Diego Lopez

Performance of the SciBar cosmic ray telescope (SciCRT) toward the detection of high-energy solar neutrons in solar cycle 24

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.

Search for solar neutrons at Mount Chacaltaya associated with M- and X-class flares during the rising period of solar cycle 24

To better understand the acceleration mechanism of high-energy particles that are driven by solar flares, we examined solar neutron signals. We have performed a statistical analysis by reviewing the data collected by a neutron monitor during the period of January 2010 to August 2013. This detector operates at Mount Chacaltaya in Bolivia at 5,200 m above sea level. Our aim is to search for solar neutron events in association with large solar flares observed by the GOES satellite. We report that our analysis did not yield any positive excess due to solar neutrons that are statistically significant. Hence, we calculated the upper limit of the number of solar neutrons for the X2.8-class solar flare which occurred on 13 May 2013. We performed a similar calculation with a solar neutron event that occurred on 7 September 2005. Our upper limit is seven times less than the one produced by the real signal.

Upgrade of a data acquisition system for SciBar Cosmic Ray Telescope (SciCRT) at Mt. Sierra Negra, Mexico

Yoshinori Sasai∗,a Tetsuya Kawabata,a Masahiro Ikeno,b Tomohisa Uchida,b Manobu Tanaka,b Yutaka Matsubara,a Yoshitaka Itow,a Takashi Sako,a Diego Lopez,a Rikiya Hikimochi,a Kazuoki Munakata,c Chihiro Kato,c Masayoshi Kozai,c Takaaki Nakajima,c Yoshiaki Nakamura,c Shoichi Shibata,d Akitoshi Oshima,d Hisanori Takamaru,d Hiroshi Kojima,e Harufumi Tsuchiya, f Kyoko Watanabe,g Tatsumi Koi,h J.F.Valdés-Galicia,i Ernesto Ortiz,i Octavio Musalem,i Alejandro Hurtado,i Rocio Garcia,i Marcos Anzorena,i Roberto Taylor,i Marco Barrantes,i and L.X.González, j

Search for solar neutrons during the maximum activity of solar cycle 24

During the second period of maximum solar activity (October 2013 through October 2014) of the current solar cycle we have searched for solar neutron events. When a solar flare occurs, ions are sometimes accelerated. Those ions interact with the solar atmosphere and produce solar neutrons. We examined recent data from six stations of the International Network of Solar Neutron Telescopes (Gornergrat, Switzerland; Mauna Kea, USA; Mt. Chacaltaya, Bolivia; Mt. Norikura, Japan; Mt. Sierra Negra, Mexico and Yangbajing, China). We report that no statistically significant solar neutron event associated to a solar flare has been found. Therefore, we calculated the upper limit of the neutron fluxes at the Sun based on a statistical analysis and considering impulsive emission. We report that our upper limits are consistent with the successful detections of solar neutrons made in solar cycle 23.