Aircrew Exposure from Cosmic Radiation on Commercial Airline Routes

Abstract

As a result of the recent recommendations of the ICRP 60, and in anticipation of possible regulation on occupational exposure of Canadian-based aircrew, an extensive study was carried out by the Royal Military College of Canada over a one-year period to measure the cosmic radiation at commercial jet altitudes. A tissue-equivalent proportional counter was used to measure the ambient total dose equivalent rate on 62 flight routes, resulting in over 20,000 data points at one-minute intervals at various altitudes and geomagnetic latitudes (i.e. which span the full cut-off rigidity of the Earth's magnetic field). These data were then compared to similar experimental work at the Physikalisch Technische Bundesanstalt, using a different suite of equipment, to measure separately the low and high linear energy transfer components of the mixed radiation field, and to predictions with the LUIN transport code. All experimental and theoretical results were in excellent agreement. From these data, a semiempirical model was developed to allow for the interpolation of the dose rate for any global position, altitude and date (i.e. heliocentric potential). Through integration of the dose rate function over a great circle flight path, a computer code was developed to provide an estimate of the total dose equivalent on any route worldwide at any period in the solar cycle.

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“…[6] The tissue equivalent proportional counter (TEPC), which measures both low and high linear energy transfer (LET) radiation, is most often utilized at altitude [Lewis et al, 2001;Taylor et al, 2002]. In this study and supplementary to the TEPC, the equipment used (QinetiQ QDOS/ Rayhound spectrometer, Liulin 4SA, Eberline FH 41B, and neutron-sensitive bubble detectors) all provide data allowing an estimate of the total accumulated dose for the flight (Table 1).…”

“…The measurements have been further adjusted to a sensitivity of 1.7 bubbles mSv À1 , allowing for the neutron spectrum at altitude [Lewis et al, 2001]. From the manufacturer's AmBe spectrum calibration at 20°C, the accuracy is ±20%.…”

Predicting well-connected SEP events from observations of solar soft X-rays and near-relativistic electrons

“…These energetic particles can cause Single Event Upsets (SEUs), interference with CCD imaging devices, and space radiation for space missions (Shea & Smart 2012). At Earth, they may irradiate passengers and flight crews in aircraft flying at polar latitudes (Lewis et al 2001;Beck et al 2005;Mertens et al 2010).…”

“…Given prompt and accurate Solar Energetic Proton (SEP) event predictions, pilots are able to re-route their planes at lower altitude and latitude in order to be better protected by the geomagnetic field and atmosphere (Lewis et al, 2001;Mertens et al, 2010), and launch operators to postpone or re-schedule a rocket launch (Shea & Smart, 2012). Most empirical SEP event forecasters rely on early observations of solar eruptive signatures (Kahler et al, 2007;Balch, 2008;Laurenza et al, 2009;Papaioannou et al, 2016).…”

Measurements of Cosmic-Ray Neutron Energy Spectra from Thermal to 15 MeV with Bonner Ball Neutron Detector in Aircraft

“…Many neutron measurements in aircraft have been performed in Europe and North America for verification. [2][3][4][5][6][7][8][9][10][11] However, only one neutron spectrum measurement on board was performed in the low cutoff rigidity region over Japan on Feb. 27,1985, by Nakamura et al 12) A multimoderator spectrometer, the so-called Bonner ball detector, is the standard neutron spectrometer used for radiological protection and environmental measurements, where the neutron energy range is below 15 MeV. In most aircraft measurements of the cosmic neutron energy spectrum, [2][3][4]6) a specially constructed Bonner ball spectrometer, to which a metal shell converter was added, was used to extend the energy range over 1 GeV.…”