Comparison of the characteristics of 1D and 3D dosimetric telescopes in an anisotropic radiation field in Low Earth Orbit

Paper number

IAC-08.A1.4.4

Author

Mr. Attila Hirn, Hungarian Academy of Sciences KFKI Atomic Energy Research Institute, Hungary

Year

2008

Abstract

Nowadays the human presence in space owing to the operation of the International Space Station (ISS) is continuous. Albeit there are many researchers and engineers who question the necessity of manned spaceflights in space research, the visions of the space-faring nations and the future plans of private commercial spacelines predict an even more significant human presence in space in the decades to come. 
Even in the low Earth orbit of the ISS, where the astronauts are protected to some extent by the Earth’s geomagnetic field, cosmic radiation poses probably the most important long term risk and overall flight time limitation to the crew. In order to successfully implement the "As Low As Reasonably Achieveable" (ALARA) principle in the radiation protection of astronauts, performing a wide range of dosimetric measurements is necessary. In the case of ISS, the attitude of which is normally stabilized in the local vertical reference frame (airplane-like attitude), the anisotropies in the radiation field, such as the effect of the Earth shadow, the angular dependence of the geomagnetic transmission factors and the East-West asymmetry in the South Atlantic Anomaly (SAA), cannot be ignored. Although, lately, more and more models are capable of predicting the directional flux of the charged particles, most of the cosmic radiation models that has been used for describing the cosmic radiation field are omnidirectional, including the "de-facto" standard AP8 and AE8 trapped proton and electron models. However, there are not only models but dosimeters that shall also take into consideration the anisotropy of the radiation field. One dimensional telescopes used for dosimetry have strong directional sensitivity and therefore they might either under- or overestimate the dose equivalent. The application of  3D telescopes comprising three, mutually orthogonal axes improves significantly the measuring precision of the instrument. 
The present paper addresses the expected responses of the 1D and the 3D arrangements for anisotropic radiation in low Earth orbit onboard the ISS. The expected uncertainties in determining the average quality factor and the dose equivalent are also given for GCR particles as well as for trapped protons in the SAA.

Abstract document

IAC-08.A1.4.4.pdf

Manuscript document

IAC-08.A1.4.4.pdf (🔒 authorized access only).

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