Browsing by Autor "S. Masuda"

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Detection of high-energy solar neutrons and protons by ground level detectors on April 15, 2001
(Elsevier BV, 2008) Y. Muraki; Y. Matsubara; S. Masuda; S. Sakakibara; T. Sako; K. Watanabe; R. Bütikofer; E. O. Flückiger; A. Chilingarian; G. Hovsepyan
Detection of Solar Neutrons and Solar Neutron Decay Protons
(2023) Y. Muraki; Tatsumi Koi; Y. Matsubara; S. Masuda; Pedro Miranda; Shoko Miyake; T. Naito; Ernesto Ortiz Fragoso; A. Oshima; T. Sako
Solar flares are broadly classified as impulsive or gradual. Ions accelerated in a gradual flare are thought to be accelerated through a shock acceleration mechanism, but the particle acceleration process in an impulsive flare is still largely unexplored. To understand the acceleration process, it is necessary to measure the high-energy gamma-rays and neutrons produced by the impulsive flare. Under such circumstances, on November 7, 2004, a huge X2.0 flare occurred on the solar surface, where ions were accelerated to energies greater than 10 GeV. The accelerated primary protons collided with the solar atmosphere and produced line gamma-rays and neutrons. These particles were received as neutrons and line gamma-rays, respectively. Neutrons of a few GeV, on the other hand, decay to produce secondary protons while traveling 0.06 au in the solar-terrestrial space. These secondary protons arrived at the magnetopause. Although the flux of secondary protons is very low, the effect of collecting secondary protons arriving in a wide region of the magnetosphere (the Funnel or Horn effect) has resulted in significant signals being received by the solar neutron telescope at Mt. Sierra Negra (4,600 m). This information suggests that ions on the solar surface are accelerated to over 10 GeV with an impulsive flare.
Detection of Solar Neutrons and Solar Neutron Decay Protons
(Multidisciplinary Digital Publishing Institute, 2023) Y. Muraki; Tatsumi Koi; S. Masuda; Y. Matsubara; Pedro Miranda; Shoko Miyake; T. Naito; E. Ortiz; A. Oshima; T. Sako
Solar flares are broadly classified as impulsive or gradual. Ions accelerated in a gradual flare are thought to be accelerated through a shock acceleration mechanism, but the particle acceleration process in an impulsive flare is still largely unexplored. To understand the acceleration process, it is necessary to measure the high-energy gamma rays and neutrons produced by the impulsive flare. Under such circumstances, on 7 November 2004, a huge X2.0 flare occurred on the solar surface, where ions were accelerated to energies greater than 10 GeV. The accelerated primary protons collided with the solar atmosphere and produced line gamma rays and neutrons. These particles were received as neutrons and line gamma rays, respectively. Neutrons of a few GeV, on the other hand, decay to produce secondary protons while traveling 0.06 au in the solar–terrestrial space. These secondary protons arrive at the magnetopause. Although the flux of secondary protons is very low, the effect of collecting secondary protons arriving in a wide region of the magnetosphere (the Funnel or Horn effect) has resulted in significant signals being received by the solar neutron telescope at Mt. Sierra Negra (4600 m). This information suggests that ions on the solar surface are accelerated to over 10 GeV with an impulsive flare.
Proton penetration efficiency over a high altitude observatory in Mexico
(SciPost.org, 2023) Shoko Miyake; T. Koi; Y. Muraki; Y. Matsubara; S. Masuda; P. Miranda; T. Naito; E. Ortiz; A. Oshima; T. Sakai
In association with a large solar flare on November 7, 2004, the solar neutron detectors located at Mt. Chacaltaya (5,250 m) in Bolivia and Mt. Sierra Negra (4,600 m) in Mexico recorded very interesting events. In order to explain these events, we have performed a calculation solving the equation of motion of anti-protons inside the magnetosphere. Based on these results, the Mt. Chacaltaya event may be explained by the detection of solar neutrons, while the Mt. Sierra Negra event may be explained by the first detection of very high energy solar neutron decay protons (SNDPs) around 6 GeV.
