monitor. These low-current IDTLs seek to measure the current in the final power feed with high fidelity. After three generations of development, IDTL current monitors frequently return cleaner current measurements than the standard B-dot sensors that are fielded on Z. This is especially true on high-inductance experiments where the harshest conditions are created in the nal power feed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Imaging Wavepackets in Real-Space & Disentangling Ultrafast Solvation Dynamics with High-Energy Ultrafast X-ray Scattering

The microscopic information of solute and solute-solvent motions can be measured using ultrafast diffuse x-ray scattering, and compared to molecular dynamics simulations, as demonstrated in studies of solvated molecular systems done in X-ray free-electron lasers. However, for the typical photon energies used in these experiments, the photon momentum transfer range was limited to lower Q values where the signals arising from different parts of the studied system overlap significantly. Recently, this limitation was greatly alleviated by extending the photon energy at the Linac Coherent Light-Source (LCLS), significantly increasing the accessible momentum transfer range. This improvement is transformative for ultrafast diffuse x-ray scattering measurements, enabling for the first time to disentangle the solute scattering difference signal, that persists to higher Q values, from the bulk solvent and solute-solvent cross-terms difference signals. In addition, it enhances the prediction ability of modeling and simulation methods such as the hybrid QM/MM approach. The extended Q range also opens the way to resolve in real-space details regarding coherent wavepackets motions beyond their center-of-mass positions. Here, we present the first results on high-energy (18keV) diffuse x-ray scattering in solution, demonstrating high fidelity time-resolved scattering and analysis of the photoexcited model photocatalysts PtPOP ([Pt2(POP)4]4-), and IrDimen ([Ir2(dimen)4]2+) in several solvents. These complexes provide ideal systems for demonstrating the ability of high-Q ultrafast scattering and QM/MM simulations to decompose ultrafast solvation dynamics into specific changes in the solute-solvent pair distribution function with a particular focus on how electronically excited states change the interaction between the solvent and photo-catalytically active metal sites. We introduce an approach to further utilize the high-energy capability and demonstrate a single-shot ultra-wide-angle X-ray Scattering modality using two perpendicular detectors, spanning a scattering angle range of more than 100 degrees, allowing to extend the accessible momentum transfer range up to Q~14 Å-1. We develop a model-free method to invert the x-ray scattering signals and enable the recovery of multiple pair-density motions that happen simultaneously, allowing us to directly measure in real-space nuclear wavepacket motions. . [1] Natan, Adi. "Real-Space Inversion and Super-Resolution of Ultrafast X-ray Scattering using Natural Scattering Kernels." arXiv preprint arXiv:2107.05576 (2021)

Natan, Adi↗
DOE OSTI2023

Creating a high energy alert system for the HAWC gamma ray observatory

One of the greatest mysteries in astrophysics is exactly how Cosmic Rays (CRs) are accelerated up to extremely high energies within our galaxy. The highest-energy galactic CRs are associated with gamma rays at ~100 TeV. Hadronic models of possible CR accelerators, including supernova remnants and pulsars, require the production of both gamma rays and neutrinos at these sources. Searching for coincidences between neutrino and the highest energy gamma ray observations can help confirm these theories. The High Altitude Water Cherenkov (HAWC) observatory is a ground based gamma ray observatory located in Puebla, Mexico. HAWC is able to detect gamma rays with energies greater than 100 TeV. It has a wide field of view and a 95% duty cycle, making it ideal for these types of coincidence searches. This work aims to create a high energy alert system for HAWC, sending out an alert to other experiments for high-energy gamma ray events it sees.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Search for New Cosmic-Ray Acceleration Sites within the 4FGL Catalog Galactic Plane Sources

Cosmic rays are mostly composed of protons accelerated to relativistic speeds. When those protons encounter interstellar material, they produce neutral pions, which in turn decay into gamma-rays. This offers a compelling way to identify the acceleration sites of protons. A characteristic hadronic spectrum, with a low-energy break around 200 MeV, was detected in the gamma-ray spectra of four supernova remnants (SNRs), IC 443, W44, W49B, and W51C, with the Fermi Large Area Telescope. This detection provided direct evidence that cosmic-ray protons are (re-)accelerated in SNRs. Here, we present a comprehensive search for low-energy spectral breaks among 311 4FGL catalog sources located within 5° from the Galactic plane. Using 8 yr of data from the Fermi Large Area Telescope between 50 MeV and 1 GeV, we find and present the spectral characteristics of 56 sources with a spectral break confirmed by a thorough study of systematic uncertainty. Our population of sources includes 13 SNRs for which the proton–proton interaction is enhanced by the dense target material; the high-mass gamma-ray binary LS I+61 303; the colliding wind binary η Carinae; and the Cygnus star-forming region. This analysis better constrains the origin of the gamma-ray emission and enlarges our view to potential new cosmic-ray acceleration sites.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

