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Papers by Kyle Copeland

Research paper thumbnail of Influence of the superposition approximation on calculated effective dose rates from galactic cosmic rays at aerospace-related altitudes

Space Weather, 2015

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Research paper thumbnail of CAMI Tools and Services for Evaluating Space Weather

Aviation, Space, and Environmental Medicine, 2012

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Research paper thumbnail of State-Resolved Differential Cross Sections and Silicon Nanostructures Based on Atomic Fluorine Beam

We have developed a new beam source for atomic fluorine, based on thermal dissociation of F2 flow... more We have developed a new beam source for atomic fluorine, based on thermal dissociation of F2 flowing through single-crystal MgF2 (T. Ericson, K. Copeland, M. Keil, Y. Apelblat, and Y. B. Fan, ``Fluoride Salts as Supersonic Nozzle Materials for Hot Fluorine'', Rev. Sci. Inst. 65, 3587 (1994)) tubes heated to 1100 ^0C. The source yields excellent beam quality (velocity fwhm=13%) and intensity (almost as intense as a He beam!), and is very stable and easy to use. Applications of this source to gas-phase reactive scattering in a crossed-beam experiment with H_2, based on bolometric detection of individual vib-rotational states of HF, (L. J. Rawluk, Y. B. Fan, Y. Apelblat, and M. Keil, ``Differential Cross Sections for Rotationally State--Resolved Inelastic Scattering of HF by Ar'', J. Chem. Phys. 94, 4205 (1991)) will be discussed. Modelling results for these experiments using exact quantum chemical dynamics will be presented. Finally, we will discuss applications for su...

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Research paper thumbnail of Atomic fluorine beam etching of silicon and related materials

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

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Research paper thumbnail of Angular Dependence for ν‘,  j‘ -Resolved States in F + H 2 → HF(ν‘,  j‘ ) + H Reactive Scattering Using a New Atomic Fluorine Beam Source

The Journal of Physical Chemistry A, 1997

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Research paper thumbnail of Fluoride salts as supersonic nozzle materials for hot fluorine

Review of Scientific Instruments, 1994

An intense supersonic beam of atomic fluorine has been generated using nozzles fabricated from si... more An intense supersonic beam of atomic fluorine has been generated using nozzles fabricated from single-crystal CaF2 and MgF2. The latter material has been tested up to 1000 °C with no observable damage. This is ≳250 °C hotter than previously achieved, increasing the atomic beam intensity by ≳5×.

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Research paper thumbnail of Annual effective dose of ionizing radiation from natural sources received by airline aircrew members compared with that received by non-flying residents of the United States

In evaluating health aspects of the ionizing radiation exposure of aircrews, risk estimates are n... more In evaluating health aspects of the ionizing radiation exposure of aircrews, risk estimates are normally based on the amount of cosmic radiation received in flight. Not considered is that aircrews spend most of their time on the ground. In this report, annual total effective doses of ionizing radiation from natural sources received by aircrews on and off the job, flying between Los Angeles and Tokyo or Chicago and London, are compared with doses to non-flying residents of the United States and non-flying residents of Environmental Protection Agency Region 8 (Montana, North Dakota, South Dakota, Wyoming, Utah, Colorado --- the region in the United States with the highest dose rates of natural ionizing radiation at ground level). Occupational exposure of aircrews to ionizing radiation is thought to increase their risk of fatal cancer. It may not be a significant concern if one considers: (a) the annual dose of ionizing radiation to the crewmembers in our study is only 7-41% higher than that received by non-flying residents of Region 8 (terrestrial gamma and cosmic radiation in the Denver, Colorado, area of Region 8); (b) the dose to non-flying residents of Region 8 is 87% higher than the average dose to non-flying residents of the United States; and (c) the estimated death rate from cancer in the six states in Region 8 is 3-26% lower than the average for the United States. When considering health concerns of aircrew members, one should recognize that the standard risk coefficient for radiation-induced fatal cancer is derived primarily from studies on individuals exposed to radiation at higher doses and dose rates and of generally lower energy, than the galactic cosmic radiation to which aircrews are exposed. These differences are a major reason that epidemiology studies are important in evaluating health aspects of the occupational radiation exposure of aircrews.

