scholarly journals SEP spectra derived from neutron monitor data and from EPHIN space detector data during recent GLEs and sub-GLEs

2021 ◽  
pp. 89-95
Author(s):  
Rolf Bütikofer ◽  
Patrick Kühl ◽  
Athanasios Papaioannou
Keyword(s):  
Neutron Monitor ◽  
Count Rate ◽  
Rate Increase ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
Heliospheric Observatory ◽  
Proton Intensity ◽  
Worldwide Network ◽  
Monitor Data ◽  
Modelling Approach

The Electron Proton Helium Instrument (EPHIN) aboard the Solar Heliospheric Observatory (SOHO) observed several SEP events with protons accelerated to energies E>500 MeV, whereas no neutron monitor (NM) of the worldwide network showed a significant increase in their counting rate. For instance, the SEP event on 8 November 2000 with maximum proton intensity at 500 MeV of >0.1 (cm2 s sr MeV)-1 is outstanding, as this maximum pro-ton flux is comparable with the GLEs on 14 July 2000 and on 15 April 2001 (max. count rate increase in 5-min data of 225% at South Pole NM). In a first step we applied a forward modelling approach of the SEP event on 8 November 2000, i.e. we computed the expected NM count rate increases for selected NM stations, utilizing as input para-meters the SEP spectra determined from EPHIN data as well as anticipated pitch angle distribution and apparent source direction. The simulated count rate increases for selected NM stations showed that this SEP event should have be seen as a clear GLE. To further understand this situation, we investigated in a next step recent GLEs and sub-GLEs. Consequently, a total of four SEP events were selected, two clearly identified GLEs and two sub-GLEs. We performed a “GLE analysis” based on the data of the worldwide network of NMs for each of the four SEP events and then compared the derived SEP spectra with the proton spectra as determined from EPHIN measurements.

scholarly journals Method of automatic correction of neutron monitor data for precipitation in the form of snow in real time

2021 ◽  
Vol 7 (3) ◽  
pp. 120-126
Author(s):  
Valery Yanchukovsky ◽  
Vasiliy Kuz'menko
Keyword(s):  
Snow Cover ◽  
Real Time ◽  
Neutron Monitor ◽  
Count Rate ◽  
Continuous Monitoring ◽  
Laser Rangefinder ◽  
Flux Intensity ◽  
Time Correction ◽  
Neutron Monitor Data ◽  
Monitor Data

We have carried out an experimental study of the influence of precipitation in the form of snow on measurements of the neutron flux intensity near Earth's surface. We have examined the state of the snow cover and its density, and found out that the density depends on the depth of the snow cover. Using the experimental results, we estimate the neutron absorption path in the snow. Changes in snow cover by 10–12 cm at a depth of 80 cm are shown to cause variations in the monitor count rate with an amplitude of 0.9 %. At the snow depth of 80 cm, the neutron monitor count rate decreases by about 8 %. The observed variations should be attributed to the meteorological effects of cosmic rays. The absorption coefficient of neutrons in the snow was also found from the correlation between the count rate of the neutron monitor and the amount of snow above the detector. We propose a real-time correction of the neutron monitor data for precipitation in the form of snow. For this purpose, we implement continuous monitoring of the amount of snow cover. The monitoring is provided by a snow meter made using a laser rangefinder module. We discuss the results obtained.

scholarly journals GLE # 67 Event on 2 November 2003: An Analysis of the Spectral and Anisotropy Characteristics Using Verified Yield Function and Detrended Neutron Monitor Data

Solar Physics ◽  
2021 ◽  
Vol 296 (5) ◽  
Author(s):  
Alexander L. Mishev ◽  
Sergey A. Koldobskiy ◽  
Leon G. Kocharov ◽  
Ilya G. Usoskin
Keyword(s):  
Neutron Monitor ◽  
Dynamical Evolution ◽  
Ground Level ◽  
High Energy ◽  
Yield Function ◽  
Angle Distribution ◽  
Ground Level Enhancement ◽  
Solar Particles ◽  
Monitor Data

AbstractDuring Solar Cycle 23 16 ground-level enhancement events were registered by the global neutron monitor network. In this work we focus on the period with increased solar activity during late October – early November 2003 producing a sequence of three events, specifically on ground-level enhancement GLE 67 on 2 November 2003. On the basis of an analysis of neutron monitor and space-borne data we derived the spectra and pitch-angle distribution of high-energy solar particles with their dynamical evolution throughout the event. According to our analysis, the best fit of the spectral and angular properties of solar particles was obtained by a modified power-law rigidity spectrum and a double Gaussian, respectively. The derived angular distribution is consistent with the observations where an early count rate increase at Oulu neutron monitor with asymptotic viewing direction in the anti-Sun direction was registered. The quality of the fit and model constraints were assessed by a forward modeling. The event integrated particle fluence was derived using two different methods. The derived results are briefly discussed.

scholarly journals Method of automatic correction of neutron monitor data for precipitation in the form of snow in real time