Proton Penetration Efficiency over Sierra Negra (Mexico) and Oulu (Finland)
(2023) Y. Muraki; Shoko Miyake; T. Koi; Y. Matsubara; S. Masuda; P. Miranda; T. Naito; E. Ortiz; A. Oshima; T. Sako
On November 7, 2004, a large solar flare was observed, which had a notable impact on the solar neutron detectors located at Mt. Chacaltaya (5,250 m) in Bolivia and Mt. Sierra Negra (4,600 m) in Mexico. In addition, the neutron monitor at Oulu, Finland, recorded a 5-sigma enhancement. In order to determine the causes of these enhancements, we performed trajectory simulations ejecting anti-protons from 20 km above each location, and checked whether or not these anti-protons could reach the magnetopause (∼8𝑅E). Then, we understand that the Chacaltaya enhancement was caused by solar neutrons themselves, while the Mt. Sierra Negra event may have been produced by high-energy solar neutron decay protons (SNDPs) with energies ≥ 6 GeV. Based on our anti- proton trajectory analysis, we suggest that the enhancement at Oulu may also have been produced by solar neutron decay protons with energies around ≥ 200 MeV. During this flare, protons were accelerated up to 10 GeV within one minute, leading to the production of SNDPs.
Report on scipost_202207_00031v1
(2022) Shoko Miyake; T. Koi; Y. Muraki; Y. Matsubara; S. Masuda; Pedro Miranda; T. Naito; E. Ortiz; A. Oshima; T. Sakai
In association with a large solar flare on November 7, 2004, the solar neutron detectors located at Mt. Chacaltaya (5,250 m) in Bolivia and Mt.Sierra Negra (4,600 m) in Mexico recorded very interesting events.In order to explain these events, we have performed a calculation solving the equation of motion of anti-protons inside the magnetosphere.Based on these results, the Mt.Chacaltaya event may be explained by the detection of solar neutrons, while the Mt.Sierra Negra event may be explained by the first detection of very high energy solar neutron decay protons (SNDPs) around 6 GeV.
Simultaneous Observation of Solar Neutrons from the International Space Station and High Mountain Observatories in Association with a Flare on July 8, 2014
(Springer Science+Business Media, 2016) Y. Muraki; D. Lopez; K. Koga; F. Kakimoto; T. Goka; L. X. González; S. Masuda; Y. Matsubara; H. Matsumoto; P. Miranda
Solar Neutron Decay Protons Observed in November 7, 2004
(2021) Y. Muraki; Jose F. Valdés Galicia; E. Ortiz; Y. Matsubara; S. Shibata; T. Sako; S. Masuda; Shoko Miyake; M. Tokumaru; Tatsumi Koi
We have found an interesting event registered by the solar neutron telescopes installed at high mountains in Bolivia (5250 m a.s.l.) and Mexico (4600 m a.s.l.). The event was observed on November 7th of 2004 in association with a large solar flare of magnitude X2.0. Some features in the registers reveal the presence of solar neutrons, but also possible solar neutron decay protons (SNDP). SNDPs were recorded on board ISEE3 satellite in June 3rd, 1982 . On October 19th, 1989, the ground level detectors installed in Goose Bay and Deep River revealed the registration of SNDPs. Therefore this is the second example that such an evidence is registered on the Earth’s surface.
Solar Neutron Event in Association with a Large Solar Flare on 2000 November 24
(IOP Publishing, 2003) K. Watanabe; Y. Muraki; Y. Matsubara; Kazuaki Murakami; T. Sako; H. Tsuchiya; S. Masuda; M. Yoshimori; N. Ohmori; P. Miranda
Solar neutrons have been detected using the neutron monitor located at Mt. Chacaltaya, Bolivia, in association with a large solar flare on November 24, 2000. This is the first detection of solar neutrons by the neutron monitor that have been reported so far in solar cycle 23. The statistical significance of the detection is 5.5 sigma. In this flare, the intense emission of hard X-rays and gamma-rays has been observed by the Yohkoh Hard X-ray Telescope (HXT) and Gamma Ray Spectrometer (GRS), respectively. The production time of solar neutrons is better correlated with those of hard X-rays and gamma-rays than with the production time of soft X-rays. The observations of the solar neutrons on the ground have been limited to solar flares with soft X-ray class greater than X8 in former solar cycles. In this cycle, however, neutrons were detected associated with an X2.3 solar flare on November 24, 2000. This is the first report of the detection of solar neutrons on the ground associated with a solar flare with its X-ray class smaller than X8.