Introduction to the workshop from Veronica Bindi
The dual-spacecraft Van Allen Probes mission has provided a new window into megaelectron Volt (MeV) particle dynamics in the Earth’s radiation belts. Observations (up to E ~10 MeV) show clearly the behavior of the outer electron radiation belt at different time scales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes...
This presentation addresses the theory of shock acceleration as applied to gradual events (the large temporally-extended high-energy events responsible for inclement weather in space), including the basic elements of first-order Fermi and shock drift acceleration at CME-driven shocks, wave excitation (which enhances the efficiency of shock acceleration), the effect of shock obliquity, the...
Klassen, etal discussed observations of a spike event of 55-65 keV electrons which occurred very nearly simultaneously at STEREO A and STEREO B, which at the time were separated in longitude by 38 degrees. The authors associated the spikes with a flare at the Sun near the footpoint of the nominal Archimedean spiral magnetic field line passing through STEREO A. The spike at STEREO A was...
We present updated event integrated spectra from several SEP events occurring from 2006 to 2014 in the energy range starting at 80 MeV and extending well above the neutron monitor threshold. The PAMELA instrument is in a high inclination, low Earth orbit and has access to SEPs when at high geographic latitudes. This means that the spectra have been assembled from regularly spaced...
Short-term (few-day duration) modulations of the galactic cosmic ray intensity have been observed for many decades by ground-based instruments and spacecraft, and are associated with structures in the heliosphere, in particular, interplanetary coronal mass ejections (including magnetic clouds) and co-rotating interaction regions. For all of the observations, there is still no consensus on the...
The satellite-borne experiment PAMELA (A Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics) has been continuously collecting data since June 15th of 2006, when it was launched from the Baikonur cosmodrome. Its main scientific goal is the detection of the charged component of the cosmic radiation over a wide energy range and with high precision. The apparatus design is...
The satellite-borne PAMELA experiment was launched on the 15th June 2006 from the Baikonur cosmodrome. Till January 2016 PAMELA has detected the charged component of cosmic-rays over a wide energy range measuring both particles and antiparticles. In particular, as a result of its highly inclined orbit, the instrument samples low geomagnetic cut-off regions and can explore in detail the low...
The PAMELA satellite experiment, in low Earth orbit since June 2006, is providing comprehensive observations of the Solar Energetic Particle (SEP) events between solar cycles 23 and 24. Its unique capabilities include the possibility of accurately measuring the SEP energetic spectra in a large interval (>80 MeV), encompassing the low energy data by other space-based instruments and the Ground...
Solar activity was at its lowest level since the beginning of the space exploration era from 2006 to 2009. During this period, the PAMELA space experiment observed spectra for galactic protons and electrons down to 70 MV and 400 MV, respectively, during what is called an A < 0 solar magnetic polarity cycle. This provides the opportunity to study charge-sign-dependent modulation under very...
A three-dimensional (3D) diffusion-barrier-type model is constructed for producing Forbush decreases (Fds) in the heliosphere. It is based on reduced diffusion inside these barriers, which is incorporated into a Stochastic Differential Equation (SDE) based time-dependent, cosmic ray transport model. This 3D numerical model for simulating Fds is built for and applied to a period of relatively...
Large gradual solar energetic particle (SEP) events are of particular importance because of their hazardous threats to astronauts and equipment in space. Although there are compelling observational evidence supporting the scenario of particle acceleration at strong shocks driven by coronal mass ejections, it is not clear how those high-energy particles are accelerated and what the determining...
Magnetic reconnection is an important driver of energetic particles in a variety of astrophysical phenomena, and may play a key role role in pre-heating and accelerating Solar Energetic Particles during events. Recently, we developed a guiding-center model that successfully described the fundamental electron energization mechanisms that operate during reconnection. The most efficient mechanism...
The space radiation environment is one of the outstanding challenges of a manned deep-space mission to Mars. To improve our understanding and take us one step closer to enabling a human Mars to mission, the Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) has been characterizing the radiation environment, both during cruise and on the surface of Mars for the past 4...
