PoS - Proceedings of Science
Volume 301 - 35th International Cosmic Ray Conference (ICRC2017) - Session Solar & Heliospheric. SH-Transient solar phenomena (SEP, GLE, Forbush decreases)
Short-term variation in the galactic cosmic ray intensity measured with the PAMELA experiment
R. Munini*, A. Bruno, C. Eric, G.A. De Nolfo, M. Matteo, M. Matteo, R. James, S. Steve, d.F. Valeria, B. Mirko, P. Marius, V. Di Felice, M. Boezio, O. Adriani, G.C. Barbarino, G.A. Bazilevskaya, R. Bellotti, E.A. Bogomolov, M. Bongi, G. Bonvicini, S. Bottai, A. Bruno, F. Cafagna, D. Campana, M. Casolino, G. Castellini, C. De Santis, A.M. Galper, A.V. Karelin, S.V. Koldashov, S.Y. Krutkov, A.N. Kvashnin, A. Leonov, V. Malakhov, L. Marcelli, M. Martucci, A.G. Mayorov, W. Menn, M. Merge', V.V. Mikhailov, E. Mocchiutti, A. Monaco, N. Mori, G. Osteria, B. Panico, P. Papini, M. Pearce, P. Picozza, M. Ricci, S.B. Ricciarini, M. Simon, R. Sparvoli, P. Spillantini, Y.I. Stozhkov, A. Vacchi, E. Vannuccini, G. Vasilyev, S.A. Voronov, Y.T. Yurkin, G. Zampa, N. Zampa, M.S. Potgieter, E.C. Christian, I. Richardson, J.M. Ryan and S. Stochajet al. (click to show)
Full text: pdf
Pre-published on: August 16, 2017
Published on: August 03, 2018
New results on the galactic cosmic ray (GCR) short-term intensity variation
associated with Forbush decrease and co-rotating interaction regions (CIRs) measured by the PAMELA instrument between November 2006 and March 2007 are presented. Most of the past measurements on Forbush decrease events were carried out with neutron monitor detector. This tecnique allows only indirect detection of the overall GCR intensity over an integrated energy range. For the first time, thanks to the unique features of the PAMELA magnetic spectrometer, the Forbush decrease associated with the December 13th coronal mass ejection (CME) was studied in a wide rigidity range (0.4-20 GV) and for different species of GCRs detected directly in space. Using GCR protons, the amplitude and the recovery time of the Forbush decrease were studied for ten rigidity interval with a temporal resolution of one day. For comparison the helium and the electron intensity over time were also studied. The temporal evolution of the helium and proton intensity was found in good agreement while the electrons show, on average, a faster recovery time. This was interpreted as a charge-sign dependence introduced by drift motion experienced by the low rigidity (<5 GV) GCRs during their propagation through the heliosphere. Moreover a clear 13.5 days cyclical variation was observed in the GCR proton intensity after the Forbush decrease. This phenomena could be interpreted as an effect of prominent structures of compressed plasma in the solar wind, i.e. CIRs, or to the latitudinal gradient due to the crossing of the heliospheric current sheet (HCS).
DOI: https://doi.org/10.22323/1.301.0091
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access
Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.