Energetic particle experiment ERNE

Torsti, J.; Валтонен, Э.; Lumme, M.; Peltonen, P.; Eronen, T.; Louhola, M.; Riihonen, E.; Schultz, G.; Teittinen, M.; Ahola, Kimmo; Holmlund, Christer; Kelh�, V.; Lepp�l�, K.; Ruuska, Pekka; Str�mmer, E.

doi:10.1007/bf00733438

Cited by 176 publications

(107 citation statements)

References 7 publications

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“…In the case of the Apr00 event we have reproduced the 0.59-80 MeV proton differential intensity-time profiles measured by ACE/EPAM, 0.59-1.90 MeV (Gold et al 1998) and SOHO/ERNE, 1.8-80 MeV protons (Torsti et al 1995), summing up a total number of n p = 19 energy channels. In the case of the Dec06 event, we have used n p = 25 channels, reproducing the 0.3-500 MeV proton differential intensities measured from various instruments: 0.58-1.90 MeV from ACE/EPAM, 1.8-13 MeV from SOHO/ERNE, 14-100 MeV STEREOA/IMPACT/HET (von Rosenvinge et al 2008) and 80-500 MeV GOES/EPS (Sauer 1993).…”

Section: The Injection Rate Of Escaping Protonsmentioning

confidence: 93%

“…For a detailed analysis of the solar origin and the interplanetary conditions during this SEP event we refer to Rodriguez et al (2009). The proton differential intensity enhancements extend only up to 80 MeV protons as measured by the SOHO/ERNE experiment (Torsti et al 1995). On the other hand, the 2006 December 13 SEP event happened close to the minimum phase of Solar Cycle 23 and it was the last event of the cycle to produce a Ground Level Event (GLE; e.g., Storini et al 2008).…”

Section: Overviews Of the Eventsmentioning

confidence: 99%

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Modelling large solar proton events with the shock-and-particle model

Pomoell

Aran

Jacobs

et al. 2015

J. Space Weather Space Clim.

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We have developed a new version of a model that combines a two-dimensional Sun-to-Earth magnetohydrodynamic (MHD) simulation of the propagation of a CME-driven shock and a simulation of the transport of particles along the interplanetary magnetic field (IMF) line connecting the shock front and the observer. We assume that the shock-accelerated particles are injected at the point along the shock front that intersects this IMF line, i.e. at the cobpoint. Novel features of the model are an improved solar wind model and an enhanced fully automated algorithm to extract the necessary plasma characteristics from the shock simulation. In this work, the new algorithms have been employed to simulate the 2000 April 4 and the 2006 December 13 SEP events. In addition to quantifying the performance of the new model with respect to results obtained using previous versions of the shock-and-particle model, we investigate the semi-empirical relation between the injection rate of shock-accelerated particles, Q, and the jump in speed across the shock, VR, known as the Q(VR) relation. Our results show that while the magnetic field and density compression at the shock front is markedly different than in our previous modeling, the evolution of VR remains largely similar. As a result, we confirm that a simple relation can still be established between Q and VR, which enables the computation of synthetic intensity-time profiles at any location in interplanetary space. Furthermore, the new shock extraction tool is found to yield improved results being in general more robust. These results are important not only with regard to efforts to develop coupled magnetohydrodynamic and particle simulation models, but also to improve space weather related software tools that aim to predict the peak intensities, fluences and proton intensity-time profiles of SEP events (such as the SOLPENCO tool).

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Section: The Injection Rate Of Escaping Protonsmentioning

confidence: 93%

Section: Overviews Of the Eventsmentioning

confidence: 99%

Modelling large solar proton events with the shock-and-particle model

Pomoell

Aran

Jacobs

et al. 2015

J. Space Weather Space Clim.

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“…8.3 are associated with SEP events observed at 1 AU from the Sun, by instruments at L1 or by the twin STEREO spacecraft, or both. Proton and/or electron enhancements are observed with SoHO/ERNE (Torsti et al 1995), STEREO/LET (Mewaldt et al 2008), STEREO/HET (von Rosenvinge et al 2008), STEREO/SEPT (Müller-Mellin et al 2008), and ACE/EPAM (Gold et al 1998) over a wide range of energy (55 keV to 4 MeV for electrons and 1.6 to 130 MeV for protons). Higher energy protons are available from SoHO/EPHIN (penetrating protons at 100-1000 MeV energies) as well as from GOES/HEPAD (only for 9 of the 25 investigated Fermi/LAT events, see Fig.…”