γ-Ray Emission from Classical Nova V392 Per: Measurements from Fermi and HAWC

This paper reports on the γ -ray properties of the 2018 Galactic nova V392 Per, spanning photon energies ~0.1 GeV–100 TeV by combining observations from the Fermi Gamma-ray Space Telescope and the HAWC Observatory. As one of the most rapidly evolving γ -ray signals yet observed for a nova, GeV γ -rays with a power-law spectrum with an index Γ = 2.0 ± 0.1 were detected over 8 days following V392 Per’s optical maximum. HAWC observations constrain the TeV γ -ray signal during this time and also before and after. We observe no statistically significant evidence of TeV γ -ray emission from V392 Per, but present flux limits. Tests disfavor the extension of the Fermi Large Area Telescope spectrum to energies above 5 TeV by 2 standard deviations (95%) or more. We fit V392 Per’s GeV γ -rays with hadronic acceleration models, incorporating optical observations, and compare the calculations with HAWC limits.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Search for High-energy Neutrino Emission from Galactic X-Ray Binaries with IceCube

We present the first comprehensive search for high-energy neutrino emission from high- and low-mass X-ray binaries conducted by IceCube. Galactic X-ray binaries are long-standing candidates for the source of Galactic hadronic cosmic rays and neutrinos. The compact object in these systems can be the site of cosmic-ray acceleration, and neutrinos can be produced by interactions of cosmic rays with radiation or gas, in the jet of a microquasar, in the stellar wind, or in the atmosphere of the companion star. We study X-ray binaries using 7.5 yr of IceCube data with three separate analyses. In the first, we search for periodic neutrino emission from 55 binaries in the Northern Sky with known orbital periods. In the second, the X-ray light curves of 102 binaries across the entire sky are used as templates to search for time-dependent neutrino emission. Finally, we search for time-integrated emission of neutrinos for a list of 4 notable binaries identified as microquasars. In the absence of a significant excess, we place upper limits on the neutrino flux for each hypothesis and compare our results with theoretical predictions for several binaries. In addition, we evaluate the sensitivity of the next generation neutrino telescope at the South Pole, IceCube-Gen2, and demonstrate its power to identify potential neutrino emission from these binary sources in the Galaxy.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Chandra Discovery of a Candidate Hyperluminous X-Ray Source in MCG+11-11-032

We present a multiwavelength analysis of MCG+11-11-032, a nearby active galactic nucleus (AGN), with a unique classification as being both a binary and a dual AGN candidate. With new Chandra observations, we aim to resolve any dual AGN system via imaging data and search for signs of a binary AGN via analysis of the X-ray spectrum. Analyzing the Chandra spectrum, we find no evidence of the previously suggested double-peaked Fe Kα lines; the spectrum is instead best fit by an absorbed power law with a single Fe Kα line, as well as an additional line centered at ≈7.5 keV. The Chandra observation reveals faint, soft, and extended X-ray emission, possibly linked to low-level nuclear outflows. Further analysis shows evidence for a compact hard source—MCG+11-11-032 X2—located 3.″3 from the primary AGN. Modeling MCG+11-11-032 X2 as a compact source, we find that it is relatively luminous (L2–10 keV=1.5−0.5+0.9×1041erg s$^{−1}$), and the location is coincident with a compact and off-nuclear source resolved in Hubble Space Telescope infrared (F105W) and optical (F621M, F547M) bands. Pairing our X-ray results with a 144 MHz radio detection at the host galaxy location, we observe X-ray and radio properties similar to those of ESO 243-49 HLX-1, suggesting that MCG+11-11-032 X2 may be a hyperluminous X-ray source. This detection with Chandra highlights the importance of a high-resolution X-ray imager as well as how previous binary AGN candidates detected with large-aperture instruments can benefit from high-resolution follow-up. Future spatially resolved optical spectra, and deeper X-ray observations, can better constrain the origin of MCG+11-11-032 X2.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Quantum Imaging with X-rays

