Monte Carlo simulations of CASSINI/LEMMS

In an effort to characterize the response of the low energy magnetospheric measurements system (LEMMS) on the CASSINI spacecraft to energetic ions and electrons we have taken advantage of the excellent pre-launch beam calibrations in comparison to an extensive series of electron and ion Monte Carlo simulations. We selected the geometry and tracking toolkit to provide the framework for the instrument modeling and simulation environment. The results from these simulations match very well with the data collected during the instrument calibration. This gives us confidence that this simulation toolkit handles both electron and ion interactions in a reasonable fashion and that we can successfully apply this tool to regions of the spectrum where calibration data is not available.     

Status of the GAMMA-400 project

The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV–3 TeV is presented. The angular resolution of the instrument, 1–2° at E_γ ∼ 100 MeV and ∼0.01° at E_γ > 100 GeV, its energy resolution ∼1% at E_γ > 100 GeV, and the proton rejection factor ∼10⁶ are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.     

Cosmic Ray Electrons

Modulation of cosmic electrons is similar to that of nuclei, but there are clear differences. At energies below 100 MeV the electron spectrum has a negative slope, which may in some way be related to electrons released from the magnetosphere of the planet Jupiter. If there is such a relationship, its nature is not established, and alternative explanations for the upturn exist. At higher energies, electrons are predominantly negatively charged, and it is probable that the difference in net charge sign from that of nuclei is responsible for many of the observed differences in the behavior of electrons and nuclei under modulation. A consistent picture of the cosmic positron abundance and its time variation may be emerging from the world dataset.     

The Energetic Particle and Plasma Spectrometer Instrument on the MESSENGER Spacecraft

The Energetic Particle and Plasma Spectrometer (EPPS) package on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury is composed of two sensors, the Energetic Particle Spectrometer (EPS) and the Fast Imaging Plasma Spectrometer (FIPS). EPS measures the energy, angular, and compositional distributions of the high-energy components of the in situ electrons (>20 keV) and ions (>5 keV/nucleon), while FIPS measures the energy, angular, and compositional distributions of the low-energy components of the ion distributions (<50 eV/charge to 20 keV/charge). Both EPS and FIPS have very small footprints, and their combined mass (∼3 kg) is significantly lower than that of comparable instruments.