Recurrent modulation of galactic cosmic ray electrons and protons: Ulysses COSPIN/KET observations
Abstract
Since measurements of space probes in the interplanetary space became available it has been known that associated with the occurrence of recurrent fast and slow solar wind streams, forming Corotating Interaction Regions, recurrent variations in the cosmic ray nuclei flux are observed (1). As pointed out recently by Jokipii and Kota (2) recurrent modulation for positively and negatively charged particles may be different. In the time interval extending from July 1992 to July 1994, Ulysses on its journey to high heliographic latitudes registered ~20 stable and long-lasting Corotating Interaction Regions (CIRs). In this work we use data from the Cosmic Ray and Solar Particle Investigation Kiel Electron Telescope (COSPIN/KET) instrument on board Ulysses to study the recurrent variation of 2.5 GV electrons and protons. We find that 1) electrons are indeed periodically modulated, but that 2) the periodicity of ~29 days is longer than the period of ~26 days for protons, and that 3) the amplitude is larger than the one observed for protons. .
- Publication:
-
Acceleration and Transport of Energetic Particles Observed in the Heliosphere
- Pub Date:
- September 2000
- DOI:
- 10.1063/1.1324339
- Bibcode:
- 2000AIPC..528..357H
- Keywords:
-
- 96.40.Kk;
- 98.70.Sa;
- 95.85.Ry;
- Cosmic rays;
- Neutrino muon pion and other elementary particles;
- cosmic rays