Quantum imaging encompasses a broad range of methods that exploit the quantum properties of light to capture information about an object. One such approach involves using a two-photon quantum state, where only one photon interacts with the object being imaged while its entangled partner carries spatial or temporal information. To implement this technique, it is necessary to generate specific quantum states of light and detect photons at the single-photon level. While this method has been successfully demonstrated in the visible electromagnetic spectrum, extending it to X-rays has faced significant challenges due to the difficulties in producing a sufficient rate of X-ray photon pairs and detecting them with adequate resolution. Here, we demonstrate record high rates of correlated X-ray photon pairs produced via a spontaneous parametric down-conversion process and we employ these photons to perform quantum correlation imaging of several objects, including a biological sample (E. cardamomum seedpod). Notably, we report an unprecedented detection rate of about 6,300 pairs per hour and the observation of energy anti-correlation for the X-ray photon pairs. We also present a detailed analysis of the properties of the down-converted X-ray photons, as well as a comprehensive study of the correlation imaging formation, including a study of distortions and corrections. These results mark a substantial advancement in X-ray quantum imaging, expanding the possibilities of X-ray quantum optical technologies, and illustrating the pathway towards enhancing biological imaging with reduced radiation doses.

Gofron, Kaz [ORNL] (ORCID:0000000314415736)↗
NASA NTRS1972

X-ray fluorescence experiment

The preliminary results from the Sco X-1 and Cyg X-1 obtained from the Apollo 15 X-ray detector data are presented along with preliminary results of the X-ray fluorescence spectrometric data of the lunar surface composition. The production of the characteristic X-rays following the interaction of solar X-rays with the lunar surface is described along with the X-ray spectrometer. Preliminary analyses of the astronomical X-ray observation and the X-ray fluorescence data are presented.

Adler, I.↗
NASA NTRS1974

International Cosmic Ray Conference, 13th, University of Denver, Denver, Colo., August 17-30, 1973, Proceedings. Volumes 1 & 2

Topics discussed include diffuse gamma rays, gamma ray sources (in particular, the Crab Nebula and Crab Pulsar), X-ray sources, isotopic and nuclear composition, spectra of nuclei, searches for antinuclei, studies of VH and VVH nuclei, measurements of electrons and positrons, the spectra of high-energy electrons, cosmic gamma rays, cosmic ray sources, interplanetary radial gradients, the theory and observation of electron modulation, short-period cosmic ray intensity variations, atmospheric and coupling effects on neutron monitors and muon telescopes, secondary particles and photons in the atmosphere, harmonics of diurnal variations, geomagnetic effects and cutoffs, planetary and interplanetary effects, solar particle access observations, long-term cosmic ray intensity modulation by solar activity and interplanetary effects, Forbush decreases, modulation and anisotropy of low-energy particles, the theory and models of solar particle propagation, solar flare particle composition, and relativistic solar particles. Individual items are announced in this issue.

Source record↗
NASA NTRS1974

International Cosmic Ray Conference, 13th, University of Denver, Denver, Colo., August 17-30, 1973, Proceedings. Volume 5

An X-ray observation of the Norma-Lupus region, charge and isotope measurements of heavy cosmic ray nuclei and their role in the determination of cosmic ray age, and the possibility of a contribution to primary cosmic ray spectra from pulsars are among the topics covered in papers concerned with some of the results of recent cosmic ray research. Other topics covered include multiple scattering of charged particles in magnetic fields, absorption of primary cosmic rays in the atmosphere, and phase lag effects on cosmic ray modulation during a recent solar cycle. Individual items are announced in this issue.

Source record↗
NASA NTRS1974

Gamma ray astronomy

The various source mechanisms for celestial gamma rays are reviewed. The gamma-ray data are examined as a source of information about the processes and source locations for the production of charged particle cosmic rays, galactic structure, explosive nucleosynthesis in supernovae, regions of confinement for cosmic rays, regions where matter-antimatter annihilation occurs, and the general condition in cosmological space both in the past and present. Topics include gamma rays from pi mesons by nuclear interactions, nuclear and supernovae lines, diffuse emission and discrete sources, interstellar absorption and detection of gamma rays, and others. A brief view of the available gamma-ray detection systems and techniques is presented.

Fichtel, C. E.↗
NASA NTRS1975

Slow X-ray bursts and chromospheric flares with filament disruption

The data from OGO-5 and OSO-7 X-ray experiments have been analyzed to study six chromospheric flares with filament disruption associated with slow thermal X-ray bursts. Filament activation accompanied by a slight X-ray enhancement precedes the first evidence of H alpha flare by a few minutes. Rapid increase of the soft X-ray flux is accompanied by a sudden brightening of the filament when viewed on-band H alpha. Thereafter the bright chromospheric strands reach their maximum brightness with maximum X-ray flux. Any plateau or slow decay phase in the X-ray flux is accompanied by a quieting in filament activity and even by filament re-appearance. The height of the disrupted prominence is proportional to the soft X-ray flux for the August 3, 1970 limb occulted event.

