A5062150564- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Dark Matter and Cosmic Phenomena
- Ionosphere and magnetosphere dynamics
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Solar Radiation and Photovoltaics
- Radiation Therapy and Dosimetry
- Atmospheric Ozone and Climate
- Stellar, planetary, and galactic studies
- Particle Detector Development and Performance
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Geomagnetism and Paleomagnetism Studies
- Radiation Detection and Scintillator Technologies
- Geophysics and Gravity Measurements
- Planetary Science and Exploration
- Earthquake Detection and Analysis
- Neutrino Physics Research
- Global Energy and Sustainability Research
- Radioactive Decay and Measurement Techniques
- Nuclear physics research studies
- Space Science and Extraterrestrial Life
- Astronomy and Astrophysical Research
- Photocathodes and Microchannel Plates
California Institute of Technology
2015-2024
Jet Propulsion Laboratory
2001-2022
University of Delaware
2021
Electric Propulsion Laboratory (United States)
2021
Princeton University
2021
Southwest Research Institute
2008-2021
University of New Hampshire at Manchester
2021
University of Arizona
2021
Washington University in St. Louis
1968-2019
Goddard Space Flight Center
1988-2019
We have evaluated the energetics of 38 solar eruptive events observed by a variety spacecraft instruments between 2002 February and 2006 December, as accurately observations allow. The measured energetic components include: (1) radiated energy in Geostationary Operational Environmental Satellite 1–8 Å band, (2) total from soft X-ray (SXR) emitting plasma, (3) peak SXR-emitting (4) bolometric over full duration event, (5) flare-accelerated electrons above 20 keV ions 1 MeV, (6) kinetic...
Above a few tens of MeV per nucleon, large, gradual solar energetic particle (SEP) events are highly variable in their spectral characteristics and elemental composition. The origin this variability has been matter intense ongoing debate. In paper, we propose that arises from the interplay two factors—shock geometry compound seed population, typically comprising both solar-wind flare suprathermals. Whereas quasi-parallel shocks generally draw seeds suprathermals, quasi-perpendicular...
The Integrated Science Investigation of the Sun (ISIS) is a complete science investigation on Solar Probe Plus (SPP) mission, which flies to within nine solar radii Sun’s surface. ISIS comprises two-instrument suite measure energetic particles over very broad energy range, as well coordinated management, operations, data processing, and scientific analysis. Together, observations allow us explore mechanisms dynamics, including their: (1) Origins—defining seed populations physical conditions...
The IMPACT (In situ Measurements of Particles And CME Transients) investigation on the STEREO mission was designed and developed to provide multipoint solar wind suprathermal electron, interplanetary magnetic field, energetic particle information required unravel nature coronal mass ejections their heliospheric consequences. consists seven individual sensors which are packaged into a boom suite, SEP suite. This review summarizes science objectives IMPACT, instruments that comprise...
During a passage through the Earth's dawn‐side outer radiation belt, whistler‐mode waves with amplitudes up to more than ∼240 mV/m were observed by STEREO S/WAVES instrument. These are an order of magnitude larger previously for whistlers in belt. Although peak frequency is similar whistler chorus, there distinct differences from addition amplitudes, including lack drift and oblique propagation large longitudinal electric field component. Simulations show that these amplitude can energize...
Using coordinated observations from instruments on the Advanced Composition Explorer (ACE), Solar and Heliospheric Observatory (SOHO), Ramaty High Energy Spectroscopic Imager (RHESSI), we have evaluated energetics of two well‐observed flare/CME events 21 April 2002 23 July 2002. For each event, estimated energy contents (and likely uncertainties) (1) coronal mass ejection, (2) thermal plasma at Sun, (3) hard X‐ray producing accelerated electrons, (4) gamma‐ray ions, (5) solar energetic...
High‐energy electrons have been measured systematically in a low‐altitude (520 × 675 km), nearly polar (inclination = 82°) orbit by sensitive instruments onboard the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX). Count rate channels with electron energy thresholds ranging from 0.4 MeV to 3.5 three different used examine relativistic variations as function of L‐shell parameter time. A long run essentially continuous data (July 1992–July 1993) shows substantial acceleration...
The extraordinary period from late October through early November 2003 was marked by more than 40 coronal mass ejections (CME), eight X‐class flares, and five large solar energetic particle (SEP) events. Using data instruments on the ACE, SAMPEX, GOES‐11 spacecraft, fluences of H, He, O, electrons have been measured in these events over energy interval ∼0.1 to >100 MeV/nucleon for ions ∼0.04 8 MeV electrons. O spectra are found resemble double power laws, with a break spectral index...
We report on abundance measurements of 10Be, 26Al, 36Cl, and 54Mn in the Galactic cosmic rays (GCRs) using Cosmic-Ray Isotope Spectrometer (CRIS) instrument aboard Advanced Composition Explorer spacecraft at energies from ~70 to ~400 MeV nucleon-1. also an upper limit GCR 14C. The high statistical significance these allows energy dependence their relative abundances be studied. A steady-state, leaky-box propagation model, incorporating observations local interstellar medium (ISM) composition...
