Air Crew Hazards and Safety: FAA Uses of Neutron Monitor Data in Aviation Radiation Safety Presented by Kyle A. Copeland, Ph.D Neutron Monitor Community Workshop October

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Ten highest average annual effective doses among monitored workers worldwide ( ) [UNSCEAR, 2000]. 3 The annual dose for aircrew will increase as the average flight altitude increases! In 2012 there were about 200,000 US crewmembers (U.S. BLS).

Ionizing Radiation in Aviation <0.13 mSv <30 mSv per event, rare <6 mSv, primary source <10 mSv per event, rare 4

Stochastic and Deterministic Effects Increased lifetime risk* Stochastic EffectWhole population Age group years Genetic defect in first or second generation (child or grandchild) following irradiation before conception 0.4 in 100,000 per mSv 2.4 in 1,000,000 per mSv Cancer (non-fatal or fatal) 34 in 100,000 per mSv 23 in 100,000 per mSv Cancer (fatal only) 8.0 in 100,000 per mSv6.3 in 100,000 per mSv *Risks assumes exposure to high-LET radiation (i.e., no DDREF) [ICRP Pub. 103] Deterministic Effect Threshold Dose None Significant <0.1 Gy Risks to conceptus (mental retardation, malformation, etc.) Gy Transient mild nausea and headache in adults 0.35 Gy Effective Dose Limits for Workers Pregnant 1 mSv for duration of pregnancy and 0.5 mSv per month Other 100 mSv per 5 years and no more than 50 mSv in any one year 5

1.The heliosphere 2. Solar wind 6 Galactic Cosmic Radiation: How does it get here? Source: NASA Shea and Smart, 2001

Earth’s Atmosphere For aviation, the practical boundary of the atmosphere is 100 km (328,000 ft) 78% nitrogen 21% oxygen 0.93% argon 0.034% (average) carbon dioxide trace amounts of other gases 7

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Galactic Cosmic Radiation Levels, January 1958 through December and-north-america-solar-and-ocean-cycles-bode-of-an-approaching- little-ice-age/#sthash.GG7K40fN.dpbs Percent, % 10

Solar Dose Rates During an SPE, cosmic ray spectrum modelling is more complex. -The particle spectra are constantly changing. -GOES satellite instruments provide good data for protons up to about 1 GV, but not higher energies. -Isotropy of incident cosmic ray flux is often a poor assumption, particular at the start of events when fluxes are usually highest. -To provide a good picture of anisotropy, a world grid of neutron monitors is needed. Data from many monitors is needed to maximize accuracy of post-event assessments. (Smart and Shea, 1990) 10

Summary: Why Neutron Monitors Matter Galactic Cosmic Radiation - NMs are used for observing solar modulation in real time. - High resolution (hourly) data covers practically the entire jet age of civilian flight (starting in the late 1950s). - Useful for both long-term monitoring (solar cycle) and short-term variations (Forbush effects). - One monitor is enough, if statistics are really good. Solar Cosmic Radiation - Need multiple monitors at different altitudes and geomagnetic latitudes, both N and S. - NM data, along with GOES data, are the basis for calculation of SPE intensities. - Provide the best data for anisotropy calculations needed to drive more sophisticated SPE flight dose models. - Provide the best insight into multi-GeV proton and alpha spectra during a SPE, satellite instruments do not have enough shielding to discriminate well. 11