D . F . Smart

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Galactic cosmic rays, which are thought to be produced and accelerated by a variety of mechanisms in the Milky Way galaxy, interact with the solar wind, the earth's magnetic field, and its atmosphere to produce hadron, lepton, and photon fields at aircraft altitudes that are quite unlike anything produced in the laboratory. The energy spectra of these(More)
The sun has produced several high energy and large fluence solar proton events during solar cycle 22. This recent activity is similar to activity that occurred in the 19th solar cycle before the advent of routine space measurements. In a review of the recent events and a comparison with significant solar proton events of previous solar cycles, it appears(More)
Solar cycle 22 had significant, large fluence, energetic particle events on a scale reminiscent of the 19th solar cycle. Examination of the characteristics of these large events suggests that some of the old concepts of spectral form, intensity-time envelope and energy extrapolations, used to estimate the dose from large events that occurred during previous(More)
Geomagnetic cutoff rigidities are a quantitative measure of the shielding provided by the earth s magnetic field. More precisely, geomagnetic cutoff rigidities predict the energetic charged particle transmission through the magnetosphere to a specific location as a function of direction. The generally accepted manner for determining cutoff rigidities is by(More)
The calculation of particle trajectories in the Earth’s magnetic field has been a subject of interest since the time of Störmer. The fundamental problem is that the trajectory-tracing process involves using mathematical equations that have ‘no solution in closed form’. This difficulty has forced researchers to use the ‘brute force’ technique of numerical(More)
Estimates of the energetic proton environment for a Mars mission are generally extrapolated from the solar proton observations at 1 AU. We find that solar particle events may be divided into two general classes. Events dominated by a near-sun injection of particles onto interplanetary magnetic field lines leading to the spacecraft position represent the(More)
Solar particle events can give greatly enhanced radiation at aircraft altitudes, but are both difficult to predict and to calculate retrospectively. This enhanced radiation can give significant dose to aircrew and greatly increase the rate of single event effects in avionics. Validation of calculations is required but only very few events have been measured(More)
A greatly improved version of the computer program to calculate radiation dosage to air crew members is now available. Designated CARI-6, this program incorporates an updated geomagnetic cutoff rigidity model and a revision of the primary cosmic ray spectrum based on recent work by Gaisser and Stanev (1998). We believe CARI-6 provides the most accurate(More)
A case of metastatic melanoma of the stomach is reported with illustrative endoscopic and radiographic findings. Metastatic melanoma of the stomach may present with vague gastrointestinal symptoms, abdominal pain, or gastrointestinal bleeding. A history of melanoma may not be readily obtainable. When gastrointestinal symptoms occur in a patient with known(More)
The present study examines the effects of orbit progression on the exposures within a Space Station Freedom module in a 51.6-degree inclined orbit at 450 km. The storm evolution is modeled after the November 1960 event, and the solar proton flux evolution is taken from the August 1972 solar proton event. The effects of a strong magnetic shock, such as was(More)