@article{eec392797d074709a6ac4588fb5ef0ea,
title = "Observation of GeV solar energetic particles from the 1997 November 6 event using Milagrito",
abstract = "Milagrito was an extensive air-shower observatory that served as a prototype for the larger Milagro instrument. Milagrito operated from 1997 February to 1998 May. Although it was designed as a very high energy (few hundred GeV threshold) water-Cerenkov gamma-ray observatory, it could also be used to study solar energetic particles (SEPs). By recording sealer data, which correspond to photomultiplier tube singles rates, it was sensitive to muons and small showers from hadronic primary particles with rigidities above ∼4 GV. Milagrito simultaneously recorded air-shower trigger data of primary particles with energies greater than ∼100 GeV that provide the data to help reconstruct event directions. The Milagrito sealers registered a ground-level enhancement associated with the 1997 November 6 SEP event and X9 solar flare. At its peak, the enhancement was 22 times the background rms fluctuations. Based on comparisons to neutron monitor and satellite data, we find evidence that the rigidity power-law spectrum for the differential flux of energetic protons steepened above ∼4 GV and that the acceleration site was high in the corona (at ∼3 R⊙ above the photosphere), assuming that a CME-driven shock was responsible for the ground-level enhancement.",
keywords = "Acceleration of particles, Interplanetary medium, Sun: flares, Sun: particle emission",
author = "A. Falcone and R. Atkins and W. Benbow and D. Berley and Chen, {M. L.} and Coyne, {D. G.} and Dingus, {B. L.} and Dorfan, {D. E.} and Ellsworth, {R. W.} and L. Fleysher and R. Fleysher and G. Gisler and Goodman, {J. A.} and Haines, {T. J.} and Huffman, {C. M.} and S. Hugenberger and Kelley, {L. A.} and I. Leonor and McCullough, {J. F.} and McEnery, {J. E.} and Miller, {R. S.} and Mincer, {A. I.} and Morales, {M. F.} and P. Nemethy and Ryan, {J. M.} and B. Shen and A. Shoup and G. Sinnis and Smith, {A. J.} and Sullivan, {G. W.} and T. Tumer and K. Wang and Wascko, {M. O.} and S. Westerhoff and Williams, {D. A.} and T. Yang and Yodh, {G. B.}",
note = "Funding Information: Acknowledgements We express our gratitude to the skipper of {\textquoteleft}{\textquoteleft}Na Marinada{\textquoteright}{\textquoteright}, J. Llambrich, as well as to the rest of its crew, for their help on board and the provision of valuable data. The skippers A. Cruelles ({\textquoteleft}{\textquoteleft}Cruelles-Montserrat{\textquoteright}{\textquoteright}), J. F{\`a}brega ({\textquoteleft}{\textquoteleft}Germans F{\`a}bre-ga{\textquoteright}{\textquoteright}) and J.P. Llambrich ({\textquoteleft}{\textquoteleft}Pepito la Lula{\textquoteright}{\textquoteright}), and their respective crews, also helped during the fieldwork on board trawlers. Data obtained on board the R.V. {\textquoteleft}{\textquoteleft}Cornide de Saavedra{\textquoteright}{\textquoteright} was collected with the help of the participants in the cruise MEDITS_ES00, and particularly its Chief Scientist L. Gil de Sola, as well as the officers and crew of this vessel. A. Bertolero, J. Jofre, C. Escoda, P. Abell{\'o} and M. Rufino helped with the fieldwork at sea. X. Ruiz, C.J. Camphuysen and two anonymous referees made valuable comments on previous drafts of this manuscript, and D. Bowler kindly revised the English text. This study was performed within the framework of the research project LIFE B4-3200/96/502 funded by the European Commission and the DARP-Generalitat de Catalu-nya. J.M.A. was also supported by a fellowship from the DURSI-Generalitat de Catalunya (FI/FIAP 98).",
year = "2003",
month = may,
day = "1",
doi = "10.1086/373950",
language = "English (US)",
volume = "588",
pages = "557--565",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 I",
}