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Research paper thumbnail of Galactic Cosmic Radiation Exposure of Pregnant Aircrew Members II

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Research paper thumbnail of Solar Radiation Alert System

The Solar Radiation Alert (SRA) system continuously evaluates measurements of high-energy protons... more The Solar Radiation Alert (SRA) system continuously evaluates measurements of high-energy protons made by instruments on GOES satellites. If the measurements indicate a substantial elevation of effective dose rates at aircraft flight altitudes, the Civil Aerospace Medical Institute issues an SRA via the National Oceanic and Atmospheric Administration Weather Wire Service. This report describes a revised SRA system. SRA issue-criteria remain the same but significant improvements have been made in the calculations. The solar proton fluence to effective dose conversion coefficients have been recalculated using 2007 recommendations of the International Commission on Radiological Protection and the latest release of the Monte Carlo transport code, MCNPX 2.6.0. The shape of the <10 MeV secondary neutron spectrum is now accounted for down to 100 eV. The flux correction based on spectral index has been revised to smooth the flux spectrum of solar protons. Estimates of the >605 MeV spe...

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Research paper thumbnail of The Radiation Dose at Commercial Aircraft Altitudes During the January 2005 High-Energy Solar Cosmic ray Event and the Effects of the Solar Cosmic ray Anisotropy

The radiation dose to aircrews and passengers is a phenomenon of societal interest. There is a re... more The radiation dose to aircrews and passengers is a phenomenon of societal interest. There is a requirement to provide alerts whenever the radiation dose exceeds 20 micro-sieverts per hour at flight altitudes. The possibility that this might occur during a large high-energy solar cosmic ray event has resulted in much speculation. During the 20 January 2005 ground-level event the FAA Solar Radiation Alert System would have issued such an alert for aircraft at high latitudes for flight altitudes above 40,000 feet. Analysis of the GOES high-energy proton data results in a predicted dose rate of 23 micro Sv per hour at 60,000 feet for the first hour of the event. We also predict that the maximum peak dose rate would have been higher at the geographical position corresponding to the peak anisotropic flux intensity and would be correspondingly lower at geographical positions receiving a lower high energy solar cosmic ray flux. The solar high-energy flux anisotropy is extremely variable amo...

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Research paper thumbnail of Ionizing Radiation in Earth's Atmosphere and in Space Near Earth

The Civil Aerospace Medical Institute of the FAA is charged with identifying health hazards in ai... more The Civil Aerospace Medical Institute of the FAA is charged with identifying health hazards in air travel and in commercial human space travel. This report addresses one of these hazards - ionizing radiation. Ionizing radiation is a subatomic particle of matter or packet of energy (photon) with sufficient energy to eject an orbital electron from an atom. Charged subatomic particles from exploding stars (supernovae) are a constant source of ionizing radiation in the atmosphere and in space. In space another constant source of ionizing radiation is the solar wind from the Sun. The solar wind consists mostly of electrons and protons with energies between 10 and 100 keV. The Sun undergoes an approximately 11-year cycle of rise and decline in activity and during its active phase there is an increased emission of the solar wind and occasional eruptions of high-energy particles (coronal mass ejections). Other sources of ionizing radiation during air travel include radioactive cargo, radioa...

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Research paper thumbnail of Radiation exposure of aircrews

Occupational medicine (Philadelphia, Pa.)

