Observation of galactic cosmic ray spallation events from the SoHO mission 20-Year operation of LASCO

TL;DR

This paper reports the first observation of galactic cosmic ray spallation events outside Earth's magnetosphere using 20 years of LASCO data from the SoHO mission, revealing new insights into cosmic ray interactions in space.

Contribution

It presents the first detection of galactic cosmic ray spallation events outside Earth's magnetosphere, using space-based coronagraph images from the SoHO mission.

Findings

First spallation event observed outside Earth's magnetosphere.

Identification of cosmic ray tracks in LASCO images.

Evidence of galactic cosmic rays interacting with space environment.

Abstract

A shower of secondary Cosmic Ray (CR) particles is produced at high altitudes in the Earth's atmosphere, so the primordial Galactic Cosmic Rays (GCRs) are never directly measured outside the Earth magnetosphere and atmosphere. They approach the Earth and other planets in the complex pattern of rigidity's dependence, generally excluded by the magnetosphere. GCRs revealed by images of single nuclear reactions also called spallation events are described here. Such an event was seen on Nov. 29, 2015 using a unique LASCO C3 space coronagraph routine image taken during the Solar and Heliospheric Observatory (SoHO) mission observing uninterruptedly at the Lagrangian L1 point. The spallation signature of a GCR identified well outside the Earth's magnetosphere is obtained for the 1st time. The resulting image includes different diverging linear "tracks" of varying intensity, leading to a single pixel, this frame identifies the site on the silicon CCD chip of the coronagraph camera. There was no solar flare reported at that time, nor Coronal Mass Ejection (CME) and no evidence of optical debris around the spacecraft. More examples of smaller CR events have been discovered through the 20 years of continuous observations from SoHO. This is the first spallation event from a CR, recorded outside the Earth's magnetosphere. We evaluate the probable energy of these events suggesting a plausible galactic source. Key words: Sun: Galactic Cosmic Rays, Solar Energetic Particles, Heliosphere.