2021 ◽  
Vol 7 (3) ◽  
pp. 114-120
Author(s):  
Valery Yanchukovsky ◽  
Vasiliy Kuz'menko
Keyword(s):  
Snow Cover ◽  
Real Time ◽  
Neutron Monitor ◽  
Count Rate ◽  
Continuous Monitoring ◽  
Laser Rangefinder ◽  
Flux Intensity ◽  
Time Correction ◽  
Neutron Monitor Data ◽  
Monitor Data

We have carried out an experimental study of the influence of precipitation in the form of snow on measurements of the neutron flux intensity near Earth's surface. We have examined the state of the snow cover and its density, and found out that the density depends on the depth of the snow cover. Using the experimental results, we estimate the neutron absorption path in the snow. Changes in snow cover by 10–12 cm at a depth of 80 cm are shown to cause variations in the monitor count rate with an amplitude of 0.9 %. At the snow depth of 80 cm, the neutron monitor count rate decreases by about 8 %. The observed variations should be attributed to the meteorological effects of cosmic rays. The absorption coefficient of neutrons in the snow was also found from the correlation between the count rate of the neutron monitor and the amount of snow above the detector. We propose a real-time correction of the neutron monitor data for precipitation in the form of snow. For this purpose, we implement continuous monitoring of the amount of snow cover. The monitoring is provided by a snow meter made using a laser rangefinder module. We discuss the results obtained.

Early Observations from the Solar Orbiter SWA/Electron Analyser System

2021 ◽  
Author(s):  
Christopher Owen ◽  
Keyword(s):  
Solar Wind ◽  
Field Vector ◽  
Field Of View ◽  
High Time Resolution ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
Burst Mode ◽  
Steering Mechanism ◽  
Operational Issues ◽  
Electrostatic Analyser

<p>Solar Orbiter carries a total of 10 instrument suites making up the payload for the mission.  One of these, the Solar Wind Analyser (SWA) instrument, is comprised of 3 sensor units which are together served by a central DPU unit.  Of particular focus in this presentation are the early measurements from one of these sensors, the Electron Analyser System (EAS).  EAS is a dual-head, top-hat electrostatic analyser system that is capable of making 3D measurements of solar wind electrons at energies below ~5 keV from a vantage point at the end of a 4-metre boom extending into the shadow of the spacecraft.  The sensor was accommodated in this location to both maximise the unobstructed field of view and to minimise the effect of spacecraft related disturbances on the low-energy (less than a few tens of eV) electrons expected the core population of the solar wind.</p><p>To date the SWA instrument sensors have operated sporadically during the mission cruise phase, which began in June 2020.  This is due to a number of operational issues faced by the SWA team, which mean we have not been able to take data in a continuous manner.  However, the data that has been taken shows the clear promise of the SWA measurements, in general, once these issues can be overcome.  For example, EAS is using a novel sample steering mechanism in burst mode which, with reference to a magnetic field vector shared onboard by the MAG instrument, allows the capture of the electron pitch angle distribution at unusually high time resolution.  We discuss these observations here, and illustrate the potential science returns from the burst mode.  We also present results from the new EAS observations in the vicinity of reconnecting current sheets in the solar wind, to more generally illustrate the capability of the sensor. </p>

scholarly journals Multitaper spectral analysis of cosmic rays São Martinho da Serra's muon telescope and Newark's neutron monitor data

2007 ◽  
Vol 25 ◽  
pp. 163-167 ◽  
Author(s):  
Marlos Rockenbach da Silva ◽  
Walter Demetrio Gonzalez Alarcon ◽  
Ezequiel Echer ◽  
Alisson Dal Lago ◽  
Luis Eduardo Antunes Vieira ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Cosmic Rays ◽  
Neutron Monitor ◽  
Muon Telescope ◽  
Neutron Monitor Data ◽  
Monitor Data

scholarly journals Observing the neutron component during thunderstorm activity at a mountain CR station

2019 ◽  
Vol 5 (3) ◽  
pp. 54-58
Author(s):  
Анна Луковникова ◽  
Anna Lukovnikova ◽  
Виктор Алешков ◽  
Viktor Aleshkov ◽  
Алексей Лысак ◽  
...  
Keyword(s):  
Field Strength ◽  
Sea Level ◽  
Neutron Monitor ◽  
Electromagnetic Interference ◽  
Count Rate ◽  
Cosmic Ray ◽  
Thunderstorm Activity ◽  
Signal Discrimination ◽  
Lightning Discharges ◽  
Neutron Component

During three summer months in 2015, the Cosmic Ray (CR) station Irkutsk-3000, located at 3000 m above sea level, measured the CR neutron component intensity with the 6NM64 neutron monitor, as well as the atmospheric electric field strength and the level of electromagnetic interference during lightning discharges. It is shown that the level of electromagnetic interference, when registered during lightning discharges, depends considerably on the fixed level of signal discrimination. During observations, we observed no effects of thunderstorm discharges at the neutron monitor count rate at the CR station Irkutsk-3000.

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