Information is provided about the radiation to which aircrews are exposed and possible health con... more Information is provided about the radiation to which aircrews are exposed and possible health consequences. Recommended radiation exposure limits are given. Crewmembers on commercial aircraft are exposed to higher doses of ionizing radiation than normally received by members of the general population in most parts of the world. The principal ionizing radiation is galactic cosmic radiation. On infrequent occasions, radiation from the sun leads to an increase in the ionizing radiation at aircraft flight altitudes. Radioactive cargo is another possible source of exposure to ionizing radiation. Crewmembers are exposed to nonionizing radiation in the form of electric and magnetic fields generated by the aircraft s electronic and electrical systems. Other potential sources of nonionizing radiation exposure are microwave radiation from the aircraft's weather radar, laser radiation, and ultraviolet radiation.

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Research paper thumbnail of Galactic cosmic radiation exposure of pregnant flight crewmembers

Aviation, space, and environmental medicine, 2000

In recommending the occupational dose limit of ionizing radiation for pregnant women, the Interna... more In recommending the occupational dose limit of ionizing radiation for pregnant women, the International Commission on Radiological Protection apparently assumes that the dose to the conceptus from ionizing radiation exposure is about half the dose at the surface of the mother's abdomen. To test this assumption with respect to galactic cosmic radiation, calculations were made using FAA computer program CARI-LF2, which calculates equivalent doses from galactic cosmic rays at selected depths in soft tissue at any specified location in the atmosphere or on user-entered flight profiles. The calculations showed that the equivalent dose of galactic radiation was almost the same at all depths. Thus the assumption of considerable shielding of the conceptus being provided by the woman's body is not correct with respect to galactic cosmic radiation, the principal type of radiation to which aircrews are exposed. The effective dose as calculated with FAA computer program CARI-5E, which c...

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Research paper thumbnail of Health aspects of radiation exposure on a simulated mission to Mars

A major consideration in planning a manned mission in space is exposure of the space travelers to... more A major consideration in planning a manned mission in space is exposure of the space travelers to ionizing radiation. Mission planners want to minimize long-term health effects and prevent acute health effects that could jeopardize a mission. At the radiation doses likely to be received during space travel, the major health concern is fatal cancer—the latency period is in years. However, space travelers who are inadequately shielded from radiation during a large solar-proton event may receive a dose sufficient to cause serious health effects within hours or up to a couple of months after the event. The amount of radiation received by the space travelers on the simulated mission to Mars translates into risks of radiation-induced fatal cancer that, for all but men of ages 55–64, exceed the 3% career limit currently recommended by the National Council on Radiation Protection and Measurements for space crews on low-Earth orbit missions.

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Research paper thumbnail of Atmospheric Ionizing Radiation and Human Exposure

Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures,... more Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures, because it is a principal source of human exposure to radiations with high linear energy transfer (LET). The ionizing radiations of the lower atmosphere tend to be dominated by the terrestrial radioisotopes especially along the costal plain and interior low lands and have only minor contributions

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Research paper thumbnail of Tritons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

Radiation Protection Dosimetry, 2010

Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose,... more Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to tritons ((3)H(+)) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Coefficients were calculated using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and calculation of gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 3%. The greatest difference, 43%, occurred at 30 MeV.

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Research paper thumbnail of Fluence to absorbed dose, effective dose and gray equivalent conversion coefficients for iron nuclei from 10 MeV to 1 TeV, calculated using Monte Carlo radiation transport code MCNPX 2.7.A

Radiation Protection Dosimetry, 2010

Conversion coefficients have been calculated for fluence-to-absorbed dose, fluence-to-effective d... more Conversion coefficients have been calculated for fluence-to-absorbed dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult male and an adult female to (56)Fe(26+) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Calculations using ICRP 2007 recommendations result in fluence-to-effective dose conversion coefficients that are almost identical at most energies to those calculated using ICRP 1990 recommendations.

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Research paper thumbnail of Alpha particles at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, effective dose, and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.A

Radiation Protection Dosimetry, 2010

Conversion coefficients have been calculated for fluence to absorbed dose, fluence to effective d... more Conversion coefficients have been calculated for fluence to absorbed dose, fluence to effective dose and fluence to gray equivalent, for isotropic exposure to alpha particles in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for effective dose are within 30 % of those calculated using ICRP 1990 recommendations.

