Contributions of Primary Particles to Observed LET for the CRaTER Instrument on LRO

Abstract

The Cosmic Ray Telescope for the Effects of Radiation (CRATER) is an instrument on the Lunar Reconnaissance Orbiter (LRO) spacecraft in orbit around the Moon. CRaTER directly measures the energy depositions by space radiation in each of its six silicon wafer detectors as ionizing particles travel through them. These energy depositions are converted to linear energy transfer (LET). High LET particles are of particular importance because of their potential to cause significant biological damage to human tissue as well as a variety of damage effects in electronic components. These high LET particles are mainly high energy heavy ions found in the incident galactic cosmic ray spectrum or secondary fragments and recoils produced by protons and heavier ions. In this work the Monte Carlo transport code HETC-HEDS (High Energy Transport Code – Human Exploration and Development in Space) is used to estimate LET contributions from the incident primary ions as they pass through all 6 detectors in the CRaTER instrument.