Preliminary results from the heavy ions in space experiment

The Heavy Ions In Space (HIIS) experiment is intended to provide a deep survey of intensely ionizing particles in low earth orbit. Intensely ionizing particles produce single event effects in microelectronic components and are now recognized as the principal cause of spacecraft anomalies. These particles also make an important contribution to radiation doses. Besides the practical applications, HIIS data will be used to study several important scientific questions. By measuring heavy ions that stop in HIIS, the anomalous component of cosmic rays can be studied, evidence can be searched for of heavy ions trapped in the earth's magnetic field and by comparing HISS data with observations from outside the magnetosphere, the mean ionic charge state can be determined of solar energetic particles. HIIS will also record relativistic ultraheavy galactic cosmic rays. Their elemental composition will be measured from tin to uranium. Results are presented on the elemental resolution for stopping heavy ions and relativistic heavy ions.