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Research paper thumbnail of Comparison of fluence-to-dose conversion coefficients for deuterons, tritons and helions

Radiation Protection Dosimetry, 2012

Secondary radiation in aircraft and spacecraft includes deuterons, tritons and helions. Two sets ... more Secondary radiation in aircraft and spacecraft includes deuterons, tritons and helions. Two sets of fluence-to-effective dose conversion coefficients for isotropic exposure to these particles were compared: one used the particle and heavy ion transport code system (PHITS) radiation transport code coupled with the International Commission on Radiological Protection (ICRP) reference phantoms (PHITS-ICRP) and the other the Monte Carlo N-Particle eXtended (MCNPX) radiation transport code coupled with modified BodyBuilder™ phantoms (MCNPX-BB). Also, two sets of fluence-to-effective dose equivalent conversion coefficients calculated using the PHITS-ICRP combination were compared: one used quality factors based on linear energy transfer; the other used quality factors based on lineal energy (y). Finally, PHITS-ICRP effective dose coefficients were compared with PHITS-ICRP effective dose equivalent coefficients. The PHITS-ICRP and MCNPX-BB effective dose coefficients were similar, except at high energies, where MCNPX-BB coefficients were higher. For helions, at most energies effective dose coefficients were much greater than effective dose equivalent coefficients. For deuterons and tritons, coefficients were similar when their radiation weighting factor was set to 2.

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Research paper thumbnail of Guidelines and Technical Information Provided by the US Federal Aviation Administration to Promote Radiation Safety for Air Carrier Crew Members

Radiation Protection Dosimetry, 1999

... GUIDELINES AND TECHNICAL INFORMATION PROVIDED BY THE US FEDERAL AVIATION ADMINISTRATION TO ..... more ... GUIDELINES AND TECHNICAL INFORMATION PROVIDED BY THE US FEDERAL AVIATION ADMINISTRATION TO ... association of long-term exposure to galactic radiation and health effects in ... compo-sition of the galactic radiation varied appreciably with changes in altitude ...

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Research paper thumbnail of Influence of the superposition approximation on calculated effective dose rates from galactic cosmic rays at aerospace-related altitudes

Space Weather, 2015

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Research paper thumbnail of CAMI Tools and Services for Evaluating Space Weather

Aviation, Space, and Environmental Medicine, 2012

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Research paper thumbnail of State-Resolved Differential Cross Sections and Silicon Nanostructures Based on Atomic Fluorine Beam

We have developed a new beam source for atomic fluorine, based on thermal dissociation of F2 flow... more We have developed a new beam source for atomic fluorine, based on thermal dissociation of F2 flowing through single-crystal MgF2 (T. Ericson, K. Copeland, M. Keil, Y. Apelblat, and Y. B. Fan, ``Fluoride Salts as Supersonic Nozzle Materials for Hot Fluorine'', Rev. Sci. Inst. 65, 3587 (1994)) tubes heated to 1100 ^0C. The source yields excellent beam quality (velocity fwhm=13%) and intensity (almost as intense as a He beam!), and is very stable and easy to use. Applications of this source to gas-phase reactive scattering in a crossed-beam experiment with H_2, based on bolometric detection of individual vib-rotational states of HF, (L. J. Rawluk, Y. B. Fan, Y. Apelblat, and M. Keil, ``Differential Cross Sections for Rotationally State--Resolved Inelastic Scattering of HF by Ar'', J. Chem. Phys. 94, 4205 (1991)) will be discussed. Modelling results for these experiments using exact quantum chemical dynamics will be presented. Finally, we will discuss applications for su...

