Detectors for Micro- and Nanodosimetry in Space Radiation Fields

Jayde Livingstone
Centre for Medical Radiation Physics, University of Wollongo

Dale Prokopovich
Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia

Marco Petasecca
Centre for Medical Radiation Physics, University of Wollongong, Australia

Michael Lerch
Centre for Medical Radiation Physics, University of Wollongong, Australia

Yigal Horowitz
Physics Department, Ben-Gurion University of the Negev, Beer Sheva, Israel

Mark Reinhard
Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia

Vladimir Perevertaylo
SPA-BIT, Kiev, Ukraine

Anatoly Rosenfeld
Centre for Medical Radiation Physics, University of Wollongong, Australia

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     Last modified: July 30, 2011

Abstract
There is increasing concern that heavy ions, protons and secondary neutrons are producing harmful effects on humans in space and avionics. The dose rate in space is much higher than that of natural radiation on the ground and the accumulated dose during a long space mission could present a cancer risk to personnel as well as cause damage to microelectronics. New radiation detection instrumentation is required to better understand the space radiation health risk and single event upsets (SEU) in microelectronic devices due to the stochastic deposition of energy that is not directly correlated with a deterministic parameter such as absorbed dose.

Innovative solid state radiation detectors have been developed to estimate the relative biological effectiveness (RBE) of mixed radiation fields. Micro- and nanodosimetric approaches are used to measure the ionising energy deposition on cellular and DNA scales. A new generation of large sensitive area (5x5 mm2) silicon microdosimeters for space crew personal dosimetry based on n-type silicon-on-insulator and epitaxial designs, with single “cell” sizes 6 and 10 microns have been developed at CMRP. Investigation of charge collection in cells using the heavy ion microprobe at ANSTO have revealed 100% yield of operational cells and absence of cross talk between cells. The response of these microdosimeters in a phantom to fields of high-charge and high-energy (0.5-2 GeV/u) ions typical of galactic cosmic radiation, such as Fe and O, is under investigation. The microdosimetric spectra and derived RBE for microdosimeters with different “cell” sizes at different points in a phantom will be compared with published TEPC data.

Thermoluminescent detectors (TLDs) will also be irradiated at the same points in a phantom to investigate nanodosimetric features of its response and to determine a correlation with ion track structure and Si microdosimeters.

The outcomes from this study will include the characterisation of innovative radiation detection instruments for prediction of radiobiological effects on space radiation.