Under the Next Space Technologies for Exploration Partnerships (NextSTEP), NASA is collaborating with six companies to design, develop, and test habitat concepts for human missions beyond low Earth orbit. A method for protecting astronauts from the harmful effects of Solar Particle Events (SPEs) must be incorporated into these habitats. This radiation protection may take the form of a...
The Alpha Magnetic Spectrometer (AMS) is a general-purpose high-energy particle physics detector. It was installed on the International Space Station (ISS) in May 2011 to conduct a unique long-duration mission of fundamental physics research in space. AMS has acquired the largest number of particles ever measured in space by a single experiment, performing the most precise measurement of...
The Alpha Magnetic Spectrometer (AMS), on the International Space Station (ISS) since May 2011, has acquired the largest number of particles ever measured in space by a single experiment, performing the most precise measurement of galactic cosmic rays (GCR) to-date. For the first time we present the detailed time variation of multiple particle species fluxes measured in the first five years of...
During the first 5 years of operations on board of the International Space Station, from May 2011 to May 2016, AMS has detected many short-term increases in the proton flux due to solar energetic particle (SEP) events and many sudden suppressions of the galactic cosmic ray (GCR) flux, called Forbush decreases (FD). AMS is able to measure the most energetic SEPs and has observed 27 SEP events...
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Approved for Public Release
17-MDA-9077 (7 March 17)
Design and planning for space missions must account for possible solar energetic particle events (SEPEs) during these missions. Missions account for SEPEs by designing or planning to the worst operating reference environment. It is important to choose...
Radiation exposure from solar energetic particle (SEP) events becomes a much greater concern as human exploration extends beyond low Earth orbit (LEO) and the protective environment of Earth’s magnetic field. Free space SEP events have an increased impact on mission planning and operations, as countermeasures may be necessary to avoid exceeding astronaut permissible exposure limits (PELs) and...
The Earth’s energetic particle environment consists of several components of the ionizing radiation: galactic cosmic rays (GCRs), solar energetic particles (SEP), and particles populating two radiation belts. Of those, it is SEPs and GCRs that are critical for evaluating the safety of space operations performed in the LEO altitude range.
According to the current paradigm, GCRs are produced...
The Sun does not shine at GeV-TeV energies on its own power, but because Galactic cosmic rays (CR) interact with its matter and light. By observing and modeling these interactions in and near the Sun, one may learn about CR propagation in the inner heliosphere and in the solar atmosphere. In this talk, I will present observations and a set of ongoing calculations that sharpen our...
The AMS-02 experiment on board the International Space Station measured with unprecedented accuracy the time variation of the cosmic ray proton and helium flux between May 2011 and May 2016 in the rigidity range from 1 to 100 GV. A comprehensive 3D steady-state numerical model is used to solve the Parker's transport equation and to reproduce the monthly fluxes observed by AMS-02. The...
The Sun is an effective particle accelerator producing solar energetic particle (SEP) events during which particles up to several GeVs can be observed. Those events observed at Earth with the neutron monitor network are called ground level enhancements (GLEs). In this work, SEP events with protons accelerated to above 500 MeV have been identified using data from the Electron Proton Helium...
An overview of the theoretical modeling of acceleration of solar energetic particles at interplanetary shocks will be presented. The basic tenets of diffusive shock acceleration will be discussed in the framework of particle acceleration at coronal mass ejection-driven shocks using the Particle Acceleration Throughout the Heliosphere (PATH) code. The original PATH code was restricted to a...
There have been significantly fewer large solar proton events (SPEs) in the current solar cycle (solar cycle 24) compared to the previous one. Solar proton events occur when the flux of solar-energetic particles with energies greater than 10 MeV exceeds 10 protons/(cm2 s sr) and are reported by NOAA/GOES. Such events are usually associated with shock waves driven by fast coronal mass...
