Identification of high energy solar particle signals on the Mexico City neutron monitor database (original) (raw)
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Modeling the solar cosmic ray event of 13 December 2006 using ground level neutron monitor data
Advances in Space Research, 2009
In order to understand the physics under extreme solar conditions such as those producing ground level enhancements of solar cosmic rays, it is important to use accurate and reliable models. The NM-BANGLE Model is a new cosmic ray model which couples primary solar cosmic rays at the top of the Earth's atmosphere with the secondary ones detected at ground level by neutron monitors during GLEs. This model calculates the evolution of several GLE parameters such as the solar cosmic ray spectrum, anisotropy and particle flux distribution, revealing crucial information on the energetic particle propagation and distribution. The total output of the NM-BANGLE Model is a multi-dimensional GLE picture that gives an important contribution to revealing the characteristics of solar energetic particle events recorded at ground level. In this work, the results of the NM-BANGLE Model application to the recent GLE of 13 December 2006 are presented and discussed. Moreover, a comparison with the extreme event of 20 January 2005 (GLE69) has been realized.
Detection of high-energy solar neutrons and protons by ground level detectors on April 15, 2001
Astroparticle Physics, 2008
In association with the large solar flare of April 15, 2001, the Chacaltaya neutron monitor observed a 3.6r enhancement of the counting rate between 13:51 and 14:15 UT. Since the enhancement was observed beginning 11 min before the GLE, solar neutrons must be involved in this enhancement. The integral energy spectrum of solar neutrons can be expressed by a simple power law in energy with the index c ¼ À3:0 AE 1:0. On the other hand, an integral energy spectrum of solar protons has been obtained in the energy range between 650 MeV and 12 GeV. The spectrum can also be expressed by a power law with the power index c ¼ À2:75 AE 0:15. The flux of solar protons observed at Chacaltaya (at P12 GeV) was already one order less than the flux of the galactic cosmic rays. It may be the first simultaneous observation of the energy spectra of both high-energy protons and neutrons. Comparing the Yohkoh soft X-ray telescope images with the observed particle time profiles, an interesting picture of the particle acceleration mechanism has been deduced.
27-DAY Variations of Solar Indices and Cosmic Ray Neutron Monitor Intensities
Astronomische Nachrichten, 2008
Solar activity indices (coronal, chromospheric as well as photospheric) and cosmic ray neutron monitor rates (different cut-off rigidity) have been used to study 27-day variations in the years from 1957 to 2004. Daily data were employed for this purpose, analysed by the FFT and wavelet techniques. To work with a continuous data set for the cosmic rays (CR), the 'Composite Cosmic Ray' (CCR) set was first created from the observations carried out at different neutron monitor stations. The CCR frequency analysis shows significant 27-day variations in the intensity of CR, with its amplitude's values very sensitive to the sign of the quantity qA. The most significant 27-day variations of CR were found not to correlate with those of other solar indices.
Modeling of the solar energetic particles recorded at Neutron Monitors
AIP Conference Proceedings, 2006
Last year the worldwide network of neutron monitors recorded a new ground level enhancement (GLE) of cosmic ray intensity (CR) on 20 th of January 2005, during the recovery phase of a series of Forbush effects taking place at a time-period very close to the minimum of the current cycle of solar activity. This enhancement seems to be the greatest GLE of the current solar cycle, reaching almost 5000% in some polar stations. A joint analysis of data from ground level stations (neutron monitors) and satellite measurements has been performed in order to calculate the amplitude and the anisotropy of the event as well as the energy of the more fast particles arriving at the Earth. A new GLE-model has been created in order to couple the primary solar cosmic ray flux on the top of the magnetosphere with the flux recorded by neutron monitors and define this way the primary solar cosmic ray spectrum during the event. Moreover, the absorption length of solar energetic particles propagating through the Earth's atmosphere has been calculated applying the Wilson et al. method (1967). These results have been compared with the respective results calculated for other ground level enhancements. Finally, a comparison between this enhancement and the big GLE of 1956 has been performed.
