Flight attendant radiation

[ROBBARISH@aol.com]

To Wes Van Pelt: Yes, I saw the question about in-flight radiation 

measurements.



Here are my thoughts:



Galactic cosmic radiation has an energy distribution that ranges to the PeV 

level. The particle mix is typically about 95% protons, 3.5% alphas with the 

remainder being heavier nuclei.

Once these galactic cosmic rays interact with the earth's magnetic field, the 

solar wind and the atmosphere, a complex secondary particle spectrum is 

created, with energies up to the EeV range. At typical airliner cruising altitudes 

(10,000 - 13,000 m) the radiation environment is a mixture of these energetic 

secondary particles, including nuclei, leptons, meson, baryons and energetic 

photons.

So any radiation detector that intends to make accurate measurements of the 

in-flight radiation environment must be able to accurately detect this particle 

mix and convert that measurement to effective dose. 

Considering particle flux, energetic neutrons are the dominant component of 

the radiation mix at airliner altitudes. The other particles are considerably 

lower in intensity, but are of very high energy. So it is generally accepted 

that, at airliner altitudes, neutrons dominate the contribution to equivalent 

dose, with muons, electromagnetic showers, charged pions, and protons also 

contributing to a lesser extent.

Radiation measurements in airplanes thus require a relatively sophisticated 

approach, both because of the complex particle mix and the extreme energy range 

required. The detectors must have an upper limit of at least 10 GeV.

Groups that have made measurements during the past ten or twelve years have 

been using TEPC (tissue-equivalent proportional counter) instruments with 

sophisticated algorithms to convert the particle-count measurements to equivalent 

dose. At present, there are commercial companies "making a buck" by selling far 

less reliable monitoring using ordinary TLD badges of the sort employed in 

the typical medical or industrial environment. These devices will, of course, 

register only those components of the radiation field to which they are 

sensitive. They are by no means an accurate dosimeter in this application. A GM-system 

that detects only a low-LET component of the total spectrum is certainly not 

adequate for making these measurements.



Robert J. Barish, Ph.D., CHP

robbarish@aol.com



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