Gersey, B. B., Borak, T. B., Guetersloh, S. B., Zeitlin, C., Miller, J., Heilbronn, L., Murakami, T. and Iwata, Y. The Response of a Spherical Tissue-Equivalent Proportional Counter to Iron Particles from 200 – 1000 MeV/nucleon. Radiat. Res. 157, 350 – 360 (2002).

The radiation environment on board the space shuttle and the International Space Station includes high-Z and high-energy (HZE) particles that are part of the galactic cosmic radiation (GCR) spectrum. Iron-56 particles are considered to be one of the most biologically important parts of the GCR spectrum. Tissue-equivalent proportional counters (TEPCs) are used as active dosimeters on manned space flights. These TEPCs are further used to determine the average quality factor for each space mission. A TEPC simulating a 1-μm-diameter sphere of tissue was exposed as part of a particle spectrometer to ⁵⁶Fe particles at energies from 200 – 1000 MeV/nucleon. The response of TEPCs in terms of mean lineal energy, ȳ_F, and dose mean lineal energy, ȳ_D, as well as the energy deposited at different impact parameters through the detector was determined for six different incident energies of ⁵⁶Fe particles in this energy range. Calculations determined that charged-particle equilibrium was achieved for each of the six experiments. Energy depositions at different impact parameters were calculated using a radial dose distribution model, and the results were compared to experimental data.