Roy, J. R.↗
NASA NTRS1974

X-ray structure of the Cygnus loop

An X-ray surface brightness map of the Cygnus Loop in the energy range 0.15-0.85 keV is presented. The X-ray distribution is compared with the optical and radio pictures of the Loop. The location of the center of the supernova shell as derived from the X-ray data is in excellent agreement with the apparent optical and radio centers. We obtain a mean diameter for the X-ray shell of 2.75 (+ or - 0.2) deg. The X-ray spectral data yield a characteristic thermal temperature averaged over the Loop of 2.9 million (+ or - 1.5 million) K. We have calculated anew X-ray parameters for adiabatic blast waves using X-ray production spectra which include line radiation. These parameters are compared with the results of the present experiment. An age of 18,000 years, initial blast energy equal to 3 times 10 to the 50-th power ergs, and ambient interstellar density of 0.25 per cu cm are found.

Rappaport, S.↗
NASA NTRS1975

Slow X-ray bursts and flares with filament disruption

The data from OGO-5 and OSO-7 X-ray experiments have been compared with optical data from six chromospheric flares with filament disruption associated with slow thermal X-ray bursts. Filament activation accompanied by a slight X-ray enhancement precedes the first evidence of H-alpha flare by a few minutes. Rapid increase of the soft X-ray flux accompanies the phase of fastest expansion of the filament. Plateau or slow decay phases in the X-ray flux are associated with slowing and termination of filament expansion. The soft X-ray flux increases as F approaches (A + Bh)h, where h is the height of the disrupted prominence at any given time and A and B are constants. We suggest that the soft X-ray emission originates from a growing shell of roughly constant thickness of high-temperature plasma due to the compression of the coronal gas by the expanding prominence.

Roy, J.-R.↗
NASA NTRS1975

Observation of soft X-rays from cosmic sources

A binary X-ray source, an extended extragalactic X-ray source and several nearby stars were surveyed for X-ray emission. The energy spectrum and time structure of X-ray flux from the binary source, Her X-l, was investigated in the range from 0.15 to 6 KeV. This source was observed at a binary phase of 0.18 with the system near elongation normal to the line of sight. Intense pulsations were observed in optical emission lines near this binary phase. The spectrum and angular distribution of X-ray emission from the X-ray source in the Virgo Cluster of Galaxies, near M 87, was also observed. In addition, the stars Alpha Leo, Zeta Her, and Epsilon Vir were investigated. Epsilon Aur and Alpha Aur were also scanned. These stars were studied since there is increasing evidence that such objects may be transient sources of soft X-rays.

Catura, R. C.↗
NASA NTRS1976

SAS-2 galactic gamma ray results. 2. Localized sources

Gamma-ray emission was detected from the radio pulsars PSR1818-04 and PSR1747-46, in addition to the previously reported gamma-ray emission from the Crab and Vela pulsars. Since the Crab pulsar is the only one observed in the optical and X-ray bands, these gamma-ray observations suggest a uniquely gamma-ray phenomenon occurring in a fraction of the radio pulsars. Using distance estimates it is found that PSR1818-04 has a gamma-ray luminosity comparable to that of the Crab pulsar, while the luminosities of PSR1747-46 and the Vela pulsar are approximately an order of magnitude lower. This survey of SAS-2 data for pulsar correlations has also yielded upper limits to gamma-ray luminosity for 71 other radio pulsars.

Hartman, R. C.↗
NASA NTRS1976

Diffuse galactic gamma ray lines

The origin and observability were studied of diffuse gamma ray line emission from the galaxy. It was found that such lines could be formed by nuclear excitation interactions of low energy cosmic rays with both interstellar gas and dust grains. The gamma ray emission lines from deexcitation of grain nuclei are sharp with Doppler widths of the order of 10 kev or less; the lines from gas nuclei are also relatively sharp with widths of the order of 100 kev for the most intense line; and the lines from cosmic ray nuclei are broad with widths of the order of several hundred kev. A detailed evaluation is presented of the production rate of the 4.44 Mev line for a variety of assumed cosmic ray spectra. Results are compared with reported galactic gamma ray line intensities and it is concluded that the measurements are consistent with a low energy cosmic ray density which increases toward the galactic center in proportion to the molecular gas density.

Lingenfelter, R. E.↗