2003ApJ...588..557F
Observation of GeV Solar Energetic Particles from the 1997 November 6 Event Using Milagrito
Falcone, A. ( Space Science Center, University of New Hampshire, Durham, NH 03824; Purdue University, West Lafayette, IN 47907 ); Atkins, R. ( Physics Department, University of Wisconsin, Madison, WI 53706. ); Benbow, W. ( Physics Department, University of California, Santa Cruz, CA 95064. ); Berley, D. ( Physics Department, University of Maryland, College Park, MD 20742. ); Chen, M. L. ( Physics Department, University of Maryland, College Park, MD 20742; Brookhaven National Laboratory, Upton, NY 11973. ); Coyne, D. G. ( Physics Department, University of California, Santa Cruz, CA 95064. ); Dingus, B. L. ( Physics Department, University of Wisconsin, Madison, WI 53706. ); Dorfan, D. E. ( Physics Department, University of California, Santa Cruz, CA 95064. ); Ellsworth, R. W. ( George Mason University, Fairfax, VA 22030. ); Fleysher, L. ( Physics Department, New York University, New York, NY 10003. ); Fleysher, R. ( Physics Department, New York University, New York, NY 10003. ); Gisler, G. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Goodman, J. A. ( Physics Department, University of Maryland, College Park, MD 20742. ); Haines, T. J. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Hoffman, C. M. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Hugenberger, S. ( Physics Department, University of California, Irvine, CA 92717. ); Kelley, L. A. ( Physics Department, University of California, Santa Cruz, CA 95064. ); Leonor, I. ( Physics Department, University of California, Irvine, CA 92717. ); McCullough, J. F. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); McEnery, J. E. ( Physics Department, University of Wisconsin, Madison, WI 53706. ); Miller, R. S. ( Space Science Center, University of New Hampshire, Durham, NH 03824. ); Mincer, A. I. ( Physics Department, New York University, New York, NY 10003. ); Morales, M. F. ( Physics Department, University of California, Santa Cruz, CA 95064. ); Nemethy, P. ( Physics Department, New York University, New York, NY 10003. ); Ryan, J. M. ( Space Science Center, University of New Hampshire, Durham, NH 03824. ); Shen, B. ( Physics Department, University of California, Riverside, CA 92521. ); Shoup, A. ( Physics Department, University of California, Irvine, CA 92717. ); Sinnis, G. ( Los Alamos National Laboratory, Los Alamos, NM 87545. ); Smith, A. J. ( Physics Department, University of Maryland, College Park, MD 20742. ); Sullivan, G. W. ( Physics Department, University of Maryland, College Park, MD 20742. ); Tumer, T. ( Physics Department, University of California, Riverside, CA 92521. ); Wang, K. ( Physics Department, University of California, Riverside, CA 92521. ); Wascko, M. O. ( Los Alamos National Laboratory, Los Alamos, NM 87545; Louisiana State University, Baton Rouge, LA 70803. ); Westerhoff, S. ( Los Alamos National Laboratory, Los Alamos, NM 87545; Columbia University, New York, NY 10027. ); Williams, D. A. ( Physics Department, University of California, Santa Cruz, CA 95064. ); Yang, T. ( Physics Department, University of California, Santa Cruz, CA 95064. ); Yodh, G. B. ( Physics Department, University of California, Irvine, CA 92717. ) and 27 coauthors show affiliations
The Astrophysical Journal, Volume 588, Issue 1, pp. 557-565.
Published in May 2003
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 scaler 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 scalers 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 Rsolar above the photosphere), assuming that a CME-driven shock was responsible for the ground-level enhancement.
Keywords:
Free Keywords: Acceleration of Particles; Interplanetary Medium; Sun: Flares; Sun: Particle Emission
Astronomy: Acceleration of Particles; Interplanetary Medium; Sun: Flares; Sun: Particle Emission
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