Section: Solar Energetic Particle Events Associated With Fermi/lat Gamentioning

confidence: 99%

X-Ray, Radio and SEP Observations of Relativistic Gamma-Ray Events

Klein¹,

Tziotziou²,

Zucca³

et al. 2017

Astrophysics and Space Science Library

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The rather frequent occurrence, and sometimes long duration, ofray events at photon energies above 100 MeV challenges our understanding of particle acceleration processes at the Sun. The emission is ascribed to pion-decay photons due to protons with energies above 300 MeV. We study the X-ray and radio emissions and the solar energetic particles (SEPs) in space for a set of 25 Fermi -ray events. They are accompanied by strong SEP events, including, in most cases where the parent activity is well-connected, protons above 300 MeV. Signatures of energetic electron acceleration in the corona accompany the impulsive and early post-impulsive -ray emission. -ray emission lasting several hours accompanies in general the decay phase of long-lasting soft X-ray bursts and decametric-tokilometric type II bursts. We discuss the impact of these results on the origin of the -ray events. IntroductionThe advent of the Fermi mission showed that the Sun is an occasional, but unexpectedly frequent, emitter of -ray photons above 100 MeV. These are understood to be produced by pion decays in nuclear interactions involving protons or He-nuclei at energies above 300 MeV/nucleon. One did not expect that the Sun was able to accelerate relativistic protons and nuclei even in seemingly modest flares. These particles are rarely detected in space (<1 event per year). Furthermore, the duration, several hours, of some -ray events is much longer than that of hard X-ray signatures of electron acceleration in the impulsive flare phase.The question of how the -ray emission is related to other signatures of particle acceleration and energy release in the corona is crucial to understanding the origin of the high-energy protons. It might also be expected that such high-energy populations interacting at the Sun are accompanied by particularly energetic solar energetic particle (SEP) events. This chapter is based on 25 events. The Fermi/LAT temporal data were made available to the HESPERIA project by G. Share prior to their publication in a comprehensive paper ). The present chapter introduces the relevant process of emission and pre-Fermi observations of piondecay -rays (Sect. 8.2), and gives an overview of the Fermi/LAT observations (Sect. 8.3). Section 8.3 was prepared by Gerald Share and Ron Murphy. Related X-ray and radio observations and associated SEP events are presented in Sects. 8.4 and 8.5, respectively. Preliminary conclusions on the interpretation of the -ray events are in Sect. 8.6. Theory and Early Observations of Gamma-Ray Emission at Photon Energies >60 MeVOn 1982 Jun 3 the gamma-ray spectrometer on the Solar Maximum Mission satellite observed emission from 0.3 to 100 MeV from a X8.0 GOES-class flare (Forrest et al. 1986). The impulsive flare lasted about 1 min and was followed by a distinct harder emission phase that peaked in about 1 min and lasted for over 15 min. The energy spectrum of this sustained emission displayed a characteristic hump at photon energies above 60 MeV (Fig. 8.1a), which appeared to be consistent with th...

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“…We have extended the period of interest to cover the years 2011-2016 and also revisited the proton velocity dispersion analysis (VDA), electron event onset times, as well as electromagnetic (soft X-ray) and CME observations for the events listed in Vainio et al (2013). Based on data from the Energetic and Relativistic Nuclei and Electron (ERNE) experiment (Torsti et al 1995), the Large Angle and Spectrometric Coronagraph (LASCO; Brueckner et al 1995), and the Electron Proton Helium Instrument (EPHIN; Müller-Mellin et al 1995) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft, as well as the Electron, Proton and Alpha Monitor (EPAM; Gold et al 1998) aboard the Advanced Composition Explorer (ACE) and the X-ray flux measuring instrumentation on the Geostationary Operational Environmental Satellites (GOES) in active operation during the period of interest, our catalogue comprises a total of 176 energetic solar particle events between 1996 and 2016. This time span covers solar cycle 23 in its entirety and more than the first half of solar cycle 24, which allows us to gain some insight into the differences of these two cycles.…”

Section: Introductionmentioning

confidence: 99%

Catalogue of 55–80 MeV solar proton events extending through solar cycles 23 and 24

Paassilta

Raukunen

Vainio

et al. 2017

J. Space Weather Space Clim.

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We present a new catalogue of solar energetic particle events near the Earth, covering solar cycle 23 and the majority of solar cycle 24 (1996-2016), based on the 55-80 MeV proton intensity data gathered by the Solar and Heliospheric Observatory/the Energetic and Relativistic Nuclei and Electron experiment (SOHO/ERNE). In addition to ERNE proton and heavy ion observations, data from the Advanced Composition Explorer/Electron, Proton and Alpha Monitor (ACE/EPAM) (near-relativistic electrons), SOHO/EPHIN (Electron Proton Helium Instrument) (relativistic electrons), SOHO/LASCO (Large Angle and Spectrometric Coronagraph) (coronal mass ejections, CMEs) and Geostationary Operational Environmental Satellite (GOES) soft X-ray experiments are also considered and the associations between the particle and CME/X-ray events deduced to obtain a better understanding of each event. A total of 176 solar energetic particle (SEP) events have been identified as having occurred during the time period of interest; their onset and solar release times have been estimated using both velocity dispersion analysis (VDA) and time-shifting analysis (TSA) for protons, as well as TSA for near-relativistic electrons. Additionally, a brief statistical analysis was performed on the VDA and TSA results, as well as the X-rays and CMEs associated with the proton/electron events, both to test the viability of the VDA and to investigate possible differences between the two solar cycles. We find, in confirmation of a number of previous studies, that VDA results for protons that yield an apparent path length of 1 AU < s [ 3 AU seem to be useful, but those outside this range are probably unreliable, as evidenced by the anticorrelation between apparent path length and release time estimated from the X-ray activity. It also appears that even the first-arriving energetic protons apparently undergo significant pitch angle scattering in the interplanetary medium, with the resulting apparent path length being on average about twice the length of the spiral magnetic field. The analysis indicates an increase in high-energy SEP events originating from the far-eastern solar hemisphere; for instance, such an event with a well-established associated GOES flare has so far occurred three times during cycle 24 but possibly not at all during cycle 23. The generally lower level of solar activity during cycle 24, as opposed to cycle 23, has probably caused a significant decrease in total ambient pressure in the interplanetary space, leading to a larger proportion of SEP-associated halo-type CMEs. Taken together, these observations point to a qualitative difference between the two solar cycles.

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Energetic particle experiment ERNE

Cited by 176 publications

References 7 publications

Modelling large solar proton events with the shock-and-particle model

Modelling large solar proton events with the shock-and-particle model

X-Ray, Radio and SEP Observations of Relativistic Gamma-Ray Events

Catalogue of 55–80 MeV solar proton events extending through solar cycles 23 and 24

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