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Research paper thumbnail of Atomic fluorine beam etching of silicon and related materials

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2000

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Research paper thumbnail of Angular Dependence for ν‘,  j‘ -Resolved States in F + H 2 → HF(ν‘,  j‘ ) + H Reactive Scattering Using a New Atomic Fluorine Beam Source

The Journal of Physical Chemistry A, 1997

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Research paper thumbnail of Fluoride salts as supersonic nozzle materials for hot fluorine

Review of Scientific Instruments, 1994

An intense supersonic beam of atomic fluorine has been generated using nozzles fabricated from si... more An intense supersonic beam of atomic fluorine has been generated using nozzles fabricated from single-crystal CaF2 and MgF2. The latter material has been tested up to 1000 °C with no observable damage. This is ≳250 °C hotter than previously achieved, increasing the atomic beam intensity by ≳5×.

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Research paper thumbnail of Annual effective dose of ionizing radiation from natural sources received by airline aircrew members compared with that received by non-flying residents of the United States

In evaluating health aspects of the ionizing radiation exposure of aircrews, risk estimates are n... more In evaluating health aspects of the ionizing radiation exposure of aircrews, risk estimates are normally based on the amount of cosmic radiation received in flight. Not considered is that aircrews spend most of their time on the ground. In this report, annual total effective doses of ionizing radiation from natural sources received by aircrews on and off the job, flying between Los Angeles and Tokyo or Chicago and London, are compared with doses to non-flying residents of the United States and non-flying residents of Environmental Protection Agency Region 8 (Montana, North Dakota, South Dakota, Wyoming, Utah, Colorado --- the region in the United States with the highest dose rates of natural ionizing radiation at ground level). Occupational exposure of aircrews to ionizing radiation is thought to increase their risk of fatal cancer. It may not be a significant concern if one considers: (a) the annual dose of ionizing radiation to the crewmembers in our study is only 7-41% higher than that received by non-flying residents of Region 8 (terrestrial gamma and cosmic radiation in the Denver, Colorado, area of Region 8); (b) the dose to non-flying residents of Region 8 is 87% higher than the average dose to non-flying residents of the United States; and (c) the estimated death rate from cancer in the six states in Region 8 is 3-26% lower than the average for the United States. When considering health concerns of aircrew members, one should recognize that the standard risk coefficient for radiation-induced fatal cancer is derived primarily from studies on individuals exposed to radiation at higher doses and dose rates and of generally lower energy, than the galactic cosmic radiation to which aircrews are exposed. These differences are a major reason that epidemiology studies are important in evaluating health aspects of the occupational radiation exposure of aircrews.

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Research paper thumbnail of Galactic Cosmic Radiation Exposure of Pregnant Aircrew Members II

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Research paper thumbnail of Solar Radiation Alert System

The Solar Radiation Alert (SRA) system continuously evaluates measurements of high-energy protons... more The Solar Radiation Alert (SRA) system continuously evaluates measurements of high-energy protons made by instruments on GOES satellites. If the measurements indicate a substantial elevation of effective dose rates at aircraft flight altitudes, the Civil Aerospace Medical Institute issues an SRA via the National Oceanic and Atmospheric Administration Weather Wire Service. This report describes a revised SRA system. SRA issue-criteria remain the same but significant improvements have been made in the calculations. The solar proton fluence to effective dose conversion coefficients have been recalculated using 2007 recommendations of the International Commission on Radiological Protection and the latest release of the Monte Carlo transport code, MCNPX 2.6.0. The shape of the <10 MeV secondary neutron spectrum is now accounted for down to 100 eV. The flux correction based on spectral index has been revised to smooth the flux spectrum of solar protons. Estimates of the >605 MeV spe...

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Research paper thumbnail of The Radiation Dose at Commercial Aircraft Altitudes During the January 2005 High-Energy Solar Cosmic ray Event and the Effects of the Solar Cosmic ray Anisotropy

The radiation dose to aircrews and passengers is a phenomenon of societal interest. There is a re... more The radiation dose to aircrews and passengers is a phenomenon of societal interest. There is a requirement to provide alerts whenever the radiation dose exceeds 20 micro-sieverts per hour at flight altitudes. The possibility that this might occur during a large high-energy solar cosmic ray event has resulted in much speculation. During the 20 January 2005 ground-level event the FAA Solar Radiation Alert System would have issued such an alert for aircraft at high latitudes for flight altitudes above 40,000 feet. Analysis of the GOES high-energy proton data results in a predicted dose rate of 23 micro Sv per hour at 60,000 feet for the first hour of the event. We also predict that the maximum peak dose rate would have been higher at the geographical position corresponding to the peak anisotropic flux intensity and would be correspondingly lower at geographical positions receiving a lower high energy solar cosmic ray flux. The solar high-energy flux anisotropy is extremely variable amo...