We report measurements of record-setting intensities cosmic-ray nuclei from C to Fe, made with the Cosmic Ray Isotope Spectrometer carried on Advanced Composition Explorer in orbit about inner Sun–Earth Lagrangian point. In energy interval ∼70 ∼450 MeV nucleon−1, near peak near-Earth spectrum, measured major species Fe were each 20%–26% greater late 2009 than 1997–1998 minimum and previous solar minima space age (1957–1997). The elevated reported here also at neutron monitor energies...
We use combined high-cadence, high-resolution, and multi-point imaging by the Solar-Terrestrial Relations Observatory (STEREO) Solar Heliospheric to investigate hour-long eruption of a fast wide coronal mass ejection (CME) on 2011 March 21 when twin STEREO spacecraft were located beyond solar limbs. analyze relation between CME, evolution an Extreme Ultraviolet (EUV) wave, onset energetic particle (SEP) event measured in situ near-Earth orbiting spacecraft. Combined ultraviolet white-light...
The giant, superfast, interplanetary coronal mass ejection, detected by STEREO A on 2012 July 23, well away from Earth, appears to have reached 1 AU with an unusual set of leading bow waves resembling in some ways a subsonic interaction, possibly due the high pressures present very energetic particles produced this event. Eventually, front record high-speed flow STEREO. behavior event is illustrated using magnetic field, plasma, and ion observations obtained Had Earth been at location...
Iron-60 ((60)Fe) is a radioactive isotope in cosmic rays that serves as clock to infer an upper limit on the time between nucleosynthesis and acceleration. We have used ACE-CRIS instrument collect 3.55 × 10(5) iron nuclei, with energies ~195 ~500 mega-electron volts per nucleon, of which we identify 15 (60)Fe nuclei. The (60)Fe/(56)Fe source ratio (7.5 ± 2.9) 10(-5) detection supernova-produced implies required for acceleration transport Earth does not greatly exceed half-life 2.6 million...
ABSTRACT We study the link between an expanding coronal shock and energetic particles measured near Earth during ground level enhancement of 2012 May 17. developed a new technique based on multipoint imaging to triangulate three-dimensional (3D) expansion forming in corona. It uses images from three vantage points by mapping outermost extent region perturbed pressure front. derive for first time 3D velocity vector distribution Mach numbers, M FM , entire front as function time. Our approach...
ABSTRACT Since the AD 775 and 994 Δ 14 C peak (henceforth M12) was first measured by Miyake et al. (2012, 2013), several possible production mechanisms for these spike have been suggested, but work of Mekhaldi (2015) shows that a very soft energy spectrum involved, implying strong solar energetic particle (SEP) event (or series events) responsible. Here we present values from 721–820 Sequoiadendron giganteum annual tree-ring samples Sequoia National Park in California, USA, together with...
Abstract On 2022 September 5, Parker Solar Probe (Parker) observed a large solar energetic particle (SEP) event at the unprecedented distance of only 15 R S from Sun. The observations Integrated Science Investigation Sun (IS⊙IS) obtained over course this are remarkably rich, and an overview is presented here. IS⊙IS capable measuring ions 20 keV to 100 MeV nuc −1 electrons 30 6 MeV; here, we primarily focus on proton helium measurements above 80 keV. Among surprising results evidence inverse...
A study has been made of 29 intense, solar particle events observed in the energy range 25–80 MeV/nuc near Earth years 1997 through 2001. It is found that majority (19/29) had Fe/O ratios were reasonably constant with time and energy, values above coronal. These all originated on Sun's western hemisphere most intensities rose rapidly at an associated flare (and coronal mass ejection). Interplanetary shocks little effect during these events. The remaining 10 different intensity‐time profiles...
The cosmic-ray proton and helium spectra from 0.2 GeV nucleon~1 to about 200 have been measured with the balloon-borne experiment Isotope Matter-Antimatter Experiment (IMAX) launched Lynn Lake, Manitoba, Canada, in 1992.IMAX was designed search for antiprotons light isotopes using a superconducting magnet spectrometer together scintillators, time-of-Ñight system, Cherenkov detectors.Using redundant detectors, an extensive examination of instrument efficiency carried out.We present here...
New, coordinated measurements from the International Solar‐Terrestrial Physics (ISTP) constellation of spacecraft are presented to show causes and effects recurrent geomagnetic activity during recent solar minimum conditions. It is found using WIND POLAR data that even for modest storms, relativistic electron fluxes strongly rapidly enhanced within outer radiation zone Earth's magnetosphere. Solar wind utilized identify drivers magnetospheric acceleration processes. Yohkoh soft X‐ray also...