During solar cycle 24, thanks largely to the Solar Terrestrial Relations Observatory (STEREO), many solar energetic particle (SEP) events have been observed at widely separate heliographic longitudes, even including impulsive events. The particle intensity profiles sometimes show rather quick onsets after the solar event even if the measurements are made at a longitude generally considered to...
Traditionally, Galactic Cosmic Rays (GCR) models are used as a boundary condition input to the
deterministic or stochastic (e.g. Monte Carlo) based radiation transport codes with the goal of extracting
dosimetric quantities of interest such as dose, dose equivalent, effective dose, etc. at a desired target
point within the spacecraft. To compute the dosimetric quantities of interest, the...
The Fermi Large Area Telescope (LAT) observations of the active Sun provide the largest sample of detected solar flares with emission greater than 30 MeV to date. These include detections of impulsive and sustained emission, extending up to ~20 hours in the case of the 2012 March 7 X-class flares. These high-energy flares are coincident with GOES X-ray flares of X, M and C classes as well as...
Electron beams accelerated by solar flares and nanoflares are believed to be responsible for several types of solar radio bursts observed in the corona and interplanetary medium, including flare-associated coronal Type U and J and interplanetary Type III radio bursts, and nanoflare-associated weak coronal type III bursts. The characteristic of these radio bursts is their frequency is...
The South Pole is an ideal location for the detecting solar energetic particles because of its low geomagnetic cutoff and high altitude. Neutron Monitors have operated at the South Pole for many decades, and they are able to distinguish between Solar and Galactic cosmic ray variations. They are excellent devices for observing space weather. Physicists at the University of Wisconsin-River...
The level of solar modulation phi at different times (related to the solar activity) is a central question of solar and galactic cosmic-ray physics. We detail a procedure to obtain a reference time series from neutron monitor data. We obtain an unbiased and accurate reconstruction at a precision of 10%. Reconstructed time series from the 50's are compared to the previous time-series of Usoskin...
Neutron monitors (NMs) are the premier instruments for precisely tracking time variations in the Galactic cosmic ray (GCR) flux at the GV-range. The worldwide NM network has provided continuous measurements of the solar induced variations of the GCR flux impinging Earth and the data cover about six 11-year solar cycles. The recent rise of space exploration, with PAMELA and AMS-02 spacecraft,...
The Alpha Magnetic Spectrometer (AMS) was installed on the International Space Station in May 2011. During the first 5 years of operations, AMS observed several fast depletions of the galactic cosmic ray (GCR) flux followed by a recovery period. These phenomena are called Forbush decreases (FDs) and are temporary decreases in GCR flux due to heliospheric disturbances. Thanks to its large...
Little is known still about the origin of the high-energy and sustained emission from Long Duration Gamma-Ray Flares (LDGRFs), identified with Compton Gamma-Ray Observatory (CGRO), the Solar Maximum Mission (SMM), and now Fermi. Though Fermi/LAT has identified dozens of flares with LDGRF emission, the nature of this emission has been a challenge to explain both due to the extreme energies and...
The protons in large solar energetic particle events are accelerated in the inner heliosphere by fast shocks produced by coronal mass ejections. Unless there are other sources, the protons these shocks act upon would be the solar wind. The efficiency of the acceleration depends on the kinetic energy of the protons. For 1 - 2 thousand km/s shocks, the most effective proton energies would be 10...
Solar energetic particles (SEPs) with energies of about a few hundred MeV and above are not well studied. AMS was installed on the ISS on May 19, 2011, during the ascending phase of the solar cycle; it will take measurements until the end of ISS operations, covering solar cycle 24 and beyond. It is the largest experiment capable of studying these particles directly. In its first five years of...
In recent years, the increasing precision of direct cosmic rays measurements opened the door to high-sensitivity indirect searches of dark matter and to more accurate predictions for radiation doses received by astronauts and electronics in space. The key ingredients in the study of these phenomena are the knowledge of the local interstellar spectrum (LIS) of galactic cosmic rays and the...
