Voyager LECP/LEMPA instrument modeling with Geant4
Abstract
Using publicly available data from the Voyager Low Energy Charged Particle (LECP) instruments, we investigate the form of the solar wind ion suprathermal tail in the outer heliosphere inside the termination shock. This tail has a commonly observed form in the inner heliosphere, that is, a power law with a particular spectral index. The Voyager spacecraft have taken data beyond 100 AU, farther than any other spacecraft. However, during extended periods of time, the data appears to be mostly background. Here, we report initial results from a model to self-consistently estimate the background seen by LECP/LEMPA due to cosmic rays using data from the Voyager cosmic ray instruments and a fully three-dimensional Geant4 instrument model, based on actual drawings of the LECP/LEMPA instrument. We describe the model in detail and present initial results of applying the model to solar wind, heliosheath, and interstellar medium data. We also compare to previous efforts performed using a simple, semi-analytical model and discuss relevant physics.
- Publication:
-
Solar Heliospheric and INterplanetary Environment (SHINE 2015)
- Pub Date:
- July 2015
- Bibcode:
- 2015shin.confE..90R