Computer simulations for a cosmic ray heavy ion telescope

Abstract

Computer simulations were carried out to evaluate the basic characters of a ΔE × E cosmic ray telescope consisting of 23 solid state detectors including three position-sensitive detectors with large effective area. Based on the simulation, the geometric factor of the telescope is deduced to be 22.5 cm2 sr and almost independent of particle charge and energy although the energy range covered by the telescope shifts toward lower energies for the lighter elements. Several sets of simulated data were produced and analyzed. For better identification of isotopes, we analyzed the simulated data based on a new ΔE × E technique in which some detectors are combined into a thick ΔE detector to minimize the influence of energy straggling in the ΔE detector. By analyzing the simulated data based on the above technique, the mass resolution for iron in the full energy range covered by the telescope is estimated to be about 0.22 amu (standard deviation). It is also found that the mass resolution for a heavy element, such as iron, is very sensitive to irregularities in thickness of the detectors. On the other hand, the mass resolution for a light element, such as lithium, is found to be affected by the position resolution. The expected counting rates and mass histograms to be observed in galactic cosmic rays and solar energetic particles have been obtained as well.