First results from the RAPID imaging energetic particle spectrometer on board Cluster

B. Wilken, P. W. Daly, U. Mall*, K. Aarsnes, D. N. Baker, R. D. Belian, J. B. Blake, H. Borg, J. Büchner, M. Carter, J. F. Fennell, R. Friedel, T. A. Fritz, F. Gliem, M. Grande, K. Kecskemety, G. Kettmann, A. Korth, S. Livi, S. McKenna-LawlorK. Mursula, B. Nikutowski, C. H. Perry, Z. Y. Pu, J. Roeder, G. D. Reeves, E. T. Sarris, I. Sandahl, F. Søraas, J. Woch, Q. G. Zong

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

147 Citations (Scopus)


The advanced energetic particle spectrometer RAPID on board Cluster can provide a complete description of the relevant particle parameters velocity, V, and atomic mass, A, over an energy range from 30 keV up to 1.5 MeV. We present the first measurements taken by RAPID during the commissioning and the early operating phases. The orbit on 14 January 2001, when Cluster was travelling from a perigee near dawn northward across the pole towards an apogee in the solar wind, is used to demonstrate the capabilities of RAPID in investigating a wide variety of particle populations. RAPID, with its unique capability of measuring the complete angular distribution of energetic particles, allows for the simultaneous measurements of local density gradients, as reflected in the anisotropies of 90° particles and the remote sensing of changes in the distant field line topology, as manifested in the variations of loss cone properties. A detailed discussion of angle-angle plots shows considerable differences in the structure of the boundaries between the open and closed field lines on the nightside fraction of the pass and the magnetopause crossing. The 3 March 2001 encounter of Cluster with an FTE just outside the magnetosphere is used to show the first structural plasma investigations of an FTE by energetic multi-spacecraft observations.

Original languageEnglish
Pages (from-to)1355-1366
Number of pages12
JournalAnnales Geophysicae
Issue number12 PART I
Publication statusPublished - Oct 2001


  • Magnetospheric physics (energetic particles, trapped; magnetopause, cusp and boundary layers; magnetosheath)


Dive into the research topics of 'First results from the RAPID imaging energetic particle spectrometer on board Cluster'. Together they form a unique fingerprint.

Cite this