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Research paper thumbnail of Ionizing Radiation in Earth's Atmosphere and in Space Near Earth

The Civil Aerospace Medical Institute of the FAA is charged with identifying health hazards in ai... more The Civil Aerospace Medical Institute of the FAA is charged with identifying health hazards in air travel and in commercial human space travel. This report addresses one of these hazards - ionizing radiation. Ionizing radiation is a subatomic particle of matter or packet of energy (photon) with sufficient energy to eject an orbital electron from an atom. Charged subatomic particles from exploding stars (supernovae) are a constant source of ionizing radiation in the atmosphere and in space. In space another constant source of ionizing radiation is the solar wind from the Sun. The solar wind consists mostly of electrons and protons with energies between 10 and 100 keV. The Sun undergoes an approximately 11-year cycle of rise and decline in activity and during its active phase there is an increased emission of the solar wind and occasional eruptions of high-energy particles (coronal mass ejections). Other sources of ionizing radiation during air travel include radioactive cargo, radioa...

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Research paper thumbnail of Radiation exposure of aircrews

Occupational medicine (Philadelphia, Pa.)

Information is provided about the radiation to which aircrews are exposed and possible health con... more Information is provided about the radiation to which aircrews are exposed and possible health consequences. Recommended radiation exposure limits are given. Crewmembers on commercial aircraft are exposed to higher doses of ionizing radiation than normally received by members of the general population in most parts of the world. The principal ionizing radiation is galactic cosmic radiation. On infrequent occasions, radiation from the sun leads to an increase in the ionizing radiation at aircraft flight altitudes. Radioactive cargo is another possible source of exposure to ionizing radiation. Crewmembers are exposed to nonionizing radiation in the form of electric and magnetic fields generated by the aircraft s electronic and electrical systems. Other potential sources of nonionizing radiation exposure are microwave radiation from the aircraft's weather radar, laser radiation, and ultraviolet radiation.

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Research paper thumbnail of Galactic cosmic radiation exposure of pregnant flight crewmembers

Aviation, space, and environmental medicine, 2000

In recommending the occupational dose limit of ionizing radiation for pregnant women, the Interna... more In recommending the occupational dose limit of ionizing radiation for pregnant women, the International Commission on Radiological Protection apparently assumes that the dose to the conceptus from ionizing radiation exposure is about half the dose at the surface of the mother's abdomen. To test this assumption with respect to galactic cosmic radiation, calculations were made using FAA computer program CARI-LF2, which calculates equivalent doses from galactic cosmic rays at selected depths in soft tissue at any specified location in the atmosphere or on user-entered flight profiles. The calculations showed that the equivalent dose of galactic radiation was almost the same at all depths. Thus the assumption of considerable shielding of the conceptus being provided by the woman's body is not correct with respect to galactic cosmic radiation, the principal type of radiation to which aircrews are exposed. The effective dose as calculated with FAA computer program CARI-5E, which c...

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Research paper thumbnail of Health aspects of radiation exposure on a simulated mission to Mars

A major consideration in planning a manned mission in space is exposure of the space travelers to... more A major consideration in planning a manned mission in space is exposure of the space travelers to ionizing radiation. Mission planners want to minimize long-term health effects and prevent acute health effects that could jeopardize a mission. At the radiation doses likely to be received during space travel, the major health concern is fatal cancer—the latency period is in years. However, space travelers who are inadequately shielded from radiation during a large solar-proton event may receive a dose sufficient to cause serious health effects within hours or up to a couple of months after the event. The amount of radiation received by the space travelers on the simulated mission to Mars translates into risks of radiation-induced fatal cancer that, for all but men of ages 55–64, exceed the 3% career limit currently recommended by the National Council on Radiation Protection and Measurements for space crews on low-Earth orbit missions.