Galactic cosmic ray fluctuations during solar cycles 22 and 23 at high altitude neutron monitors
Advances in Space Research, 2001
Cosmic ray detectors installed at high magnetic cutoff rigidity and mountain elevation are only a few. It is therefore important to have reliable data for active monitors with these characteristics. The Mexico City 6-NM64 has been in continues operation since 1990. It is located at an altitude of 2274 m above sea level and has a vertical magnetic cutoff rigidity of 8.2 GV for the 1990 epoch (Shea and Smart, 1997). In this work we make a study of the cosmic ray intensity fluctuations observed in Mexico City and compare it with other mountain altitude neutron monitors of the american sector during the years 1990-1999. The period comprises the maximum and declining phase of solar cycle 22 and the beginning of cycle 23. Evolution of important variation periodicities compared with solar activity indicators are presented. We have also constructed a new solar activity index based on the measured hard x-rays flux.
Early Forecast of Radiation Hazardous Solar Cosmic Ray Fluxes on the Neutron Monitors Data
Possibility of the forecast of radiation-hazardous solar cosmic ray fluxes with energies in tens-hundreds MeV according to the neutron monitors located on a ground surface is discussed. Neutron monitors register the relativistic SCR (energies from 0.5 to a several GeV) with the minimal delay, however in a high-energy region intensity SCR is small and does not represent serious radiation hazard. At the same time, having spotted a spectrum a SCR in a high-energy region it is possible to give the forecast of radiation-hazardous fluxes of particles of moderate energies with advance time till several hours. However this forecast is possible only by data from so-called «delayed component» of relativistic cosmic rays.
Unexpected burst of solar activity recorded by neutron monitors during October–November 2003
Advances in Space Research, 2005
During the extreme burst of solar activity in October-November 2003, a series of outstanding events distinguished by their magnitude and peculiarities were recorded by the ground based neutron monitor network. The biggest and most productive in 23rd solar cycle active region 486 generated the most significant series of solar flares among of which the flare X28/3B on November 4, 2003 was the mostly powerful over the history of X-ray solar observations. The fastest arrival of the interplanetary disturbance from the Sun after the flare event in August 1972 and the highest solar wind velocity and IMF intensity were observed during these events. In one-week period three ground level enhancements (GLEs) of solar cosmic rays were recorded by neutron monitor network (28, 29 October and 2 November 2003). Maximum proton energy in these events seems to be ranged from 5 to 10 GeV. Joint analysis of data from ground level stations (neutron monitors) and satellite measurements allows the estimation of the particle path length, the onset time of the injection on the Sun and some other proton flux characteristics.
Earth, Planets and Space, 2014
We plan to observe solar neutrons at Mt. Sierra Negra (4,600 m above sea level) in Mexico using the SciBar detector. This project is named the SciBar Cosmic Ray Telescope (SciCRT). The main aims of the SciCRT project are to observe solar neutrons to study the mechanism of ion acceleration on the surface of the sun and to monitor the anisotropy of galactic cosmic-ray muons. The SciBar detector, a fully active tracker, is composed of 14,848 scintillator bars, whose dimension is 300 cm × 2.5 cm × 1.3 cm. The structure of the detector enables us to obtain the particle trajectory and its total deposited energy. This information is useful for the energy reconstruction of primary neutrons and particle identification. The total volume of the detector is 3.0 m × 3.0 m × 1.7 m. Since this volume is much larger than the solar neutron telescope (SNT) in Mexico, the detection efficiency of the SciCRT for neutrons is highly enhanced. We performed the calibration of the SciCRT at Instituto Nacional de Astrofisica, Optica y Electronica (INAOE) located at 2,150 m above sea level in Mexico in 2012. We installed the SciCRT at Mt. Sierra Negra in April 2013 and calibrated this detector in May and August 2013. We started continuous observation in March 2014. In this paper, we report the detector performance as a solar neutron telescope and the current status of the SciCRT.
Astrophysics and Space Sciences Transactions, 2011
The Standard Radiation Environment Monitor (SREM) is a particle detector developed by the European Space Agency for satellite applications with the main purpose to provide radiation hazard alarms to the host spacecraft. SREM units have been constructed within a radiation hardening concept and therefore are able to register extreme solar particle events (SPEs). Large SPEs are registered at Earth, by ground based detectors as neutron monitors, in the form of Ground Level Enhancements of solar cosmic rays. In this work, a feasibility study of a possible radiation alert, deduced by SREM measurements was implemented for the event of 20 January 2005. Taking advantage of the neutron monitor's experience, the steps of the GLE alert algorithm were put into practice on SREM measurements. The outcome was that SREM units did register the outgoing SPE on-time and that these could serve as indicators of radiation hazards, leading to successful alerts.