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Research paper thumbnail of Atmospheric Ionizing Radiation and Human Exposure

Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures,... more Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures, because it is a principal source of human exposure to radiations with high linear energy transfer (LET). The ionizing radiations of the lower atmosphere tend to be dominated by the terrestrial radioisotopes especially along the costal plain and interior low lands and have only minor contributions

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Research paper thumbnail of Tritons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

Radiation Protection Dosimetry, 2010

Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose,... more Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to tritons ((3)H(+)) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Coefficients were calculated using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and calculation of gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 3%. The greatest difference, 43%, occurred at 30 MeV.

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Research paper thumbnail of Fluence to absorbed dose, effective dose and gray equivalent conversion coefficients for iron nuclei from 10 MeV to 1 TeV, calculated using Monte Carlo radiation transport code MCNPX 2.7.A

Radiation Protection Dosimetry, 2010

Conversion coefficients have been calculated for fluence-to-absorbed dose, fluence-to-effective d... more Conversion coefficients have been calculated for fluence-to-absorbed dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult male and an adult female to (56)Fe(26+) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Calculations using ICRP 2007 recommendations result in fluence-to-effective dose conversion coefficients that are almost identical at most energies to those calculated using ICRP 1990 recommendations.

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Research paper thumbnail of Alpha particles at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, effective dose, and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.A

Radiation Protection Dosimetry, 2010

Conversion coefficients have been calculated for fluence to absorbed dose, fluence to effective d... more Conversion coefficients have been calculated for fluence to absorbed dose, fluence to effective dose and fluence to gray equivalent, for isotropic exposure to alpha particles in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for effective dose are within 30 % of those calculated using ICRP 1990 recommendations.

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Research paper thumbnail of Comparison of fluence-to-dose conversion coefficients for deuterons, tritons and helions

Radiation Protection Dosimetry, 2012

Secondary radiation in aircraft and spacecraft includes deuterons, tritons and helions. Two sets ... more Secondary radiation in aircraft and spacecraft includes deuterons, tritons and helions. Two sets of fluence-to-effective dose conversion coefficients for isotropic exposure to these particles were compared: one used the particle and heavy ion transport code system (PHITS) radiation transport code coupled with the International Commission on Radiological Protection (ICRP) reference phantoms (PHITS-ICRP) and the other the Monte Carlo N-Particle eXtended (MCNPX) radiation transport code coupled with modified BodyBuilder™ phantoms (MCNPX-BB). Also, two sets of fluence-to-effective dose equivalent conversion coefficients calculated using the PHITS-ICRP combination were compared: one used quality factors based on linear energy transfer; the other used quality factors based on lineal energy (y). Finally, PHITS-ICRP effective dose coefficients were compared with PHITS-ICRP effective dose equivalent coefficients. The PHITS-ICRP and MCNPX-BB effective dose coefficients were similar, except at high energies, where MCNPX-BB coefficients were higher. For helions, at most energies effective dose coefficients were much greater than effective dose equivalent coefficients. For deuterons and tritons, coefficients were similar when their radiation weighting factor was set to 2.

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Research paper thumbnail of Guidelines and Technical Information Provided by the US Federal Aviation Administration to Promote Radiation Safety for Air Carrier Crew Members

Radiation Protection Dosimetry, 1999

... GUIDELINES AND TECHNICAL INFORMATION PROVIDED BY THE US FEDERAL AVIATION ADMINISTRATION TO ..... more ... GUIDELINES AND TECHNICAL INFORMATION PROVIDED BY THE US FEDERAL AVIATION ADMINISTRATION TO ... association of long-term exposure to galactic radiation and health effects in ... compo-sition of the galactic radiation varied appreciably with changes in altitude ...

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